2.3.0-rc.0

* Error handling in ERC20 and ERC721

* Added message string for require.

* Fixed solhint errors.

* Updated PR as per issue #1709

* changes as per #1709 and openzeppelin forum.

* Changes in require statement

* Changes in require statement

* build pipeline fix

* Changes as per @nventuro's comment.

* Update revert reason strings.

* Fianal update of revert reason strings.

* WIP: Updating reason strings in test cases

* WIP: Added changes to ERC20 and ERC721

* Fixes linting errors in *.tes.js files

* Achieved 100% code coverage

* Updated the test cases with shouldFail.reverting.withMessage()

* Fix package-lock.

* address review comments

* fix linter issues

* fix remaining revert reasons

.babelrc

@@ -1,3 +0,0 @@
-{
-  "presets": ["es2015", "stage-2", "stage-3"]
-}

.editorconfig

@@ -0,0 +1,12 @@
+# EditorConfig is awesome: https://EditorConfig.org
+
+# top-most EditorConfig file
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+indent_size = 2
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true

.env.example

@@ -1,5 +0,0 @@
-# configure your infura api key (not technically required)
-INFURA_API_KEY=
-
-# change the mnemonic that your hd wallet is seeded with
-MNEMONIC=

.eslintrc

@@ -1,51 +1,58 @@
 {
   "extends" : [
     "standard",
-    "plugin:promise/recommended"
+    "plugin:promise/recommended",
   ],
   "plugins": [
-    "promise"
+    "mocha-no-only",
+    "promise",
   ],
   "env": {
     "browser" : true,
     "node"    : true,
     "mocha"   : true,
-    "jest"    : true
+    "jest"    : true,
   },
   "globals" : {
     "artifacts": false,
     "contract": false,
     "assert": false,
-    "web3": false
+    "web3": false,
   },
   "rules": {
 
     // Strict mode
-    "strict": [2, "global"],
+    "strict": ["error", "global"],
 
     // Code style
-    "indent": [2, 2],
-    "quotes": [2, "single"],
+    "camelcase": ["error", {"properties": "always"}],
+    "comma-dangle": ["error", "always-multiline"],
+    "comma-spacing": ["error", {"before": false, "after": true}],
+    "dot-notation": ["error", {"allowKeywords": true, "allowPattern": ""}],
+    "eol-last": ["error", "always"],
+    "eqeqeq": ["error", "smart"],
+    "generator-star-spacing": ["error", "before"],
+    "indent": ["error", 2],
+    "linebreak-style": ["error", "unix"],
+    "max-len": ["error", 120, 2],
+    "no-debugger": "off",
+    "no-dupe-args": "error",
+    "no-dupe-keys": "error",
+    "no-mixed-spaces-and-tabs": ["error", "smart-tabs"],
+    "no-redeclare": ["error", {"builtinGlobals": true}],
+    "no-trailing-spaces": ["error", { "skipBlankLines": false }],
+    "no-undef": "error",
+    "no-use-before-define": "off",
+    "no-var": "error",
+    "object-curly-spacing": ["error", "always"],
+    "prefer-const": "error",
+    "quotes": ["error", "single"],
     "semi": ["error", "always"],
     "space-before-function-paren": ["error", "always"],
-    "no-use-before-define": 0,
-    "eqeqeq": [2, "smart"],
-    "dot-notation": [2, {"allowKeywords": true, "allowPattern": ""}],
-    "no-redeclare": [2, {"builtinGlobals": true}],
-    "no-trailing-spaces": [2, { "skipBlankLines": true }],
-    "eol-last": 1,
-    "comma-spacing": [2, {"before": false, "after": true}],
-    "camelcase": [2, {"properties": "always"}],
-    "no-mixed-spaces-and-tabs": [2, "smart-tabs"],
-    "comma-dangle": [1, "always-multiline"],
-    "no-dupe-args": 2,
-    "no-dupe-keys": 2,
-    "no-debugger": 0,
-    "no-undef": 2,
-    "object-curly-spacing": [2, "always"],
-    "max-len": [2, 120, 2],
-    "generator-star-spacing": ["error", "before"],
-    "promise/avoid-new": 0,
-    "promise/always-return": 0
+
+    "mocha-no-only/mocha-no-only": ["error"],
+
+    "promise/always-return": "off",
+    "promise/avoid-new": "off",
   }
 }

.github/ISSUE_TEMPLATE.md

@@ -1,34 +0,0 @@
-## 🎉 Description
-
-<!-- Briefly describe the issue you are experiencing (or the feature you want to see added to OpenZeppelin). Tell us what you were trying to do and what happened instead. **Remember, this is _not_ a place to ask for help debugging code; for that, we welcome you in the [OpenZeppelin Slack Channel](https://slack.openzeppelin.org/).** -->
-
-- [ ] 🐛 This is a bug report.
-- [ ] 📈 This is a feature request.
-
-<!-- Please check one of the above by placing an x in the box. -->
-
-## 💻 Environment
-
-Next, we need to know what your environment looks like.
-
-- Which version of OpenZeppelin are you using?
-- What network are you deploying to? Ganache? Ropsten?
-- How are you deploying your OpenZeppelin-backed contracts? truffle? Remix? Let us know!
-
-## 📝 Details
-
-Describe the problem you have been experiencing in more detail. Include as much information as you think is relevant. Keep in mind that transactions can fail for many reasons; context is key here.
-
-## 🔢 Code To Reproduce Issue [ Good To Have ]
-
-Please remember that with sample code it's easier to reproduce the bug and it's much faster to fix it.
-
-```
-insert short code snippets here
-```
-
-<!-- If your code is larger, consider linking us to a repo illustrating your issue. -->
-
-## 👍 Other Information
-
-<!-- List any other information that is relevant to your issue. Error logs, related issues, suggestions on how to fix, Stack Overflow links, forum links, etc. -->

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,21 @@
+---
+name: Bug report
+about: Report a bug in OpenZeppelin
+
+---
+
+<!-- Briefly describe the issue you're experiencing. Tell us what you were trying to do and what happened instead. -->
+
+<!-- Remember, this is not a place to ask for help debugging code. For that, we welcome you in the Zeppelin Forum: https://forum.zeppelin.solutions/. -->
+
+**💻 Environment**
+
+<!-- Tell us what version of OpenZeppelin you're using, and how you're using it: Truffle, Remix, etc. -->
+
+**📝 Details**
+
+<!-- Describe the problem you have been experiencing in more detail. Include as much information as you think is relevant. Keep in mind that transactions can fail for many reasons; context is key here. -->
+
+**🔢 Code to reproduce bug**
+
+<!-- We will be able to better help if you provide a minimal example that triggers the bug. -->

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,14 @@
+---
+name: Feature request
+about: Suggest an idea for OpenZeppelin
+
+---
+
+**🧐 Motivation**
+<!-- Is your feature request related to a specific problem? Is it just a crazy idea? Tell us about it! -->
+
+**📝 Details**
+<!-- Please describe your feature request in detail. -->
+
+<!-- Make sure that you have reviewed the OpenZeppelin Contributor Guidelines. -->
+<!-- https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md -->

.github/PULL_REQUEST_TEMPLATE.md

@@ -1,17 +1,22 @@
 <!-- 0. 🎉 Thank you for submitting a PR! -->
 
-<!-- 1. **Does this close any open issues?** If so, list them here. If not, remove the `Fixes #` line. -->
+<!-- 1. Does this close any open issues? Please list them below. -->
+
+<!-- Keep in mind that new features have a better chance of being merged fast if
+they were first discussed and designed with the maintainers. If there is no
+corresponding issue, please consider opening one for discussion first! -->
 
 Fixes #
 
-# 🚀 Description
-
-<!-- 2. Describe the changes introduced in this pull request -->
+<!-- 2. Describe the changes introduced in this pull request. -->
 <!--    Include any context necessary for understanding the PR's purpose. -->
 
-<!-- 3. Before submitting, please review the following checklist: -->
-
-- [ ] 📘 I've reviewed the [OpenZeppelin Contributor Guidelines](../blob/master/CONTRIBUTING.md)
-- [ ] ✅ I've added tests where applicable to test my new functionality.
-- [ ] 📖 I've made sure that my contracts are well-documented.
-- [ ] 🎨 I've run the JS/Solidity linters and fixed any issues (`npm run lint:all:fix`).
+<!-- 3. Before submitting, please make sure that you have:
+  - reviewed the OpenZeppelin Contributor Guidelines
+    (https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md),
+  - added tests where applicable to test new functionality,
+  - made sure that your contracts are well-documented,
+  - run the Solidity linter (`npm run lint:sol`) and fixed any issues,
+  - run the JS linter and fixed any issues (`npm run lint:fix`), and
+  - updated the changelog, if applicable.
+-->

.github/stale.yml

@@ -0,0 +1,66 @@
+# Configuration for probot-stale - https://github.com/probot/stale
+
+# Number of days of inactivity before an Issue or Pull Request becomes stale
+daysUntilStale: 15
+
+# Number of days of inactivity before an Issue or Pull Request with the stale label is closed.
+# Set to false to disable. If disabled, issues still need to be closed manually, but will remain marked as stale.
+daysUntilClose: 15
+
+# Issues or Pull Requests with these labels will never be considered stale. Set to `[]` to disable
+exemptLabels:
+  - on hold
+
+# Set to true to ignore issues in a project (defaults to false)
+exemptProjects: false
+
+# Set to true to ignore issues in a milestone (defaults to false)
+exemptMilestones: false
+
+# Set to true to ignore issues with an assignee (defaults to false)
+exemptAssignees: false
+
+# Label to use when marking as stale
+staleLabel: stale
+
+# Comment to post when marking as stale. Set to `false` to disable
+markComment: >
+  Hi all!
+
+  This Pull Request has not had any recent activity, is it still relevant? If so, what is blocking it?
+  Is there anything we can do to help move it forward?
+
+  Thanks!
+
+
+# Comment to post when removing the stale label.
+# unmarkComment: >
+#   Your comment here.
+
+# Comment to post when closing a stale Issue or Pull Request.
+closeComment: >
+  Hi folks!
+
+  This Pull Request is being closed as there was no response to the previous prompt.
+  However, please leave a comment whenever you're ready to resume, so it can be reopened.
+
+  Thanks again!
+
+
+# Limit the number of actions per hour, from 1-30. Default is 30
+limitPerRun: 30
+
+# Limit to only `issues` or `pulls`
+only: pulls
+
+# Optionally, specify configuration settings that are specific to just 'issues' or 'pulls':
+# pulls:
+#   daysUntilStale: 30
+#   markComment: >
+#     This pull request has been automatically marked as stale because it has not had
+#     recent activity. It will be closed if no further activity occurs. Thank you
+#     for your contributions.
+
+# issues:
+#   exemptLabels:
+#     - confirmed

.gitignore

@@ -32,8 +32,15 @@ npm-debug.log
 # truffle build directory
 build/
 
-# lol macs
-.DS_Store/
+# macOS
+.DS_Store
 
 # truffle
 .node-xmlhttprequest-*
+
+# IntelliJ IDE
+.idea
+
+# docsite artifacts
+docsite-build
+docs/api

.jshintrc

@@ -1,48 +0,0 @@
-{
-    "bitwise": false,     // Prohibit bitwise operators (&, |, ^, etc.).
-    "browser": true,      // Standard browser globals e.g. `window`, `document`.
-    "camelcase": false,   // Permit only camelcase for `var` and `object indexes`.
-    "curly": true,        // Require {} for every new block or scope.
-    "devel": false,       // Allow development statements e.g. `console.log();`.
-    "eqeqeq": true,       // Require triple equals i.e. `===`.
-    "esnext": true,       // Allow ES.next specific features such as `const` and `let`.
-    "freeze": true,       // Forbid overwriting prototypes of native objects such as Array, Date and so on.
-    "immed": true,        // Require immediate invocations to be wrapped in parens e.g. `( function(){}() );`
-    "indent": 2,          // Specify indentation spacing
-    "latedef": true,      // Prohibit variable use before definition.
-    "newcap": false,      // Require capitalization of all constructor functions e.g. `new F()`.
-    "noarg": true,        // Prohibit use of `arguments.caller` and `arguments.callee`.
-    "node": true,         // Enable globals available when code is running inside of the NodeJS runtime environment.
-    "noempty": true,      // Prohibit use of empty blocks.
-    "nonew": true,        // Prohibits the use of constructor functions for side-effects
-    "quotmark": "single", // Define quotes to string values.
-    "regexp": true,       // Prohibit `.` and `[^...]` in regular expressions.
-    "smarttabs": false,   // Supress warnings about mixed tabs and spaces
-    "strict": true,       // Require `use strict` pragma in every file.
-    "trailing": true,     // Prohibit trailing whitespaces.
-    "undef": true,        // Require all non-global variables be declared before they are used.
-    "unused": true,       // Warn unused variables.
-
-    "maxparams": 4,       // Maximum number of parameters for a function
-    "maxstatements": 15,  // Maximum number of statements in a function
-    "maxcomplexity": 10,  // Cyclomatic complexity (http://en.wikipedia.org/wiki/Cyclomatic_complexity)
-    "maxdepth": 4,        // Maximum depth of nested control structures
-    "maxlen": 120,        // Maximum number of cols in a line
-    "multistr": true,     // Allow use of multiline EOL escaping
-    "experimental": ["asyncawait", "asyncreqawait"],
-
-    "predef": [ // Extra globals.
-        "after",
-        "afterEach",
-        "before",
-        "beforeEach",
-        "define",
-        "describe",
-        "exports",
-        "it",
-        "web3",
-        "artifacts",
-        "contract",
-        "assert"
-    ]
-}

.node-version

@@ -1 +0,0 @@
-v8.9.1

.solhint.json

@@ -0,0 +1,11 @@
+{
+  "extends": "default",
+  "rules": {
+    "indent": ["error", 4],
+
+    "bracket-align": false,
+    "compiler-fixed": false,
+    "no-simple-event-func-name": false,
+    "two-lines-top-level-separator": false
+  }
+}

.soliumignore

@@ -1 +0,0 @@
-node_modules

.soliumrc.json

@@ -1,14 +0,0 @@
-{
-  "extends": "solium:all",
-  "plugins": ["security"],
-  "rules": {
-    "quotes": ["error", "double"],
-    "no-empty-blocks": "off",
-    "indentation": ["error", 2],
-    "max-len": ["warning", 79],
-    "no-constant": ["error"],
-    "security/enforce-explicit-visibility": ["error"],
-    "security/no-block-members": ["warning"],
-    "security/no-inline-assembly": ["warning"]
-  }
-}

.travis.yml

@@ -1,27 +1,40 @@
 dist: trusty
-sudo: required
+sudo: false
 group: beta
 language: node_js
 node_js:
   - "8"
+
 cache:
   directories:
     - node_modules
-env:
-  -
-  - SOLIDITY_COVERAGE=true
-  - SOLC_NIGHTLY=true
-matrix:
+
+jobs:
+  # XXX fast_finish doesn't work with stages yet. See
+  # https://github.com/travis-ci/travis-ci/issues/8425
+  # --elopio - 20180531
   fast_finish: true
   allow_failures:
-    - env: SOLIDITY_COVERAGE=true
     - env: SOLC_NIGHTLY=true
-before_script:
-  - truffle version
-script:
-  - npm run lint
-  - npm run lint:sol
-  - npm run test
+  include:
+    - stage: tests
+      name: "Linter"
+      script: npm run lint
+
+    - stage: tests
+      name: "Unit tests"
+      script: npm run test
+
+    - stage: tests
+      name: "Unit tests with coverage report"
+      script: npm run test
+      env: SOLIDITY_COVERAGE=true
+
+    - stage: tests
+      name: "Unit tests using solc nightly"
+      script: npm run test
+      env: SOLC_NIGHTLY=true
+
 notifications:
   slack:
     rooms:

CHANGELOG.md

@@ -0,0 +1,73 @@
+# Changelog
+
+## 2.3.0 (unreleased)
+
+### New features:
+ * `ERC1820`: added support for interacting with the [ERC1820](https://eips.ethereum.org/EIPS/eip-1820) registry contract (`IERC1820Registry`), as well as base contracts that can be registered as implementers there. ([#1677](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1677))
+ * `ERC777`: initial support for the [ERC777 token](https://eips.ethereum.org/EIPS/eip-777), which has multiple improvements over `ERC20` such as built-in burning, a more  straightforward permission system, and optional sender and receiver hooks on transfer (mandatory for contracts!). ([#1684](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1684))
+ * All contracts now have revert reason strings, which give insight into error conditions, and help debug failing transactions. ([#1704](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1704))
+
+### Improvements:
+ * Upgraded the minimum compiler version to v0.5.7: this prevents users from encountering compiler bugs that were fixed in this version. ([#1724](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1724))
+
+### Bugfixes:
+ * `PostDeliveryCrowdsale`: some validations where skipped when paired with other crowdsale flavors, such as `AllowanceCrowdsale`, or `MintableCrowdsale` and `ERC20Capped`, which could cause buyers to not be able to claim their purchased tokens. ([#1721](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1721))
+
+## 2.2.0 (2019-03-14)
+
+### New features:
+ * `ERC20Snapshot`: create snapshots on demand of the token balances and total supply, to later retrieve and e.g. calculate dividends at a past time. ([#1617](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1617))
+ * `SafeERC20`: `ERC20` contracts with no return value (i.e. that revert on failure) are now supported. ([#1655](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1655))
+ * `ERC20`: added internal `_approve(address owner, address spender, uint256 value)`, allowing derived contracts to set the allowance of arbitrary accounts. ([#1609](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1609))
+ * `ERC20Metadata`: added internal `_setTokenURI(string memory tokenURI)`. ([#1618](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1618))
+ * `TimedCrowdsale`: added internal `_extendTime(uint256 newClosingTime)` as well as `TimedCrowdsaleExtended(uint256 prevClosingTime, uint256 newClosingTime)` event allowing to extend the crowdsale, as long as it hasn't already closed.
+
+### Improvements:
+ * Upgraded the minimum compiler version to v0.5.2: this removes many Solidity warnings that were false positives. ([#1606](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1606))
+ * `ECDSA`: `recover` no longer accepts malleable signatures (those using upper-range values for `s`, or 0/1 for `v`). ([#1622](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1622))
+ * `ERC721`'s transfers are now more gas efficient due to removal of unnecessary `SafeMath` calls. ([#1610](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1610))
+ * Fixed variable shadowing issues. ([#1606](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1606))
+
+### Bugfixes:
+ * (minor) `SafeERC20`: `safeApprove` wasn't properly checking for a zero allowance when attempting to set a non-zero allowance. ([#1647](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1647))
+
+### Breaking changes in drafts:
+ * `TokenMetadata` has been renamed to `ERC20Metadata`. ([#1618](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1618))
+ * The library `Counter` has been renamed to `Counters` and its API has been improved. See an example in `ERC721`, lines [17](https://github.com/OpenZeppelin/openzeppelin-solidity/blob/3cb4a00fce1da76196ac0ac3a0ae9702b99642b5/contracts/token/ERC721/ERC721.sol#L17) and [204](https://github.com/OpenZeppelin/openzeppelin-solidity/blob/3cb4a00fce1da76196ac0ac3a0ae9702b99642b5/contracts/token/ERC721/ERC721.sol#L204). ([#1610](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1610))
+
+## 2.1.3 (2019-02-26)
+ * Backported `SafeERC20.safeApprove` bugfix. ([#1647](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1647))
+
+## 2.1.2 (2019-01-17)
+ * Removed most of the test suite from the npm package, except `PublicRole.behavior.js`, which may be useful to users testing their own `Roles`.
+
+## 2.1.1 (2019-01-04)
+ * Version bump to avoid conflict in the npm registry.
+
+## 2.1.0 (2019-01-04)
+
+### New features:
+ * Now targeting the 0.5.x line of Solidity compilers. For 0.4.24 support, use version 2.0 of OpenZeppelin.
+ * `WhitelistCrowdsale`: a crowdsale where only whitelisted accounts (`WhitelistedRole`) can purchase tokens. Adding or removing accounts from the whitelist is done by whitelist admins (`WhitelistAdminRole`). Similar to the pre-2.0 `WhitelistedCrowdsale`. ([#1525](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1525), [#1589](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1589))
+ * `RefundablePostDeliveryCrowdsale`: replacement for `RefundableCrowdsale` (deprecated, see below) where tokens are only granted once the crowdsale ends (if it meets its goal). ([#1543](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1543))
+ * `PausableCrowdsale`: allows for pausers (`PauserRole`) to pause token purchases. Other crowdsale operations (e.g. withdrawals and refunds, if applicable) are not affected. ([#832](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/832))
+ * `ERC20`: `transferFrom` and `_burnFrom ` now emit `Approval` events, to represent the token's state comprehensively through events. ([#1524](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1524))
+ * `ERC721`: added `_burn(uint256 tokenId)`, replacing the similar deprecated function (see below). ([#1550](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1550))
+ * `ERC721`: added `_tokensOfOwner(address owner)`, allowing to internally retrieve the array of an account's owned tokens. ([#1522](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1522))
+ * Crowdsales: all constructors are now `public`, meaning it is not necessary to extend these contracts in order to deploy them. The exception is `FinalizableCrowdsale`, since it is meaningless unless extended. ([#1564](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1564))
+ * `SignedSafeMath`: added overflow-safe operations for signed integers (`int256`). ([#1559](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1559), [#1588](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1588))
+
+### Improvements:
+ * The compiler version required by `Array` was behind the rest of the libray so it was updated to `v0.4.24`. ([#1553](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1553))
+ * Now conforming to a 4-space indentation code style. ([1508](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1508))
+ * `ERC20`: more gas efficient due to removed redundant `require`s. ([#1409](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1409))
+ * `ERC721`: fixed a bug that prevented internal data structures from being properly cleaned, missing potential gas refunds. ([#1539](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1539) and [#1549](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1549))
+ * `ERC721`: general gas savings on `transferFrom`, `_mint` and `_burn`, due to redudant `require`s and `SSTORE`s. ([#1549](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1549))
+
+### Bugfixes:
+
+### Breaking changes:
+
+### Deprecations:
+ * `ERC721._burn(address owner, uint256 tokenId)`: due to the `owner` parameter being unnecessary. ([#1550](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1550))
+ * `RefundableCrowdsale`: due to trading abuse potential on crowdsales that miss their goal. ([#1543](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1543))

CODE_OF_CONDUCT.md

@@ -0,0 +1,73 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and maintainers pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, sex characteristics, gender identity and expression,
+level of experience, education, socio-economic status, nationality, personal
+appearance, race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and unwelcome sexual attention or
+  advances
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Our Responsibilities
+
+Project maintainers are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project maintainers have the right and responsibility to remove, edit, or
+reject comments, commits, code, wiki edits, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any contributor for other behaviors that they deem inappropriate,
+threatening, offensive, or harmful.
+
+## Scope
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. Examples of
+representing a project or community include using an official project e-mail
+address, posting via an official social media account, or acting as an appointed
+representative at an online or offline event. Representation of a project may be
+further defined and clarified by project maintainers.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by contacting the project team at maintainers@openzeppelin.org. All
+complaints will be reviewed and investigated and will result in a response that
+is deemed necessary and appropriate to the circumstances. The project team is
+obligated to maintain confidentiality with regard to the reporter of an incident.
+Further details of specific enforcement policies may be posted separately.
+
+Project maintainers who do not follow or enforce the Code of Conduct in good
+faith may face temporary or permanent repercussions as determined by other
+members of the project's leadership.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage], version 1.4,
+available at https://www.contributor-covenant.org/version/1/4/code-of-conduct.html
+
+[homepage]: https://www.contributor-covenant.org

CODE_STYLE.md

@@ -0,0 +1,63 @@
+# Code Style
+
+We value clean code and consistency, and those are prerequisites for us to
+include new code in the repository. Before proposing a change, please read this
+document and take some time to familiarize yourself with the style of the
+existing codebase.
+
+## Solidity code
+
+In order to be consistent with all the other Solidity projects, we follow the
+[official recommendations documented in the Solidity style guide](http://solidity.readthedocs.io/en/latest/style-guide.html).
+
+Any exception or additions specific to our project are documented below.
+
+### Naming
+
+* Try to avoid acronyms and abbreviations.
+
+* All state variables should be private.
+
+* Private state variables should have an underscore prefix.
+
+    ```
+    contract TestContract {
+      uint256 private _privateVar;
+      uint256 internal _internalVar;
+    }
+    ```
+
+* Parameters must not be prefixed with an underscore.
+
+    ```
+    function test(uint256 testParameter1, uint256 testParameter2) {
+    ...
+    }
+    ```
+
+* Internal and private functions should have an underscore prefix.
+
+    ```
+    function _testInternal() internal {
+      ...
+    }
+    ```
+
+    ```
+    function _testPrivate() private {
+      ...
+    }
+    ```
+
+* Events should be emitted immediately after the state change that they
+  represent, and consequently they should be named in past tense.
+
+    ```
+    function _burn(address _who, uint256 _value) internal {
+      super._burn(_who, _value);
+      emit TokensBurned(_who, _value);
+    }
+    ```
+
+  Some standards (e.g. ERC20) use present tense, and in those cases the
+  standard specification prevails.

DOCUMENTATION.md

@@ -0,0 +1,19 @@
+We're building an improved documentation website. It's still in development and
+contributions will be really appreciated.
+
+All of the content for the site is in this repository. The guides are in the
+[docs](/docs) directory, and the API Reference is extracted from comments in
+the source code. If you want to help improve the content, this is the
+repository you should be contributing to.
+
+[`solidity-docgen`](https://github.com/OpenZeppelin/solidity-docgen/tree/next) is the
+program that extracts the API Reference from source code.
+
+The [`openzeppelin-docsite`](https://github.com/OpenZeppelin/openzeppelin-docsite/tree/next)
+repository hosts the configuration for Docusaurus, the static site generator
+that we use.
+
+To run the docsite locally you should run `npm run docsite start` on this
+repository. This will live reload as the guides are edited, but not with
+changes to the source code comments, for that you need to restart the server.
+This should be improved eventually (contributions welcome!).

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2016 Smart Contract Solutions, Inc.
+Copyright (c) 2016-2019 zOS Global Limited
 
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the

README.md

@@ -1,90 +1,63 @@
-# OpenZeppelin Solidity
+# <img src="logo.png" alt="OpenZeppelin" width="400px">
+
 [![NPM Package](https://img.shields.io/npm/v/openzeppelin-solidity.svg?style=flat-square)](https://www.npmjs.org/package/openzeppelin-solidity)
-[![Build Status](https://img.shields.io/travis/OpenZeppelin/openzeppelin-solidity.svg?branch=master&style=flat-square)](https://travis-ci.org/OpenZeppelin/openzeppelin-solidity)
-[![Coverage Status](https://img.shields.io/coveralls/github/OpenZeppelin/openzeppelin-solidity/master.svg?style=flat-square)](https://coveralls.io/github/OpenZeppelin/openzeppelin-solidity?branch=master)
+[![Build Status](https://travis-ci.com/OpenZeppelin/openzeppelin-solidity.svg?branch=master)](https://travis-ci.com/OpenZeppelin/openzeppelin-solidity)
+[![Coverage Status](https://coveralls.io/repos/github/OpenZeppelin/openzeppelin-solidity/badge.svg?branch=master)](https://coveralls.io/github/OpenZeppelin/openzeppelin-solidity?branch=master)
 
-OpenZeppelin is a library for writing secure [Smart Contracts](https://en.wikipedia.org/wiki/Smart_contract) on Ethereum.
+**OpenZeppelin is a library for secure smart contract development.** It provides implementations of standards like ERC20 and ERC721 which you can deploy as-is or extend to suit your needs, as well as Solidity components to build custom contracts and more complex decentralized systems.
 
-With OpenZeppelin, you can build distributed applications, protocols and organizations:
-- using common contract security patterns (See [Onward with Ethereum Smart Contract Security](https://medium.com/bitcorps-blog/onward-with-ethereum-smart-contract-security-97a827e47702#.y3kvdetbz))
-- in the [Solidity language](https://solidity.readthedocs.io/en/develop/).
+## Install
 
-> NOTE: New to smart contract development? Check our [introductory guide](https://medium.com/zeppelin-blog/the-hitchhikers-guide-to-smart-contracts-in-ethereum-848f08001f05#.cox40d2ut).
-
-## Getting Started
-
-OpenZeppelin integrates with [Truffle](https://github.com/ConsenSys/truffle) and [Embark](https://github.com/embark-framework/embark/).
-
-## Truffle
-
-To use with Truffle, first install it and initialize your project with `truffle init`.
-
-```sh
-npm install -g truffle
-mkdir myproject && cd myproject
-truffle init
+```
+npm install openzeppelin-solidity
 ```
 
-## Embark
+OpenZeppelin features a stable API, which means your contracts won't break unexpectedly when upgrading to a newer minor version. You can read ṫhe details in our [API Stability](https://forum.zeppelin.solutions/t/api-stability/138) document.
 
-To use with Embark, first install it and initialize your project with `embark new MyApp`.
+## Usage
 
-```sh
-npm install -g embark
-embark new MyApp
-cd MyApp
-```
-
-## Installing OpenZeppelin
-
-After installing either Framework, to install the OpenZeppelin library, run the following in your Solidity project root directory:
-
-```sh
-npm init -y
-npm install -E openzeppelin-solidity
-```
-
-**Note that OpenZeppelin does not currently follow semantic versioning.** You may encounter breaking changes upon a minor version bump. We recommend pinning the version of OpenZeppelin you use, as done by the `-E` (`--save-exact`) option.
-
-After that, you'll get all the library's contracts in the `node_modules/openzeppelin-solidity/contracts` folder. You can use the contracts in the library like so:
+To write your custom contracts, import ours and extend them through inheritance.
 
 ```solidity
-import 'openzeppelin-solidity/contracts/ownership/Ownable.sol';
+pragma solidity ^0.5.0;
 
-contract MyContract is Ownable {
-  ...
+import 'openzeppelin-solidity/contracts/token/ERC721/ERC721Full.sol';
+import 'openzeppelin-solidity/contracts/token/ERC721/ERC721Mintable.sol';
+
+contract MyNFT is ERC721Full, ERC721Mintable {
+  constructor() ERC721Full("MyNFT", "MNFT") public {
+  }
 }
 ```
 
-If you are using Embark, you can also import directly from github:
+> You need an ethereum development framework for the above import statements to work! Check out these guides for [Truffle], [Embark] or [Buidler].
 
-```solidity
-import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/ownership/Ownable.sol#v1.9.0";
-
-contract MyContract is Ownable {
-  ...
-}
-```
+On our site you will find a few [guides] to learn about the different parts of OpenZeppelin, as well as [documentation for the API][API docs]. Keep in mind that the API docs are work in progress, and don’t hesitate to ask questions in [our forum][forum].
 
 ## Security
-OpenZeppelin is meant to provide secure, tested and community-audited code, but please use common sense when doing anything that deals with real money! We take no responsibility for your implementation decisions and any security problem you might experience.
 
-If you find a security issue, please email [security@openzeppelin.org](mailto:security@openzeppelin.org).
+OpenZeppelin the project is maintained by [Zeppelin] the company, and developed following our high standards for code quality and security. OpenZeppelin is meant to provide tested and community-audited code, but please use common sense when doing anything that deals with real money! We take no responsibility for your implementation decisions and any security problems you might experience.
 
-## Developer Resources
+The core development principles and strategies that OpenZeppelin is based on include: security in depth, simple and modular code, clarity-driven naming conventions, comprehensive unit testing, pre-and-post-condition sanity checks, code consistency, and regular audits.
 
-Building a distributed application, protocol or organization with OpenZeppelin?
+The latest audit was done on October 2018 on version 2.0.0.
 
-- Read documentation: https://openzeppelin.org/api/docs/open-zeppelin.html
+Please report any security issues you find to security@openzeppelin.org.
 
-- Ask for help and follow progress at: https://slack.openzeppelin.org/
+## Contribute
 
-Interested in contributing to OpenZeppelin?
-
-- Framework proposal and roadmap: https://medium.com/zeppelin-blog/zeppelin-framework-proposal-and-development-roadmap-fdfa9a3a32ab#.iain47pak
-- Issue tracker: https://github.com/OpenZeppelin/openzeppelin-solidity/issues
-- Contribution guidelines: https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md
-- Wiki: https://github.com/OpenZeppelin/openzeppelin-solidity/wiki
+OpenZeppelin exists thanks to its contributors. There are many ways you can participate and help build high quality software. Check out the [contribution guide]!
 
 ## License
-Code released under the [MIT License](https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/LICENSE).
+
+OpenZeppelin is released under the [MIT License](LICENSE).
+
+
+[API docs]: https://openzeppelin.org/api/docs/token_ERC721_ERC721BasicToken.html
+[guides]: https://openzeppelin.org/api/docs/get-started.html
+[forum]: https://forum.zeppelin.solutions
+[Zeppelin]: https://zeppelin.solutions
+[contribution guide]: CONTRIBUTING.md
+[Truffle]: https://truffleframework.com/docs/truffle/quickstart
+[Embark]: https://embark.status.im/docs/quick_start.html
+[Buidler]: https://buidler.dev/guides/#getting-started

RELEASING.md

@@ -0,0 +1,99 @@
+# Releasing
+
+This document describes our release process, and contains the steps to be followed by an OpenZeppelin maintainer at the several stages of a release.
+
+We release a new version of OpenZeppelin monthly. Release cycles are tracked in the [issue milestones](https://github.com/OpenZeppelin/openzeppelin-solidity/milestones).
+
+Each release has at least one release candidate published first, intended for community review and any critical fixes that may come out of it. At the moment we leave 1 week between the first release candidate and the final release.
+
+Before starting make sure to verify the following items.
+* Your local `master` branch is in sync with your `upstream` remote (it may have another name depending on your setup).
+* Your repo is clean, particularly with no untracked files in the contracts and tests directories. Verify with `git clean -n`.
+
+
+## Creating the release branch
+
+We'll refer to a release `vX.Y.Z`.
+
+```
+git checkout master
+git checkout -b release-vX.Y.Z
+```
+
+## Creating a release candidate
+
+Once in the release branch, change the version string in `package.json`, `package-lock.json` and `ethpm.json` to `X.Y.Z-rc.R`. (This will be `X.Y.Z-rc.1` for the first release candidate.) Commit these changes and tag the commit as `vX.Y.Z-rc.R`.
+
+```
+git add package.json package-lock.json ethpm.json
+git commit -m "Release candidate vX.Y.Z-rc.R"
+git tag -a vX.Y.Z-rc.R
+git push upstream release-vX.Y.Z
+git push upstream vX.Y.Z-rc.R
+```
+
+Draft the release notes in our [GitHub releases](https://github.com/OpenZeppelin/openzeppelin-solidity/releases). Make sure to mark it as a pre-release! Try to be consistent with our previous release notes in the title and format of the text. Release candidates don't need a detailed changelog, but make sure to include a link to GitHub's compare page.
+
+Once the CI run for the new tag is green, publish on npm under the `next` tag. You should see the contracts compile automatically.
+
+```
+npm publish --tag next
+```
+
+Publish the release notes on GitHub and the forum, and ask our community manager to announce the release candidate on at least Twitter.
+
+## Creating the final release
+
+Make sure to have the latest changes from `upstream` in your local release branch.
+
+```
+git checkout release-vX.Y.Z
+git pull upstream
+```
+
+Before starting the release process, make one final commit to CHANGELOG.md, including the date of the release.
+
+Change the version string in `package.json`, `package-lock.json` and `ethpm.json` removing the "-rc.R" suffix. Commit these changes and tag the commit as `vX.Y.Z`.
+
+```
+git add package.json package-lock.json ethpm.json
+git commit -m "Release vX.Y.Z"
+git tag -a vX.Y.Z
+git push upstream release-vX.Y.Z
+git push upstream vX.Y.Z
+```
+
+Draft the release notes in GitHub releases. Try to be consistent with our previous release notes in the title and format of the text. Make sure to include a detailed changelog.
+
+Once the CI run for the new tag is green, publish on npm. You should see the contracts compile automatically.
+
+```
+npm publish
+```
+
+Publish the release notes on GitHub and ask our community manager to announce the release!
+
+Delete the `next` tag in the npm package as there is no longer a release candidate.
+
+```
+npm dist-tag rm --otp $2FA_CODE openzeppelin-solidity next
+```
+
+## Merging the release branch
+
+After the final release, the release branch should be merged back into `master`. This merge must not be squashed because it would lose the tagged release commit. Since the GitHub repo is set up to only allow squashed merges, the merge should be done locally and pushed.
+
+Make sure to have the latest changes from `upstream` in your local release branch.
+
+```
+git checkout release-vX.Y.Z
+git pull upstream
+```
+
+```
+git checkout master
+git merge --no-ff release-vX.Y.Z
+git push upstream master
+```
+
+The release branch can then be deleted on GitHub.

contracts/ARCHITECTURE.md

@@ -0,0 +1,27 @@
+## Architecture
+
+The following provides visibility into how OpenZeppelin's contracts are organized:
+
+- **access** - Smart contracts that enable functionality that can be used for selective restrictions and basic authorization control functions.
+- **crowdsale** - A collection of smart contracts used to manage token crowdsales that allow investors to purchase tokens with ETH. Includes a base contract which implements fundamental crowdsale functionality in its simplest form. The base contract can be extended in order to satisfy your crowdsale’s specific requirements.
+	- **distribution** - Includes extensions of the base crowdsale contract which can be used to customize the completion of a crowdsale.
+	- **emission** - Includes extensions of the base crowdsale contract which can be used to mint and manage how tokens are issued to purchasers.
+	- **price** - Includes extensions of the crowdsale contract that can be used to manage changes in token prices.
+	- **validation**  - Includes extensions of the crowdsale contract that can be used to enforce restraints and limit access to token purchases.
+- **examples** - A collection of simple smart contracts that demonstrate how to add new features to base contracts through multiple inheritance.
+- **introspection**  - An interface that can be used to make a contract comply with the ERC-165 standard as well as a contract that implements ERC-165 using a lookup table.
+- **lifecycle** - A collection of base contracts used to manage the existence and behavior of your contracts and their funds.
+- **math** - Libraries with safety checks on operations that throw on errors.
+- **mocks** - A collection of abstract contracts that are primarily used for unit testing. They also serve as good usage examples and demonstrate how to combine contracts with inheritance when developing your own custom applications.
+- **ownership** - A collection of smart contracts that can be used to manage contract and token ownership
+- **payment** - A collection of smart contracts that can be used to manage payments through escrow arrangements, withdrawals, and claims. Includes support for both single payees and multiple payees.
+- **proposals** - A collection of smart contracts that reflect community Ethereum Improvement Proposals (EIPs). These contracts are under development and standardization. They are not recommended for production, but they are useful for experimentation with pending EIP standards. Go [here](https://github.com/OpenZeppelin/openzeppelin-solidity/wiki/ERC-Process) for more information.
+
+- **token** - A collection of approved ERC standard tokens -- their interfaces and implementations.
+	- **ERC20** - A standard interface for fungible tokens:
+		- *Interfaces* - Includes the ERC-20 token standard basic interface. I.e., what the contract’s ABI can represent.
+		- *Implementations* - Includes ERC-20 token implementations that include all required and some optional ERC-20 functionality.
+	- **ERC721** - A standard interface for non-fungible tokens
+		- *Interfaces* - Includes the ERC-721 token standard basic interface. I.e., what the contract’s ABI can represent.
+		- *Implementations* - Includes ERC-721 token implementations that include all required and some optional ERC-721 functionality.
+

contracts/AddressUtils.sol

@@ -1,29 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-/**
- * Utility library of inline functions on addresses
- */
-library AddressUtils {
-
-  /**
-   * Returns whether the target address is a contract
-   * @dev This function will return false if invoked during the constructor of a contract,
-   * as the code is not actually created until after the constructor finishes.
-   * @param addr address to check
-   * @return whether the target address is a contract
-   */
-  function isContract(address addr) internal view returns (bool) {
-    uint256 size;
-    // XXX Currently there is no better way to check if there is a contract in an address
-    // than to check the size of the code at that address.
-    // See https://ethereum.stackexchange.com/a/14016/36603
-    // for more details about how this works.
-    // TODO Check this again before the Serenity release, because all addresses will be
-    // contracts then.
-    // solium-disable-next-line security/no-inline-assembly
-    assembly { size := extcodesize(addr) }
-    return size > 0;
-  }
-
-}

contracts/Bounty.sol

@@ -1,72 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-import "./payment/PullPayment.sol";
-import "./lifecycle/Destructible.sol";
-
-
-/**
- * @title Bounty
- * @dev This bounty will pay out to a researcher if they break invariant logic of the contract.
- */
-contract Bounty is PullPayment, Destructible {
-  bool public claimed;
-  mapping(address => address) public researchers;
-
-  event TargetCreated(address createdAddress);
-
-  /**
-   * @dev Fallback function allowing the contract to receive funds, if they haven't already been claimed.
-   */
-  function() external payable {
-    require(!claimed);
-  }
-
-  /**
-   * @dev Create and deploy the target contract (extension of Target contract), and sets the
-   * msg.sender as a researcher
-   * @return A target contract
-   */
-  function createTarget() public returns(Target) {
-    Target target = Target(deployContract());
-    researchers[target] = msg.sender;
-    emit TargetCreated(target);
-    return target;
-  }
-
-  /**
-   * @dev Transfers the contract funds to the researcher that proved the contract is broken.
-   * @param target contract
-   */
-  function claim(Target target) public {
-    address researcher = researchers[target];
-    require(researcher != address(0));
-    // Check Target contract invariants
-    require(!target.checkInvariant());
-    asyncTransfer(researcher, address(this).balance);
-    claimed = true;
-  }
-
-  /**
-   * @dev Internal function to deploy the target contract.
-   * @return A target contract address
-   */
-  function deployContract() internal returns(address);
-
-}
-
-
-/**
- * @title Target
- * @dev Your main contract should inherit from this class and implement the checkInvariant method.
- */
-contract Target {
-
-   /**
-    * @dev Checks all values a contract assumes to be true all the time. If this function returns
-    * false, the contract is broken in some way and is in an inconsistent state.
-    * In order to win the bounty, security researchers will try to cause this broken state.
-    * @return True if all invariant values are correct, false otherwise.
-    */
-  function checkInvariant() public returns(bool);
-}

contracts/ECRecovery.sol

@@ -1,72 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-/**
- * @title Eliptic curve signature operations
- * @dev Based on https://gist.github.com/axic/5b33912c6f61ae6fd96d6c4a47afde6d
- * TODO Remove this library once solidity supports passing a signature to ecrecover.
- * See https://github.com/ethereum/solidity/issues/864
- */
-
-library ECRecovery {
-
-  /**
-   * @dev Recover signer address from a message by using their signature
-   * @param hash bytes32 message, the hash is the signed message. What is recovered is the signer address.
-   * @param sig bytes signature, the signature is generated using web3.eth.sign()
-   */
-  function recover(bytes32 hash, bytes sig)
-    internal
-    pure
-    returns (address)
-  {
-    bytes32 r;
-    bytes32 s;
-    uint8 v;
-
-    // Check the signature length
-    if (sig.length != 65) {
-      return (address(0));
-    }
-
-    // Divide the signature in r, s and v variables
-    // ecrecover takes the signature parameters, and the only way to get them
-    // currently is to use assembly.
-    // solium-disable-next-line security/no-inline-assembly
-    assembly {
-      r := mload(add(sig, 32))
-      s := mload(add(sig, 64))
-      v := byte(0, mload(add(sig, 96)))
-    }
-
-    // Version of signature should be 27 or 28, but 0 and 1 are also possible versions
-    if (v < 27) {
-      v += 27;
-    }
-
-    // If the version is correct return the signer address
-    if (v != 27 && v != 28) {
-      return (address(0));
-    } else {
-      // solium-disable-next-line arg-overflow
-      return ecrecover(hash, v, r, s);
-    }
-  }
-
-  /**
-   * toEthSignedMessageHash
-   * @dev prefix a bytes32 value with "\x19Ethereum Signed Message:"
-   * and hash the result
-   */
-  function toEthSignedMessageHash(bytes32 hash)
-    internal
-    pure
-    returns (bytes32)
-  {
-    // 32 is the length in bytes of hash,
-    // enforced by the type signature above
-    return keccak256(
-      abi.encodePacked("\x19Ethereum Signed Message:\n32", hash)
-    );
-  }
-}

contracts/LimitBalance.sol

@@ -1,31 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-/**
- * @title LimitBalance
- * @dev Simple contract to limit the balance of child contract.
- * Note this doesn't prevent other contracts to send funds by using selfdestruct(address);
- * See: https://github.com/ConsenSys/smart-contract-best-practices#remember-that-ether-can-be-forcibly-sent-to-an-account
- */
-contract LimitBalance {
-
-  uint256 public limit;
-
-  /**
-   * @dev Constructor that sets the passed value as a limit.
-   * @param _limit uint256 to represent the limit.
-   */
-  constructor(uint256 _limit) public {
-    limit = _limit;
-  }
-
-  /**
-   * @dev Checks if limit was reached. Case true, it throws.
-   */
-  modifier limitedPayable() {
-    require(address(this).balance <= limit);
-    _;
-
-  }
-
-}

contracts/MerkleProof.sol

@@ -1,43 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-/*
- * @title MerkleProof
- * @dev Merkle proof verification based on
- * https://github.com/ameensol/merkle-tree-solidity/blob/master/src/MerkleProof.sol
- */
-library MerkleProof {
-  /*
-   * @dev Verifies a Merkle proof proving the existence of a leaf in a Merkle tree. Assumes that each pair of leaves
-   * and each pair of pre-images is sorted.
-   * @param _proof Merkle proof containing sibling hashes on the branch from the leaf to the root of the Merkle tree
-   * @param _root Merkle root
-   * @param _leaf Leaf of Merkle tree
-   */
-  function verifyProof(
-    bytes32[] _proof,
-    bytes32 _root,
-    bytes32 _leaf
-  )
-    internal
-    pure
-    returns (bool)
-  {
-    bytes32 computedHash = _leaf;
-
-    for (uint256 i = 0; i < _proof.length; i++) {
-      bytes32 proofElement = _proof[i];
-
-      if (computedHash < proofElement) {
-        // Hash(current computed hash + current element of the proof)
-        computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
-      } else {
-        // Hash(current element of the proof + current computed hash)
-        computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
-      }
-    }
-
-    // Check if the computed hash (root) is equal to the provided root
-    return computedHash == _root;
-  }
-}

contracts/ReentrancyGuard.sol

@@ -1,32 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-/**
- * @title Helps contracts guard agains reentrancy attacks.
- * @author Remco Bloemen <remco@2π.com>
- * @notice If you mark a function `nonReentrant`, you should also
- * mark it `external`.
- */
-contract ReentrancyGuard {
-
-  /**
-   * @dev We use a single lock for the whole contract.
-   */
-  bool private reentrancyLock = false;
-
-  /**
-   * @dev Prevents a contract from calling itself, directly or indirectly.
-   * @notice If you mark a function `nonReentrant`, you should also
-   * mark it `external`. Calling one nonReentrant function from
-   * another is not supported. Instead, you can implement a
-   * `private` function doing the actual work, and a `external`
-   * wrapper marked as `nonReentrant`.
-   */
-  modifier nonReentrant() {
-    require(!reentrancyLock);
-    reentrancyLock = true;
-    _;
-    reentrancyLock = false;
-  }
-
-}

contracts/access/README.md

@@ -0,0 +1,7 @@
+---
+sections:
+  - title: Library
+    contracts:
+      - Roles
+  - subdirectory: roles
+---

contracts/access/Roles.sol

@@ -0,0 +1,36 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title Roles
+ * @dev Library for managing addresses assigned to a Role.
+ */
+library Roles {
+    struct Role {
+        mapping (address => bool) bearer;
+    }
+
+    /**
+     * @dev Give an account access to this role.
+     */
+    function add(Role storage role, address account) internal {
+        require(!has(role, account), "Roles: account already has role");
+        role.bearer[account] = true;
+    }
+
+    /**
+     * @dev Remove an account's access to this role.
+     */
+    function remove(Role storage role, address account) internal {
+        require(has(role, account), "Roles: account does not have role");
+        role.bearer[account] = false;
+    }
+
+    /**
+     * @dev Check if an account has this role.
+     * @return bool
+     */
+    function has(Role storage role, address account) internal view returns (bool) {
+        require(account != address(0), "Roles: account is the zero address");
+        return role.bearer[account];
+    }
+}

contracts/access/SignatureBouncer.sol

@@ -1,159 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../ownership/Ownable.sol";
-import "../ownership/rbac/RBAC.sol";
-import "../ECRecovery.sol";
-
-
-/**
- * @title SignatureBouncer
- * @author PhABC, Shrugs and aflesher
- * @dev Bouncer allows users to submit a signature as a permission to do an action.
- * If the signature is from one of the authorized bouncer addresses, the signature
- * is valid. The owner of the contract adds/removes bouncers.
- * Bouncer addresses can be individual servers signing grants or different
- * users within a decentralized club that have permission to invite other members.
- * This technique is useful for whitelists and airdrops; instead of putting all
- * valid addresses on-chain, simply sign a grant of the form
- * keccak256(abi.encodePacked(`:contractAddress` + `:granteeAddress`)) using a valid bouncer address.
- * Then restrict access to your crowdsale/whitelist/airdrop using the
- * `onlyValidSignature` modifier (or implement your own using isValidSignature).
- * In addition to `onlyValidSignature`, `onlyValidSignatureAndMethod` and
- * `onlyValidSignatureAndData` can be used to restrict access to only a given method
- * or a given method with given parameters respectively.
- * See the tests Bouncer.test.js for specific usage examples.
- * @notice A method that uses the `onlyValidSignatureAndData` modifier must make the _sig
- * parameter the "last" parameter. You cannot sign a message that has its own
- * signature in it so the last 128 bytes of msg.data (which represents the
- * length of the _sig data and the _sig data itself) is ignored when validating.
- * Also non fixed sized parameters make constructing the data in the signature
- * much more complex. See https://ethereum.stackexchange.com/a/50616 for more details.
- */
-contract SignatureBouncer is Ownable, RBAC {
-  using ECRecovery for bytes32;
-
-  string public constant ROLE_BOUNCER = "bouncer";
-  uint constant METHOD_ID_SIZE = 4;
-  // (signature length size) 32 bytes + (signature size 65 bytes padded) 96 bytes
-  uint constant SIGNATURE_SIZE = 128;
-
-  /**
-   * @dev requires that a valid signature of a bouncer was provided
-   */
-  modifier onlyValidSignature(bytes _sig)
-  {
-    require(isValidSignature(msg.sender, _sig));
-    _;
-  }
-
-  /**
-   * @dev requires that a valid signature with a specifed method of a bouncer was provided
-   */
-  modifier onlyValidSignatureAndMethod(bytes _sig)
-  {
-    require(isValidSignatureAndMethod(msg.sender, _sig));
-    _;
-  }
-
-  /**
-   * @dev requires that a valid signature with a specifed method and params of a bouncer was provided
-   */
-  modifier onlyValidSignatureAndData(bytes _sig)
-  {
-    require(isValidSignatureAndData(msg.sender, _sig));
-    _;
-  }
-
-  /**
-   * @dev allows the owner to add additional bouncer addresses
-   */
-  function addBouncer(address _bouncer)
-    onlyOwner
-    public
-  {
-    require(_bouncer != address(0));
-    addRole(_bouncer, ROLE_BOUNCER);
-  }
-
-  /**
-   * @dev allows the owner to remove bouncer addresses
-   */
-  function removeBouncer(address _bouncer)
-    onlyOwner
-    public
-  {
-    require(_bouncer != address(0));
-    removeRole(_bouncer, ROLE_BOUNCER);
-  }
-
-  /**
-   * @dev is the signature of `this + sender` from a bouncer?
-   * @return bool
-   */
-  function isValidSignature(address _address, bytes _sig)
-    internal
-    view
-    returns (bool)
-  {
-    return isValidDataHash(
-      keccak256(abi.encodePacked(address(this), _address)),
-      _sig
-    );
-  }
-
-  /**
-   * @dev is the signature of `this + sender + methodId` from a bouncer?
-   * @return bool
-   */
-  function isValidSignatureAndMethod(address _address, bytes _sig)
-    internal
-    view
-    returns (bool)
-  {
-    bytes memory data = new bytes(METHOD_ID_SIZE);
-    for (uint i = 0; i < data.length; i++) {
-      data[i] = msg.data[i];
-    }
-    return isValidDataHash(
-      keccak256(abi.encodePacked(address(this), _address, data)),
-      _sig
-    );
-  }
-
-  /**
-    * @dev is the signature of `this + sender + methodId + params(s)` from a bouncer?
-    * @notice the _sig parameter of the method being validated must be the "last" parameter
-    * @return bool
-    */
-  function isValidSignatureAndData(address _address, bytes _sig)
-    internal
-    view
-    returns (bool)
-  {
-    require(msg.data.length > SIGNATURE_SIZE);
-    bytes memory data = new bytes(msg.data.length - SIGNATURE_SIZE);
-    for (uint i = 0; i < data.length; i++) {
-      data[i] = msg.data[i];
-    }
-    return isValidDataHash(
-      keccak256(abi.encodePacked(address(this), _address, data)),
-      _sig
-    );
-  }
-
-  /**
-   * @dev internal function to convert a hash to an eth signed message
-   * and then recover the signature and check it against the bouncer role
-   * @return bool
-   */
-  function isValidDataHash(bytes32 hash, bytes _sig)
-    internal
-    view
-    returns (bool)
-  {
-    address signer = hash
-      .toEthSignedMessageHash()
-      .recover(_sig);
-    return hasRole(signer, ROLE_BOUNCER);
-  }
-}

contracts/access/Whitelist.sol

@@ -1,91 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-import "../ownership/Ownable.sol";
-import "../ownership/rbac/RBAC.sol";
-
-
-/**
- * @title Whitelist
- * @dev The Whitelist contract has a whitelist of addresses, and provides basic authorization control functions.
- * This simplifies the implementation of "user permissions".
- */
-contract Whitelist is Ownable, RBAC {
-  string public constant ROLE_WHITELISTED = "whitelist";
-
-  /**
-   * @dev Throws if operator is not whitelisted.
-   * @param _operator address
-   */
-  modifier onlyIfWhitelisted(address _operator) {
-    checkRole(_operator, ROLE_WHITELISTED);
-    _;
-  }
-
-  /**
-   * @dev add an address to the whitelist
-   * @param _operator address
-   * @return true if the address was added to the whitelist, false if the address was already in the whitelist
-   */
-  function addAddressToWhitelist(address _operator)
-    onlyOwner
-    public
-  {
-    addRole(_operator, ROLE_WHITELISTED);
-  }
-
-  /**
-   * @dev getter to determine if address is in whitelist
-   */
-  function whitelist(address _operator)
-    public
-    view
-    returns (bool)
-  {
-    return hasRole(_operator, ROLE_WHITELISTED);
-  }
-
-  /**
-   * @dev add addresses to the whitelist
-   * @param _operators addresses
-   * @return true if at least one address was added to the whitelist,
-   * false if all addresses were already in the whitelist
-   */
-  function addAddressesToWhitelist(address[] _operators)
-    onlyOwner
-    public
-  {
-    for (uint256 i = 0; i < _operators.length; i++) {
-      addAddressToWhitelist(_operators[i]);
-    }
-  }
-
-  /**
-   * @dev remove an address from the whitelist
-   * @param _operator address
-   * @return true if the address was removed from the whitelist,
-   * false if the address wasn't in the whitelist in the first place
-   */
-  function removeAddressFromWhitelist(address _operator)
-    onlyOwner
-    public
-  {
-    removeRole(_operator, ROLE_WHITELISTED);
-  }
-
-  /**
-   * @dev remove addresses from the whitelist
-   * @param _operators addresses
-   * @return true if at least one address was removed from the whitelist,
-   * false if all addresses weren't in the whitelist in the first place
-   */
-  function removeAddressesFromWhitelist(address[] _operators)
-    onlyOwner
-    public
-  {
-    for (uint256 i = 0; i < _operators.length; i++) {
-      removeAddressFromWhitelist(_operators[i]);
-    }
-  }
-
-}

contracts/access/roles/CapperRole.sol

@@ -0,0 +1,43 @@
+pragma solidity ^0.5.7;
+
+import "../Roles.sol";
+
+contract CapperRole {
+    using Roles for Roles.Role;
+
+    event CapperAdded(address indexed account);
+    event CapperRemoved(address indexed account);
+
+    Roles.Role private _cappers;
+
+    constructor () internal {
+        _addCapper(msg.sender);
+    }
+
+    modifier onlyCapper() {
+        require(isCapper(msg.sender), "CapperRole: caller does not have the Capper role");
+        _;
+    }
+
+    function isCapper(address account) public view returns (bool) {
+        return _cappers.has(account);
+    }
+
+    function addCapper(address account) public onlyCapper {
+        _addCapper(account);
+    }
+
+    function renounceCapper() public {
+        _removeCapper(msg.sender);
+    }
+
+    function _addCapper(address account) internal {
+        _cappers.add(account);
+        emit CapperAdded(account);
+    }
+
+    function _removeCapper(address account) internal {
+        _cappers.remove(account);
+        emit CapperRemoved(account);
+    }
+}

contracts/access/roles/MinterRole.sol

@@ -0,0 +1,43 @@
+pragma solidity ^0.5.7;
+
+import "../Roles.sol";
+
+contract MinterRole {
+    using Roles for Roles.Role;
+
+    event MinterAdded(address indexed account);
+    event MinterRemoved(address indexed account);
+
+    Roles.Role private _minters;
+
+    constructor () internal {
+        _addMinter(msg.sender);
+    }
+
+    modifier onlyMinter() {
+        require(isMinter(msg.sender), "MinterRole: caller does not have the Minter role");
+        _;
+    }
+
+    function isMinter(address account) public view returns (bool) {
+        return _minters.has(account);
+    }
+
+    function addMinter(address account) public onlyMinter {
+        _addMinter(account);
+    }
+
+    function renounceMinter() public {
+        _removeMinter(msg.sender);
+    }
+
+    function _addMinter(address account) internal {
+        _minters.add(account);
+        emit MinterAdded(account);
+    }
+
+    function _removeMinter(address account) internal {
+        _minters.remove(account);
+        emit MinterRemoved(account);
+    }
+}

contracts/access/roles/PauserRole.sol

@@ -0,0 +1,43 @@
+pragma solidity ^0.5.7;
+
+import "../Roles.sol";
+
+contract PauserRole {
+    using Roles for Roles.Role;
+
+    event PauserAdded(address indexed account);
+    event PauserRemoved(address indexed account);
+
+    Roles.Role private _pausers;
+
+    constructor () internal {
+        _addPauser(msg.sender);
+    }
+
+    modifier onlyPauser() {
+        require(isPauser(msg.sender), "PauserRole: caller does not have the Pauser role");
+        _;
+    }
+
+    function isPauser(address account) public view returns (bool) {
+        return _pausers.has(account);
+    }
+
+    function addPauser(address account) public onlyPauser {
+        _addPauser(account);
+    }
+
+    function renouncePauser() public {
+        _removePauser(msg.sender);
+    }
+
+    function _addPauser(address account) internal {
+        _pausers.add(account);
+        emit PauserAdded(account);
+    }
+
+    function _removePauser(address account) internal {
+        _pausers.remove(account);
+        emit PauserRemoved(account);
+    }
+}

contracts/access/roles/SignerRole.sol

@@ -0,0 +1,43 @@
+pragma solidity ^0.5.7;
+
+import "../Roles.sol";
+
+contract SignerRole {
+    using Roles for Roles.Role;
+
+    event SignerAdded(address indexed account);
+    event SignerRemoved(address indexed account);
+
+    Roles.Role private _signers;
+
+    constructor () internal {
+        _addSigner(msg.sender);
+    }
+
+    modifier onlySigner() {
+        require(isSigner(msg.sender), "SignerRole: caller does not have the Signer role");
+        _;
+    }
+
+    function isSigner(address account) public view returns (bool) {
+        return _signers.has(account);
+    }
+
+    function addSigner(address account) public onlySigner {
+        _addSigner(account);
+    }
+
+    function renounceSigner() public {
+        _removeSigner(msg.sender);
+    }
+
+    function _addSigner(address account) internal {
+        _signers.add(account);
+        emit SignerAdded(account);
+    }
+
+    function _removeSigner(address account) internal {
+        _signers.remove(account);
+        emit SignerRemoved(account);
+    }
+}

contracts/access/roles/WhitelistAdminRole.sol

@@ -0,0 +1,47 @@
+pragma solidity ^0.5.7;
+
+import "../Roles.sol";
+
+/**
+ * @title WhitelistAdminRole
+ * @dev WhitelistAdmins are responsible for assigning and removing Whitelisted accounts.
+ */
+contract WhitelistAdminRole {
+    using Roles for Roles.Role;
+
+    event WhitelistAdminAdded(address indexed account);
+    event WhitelistAdminRemoved(address indexed account);
+
+    Roles.Role private _whitelistAdmins;
+
+    constructor () internal {
+        _addWhitelistAdmin(msg.sender);
+    }
+
+    modifier onlyWhitelistAdmin() {
+        require(isWhitelistAdmin(msg.sender), "WhitelistAdminRole: caller does not have the WhitelistAdmin role");
+        _;
+    }
+
+    function isWhitelistAdmin(address account) public view returns (bool) {
+        return _whitelistAdmins.has(account);
+    }
+
+    function addWhitelistAdmin(address account) public onlyWhitelistAdmin {
+        _addWhitelistAdmin(account);
+    }
+
+    function renounceWhitelistAdmin() public {
+        _removeWhitelistAdmin(msg.sender);
+    }
+
+    function _addWhitelistAdmin(address account) internal {
+        _whitelistAdmins.add(account);
+        emit WhitelistAdminAdded(account);
+    }
+
+    function _removeWhitelistAdmin(address account) internal {
+        _whitelistAdmins.remove(account);
+        emit WhitelistAdminRemoved(account);
+    }
+}

contracts/access/roles/WhitelistedRole.sol

@@ -0,0 +1,50 @@
+pragma solidity ^0.5.7;
+
+import "../Roles.sol";
+import "./WhitelistAdminRole.sol";
+
+/**
+ * @title WhitelistedRole
+ * @dev Whitelisted accounts have been approved by a WhitelistAdmin to perform certain actions (e.g. participate in a
+ * crowdsale). This role is special in that the only accounts that can add it are WhitelistAdmins (who can also remove
+ * it), and not Whitelisteds themselves.
+ */
+contract WhitelistedRole is WhitelistAdminRole {
+    using Roles for Roles.Role;
+
+    event WhitelistedAdded(address indexed account);
+    event WhitelistedRemoved(address indexed account);
+
+    Roles.Role private _whitelisteds;
+
+    modifier onlyWhitelisted() {
+        require(isWhitelisted(msg.sender), "WhitelistedRole: caller does not have the Whitelisted role");
+        _;
+    }
+
+    function isWhitelisted(address account) public view returns (bool) {
+        return _whitelisteds.has(account);
+    }
+
+    function addWhitelisted(address account) public onlyWhitelistAdmin {
+        _addWhitelisted(account);
+    }
+
+    function removeWhitelisted(address account) public onlyWhitelistAdmin {
+        _removeWhitelisted(account);
+    }
+
+    function renounceWhitelisted() public {
+        _removeWhitelisted(msg.sender);
+    }
+
+    function _addWhitelisted(address account) internal {
+        _whitelisteds.add(account);
+        emit WhitelistedAdded(account);
+    }
+
+    function _removeWhitelisted(address account) internal {
+        _whitelisteds.remove(account);
+        emit WhitelistedRemoved(account);
+    }
+}

contracts/crowdsale/Crowdsale.sol

@@ -1,9 +1,9 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
-import "../token/ERC20/ERC20.sol";
+import "../token/ERC20/IERC20.sol";
 import "../math/SafeMath.sol";
 import "../token/ERC20/SafeERC20.sol";
-
+import "../utils/ReentrancyGuard.sol";
 
 /**
  * @title Crowdsale
@@ -11,190 +11,188 @@ import "../token/ERC20/SafeERC20.sol";
  * allowing investors to purchase tokens with ether. This contract implements
  * such functionality in its most fundamental form and can be extended to provide additional
  * functionality and/or custom behavior.
- * The external interface represents the basic interface for purchasing tokens, and conform
- * the base architecture for crowdsales. They are *not* intended to be modified / overriden.
+ * The external interface represents the basic interface for purchasing tokens, and conforms
+ * the base architecture for crowdsales. It is *not* intended to be modified / overridden.
  * The internal interface conforms the extensible and modifiable surface of crowdsales. Override
- * the methods to add functionality. Consider using 'super' where appropiate to concatenate
+ * the methods to add functionality. Consider using 'super' where appropriate to concatenate
  * behavior.
  */
-contract Crowdsale {
-  using SafeMath for uint256;
-  using SafeERC20 for ERC20;
+contract Crowdsale is ReentrancyGuard {
+    using SafeMath for uint256;
+    using SafeERC20 for IERC20;
 
-  // The token being sold
-  ERC20 public token;
+    // The token being sold
+    IERC20 private _token;
 
-  // Address where funds are collected
-  address public wallet;
+    // Address where funds are collected
+    address payable private _wallet;
 
-  // How many token units a buyer gets per wei.
-  // The rate is the conversion between wei and the smallest and indivisible token unit.
-  // So, if you are using a rate of 1 with a DetailedERC20 token with 3 decimals called TOK
-  // 1 wei will give you 1 unit, or 0.001 TOK.
-  uint256 public rate;
+    // How many token units a buyer gets per wei.
+    // The rate is the conversion between wei and the smallest and indivisible token unit.
+    // So, if you are using a rate of 1 with a ERC20Detailed token with 3 decimals called TOK
+    // 1 wei will give you 1 unit, or 0.001 TOK.
+    uint256 private _rate;
 
-  // Amount of wei raised
-  uint256 public weiRaised;
+    // Amount of wei raised
+    uint256 private _weiRaised;
 
-  /**
-   * Event for token purchase logging
-   * @param purchaser who paid for the tokens
-   * @param beneficiary who got the tokens
-   * @param value weis paid for purchase
-   * @param amount amount of tokens purchased
-   */
-  event TokenPurchase(
-    address indexed purchaser,
-    address indexed beneficiary,
-    uint256 value,
-    uint256 amount
-  );
+    /**
+     * Event for token purchase logging
+     * @param purchaser who paid for the tokens
+     * @param beneficiary who got the tokens
+     * @param value weis paid for purchase
+     * @param amount amount of tokens purchased
+     */
+    event TokensPurchased(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);
 
-  /**
-   * @param _rate Number of token units a buyer gets per wei
-   * @param _wallet Address where collected funds will be forwarded to
-   * @param _token Address of the token being sold
-   */
-  constructor(uint256 _rate, address _wallet, ERC20 _token) public {
-    require(_rate > 0);
-    require(_wallet != address(0));
-    require(_token != address(0));
+    /**
+     * @param rate Number of token units a buyer gets per wei
+     * @dev The rate is the conversion between wei and the smallest and indivisible
+     * token unit. So, if you are using a rate of 1 with a ERC20Detailed token
+     * with 3 decimals called TOK, 1 wei will give you 1 unit, or 0.001 TOK.
+     * @param wallet Address where collected funds will be forwarded to
+     * @param token Address of the token being sold
+     */
+    constructor (uint256 rate, address payable wallet, IERC20 token) public {
+        require(rate > 0, "Crowdsale: rate is 0");
+        require(wallet != address(0), "Crowdsale: wallet is the zero address");
+        require(address(token) != address(0), "Crowdsale: token is the zero address");
 
-    rate = _rate;
-    wallet = _wallet;
-    token = _token;
-  }
+        _rate = rate;
+        _wallet = wallet;
+        _token = token;
+    }
 
-  // -----------------------------------------
-  // Crowdsale external interface
-  // -----------------------------------------
+    /**
+     * @dev fallback function ***DO NOT OVERRIDE***
+     * Note that other contracts will transfer funds with a base gas stipend
+     * of 2300, which is not enough to call buyTokens. Consider calling
+     * buyTokens directly when purchasing tokens from a contract.
+     */
+    function () external payable {
+        buyTokens(msg.sender);
+    }
 
-  /**
-   * @dev fallback function ***DO NOT OVERRIDE***
-   */
-  function () external payable {
-    buyTokens(msg.sender);
-  }
+    /**
+     * @return the token being sold.
+     */
+    function token() public view returns (IERC20) {
+        return _token;
+    }
 
-  /**
-   * @dev low level token purchase ***DO NOT OVERRIDE***
-   * @param _beneficiary Address performing the token purchase
-   */
-  function buyTokens(address _beneficiary) public payable {
+    /**
+     * @return the address where funds are collected.
+     */
+    function wallet() public view returns (address payable) {
+        return _wallet;
+    }
 
-    uint256 weiAmount = msg.value;
-    _preValidatePurchase(_beneficiary, weiAmount);
+    /**
+     * @return the number of token units a buyer gets per wei.
+     */
+    function rate() public view returns (uint256) {
+        return _rate;
+    }
 
-    // calculate token amount to be created
-    uint256 tokens = _getTokenAmount(weiAmount);
+    /**
+     * @return the amount of wei raised.
+     */
+    function weiRaised() public view returns (uint256) {
+        return _weiRaised;
+    }
 
-    // update state
-    weiRaised = weiRaised.add(weiAmount);
+    /**
+     * @dev low level token purchase ***DO NOT OVERRIDE***
+     * This function has a non-reentrancy guard, so it shouldn't be called by
+     * another `nonReentrant` function.
+     * @param beneficiary Recipient of the token purchase
+     */
+    function buyTokens(address beneficiary) public nonReentrant payable {
+        uint256 weiAmount = msg.value;
+        _preValidatePurchase(beneficiary, weiAmount);
 
-    _processPurchase(_beneficiary, tokens);
-    emit TokenPurchase(
-      msg.sender,
-      _beneficiary,
-      weiAmount,
-      tokens
-    );
+        // calculate token amount to be created
+        uint256 tokens = _getTokenAmount(weiAmount);
 
-    _updatePurchasingState(_beneficiary, weiAmount);
+        // update state
+        _weiRaised = _weiRaised.add(weiAmount);
 
-    _forwardFunds();
-    _postValidatePurchase(_beneficiary, weiAmount);
-  }
+        _processPurchase(beneficiary, tokens);
+        emit TokensPurchased(msg.sender, beneficiary, weiAmount, tokens);
 
-  // -----------------------------------------
-  // Internal interface (extensible)
-  // -----------------------------------------
+        _updatePurchasingState(beneficiary, weiAmount);
 
-  /**
-   * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met. Use super to concatenate validations.
-   * @param _beneficiary Address performing the token purchase
-   * @param _weiAmount Value in wei involved in the purchase
-   */
-  function _preValidatePurchase(
-    address _beneficiary,
-    uint256 _weiAmount
-  )
-    internal
-  {
-    require(_beneficiary != address(0));
-    require(_weiAmount != 0);
-  }
+        _forwardFunds();
+        _postValidatePurchase(beneficiary, weiAmount);
+    }
 
-  /**
-   * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid conditions are not met.
-   * @param _beneficiary Address performing the token purchase
-   * @param _weiAmount Value in wei involved in the purchase
-   */
-  function _postValidatePurchase(
-    address _beneficiary,
-    uint256 _weiAmount
-  )
-    internal
-  {
-    // optional override
-  }
+    /**
+     * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met.
+     * Use `super` in contracts that inherit from Crowdsale to extend their validations.
+     * Example from CappedCrowdsale.sol's _preValidatePurchase method:
+     *     super._preValidatePurchase(beneficiary, weiAmount);
+     *     require(weiRaised().add(weiAmount) <= cap);
+     * @param beneficiary Address performing the token purchase
+     * @param weiAmount Value in wei involved in the purchase
+     */
+    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
+        require(beneficiary != address(0), "Crowdsale: beneficiary is the zero address");
+        require(weiAmount != 0, "Crowdsale: weiAmount is 0");
+    }
 
-  /**
-   * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends its tokens.
-   * @param _beneficiary Address performing the token purchase
-   * @param _tokenAmount Number of tokens to be emitted
-   */
-  function _deliverTokens(
-    address _beneficiary,
-    uint256 _tokenAmount
-  )
-    internal
-  {
-    token.safeTransfer(_beneficiary, _tokenAmount);
-  }
+    /**
+     * @dev Validation of an executed purchase. Observe state and use revert statements to undo rollback when valid
+     * conditions are not met.
+     * @param beneficiary Address performing the token purchase
+     * @param weiAmount Value in wei involved in the purchase
+     */
+    function _postValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-  /**
-   * @dev Executed when a purchase has been validated and is ready to be executed. Not necessarily emits/sends tokens.
-   * @param _beneficiary Address receiving the tokens
-   * @param _tokenAmount Number of tokens to be purchased
-   */
-  function _processPurchase(
-    address _beneficiary,
-    uint256 _tokenAmount
-  )
-    internal
-  {
-    _deliverTokens(_beneficiary, _tokenAmount);
-  }
+    /**
+     * @dev Source of tokens. Override this method to modify the way in which the crowdsale ultimately gets and sends
+     * its tokens.
+     * @param beneficiary Address performing the token purchase
+     * @param tokenAmount Number of tokens to be emitted
+     */
+    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
+        _token.safeTransfer(beneficiary, tokenAmount);
+    }
 
-  /**
-   * @dev Override for extensions that require an internal state to check for validity (current user contributions, etc.)
-   * @param _beneficiary Address receiving the tokens
-   * @param _weiAmount Value in wei involved in the purchase
-   */
-  function _updatePurchasingState(
-    address _beneficiary,
-    uint256 _weiAmount
-  )
-    internal
-  {
-    // optional override
-  }
+    /**
+     * @dev Executed when a purchase has been validated and is ready to be executed. Doesn't necessarily emit/send
+     * tokens.
+     * @param beneficiary Address receiving the tokens
+     * @param tokenAmount Number of tokens to be purchased
+     */
+    function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
+        _deliverTokens(beneficiary, tokenAmount);
+    }
 
-  /**
-   * @dev Override to extend the way in which ether is converted to tokens.
-   * @param _weiAmount Value in wei to be converted into tokens
-   * @return Number of tokens that can be purchased with the specified _weiAmount
-   */
-  function _getTokenAmount(uint256 _weiAmount)
-    internal view returns (uint256)
-  {
-    return _weiAmount.mul(rate);
-  }
+    /**
+     * @dev Override for extensions that require an internal state to check for validity (current user contributions,
+     * etc.)
+     * @param beneficiary Address receiving the tokens
+     * @param weiAmount Value in wei involved in the purchase
+     */
+    function _updatePurchasingState(address beneficiary, uint256 weiAmount) internal {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 
-  /**
-   * @dev Determines how ETH is stored/forwarded on purchases.
-   */
-  function _forwardFunds() internal {
-    wallet.transfer(msg.value);
-  }
-}
+    /**
+     * @dev Override to extend the way in which ether is converted to tokens.
+     * @param weiAmount Value in wei to be converted into tokens
+     * @return Number of tokens that can be purchased with the specified _weiAmount
+     */
+    function _getTokenAmount(uint256 weiAmount) internal view returns (uint256) {
+        return weiAmount.mul(_rate);
+    }
+
+    /**
+     * @dev Determines how ETH is stored/forwarded on purchases.
+     */
+    function _forwardFunds() internal {
+        _wallet.transfer(msg.value);
+    }
+}

contracts/crowdsale/README.md

@@ -0,0 +1,11 @@
+---
+title: Crowdsales
+sections:
+  - title: Core
+    contracts:
+      - Crowdsale
+  - subdirectory: emission
+  - subdirectory: price
+  - subdirectory: validation
+  - subdirectory: distribution
+---

contracts/crowdsale/distribution/FinalizableCrowdsale.sol

@@ -1,42 +1,51 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../../math/SafeMath.sol";
-import "../../ownership/Ownable.sol";
 import "../validation/TimedCrowdsale.sol";
 
-
 /**
  * @title FinalizableCrowdsale
- * @dev Extension of Crowdsale where an owner can do extra work
- * after finishing.
+ * @dev Extension of TimedCrowdsale with a one-off finalization action, where one
+ * can do extra work after finishing.
  */
-contract FinalizableCrowdsale is TimedCrowdsale, Ownable {
-  using SafeMath for uint256;
+contract FinalizableCrowdsale is TimedCrowdsale {
+    using SafeMath for uint256;
 
-  bool public isFinalized = false;
+    bool private _finalized;
 
-  event Finalized();
+    event CrowdsaleFinalized();
 
-  /**
-   * @dev Must be called after crowdsale ends, to do some extra finalization
-   * work. Calls the contract's finalization function.
-   */
-  function finalize() onlyOwner public {
-    require(!isFinalized);
-    require(hasClosed());
+    constructor () internal {
+        _finalized = false;
+    }
 
-    finalization();
-    emit Finalized();
+    /**
+     * @return true if the crowdsale is finalized, false otherwise.
+     */
+    function finalized() public view returns (bool) {
+        return _finalized;
+    }
 
-    isFinalized = true;
-  }
+    /**
+     * @dev Must be called after crowdsale ends, to do some extra finalization
+     * work. Calls the contract's finalization function.
+     */
+    function finalize() public {
+        require(!_finalized, "FinalizableCrowdsale: already finalized");
+        require(hasClosed(), "FinalizableCrowdsale: not closed");
 
-  /**
-   * @dev Can be overridden to add finalization logic. The overriding function
-   * should call super.finalization() to ensure the chain of finalization is
-   * executed entirely.
-   */
-  function finalization() internal {
-  }
+        _finalized = true;
 
+        _finalization();
+        emit CrowdsaleFinalized();
+    }
+
+    /**
+     * @dev Can be overridden to add finalization logic. The overriding function
+     * should call super._finalization() to ensure the chain of finalization is
+     * executed entirely.
+     */
+    function _finalization() internal {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 }

contracts/crowdsale/distribution/PostDeliveryCrowdsale.sol

@@ -1,42 +1,65 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../validation/TimedCrowdsale.sol";
-import "../../token/ERC20/ERC20.sol";
 import "../../math/SafeMath.sol";
-
+import "../../ownership/Secondary.sol";
+import "../../token/ERC20/IERC20.sol";
 
 /**
  * @title PostDeliveryCrowdsale
  * @dev Crowdsale that locks tokens from withdrawal until it ends.
  */
 contract PostDeliveryCrowdsale is TimedCrowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  mapping(address => uint256) public balances;
+    mapping(address => uint256) private _balances;
+    __unstable__TokenVault private _vault;
 
-  /**
-   * @dev Withdraw tokens only after crowdsale ends.
-   */
-  function withdrawTokens() public {
-    require(hasClosed());
-    uint256 amount = balances[msg.sender];
-    require(amount > 0);
-    balances[msg.sender] = 0;
-    _deliverTokens(msg.sender, amount);
-  }
+    constructor() public {
+        _vault = new __unstable__TokenVault();
+    }
 
-  /**
-   * @dev Overrides parent by storing balances instead of issuing tokens right away.
-   * @param _beneficiary Token purchaser
-   * @param _tokenAmount Amount of tokens purchased
-   */
-  function _processPurchase(
-    address _beneficiary,
-    uint256 _tokenAmount
-  )
-    internal
-  {
-    balances[_beneficiary] = balances[_beneficiary].add(_tokenAmount);
-  }
+    /**
+     * @dev Withdraw tokens only after crowdsale ends.
+     * @param beneficiary Whose tokens will be withdrawn.
+     */
+    function withdrawTokens(address beneficiary) public {
+        require(hasClosed(), "PostDeliveryCrowdsale: not closed");
+        uint256 amount = _balances[beneficiary];
+        require(amount > 0, "PostDeliveryCrowdsale: beneficiary is not due any tokens");
 
+        _balances[beneficiary] = 0;
+        _vault.transfer(token(), beneficiary, amount);
+    }
+
+    /**
+     * @return the balance of an account.
+     */
+    function balanceOf(address account) public view returns (uint256) {
+        return _balances[account];
+    }
+
+    /**
+     * @dev Overrides parent by storing due balances, and delivering tokens to the vault instead of the end user. This
+     * ensures that the tokens will be available by the time they are withdrawn (which may not be the case if
+     * `_deliverTokens` was called later).
+     * @param beneficiary Token purchaser
+     * @param tokenAmount Amount of tokens purchased
+     */
+    function _processPurchase(address beneficiary, uint256 tokenAmount) internal {
+        _balances[beneficiary] = _balances[beneficiary].add(tokenAmount);
+        _deliverTokens(address(_vault), tokenAmount);
+    }
+}
+
+/**
+ * @title __unstable__TokenVault
+ * @dev Similar to an Escrow for tokens, this contract allows its primary account to spend its tokens as it sees fit.
+ * This contract is an internal helper for PostDeliveryCrowdsale, and should not be used outside of this context.
+ */
+// solhint-disable-next-line contract-name-camelcase
+contract __unstable__TokenVault is Secondary {
+    function transfer(IERC20 token, address to, uint256 amount) public onlyPrimary {
+        token.transfer(to, amount);
+    }
 }

contracts/crowdsale/distribution/RefundableCrowdsale.sol

@@ -1,72 +1,82 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.7;
 
 import "../../math/SafeMath.sol";
 import "./FinalizableCrowdsale.sol";
-import "../../payment/RefundEscrow.sol";
-
+import "../../payment/escrow/RefundEscrow.sol";
 
 /**
  * @title RefundableCrowdsale
- * @dev Extension of Crowdsale contract that adds a funding goal, and
- * the possibility of users getting a refund if goal is not met.
+ * @dev Extension of FinalizableCrowdsale contract that adds a funding goal, and the possibility of users
+ * getting a refund if goal is not met.
+ *
+ * Deprecated, use RefundablePostDeliveryCrowdsale instead. Note that if you allow tokens to be traded before the goal
+ * is met, then an attack is possible in which the attacker purchases tokens from the crowdsale and when they sees that
+ * the goal is unlikely to be met, they sell their tokens (possibly at a discount). The attacker will be refunded when
+ * the crowdsale is finalized, and the users that purchased from them will be left with worthless tokens.
  */
 contract RefundableCrowdsale is FinalizableCrowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  // minimum amount of funds to be raised in weis
-  uint256 public goal;
+    // minimum amount of funds to be raised in weis
+    uint256 private _goal;
 
-  // refund escrow used to hold funds while crowdsale is running
-  RefundEscrow private escrow;
+    // refund escrow used to hold funds while crowdsale is running
+    RefundEscrow private _escrow;
 
-  /**
-   * @dev Constructor, creates RefundEscrow.
-   * @param _goal Funding goal
-   */
-  constructor(uint256 _goal) public {
-    require(_goal > 0);
-    escrow = new RefundEscrow(wallet);
-    goal = _goal;
-  }
-
-  /**
-   * @dev Investors can claim refunds here if crowdsale is unsuccessful
-   */
-  function claimRefund() public {
-    require(isFinalized);
-    require(!goalReached());
-
-    escrow.withdraw(msg.sender);
-  }
-
-  /**
-   * @dev Checks whether funding goal was reached.
-   * @return Whether funding goal was reached
-   */
-  function goalReached() public view returns (bool) {
-    return weiRaised >= goal;
-  }
-
-  /**
-   * @dev escrow finalization task, called when owner calls finalize()
-   */
-  function finalization() internal {
-    if (goalReached()) {
-      escrow.close();
-      escrow.beneficiaryWithdraw();
-    } else {
-      escrow.enableRefunds();
+    /**
+     * @dev Constructor, creates RefundEscrow.
+     * @param goal Funding goal
+     */
+    constructor (uint256 goal) public {
+        require(goal > 0, "RefundableCrowdsale: goal is 0");
+        _escrow = new RefundEscrow(wallet());
+        _goal = goal;
     }
 
-    super.finalization();
-  }
+    /**
+     * @return minimum amount of funds to be raised in wei.
+     */
+    function goal() public view returns (uint256) {
+        return _goal;
+    }
 
-  /**
-   * @dev Overrides Crowdsale fund forwarding, sending funds to escrow.
-   */
-  function _forwardFunds() internal {
-    escrow.deposit.value(msg.value)(msg.sender);
-  }
+    /**
+     * @dev Investors can claim refunds here if crowdsale is unsuccessful.
+     * @param refundee Whose refund will be claimed.
+     */
+    function claimRefund(address payable refundee) public {
+        require(finalized(), "RefundableCrowdsale: not finalized");
+        require(!goalReached(), "RefundableCrowdsale: goal reached");
 
+        _escrow.withdraw(refundee);
+    }
+
+    /**
+     * @dev Checks whether funding goal was reached.
+     * @return Whether funding goal was reached
+     */
+    function goalReached() public view returns (bool) {
+        return weiRaised() >= _goal;
+    }
+
+    /**
+     * @dev Escrow finalization task, called when finalize() is called.
+     */
+    function _finalization() internal {
+        if (goalReached()) {
+            _escrow.close();
+            _escrow.beneficiaryWithdraw();
+        } else {
+            _escrow.enableRefunds();
+        }
+
+        super._finalization();
+    }
+
+    /**
+     * @dev Overrides Crowdsale fund forwarding, sending funds to escrow.
+     */
+    function _forwardFunds() internal {
+        _escrow.deposit.value(msg.value)(msg.sender);
+    }
 }

contracts/crowdsale/distribution/RefundablePostDeliveryCrowdsale.sol

@@ -0,0 +1,20 @@
+pragma solidity ^0.5.7;
+
+import "./RefundableCrowdsale.sol";
+import "./PostDeliveryCrowdsale.sol";
+
+
+/**
+ * @title RefundablePostDeliveryCrowdsale
+ * @dev Extension of RefundableCrowdsale contract that only delivers the tokens
+ * once the crowdsale has closed and the goal met, preventing refunds to be issued
+ * to token holders.
+ */
+contract RefundablePostDeliveryCrowdsale is RefundableCrowdsale, PostDeliveryCrowdsale {
+    function withdrawTokens(address beneficiary) public {
+        require(finalized(), "RefundablePostDeliveryCrowdsale: not finalized");
+        require(goalReached(), "RefundablePostDeliveryCrowdsale: goal not reached");
+
+        super.withdrawTokens(beneficiary);
+    }
+}

contracts/crowdsale/emission/AllowanceCrowdsale.sol

@@ -1,48 +1,51 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../Crowdsale.sol";
-import "../../token/ERC20/ERC20.sol";
-import "../../token/ERC20/ERC20Basic.sol";
+import "../../token/ERC20/IERC20.sol";
 import "../../token/ERC20/SafeERC20.sol";
 import "../../math/SafeMath.sol";
+import "../../math/Math.sol";
+
 /**
  * @title AllowanceCrowdsale
  * @dev Extension of Crowdsale where tokens are held by a wallet, which approves an allowance to the crowdsale.
  */
 contract AllowanceCrowdsale is Crowdsale {
-  using SafeMath for uint256;
-  using SafeERC20 for ERC20;
+    using SafeMath for uint256;
+    using SafeERC20 for IERC20;
 
-  address public tokenWallet;
+    address private _tokenWallet;
 
-  /**
-   * @dev Constructor, takes token wallet address.
-   * @param _tokenWallet Address holding the tokens, which has approved allowance to the crowdsale
-   */
-  constructor(address _tokenWallet) public {
-    require(_tokenWallet != address(0));
-    tokenWallet = _tokenWallet;
-  }
+    /**
+     * @dev Constructor, takes token wallet address.
+     * @param tokenWallet Address holding the tokens, which has approved allowance to the crowdsale.
+     */
+    constructor (address tokenWallet) public {
+        require(tokenWallet != address(0), "AllowanceCrowdsale: token wallet is the zero address");
+        _tokenWallet = tokenWallet;
+    }
 
-  /**
-   * @dev Checks the amount of tokens left in the allowance.
-   * @return Amount of tokens left in the allowance
-   */
-  function remainingTokens() public view returns (uint256) {
-    return token.allowance(tokenWallet, this);
-  }
+    /**
+     * @return the address of the wallet that will hold the tokens.
+     */
+    function tokenWallet() public view returns (address) {
+        return _tokenWallet;
+    }
 
-  /**
-   * @dev Overrides parent behavior by transferring tokens from wallet.
-   * @param _beneficiary Token purchaser
-   * @param _tokenAmount Amount of tokens purchased
-   */
-  function _deliverTokens(
-    address _beneficiary,
-    uint256 _tokenAmount
-  )
-    internal
-  {
-    token.safeTransferFrom(tokenWallet, _beneficiary, _tokenAmount);
-  }
+    /**
+     * @dev Checks the amount of tokens left in the allowance.
+     * @return Amount of tokens left in the allowance
+     */
+    function remainingTokens() public view returns (uint256) {
+        return Math.min(token().balanceOf(_tokenWallet), token().allowance(_tokenWallet, address(this)));
+    }
+
+    /**
+     * @dev Overrides parent behavior by transferring tokens from wallet.
+     * @param beneficiary Token purchaser
+     * @param tokenAmount Amount of tokens purchased
+     */
+    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
+        token().safeTransferFrom(_tokenWallet, beneficiary, tokenAmount);
+    }
 }

contracts/crowdsale/emission/MintedCrowdsale.sol

@@ -1,8 +1,7 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../Crowdsale.sol";
-import "../../token/ERC20/MintableToken.sol";
-
+import "../../token/ERC20/ERC20Mintable.sol";
 
 /**
  * @title MintedCrowdsale
@@ -10,18 +9,16 @@ import "../../token/ERC20/MintableToken.sol";
  * Token ownership should be transferred to MintedCrowdsale for minting.
  */
 contract MintedCrowdsale is Crowdsale {
-
-  /**
-   * @dev Overrides delivery by minting tokens upon purchase.
-   * @param _beneficiary Token purchaser
-   * @param _tokenAmount Number of tokens to be minted
-   */
-  function _deliverTokens(
-    address _beneficiary,
-    uint256 _tokenAmount
-  )
-    internal
-  {
-    require(MintableToken(token).mint(_beneficiary, _tokenAmount));
-  }
+    /**
+     * @dev Overrides delivery by minting tokens upon purchase.
+     * @param beneficiary Token purchaser
+     * @param tokenAmount Number of tokens to be minted
+     */
+    function _deliverTokens(address beneficiary, uint256 tokenAmount) internal {
+        // Potentially dangerous assumption about the type of the token.
+        require(
+            ERC20Mintable(address(token())).mint(beneficiary, tokenAmount),
+                "MintedCrowdsale: minting failed"
+        );
+    }
 }

contracts/crowdsale/price/IncreasingPriceCrowdsale.sol

@@ -1,9 +1,8 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../validation/TimedCrowdsale.sol";
 import "../../math/SafeMath.sol";
 
-
 /**
  * @title IncreasingPriceCrowdsale
  * @dev Extension of Crowdsale contract that increases the price of tokens linearly in time.
@@ -11,46 +10,70 @@ import "../../math/SafeMath.sol";
  * the amount of tokens per wei contributed. Thus, the initial rate must be greater than the final rate.
  */
 contract IncreasingPriceCrowdsale is TimedCrowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  uint256 public initialRate;
-  uint256 public finalRate;
+    uint256 private _initialRate;
+    uint256 private _finalRate;
 
-  /**
-   * @dev Constructor, takes intial and final rates of tokens received per wei contributed.
-   * @param _initialRate Number of tokens a buyer gets per wei at the start of the crowdsale
-   * @param _finalRate Number of tokens a buyer gets per wei at the end of the crowdsale
-   */
-  constructor(uint256 _initialRate, uint256 _finalRate) public {
-    require(_initialRate >= _finalRate);
-    require(_finalRate > 0);
-    initialRate = _initialRate;
-    finalRate = _finalRate;
-  }
+    /**
+     * @dev Constructor, takes initial and final rates of tokens received per wei contributed.
+     * @param initialRate Number of tokens a buyer gets per wei at the start of the crowdsale
+     * @param finalRate Number of tokens a buyer gets per wei at the end of the crowdsale
+     */
+    constructor (uint256 initialRate, uint256 finalRate) public {
+        require(finalRate > 0, "IncreasingPriceCrowdsale: final rate is 0");
+        // solhint-disable-next-line max-line-length
+        require(initialRate > finalRate, "IncreasingPriceCrowdsale: initial rate is not greater than final rate");
+        _initialRate = initialRate;
+        _finalRate = finalRate;
+    }
 
-  /**
-   * @dev Returns the rate of tokens per wei at the present time.
-   * Note that, as price _increases_ with time, the rate _decreases_.
-   * @return The number of tokens a buyer gets per wei at a given time
-   */
-  function getCurrentRate() public view returns (uint256) {
-    // solium-disable-next-line security/no-block-members
-    uint256 elapsedTime = block.timestamp.sub(openingTime);
-    uint256 timeRange = closingTime.sub(openingTime);
-    uint256 rateRange = initialRate.sub(finalRate);
-    return initialRate.sub(elapsedTime.mul(rateRange).div(timeRange));
-  }
+    /**
+     * The base rate function is overridden to revert, since this crowdsale doesn't use it, and
+     * all calls to it are a mistake.
+     */
+    function rate() public view returns (uint256) {
+        revert("IncreasingPriceCrowdsale: rate() called");
+    }
 
-  /**
-   * @dev Overrides parent method taking into account variable rate.
-   * @param _weiAmount The value in wei to be converted into tokens
-   * @return The number of tokens _weiAmount wei will buy at present time
-   */
-  function _getTokenAmount(uint256 _weiAmount)
-    internal view returns (uint256)
-  {
-    uint256 currentRate = getCurrentRate();
-    return currentRate.mul(_weiAmount);
-  }
+    /**
+     * @return the initial rate of the crowdsale.
+     */
+    function initialRate() public view returns (uint256) {
+        return _initialRate;
+    }
 
+    /**
+     * @return the final rate of the crowdsale.
+     */
+    function finalRate() public view returns (uint256) {
+        return _finalRate;
+    }
+
+    /**
+     * @dev Returns the rate of tokens per wei at the present time.
+     * Note that, as price _increases_ with time, the rate _decreases_.
+     * @return The number of tokens a buyer gets per wei at a given time
+     */
+    function getCurrentRate() public view returns (uint256) {
+        if (!isOpen()) {
+            return 0;
+        }
+
+        // solhint-disable-next-line not-rely-on-time
+        uint256 elapsedTime = block.timestamp.sub(openingTime());
+        uint256 timeRange = closingTime().sub(openingTime());
+        uint256 rateRange = _initialRate.sub(_finalRate);
+        return _initialRate.sub(elapsedTime.mul(rateRange).div(timeRange));
+    }
+
+    /**
+     * @dev Overrides parent method taking into account variable rate.
+     * @param weiAmount The value in wei to be converted into tokens
+     * @return The number of tokens _weiAmount wei will buy at present time
+     */
+    function _getTokenAmount(uint256 weiAmount) internal view returns (uint256) {
+        uint256 currentRate = getCurrentRate();
+        return currentRate.mul(weiAmount);
+    }
 }

contracts/crowdsale/validation/CappedCrowdsale.sol

@@ -1,48 +1,48 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../../math/SafeMath.sol";
 import "../Crowdsale.sol";
 
-
 /**
  * @title CappedCrowdsale
  * @dev Crowdsale with a limit for total contributions.
  */
 contract CappedCrowdsale is Crowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  uint256 public cap;
+    uint256 private _cap;
 
-  /**
-   * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
-   * @param _cap Max amount of wei to be contributed
-   */
-  constructor(uint256 _cap) public {
-    require(_cap > 0);
-    cap = _cap;
-  }
+    /**
+     * @dev Constructor, takes maximum amount of wei accepted in the crowdsale.
+     * @param cap Max amount of wei to be contributed
+     */
+    constructor (uint256 cap) public {
+        require(cap > 0, "CappedCrowdsale: cap is 0");
+        _cap = cap;
+    }
 
-  /**
-   * @dev Checks whether the cap has been reached.
-   * @return Whether the cap was reached
-   */
-  function capReached() public view returns (bool) {
-    return weiRaised >= cap;
-  }
+    /**
+     * @return the cap of the crowdsale.
+     */
+    function cap() public view returns (uint256) {
+        return _cap;
+    }
 
-  /**
-   * @dev Extend parent behavior requiring purchase to respect the funding cap.
-   * @param _beneficiary Token purchaser
-   * @param _weiAmount Amount of wei contributed
-   */
-  function _preValidatePurchase(
-    address _beneficiary,
-    uint256 _weiAmount
-  )
-    internal
-  {
-    super._preValidatePurchase(_beneficiary, _weiAmount);
-    require(weiRaised.add(_weiAmount) <= cap);
-  }
+    /**
+     * @dev Checks whether the cap has been reached.
+     * @return Whether the cap was reached
+     */
+    function capReached() public view returns (bool) {
+        return weiRaised() >= _cap;
+    }
 
+    /**
+     * @dev Extend parent behavior requiring purchase to respect the funding cap.
+     * @param beneficiary Token purchaser
+     * @param weiAmount Amount of wei contributed
+     */
+    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
+        super._preValidatePurchase(beneficiary, weiAmount);
+        require(weiRaised().add(weiAmount) <= _cap, "CappedCrowdsale: cap exceeded");
+    }
 }

contracts/crowdsale/validation/IndividuallyCappedCrowdsale.sol

@@ -1,94 +1,64 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../../math/SafeMath.sol";
 import "../Crowdsale.sol";
-import "../../ownership/Ownable.sol";
-
+import "../../access/roles/CapperRole.sol";
 
 /**
  * @title IndividuallyCappedCrowdsale
- * @dev Crowdsale with per-user caps.
+ * @dev Crowdsale with per-beneficiary caps.
  */
-contract IndividuallyCappedCrowdsale is Crowdsale, Ownable {
-  using SafeMath for uint256;
+contract IndividuallyCappedCrowdsale is Crowdsale, CapperRole {
+    using SafeMath for uint256;
 
-  mapping(address => uint256) public contributions;
-  mapping(address => uint256) public caps;
+    mapping(address => uint256) private _contributions;
+    mapping(address => uint256) private _caps;
 
-  /**
-   * @dev Sets a specific user's maximum contribution.
-   * @param _beneficiary Address to be capped
-   * @param _cap Wei limit for individual contribution
-   */
-  function setUserCap(address _beneficiary, uint256 _cap) external onlyOwner {
-    caps[_beneficiary] = _cap;
-  }
-
-  /**
-   * @dev Sets a group of users' maximum contribution.
-   * @param _beneficiaries List of addresses to be capped
-   * @param _cap Wei limit for individual contribution
-   */
-  function setGroupCap(
-    address[] _beneficiaries,
-    uint256 _cap
-  )
-    external
-    onlyOwner
-  {
-    for (uint256 i = 0; i < _beneficiaries.length; i++) {
-      caps[_beneficiaries[i]] = _cap;
+    /**
+     * @dev Sets a specific beneficiary's maximum contribution.
+     * @param beneficiary Address to be capped
+     * @param cap Wei limit for individual contribution
+     */
+    function setCap(address beneficiary, uint256 cap) external onlyCapper {
+        _caps[beneficiary] = cap;
     }
-  }
 
-  /**
-   * @dev Returns the cap of a specific user.
-   * @param _beneficiary Address whose cap is to be checked
-   * @return Current cap for individual user
-   */
-  function getUserCap(address _beneficiary) public view returns (uint256) {
-    return caps[_beneficiary];
-  }
+    /**
+     * @dev Returns the cap of a specific beneficiary.
+     * @param beneficiary Address whose cap is to be checked
+     * @return Current cap for individual beneficiary
+     */
+    function getCap(address beneficiary) public view returns (uint256) {
+        return _caps[beneficiary];
+    }
 
-  /**
-   * @dev Returns the amount contributed so far by a sepecific user.
-   * @param _beneficiary Address of contributor
-   * @return User contribution so far
-   */
-  function getUserContribution(address _beneficiary)
-    public view returns (uint256)
-  {
-    return contributions[_beneficiary];
-  }
+    /**
+     * @dev Returns the amount contributed so far by a specific beneficiary.
+     * @param beneficiary Address of contributor
+     * @return Beneficiary contribution so far
+     */
+    function getContribution(address beneficiary) public view returns (uint256) {
+        return _contributions[beneficiary];
+    }
 
-  /**
-   * @dev Extend parent behavior requiring purchase to respect the user's funding cap.
-   * @param _beneficiary Token purchaser
-   * @param _weiAmount Amount of wei contributed
-   */
-  function _preValidatePurchase(
-    address _beneficiary,
-    uint256 _weiAmount
-  )
-    internal
-  {
-    super._preValidatePurchase(_beneficiary, _weiAmount);
-    require(contributions[_beneficiary].add(_weiAmount) <= caps[_beneficiary]);
-  }
-
-  /**
-   * @dev Extend parent behavior to update user contributions
-   * @param _beneficiary Token purchaser
-   * @param _weiAmount Amount of wei contributed
-   */
-  function _updatePurchasingState(
-    address _beneficiary,
-    uint256 _weiAmount
-  )
-    internal
-  {
-    super._updatePurchasingState(_beneficiary, _weiAmount);
-    contributions[_beneficiary] = contributions[_beneficiary].add(_weiAmount);
-  }
+    /**
+     * @dev Extend parent behavior requiring purchase to respect the beneficiary's funding cap.
+     * @param beneficiary Token purchaser
+     * @param weiAmount Amount of wei contributed
+     */
+    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal view {
+        super._preValidatePurchase(beneficiary, weiAmount);
+        // solhint-disable-next-line max-line-length
+        require(_contributions[beneficiary].add(weiAmount) <= _caps[beneficiary], "IndividuallyCappedCrowdsale: beneficiary's cap exceeded");
+    }
 
+    /**
+     * @dev Extend parent behavior to update beneficiary contributions.
+     * @param beneficiary Token purchaser
+     * @param weiAmount Amount of wei contributed
+     */
+    function _updatePurchasingState(address beneficiary, uint256 weiAmount) internal {
+        super._updatePurchasingState(beneficiary, weiAmount);
+        _contributions[beneficiary] = _contributions[beneficiary].add(weiAmount);
+    }
 }

contracts/crowdsale/validation/PausableCrowdsale.sol

@@ -0,0 +1,21 @@
+pragma solidity ^0.5.7;
+
+import "../Crowdsale.sol";
+import "../../lifecycle/Pausable.sol";
+
+/**
+ * @title PausableCrowdsale
+ * @dev Extension of Crowdsale contract where purchases can be paused and unpaused by the pauser role.
+ */
+contract PausableCrowdsale is Crowdsale, Pausable {
+    /**
+     * @dev Validation of an incoming purchase. Use require statements to revert state when conditions are not met.
+     * Use super to concatenate validations.
+     * Adds the validation that the crowdsale must not be paused.
+     * @param _beneficiary Address performing the token purchase
+     * @param _weiAmount Value in wei involved in the purchase
+     */
+    function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal view whenNotPaused {
+        return super._preValidatePurchase(_beneficiary, _weiAmount);
+    }
+}

contracts/crowdsale/validation/TimedCrowdsale.sol

@@ -1,64 +1,98 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../../math/SafeMath.sol";
 import "../Crowdsale.sol";
 
-
 /**
  * @title TimedCrowdsale
  * @dev Crowdsale accepting contributions only within a time frame.
  */
 contract TimedCrowdsale is Crowdsale {
-  using SafeMath for uint256;
+    using SafeMath for uint256;
 
-  uint256 public openingTime;
-  uint256 public closingTime;
+    uint256 private _openingTime;
+    uint256 private _closingTime;
 
-  /**
-   * @dev Reverts if not in crowdsale time range.
-   */
-  modifier onlyWhileOpen {
-    // solium-disable-next-line security/no-block-members
-    require(block.timestamp >= openingTime && block.timestamp <= closingTime);
-    _;
-  }
+    /**
+     * Event for crowdsale extending
+     * @param newClosingTime new closing time
+     * @param prevClosingTime old closing time
+     */
+    event TimedCrowdsaleExtended(uint256 prevClosingTime, uint256 newClosingTime);
 
-  /**
-   * @dev Constructor, takes crowdsale opening and closing times.
-   * @param _openingTime Crowdsale opening time
-   * @param _closingTime Crowdsale closing time
-   */
-  constructor(uint256 _openingTime, uint256 _closingTime) public {
-    // solium-disable-next-line security/no-block-members
-    require(_openingTime >= block.timestamp);
-    require(_closingTime >= _openingTime);
+    /**
+     * @dev Reverts if not in crowdsale time range.
+     */
+    modifier onlyWhileOpen {
+        require(isOpen(), "TimedCrowdsale: not open");
+        _;
+    }
 
-    openingTime = _openingTime;
-    closingTime = _closingTime;
-  }
+    /**
+     * @dev Constructor, takes crowdsale opening and closing times.
+     * @param openingTime Crowdsale opening time
+     * @param closingTime Crowdsale closing time
+     */
+    constructor (uint256 openingTime, uint256 closingTime) public {
+        // solhint-disable-next-line not-rely-on-time
+        require(openingTime >= block.timestamp, "TimedCrowdsale: opening time is before current time");
+        // solhint-disable-next-line max-line-length
+        require(closingTime > openingTime, "TimedCrowdsale: opening time is not before closing time");
 
-  /**
-   * @dev Checks whether the period in which the crowdsale is open has already elapsed.
-   * @return Whether crowdsale period has elapsed
-   */
-  function hasClosed() public view returns (bool) {
-    // solium-disable-next-line security/no-block-members
-    return block.timestamp > closingTime;
-  }
+        _openingTime = openingTime;
+        _closingTime = closingTime;
+    }
 
-  /**
-   * @dev Extend parent behavior requiring to be within contributing period
-   * @param _beneficiary Token purchaser
-   * @param _weiAmount Amount of wei contributed
-   */
-  function _preValidatePurchase(
-    address _beneficiary,
-    uint256 _weiAmount
-  )
-    internal
-    onlyWhileOpen
-  {
-    super._preValidatePurchase(_beneficiary, _weiAmount);
-  }
+    /**
+     * @return the crowdsale opening time.
+     */
+    function openingTime() public view returns (uint256) {
+        return _openingTime;
+    }
 
+    /**
+     * @return the crowdsale closing time.
+     */
+    function closingTime() public view returns (uint256) {
+        return _closingTime;
+    }
+
+    /**
+     * @return true if the crowdsale is open, false otherwise.
+     */
+    function isOpen() public view returns (bool) {
+        // solhint-disable-next-line not-rely-on-time
+        return block.timestamp >= _openingTime && block.timestamp <= _closingTime;
+    }
+
+    /**
+     * @dev Checks whether the period in which the crowdsale is open has already elapsed.
+     * @return Whether crowdsale period has elapsed
+     */
+    function hasClosed() public view returns (bool) {
+        // solhint-disable-next-line not-rely-on-time
+        return block.timestamp > _closingTime;
+    }
+
+    /**
+     * @dev Extend parent behavior requiring to be within contributing period.
+     * @param beneficiary Token purchaser
+     * @param weiAmount Amount of wei contributed
+     */
+    function _preValidatePurchase(address beneficiary, uint256 weiAmount) internal onlyWhileOpen view {
+        super._preValidatePurchase(beneficiary, weiAmount);
+    }
+
+    /**
+     * @dev Extend crowdsale.
+     * @param newClosingTime Crowdsale closing time
+     */
+    function _extendTime(uint256 newClosingTime) internal {
+        require(!hasClosed(), "TimedCrowdsale: already closed");
+        // solhint-disable-next-line max-line-length
+        require(newClosingTime > _closingTime, "TimedCrowdsale: new closing time is before current closing time");
+
+        emit TimedCrowdsaleExtended(_closingTime, newClosingTime);
+        _closingTime = newClosingTime;
+    }
 }

contracts/crowdsale/validation/WhitelistCrowdsale.sol

@@ -0,0 +1,21 @@
+pragma solidity ^0.5.7;
+import "../Crowdsale.sol";
+import "../../access/roles/WhitelistedRole.sol";
+
+
+/**
+ * @title WhitelistCrowdsale
+ * @dev Crowdsale in which only whitelisted users can contribute.
+ */
+contract WhitelistCrowdsale is WhitelistedRole, Crowdsale {
+    /**
+     * @dev Extend parent behavior requiring beneficiary to be whitelisted. Note that no
+     * restriction is imposed on the account sending the transaction.
+     * @param _beneficiary Token beneficiary
+     * @param _weiAmount Amount of wei contributed
+     */
+    function _preValidatePurchase(address _beneficiary, uint256 _weiAmount) internal view {
+        require(isWhitelisted(_beneficiary), "WhitelistCrowdsale: beneficiary doesn't have the Whitelisted role");
+        super._preValidatePurchase(_beneficiary, _weiAmount);
+    }
+}

contracts/crowdsale/validation/WhitelistedCrowdsale.sol

@@ -1,27 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../Crowdsale.sol";
-import "../../access/Whitelist.sol";
-
-
-/**
- * @title WhitelistedCrowdsale
- * @dev Crowdsale in which only whitelisted users can contribute.
- */
-contract WhitelistedCrowdsale is Whitelist, Crowdsale {
-  /**
-   * @dev Extend parent behavior requiring beneficiary to be in whitelist.
-   * @param _beneficiary Token beneficiary
-   * @param _weiAmount Amount of wei contributed
-   */
-  function _preValidatePurchase(
-    address _beneficiary,
-    uint256 _weiAmount
-  )
-    onlyIfWhitelisted(_beneficiary)
-    internal
-  {
-    super._preValidatePurchase(_beneficiary, _weiAmount);
-  }
-
-}

contracts/cryptography/ECDSA.sol

@@ -0,0 +1,67 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title Elliptic curve signature operations
+ * @dev Based on https://gist.github.com/axic/5b33912c6f61ae6fd96d6c4a47afde6d
+ * TODO Remove this library once solidity supports passing a signature to ecrecover.
+ * See https://github.com/ethereum/solidity/issues/864
+ */
+
+library ECDSA {
+    /**
+     * @dev Recover signer address from a message by using their signature.
+     * @param hash bytes32 message, the hash is the signed message. What is recovered is the signer address.
+     * @param signature bytes signature, the signature is generated using web3.eth.sign()
+     */
+    function recover(bytes32 hash, bytes memory signature) internal pure returns (address) {
+        // Check the signature length
+        if (signature.length != 65) {
+            return (address(0));
+        }
+
+        // Divide the signature in r, s and v variables
+        bytes32 r;
+        bytes32 s;
+        uint8 v;
+
+        // ecrecover takes the signature parameters, and the only way to get them
+        // currently is to use assembly.
+        // solhint-disable-next-line no-inline-assembly
+        assembly {
+            r := mload(add(signature, 0x20))
+            s := mload(add(signature, 0x40))
+            v := byte(0, mload(add(signature, 0x60)))
+        }
+
+        // EIP-2 still allows signature malleability for ecrecover(). Remove this possibility and make the signature
+        // unique. Appendix F in the Ethereum Yellow paper (https://ethereum.github.io/yellowpaper/paper.pdf), defines
+        // the valid range for s in (281): 0 < s < secp256k1n ÷ 2 + 1, and for v in (282): v ∈ {27, 28}. Most
+        // signatures from current libraries generate a unique signature with an s-value in the lower half order.
+        //
+        // If your library generates malleable signatures, such as s-values in the upper range, calculate a new s-value
+        // with 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEBAAEDCE6AF48A03BBFD25E8CD0364141 - s1 and flip v from 27 to 28 or
+        // vice versa. If your library also generates signatures with 0/1 for v instead 27/28, add 27 to v to accept
+        // these malleable signatures as well.
+        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) {
+            return address(0);
+        }
+
+        if (v != 27 && v != 28) {
+            return address(0);
+        }
+
+        // If the signature is valid (and not malleable), return the signer address
+        return ecrecover(hash, v, r, s);
+    }
+
+    /**
+     * toEthSignedMessageHash
+     * @dev Prefix a bytes32 value with "\x19Ethereum Signed Message:"
+     * and hash the result.
+     */
+    function toEthSignedMessageHash(bytes32 hash) internal pure returns (bytes32) {
+        // 32 is the length in bytes of hash,
+        // enforced by the type signature above
+        return keccak256(abi.encodePacked("\x19Ethereum Signed Message:\n32", hash));
+    }
+}

contracts/cryptography/MerkleProof.sol

@@ -0,0 +1,34 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title MerkleProof
+ * @dev Merkle proof verification based on
+ * https://github.com/ameensol/merkle-tree-solidity/blob/master/src/MerkleProof.sol
+ */
+library MerkleProof {
+    /**
+     * @dev Verifies a Merkle proof proving the existence of a leaf in a Merkle tree. Assumes that each pair of leaves
+     * and each pair of pre-images are sorted.
+     * @param proof Merkle proof containing sibling hashes on the branch from the leaf to the root of the Merkle tree
+     * @param root Merkle root
+     * @param leaf Leaf of Merkle tree
+     */
+    function verify(bytes32[] memory proof, bytes32 root, bytes32 leaf) internal pure returns (bool) {
+        bytes32 computedHash = leaf;
+
+        for (uint256 i = 0; i < proof.length; i++) {
+            bytes32 proofElement = proof[i];
+
+            if (computedHash < proofElement) {
+                // Hash(current computed hash + current element of the proof)
+                computedHash = keccak256(abi.encodePacked(computedHash, proofElement));
+            } else {
+                // Hash(current element of the proof + current computed hash)
+                computedHash = keccak256(abi.encodePacked(proofElement, computedHash));
+            }
+        }
+
+        // Check if the computed hash (root) is equal to the provided root
+        return computedHash == root;
+    }
+}

contracts/drafts/Counters.sol

@@ -0,0 +1,37 @@
+pragma solidity ^0.5.7;
+
+import "../math/SafeMath.sol";
+
+/**
+ * @title Counters
+ * @author Matt Condon (@shrugs)
+ * @dev Provides counters that can only be incremented or decremented by one. This can be used e.g. to track the number
+ * of elements in a mapping, issuing ERC721 ids, or counting request ids.
+ *
+ * Include with `using Counters for Counters.Counter;`
+ * Since it is not possible to overflow a 256 bit integer with increments of one, `increment` can skip the SafeMath
+ * overflow check, thereby saving gas. This does assume however correct usage, in that the underlying `_value` is never
+ * directly accessed.
+ */
+library Counters {
+    using SafeMath for uint256;
+
+    struct Counter {
+        // This variable should never be directly accessed by users of the library: interactions must be restricted to
+        // the library's function. As of Solidity v0.5.2, this cannot be enforced, though there is a proposal to add
+        // this feature: see https://github.com/ethereum/solidity/issues/4637
+        uint256 _value; // default: 0
+    }
+
+    function current(Counter storage counter) internal view returns (uint256) {
+        return counter._value;
+    }
+
+    function increment(Counter storage counter) internal {
+        counter._value += 1;
+    }
+
+    function decrement(Counter storage counter) internal {
+        counter._value = counter._value.sub(1);
+    }
+}

contracts/drafts/ERC1046/ERC20Metadata.sol

@@ -0,0 +1,24 @@
+pragma solidity ^0.5.7;
+
+import "../../token/ERC20/IERC20.sol";
+
+/**
+ * @title ERC-1047 Token Metadata
+ * @dev See https://eips.ethereum.org/EIPS/eip-1046
+ * @dev tokenURI must respond with a URI that implements https://eips.ethereum.org/EIPS/eip-1047
+ */
+contract ERC20Metadata {
+    string private _tokenURI;
+
+    constructor (string memory tokenURI_) public {
+        _setTokenURI(tokenURI_);
+    }
+
+    function tokenURI() external view returns (string memory) {
+        return _tokenURI;
+    }
+
+    function _setTokenURI(string memory tokenURI_) internal {
+        _tokenURI = tokenURI_;
+    }
+}

contracts/drafts/ERC1820Implementer.sol

@@ -0,0 +1,24 @@
+pragma solidity ^0.5.7;
+
+import "./IERC1820Implementer.sol";
+
+/**
+ * @dev ERC1820Implementer allows your contract to implement an interface for another account in the sense of ERC1820.
+ * That account or one of its ERC1820 managers can register the implementer in the ERC1820 registry, but the registry
+ * will first check with the implementer if it agrees to it, and only allow it if it does. Using the internal
+ * function _registerInterfaceForAddress provided by this contract, you are expressing this agreement,
+ * and you will be able to register the contract as an implementer in the registry for that account.
+ */
+contract ERC1820Implementer is IERC1820Implementer {
+    bytes32 constant private ERC1820_ACCEPT_MAGIC = keccak256(abi.encodePacked("ERC1820_ACCEPT_MAGIC"));
+
+    mapping(bytes32 => mapping(address => bool)) private _supportedInterfaces;
+
+    function canImplementInterfaceForAddress(bytes32 interfaceHash, address account) external view returns (bytes32) {
+        return _supportedInterfaces[interfaceHash][account] ? ERC1820_ACCEPT_MAGIC : bytes32(0x00);
+    }
+
+    function _registerInterfaceForAddress(bytes32 interfaceHash, address account) internal {
+        _supportedInterfaces[interfaceHash][account] = true;
+    }
+}

contracts/drafts/ERC20Migrator.sol

@@ -0,0 +1,102 @@
+pragma solidity ^0.5.7;
+
+import "../token/ERC20/IERC20.sol";
+import "../token/ERC20/ERC20Mintable.sol";
+import "../token/ERC20/SafeERC20.sol";
+import "../math/Math.sol";
+
+/**
+ * @title ERC20Migrator
+ * @dev This contract can be used to migrate an ERC20 token from one
+ * contract to another, where each token holder has to opt-in to the migration.
+ * To opt-in, users must approve for this contract the number of tokens they
+ * want to migrate. Once the allowance is set up, anyone can trigger the
+ * migration to the new token contract. In this way, token holders "turn in"
+ * their old balance and will be minted an equal amount in the new token.
+ * The new token contract must be mintable. For the precise interface refer to
+ * OpenZeppelin's ERC20Mintable, but the only functions that are needed are
+ * `isMinter(address)` and `mint(address, amount)`. The migrator will check
+ * that it is a minter for the token.
+ * The balance from the legacy token will be transferred to the migrator, as it
+ * is migrated, and remain there forever.
+ * Although this contract can be used in many different scenarios, the main
+ * motivation was to provide a way to migrate ERC20 tokens into an upgradeable
+ * version of it using ZeppelinOS. To read more about how this can be done
+ * using this implementation, please follow the official documentation site of
+ * ZeppelinOS: https://docs.zeppelinos.org/docs/erc20_onboarding.html
+ * Example of usage:
+ * ```
+ * const migrator = await ERC20Migrator.new(legacyToken.address);
+ * await newToken.addMinter(migrator.address);
+ * await migrator.beginMigration(newToken.address);
+ * ```
+ */
+contract ERC20Migrator {
+    using SafeERC20 for IERC20;
+
+    /// Address of the old token contract
+    IERC20 private _legacyToken;
+
+    /// Address of the new token contract
+    ERC20Mintable private _newToken;
+
+    /**
+     * @param legacyToken address of the old token contract
+     */
+    constructor (IERC20 legacyToken) public {
+        require(address(legacyToken) != address(0), "ERC20Migrator: legacy token is the zero address");
+        _legacyToken = legacyToken;
+    }
+
+    /**
+     * @dev Returns the legacy token that is being migrated.
+     */
+    function legacyToken() public view returns (IERC20) {
+        return _legacyToken;
+    }
+
+    /**
+     * @dev Returns the new token to which we are migrating.
+     */
+    function newToken() public view returns (IERC20) {
+        return _newToken;
+    }
+
+    /**
+     * @dev Begins the migration by setting which is the new token that will be
+     * minted. This contract must be a minter for the new token.
+     * @param newToken_ the token that will be minted
+     */
+    function beginMigration(ERC20Mintable newToken_) public {
+        require(address(_newToken) == address(0), "ERC20Migrator: migration already started");
+        require(address(newToken_) != address(0), "ERC20Migrator: new token is the zero address");
+        //solhint-disable-next-line max-line-length
+        require(newToken_.isMinter(address(this)), "ERC20Migrator: not a minter for new token");
+
+        _newToken = newToken_;
+    }
+
+    /**
+     * @dev Transfers part of an account's balance in the old token to this
+     * contract, and mints the same amount of new tokens for that account.
+     * @param account whose tokens will be migrated
+     * @param amount amount of tokens to be migrated
+     */
+    function migrate(address account, uint256 amount) public {
+        require(address(_newToken) != address(0), "ERC20Migrator: migration not started");
+        _legacyToken.safeTransferFrom(account, address(this), amount);
+        _newToken.mint(account, amount);
+    }
+
+    /**
+     * @dev Transfers all of an account's allowed balance in the old token to
+     * this contract, and mints the same amount of new tokens for that account.
+     * @param account whose tokens will be migrated
+     */
+    function migrateAll(address account) public {
+        uint256 balance = _legacyToken.balanceOf(account);
+        uint256 allowance = _legacyToken.allowance(account, address(this));
+        uint256 amount = Math.min(balance, allowance);
+        migrate(account, amount);
+    }
+}

contracts/drafts/ERC20Snapshot.sol

@@ -0,0 +1,140 @@
+pragma solidity ^0.5.7;
+
+import "../math/SafeMath.sol";
+import "../utils/Arrays.sol";
+import "../drafts/Counters.sol";
+import "../token/ERC20/ERC20.sol";
+
+/**
+ * @title ERC20 token with snapshots.
+ * @dev Inspired by Jordi Baylina's MiniMeToken to record historical balances:
+ * https://github.com/Giveth/minime/blob/ea04d950eea153a04c51fa510b068b9dded390cb/contracts/MiniMeToken.sol
+ * When a snapshot is made, the balances and totalSupply at the time of the snapshot are recorded for later
+ * access.
+ *
+ * To make a snapshot, call the `snapshot` function, which will emit the `Snapshot` event and return a snapshot id.
+ * To get the total supply from a snapshot, call the function `totalSupplyAt` with the snapshot id.
+ * To get the balance of an account from a snapshot, call the `balanceOfAt` function with the snapshot id and the
+ * account address.
+ * @author Validity Labs AG <info@validitylabs.org>
+ */
+contract ERC20Snapshot is ERC20 {
+    using SafeMath for uint256;
+    using Arrays for uint256[];
+    using Counters for Counters.Counter;
+
+    // Snapshotted values have arrays of ids and the value corresponding to that id. These could be an array of a
+    // Snapshot struct, but that would impede usage of functions that work on an array.
+    struct Snapshots {
+        uint256[] ids;
+        uint256[] values;
+    }
+
+    mapping (address => Snapshots) private _accountBalanceSnapshots;
+    Snapshots private _totalSupplySnapshots;
+
+    // Snapshot ids increase monotonically, with the first value being 1. An id of 0 is invalid.
+    Counters.Counter private _currentSnapshotId;
+
+    event Snapshot(uint256 id);
+
+    // Creates a new snapshot id. Balances are only stored in snapshots on demand: unless a snapshot was taken, a
+    // balance change will not be recorded. This means the extra added cost of storing snapshotted balances is only paid
+    // when required, but is also flexible enough that it allows for e.g. daily snapshots.
+    function snapshot() public returns (uint256) {
+        _currentSnapshotId.increment();
+
+        uint256 currentId = _currentSnapshotId.current();
+        emit Snapshot(currentId);
+        return currentId;
+    }
+
+    function balanceOfAt(address account, uint256 snapshotId) public view returns (uint256) {
+        (bool snapshotted, uint256 value) = _valueAt(snapshotId, _accountBalanceSnapshots[account]);
+
+        return snapshotted ? value : balanceOf(account);
+    }
+
+    function totalSupplyAt(uint256 snapshotId) public view returns(uint256) {
+        (bool snapshotted, uint256 value) = _valueAt(snapshotId, _totalSupplySnapshots);
+
+        return snapshotted ? value : totalSupply();
+    }
+
+    // _transfer, _mint and _burn are the only functions where the balances are modified, so it is there that the
+    // snapshots are updated. Note that the update happens _before_ the balance change, with the pre-modified value.
+    // The same is true for the total supply and _mint and _burn.
+    function _transfer(address from, address to, uint256 value) internal {
+        _updateAccountSnapshot(from);
+        _updateAccountSnapshot(to);
+
+        super._transfer(from, to, value);
+    }
+
+    function _mint(address account, uint256 value) internal {
+        _updateAccountSnapshot(account);
+        _updateTotalSupplySnapshot();
+
+        super._mint(account, value);
+    }
+
+    function _burn(address account, uint256 value) internal {
+        _updateAccountSnapshot(account);
+        _updateTotalSupplySnapshot();
+
+        super._burn(account, value);
+    }
+
+    // When a valid snapshot is queried, there are three possibilities:
+    //  a) The queried value was not modified after the snapshot was taken. Therefore, a snapshot entry was never
+    //  created for this id, and all stored snapshot ids are smaller than the requested one. The value that corresponds
+    //  to this id is the current one.
+    //  b) The queried value was modified after the snapshot was taken. Therefore, there will be an entry with the
+    //  requested id, and its value is the one to return.
+    //  c) More snapshots were created after the requested one, and the queried value was later modified. There will be
+    //  no entry for the requested id: the value that corresponds to it is that of the smallest snapshot id that is
+    //  larger than the requested one.
+    //
+    // In summary, we need to find an element in an array, returning the index of the smallest value that is larger if
+    // it is not found, unless said value doesn't exist (e.g. when all values are smaller). Arrays.findUpperBound does
+    // exactly this.
+    function _valueAt(uint256 snapshotId, Snapshots storage snapshots)
+        private view returns (bool, uint256)
+    {
+        require(snapshotId > 0, "ERC20Snapshot: id is 0");
+        // solhint-disable-next-line max-line-length
+        require(snapshotId <= _currentSnapshotId.current(), "ERC20Snapshot: nonexistent id");
+
+        uint256 index = snapshots.ids.findUpperBound(snapshotId);
+
+        if (index == snapshots.ids.length) {
+            return (false, 0);
+        } else {
+            return (true, snapshots.values[index]);
+        }
+    }
+
+    function _updateAccountSnapshot(address account) private {
+        _updateSnapshot(_accountBalanceSnapshots[account], balanceOf(account));
+    }
+
+    function _updateTotalSupplySnapshot() private {
+        _updateSnapshot(_totalSupplySnapshots, totalSupply());
+    }
+
+    function _updateSnapshot(Snapshots storage snapshots, uint256 currentValue) private {
+        uint256 currentId = _currentSnapshotId.current();
+        if (_lastSnapshotId(snapshots.ids) < currentId) {
+            snapshots.ids.push(currentId);
+            snapshots.values.push(currentValue);
+        }
+    }
+
+    function _lastSnapshotId(uint256[] storage ids) private view returns (uint256) {
+        if (ids.length == 0) {
+            return 0;
+        } else {
+            return ids[ids.length - 1];
+        }
+    }
+}

contracts/drafts/ERC777/ERC777.sol

@@ -0,0 +1,357 @@
+pragma solidity ^0.5.7;
+
+import "./IERC777.sol";
+import "./IERC777Recipient.sol";
+import "./IERC777Sender.sol";
+import "../../math/SafeMath.sol";
+import "../../utils/Address.sol";
+import "../IERC1820Registry.sol";
+
+/**
+ * @title ERC777 token implementation
+ * @author etsvigun <utgarda@gmail.com>, Bertrand Masius <github@catageeks.tk>
+ */
+contract ERC777 is IERC777 {
+    using SafeMath for uint256;
+    using Address for address;
+
+    IERC1820Registry private _erc1820 = IERC1820Registry(0x1820a4B7618BdE71Dce8cdc73aAB6C95905faD24);
+
+    string private _name;
+
+    string private _symbol;
+
+    mapping(address => uint256) private _balances;
+
+    uint256 private _totalSupply;
+
+    uint256 private _granularity;
+
+    bytes32 constant private TOKENS_SENDER_INTERFACE_HASH = keccak256("ERC777TokensSender");
+    bytes32 constant private TOKENS_RECIPIENT_INTERFACE_HASH = keccak256("ERC777TokensRecipient");
+
+    // This isn't ever read from - it's only used to respond to the defaultOperators query.
+    address[] private _defaultOperatorsArray;
+
+    // Immutable, but accounts may revoke them (tracked in __revokedDefaultOperators).
+    mapping(address => bool) private _defaultOperators;
+
+    // For each account, a mapping of its operators and revoked default operators.
+    mapping(address => mapping(address => bool)) private _operators;
+    mapping(address => mapping(address => bool)) private _revokedDefaultOperators;
+
+    constructor(
+        string memory name,
+        string memory symbol,
+        uint256 granularity,
+        address[] memory defaultOperators
+    ) public {
+        require(granularity > 0);
+
+        _name = name;
+        _symbol = symbol;
+        _granularity = granularity;
+
+        _defaultOperatorsArray = defaultOperators;
+        for (uint256 i = 0; i < _defaultOperatorsArray.length; i++) {
+            _defaultOperators[_defaultOperatorsArray[i]] = true;
+        }
+
+        // register interface
+        _erc1820.setInterfaceImplementer(address(this), keccak256("ERC777Token"), address(this));
+    }
+
+    /**
+     * @dev Send the amount of tokens from the address msg.sender to the address to
+     * @param to address recipient address
+     * @param amount uint256 amount of tokens to transfer
+     * @param data bytes information attached to the send, and intended for the recipient (to)
+     */
+    function send(address to, uint256 amount, bytes calldata data) external {
+        _send(msg.sender, msg.sender, to, amount, data, "");
+    }
+
+    /**
+     * @dev Send the amount of tokens on behalf of the address from to the address to
+     * @param from address token holder address.
+     * @param to address recipient address
+     * @param amount uint256 amount of tokens to transfer
+     * @param data bytes information attached to the send, and intended for the recipient (to)
+     * @param operatorData bytes extra information provided by the operator (if any)
+     */
+    function operatorSend(
+        address from,
+        address to,
+        uint256 amount,
+        bytes calldata data,
+        bytes calldata operatorData
+    )
+    external
+    {
+        require(isOperatorFor(msg.sender, from));
+        _send(msg.sender, from, to, amount, data, operatorData);
+    }
+
+    /**
+     * @dev Burn the amount of tokens from the address msg.sender
+     * @param amount uint256 amount of tokens to transfer
+     * @param data bytes extra information provided by the token holder
+     */
+    function burn(uint256 amount, bytes calldata data) external {
+        _burn(msg.sender, msg.sender, amount, data, "");
+    }
+
+    /**
+     * @dev Burn the amount of tokens on behalf of the address from
+     * @param from address token holder address.
+     * @param amount uint256 amount of tokens to transfer
+     * @param data bytes extra information provided by the token holder
+     * @param operatorData bytes extra information provided by the operator (if any)
+     */
+    function operatorBurn(address from, uint256 amount, bytes calldata data, bytes calldata operatorData) external {
+        require(isOperatorFor(msg.sender, from));
+        _burn(msg.sender, from, amount, data, operatorData);
+    }
+
+    /**
+     * @dev Authorize an operator for the sender
+     * @param operator address to be authorized as operator
+     */
+    function authorizeOperator(address operator) external {
+        require(msg.sender != operator);
+
+        if (_defaultOperators[operator]) {
+            delete _revokedDefaultOperators[msg.sender][operator];
+        } else {
+            _operators[msg.sender][operator] = true;
+        }
+
+        emit AuthorizedOperator(operator, msg.sender);
+    }
+
+    /**
+     * @dev Revoke operator rights from one of the default operators
+     * @param operator address to revoke operator rights from
+     */
+    function revokeOperator(address operator) external {
+        require(operator != msg.sender);
+
+        if (_defaultOperators[operator]) {
+            _revokedDefaultOperators[msg.sender][operator] = true;
+        } else {
+            delete _operators[msg.sender][operator];
+        }
+
+        emit RevokedOperator(operator, msg.sender);
+    }
+
+    /**
+     * @return the name of the token.
+     */
+    function name() public view returns (string memory) {
+        return _name;
+    }
+
+    /**
+     * @return the symbol of the token.
+     */
+    function symbol() public view returns (string memory) {
+        return _symbol;
+    }
+
+    /**
+     * @dev Total number of tokens in existence
+     */
+    function totalSupply() public view returns (uint256) {
+        return _totalSupply;
+    }
+
+    /**
+     * @dev Gets the balance of the specified address.
+     * @param tokenHolder The address to query the balance of.
+        * @return uint256 representing the amount owned by the specified address.
+     */
+    function balanceOf(address tokenHolder) public view returns (uint256) {
+        return _balances[tokenHolder];
+    }
+
+    /**
+     * @dev Gets the token's granularity,
+     * i.e. the smallest number of tokens (in the basic unit)
+     * which may be minted, sent or burned at any time
+     * @return uint256 granularity
+     */
+    function granularity() public view returns (uint256) {
+        return _granularity;
+    }
+
+    /**
+     * @dev Get the list of default operators as defined by the token contract.
+     * @return address[] default operators
+     */
+    function defaultOperators() public view returns (address[] memory) {
+        return _defaultOperatorsArray;
+    }
+
+    /**
+     * @dev Indicate whether an address
+     * is an operator of the tokenHolder address
+     * @param operator address which may be an operator of tokenHolder
+     * @param tokenHolder address of a token holder which may have the operator
+     * address as an operator.
+     */
+    function isOperatorFor(
+        address operator,
+        address tokenHolder
+    ) public view returns (bool) {
+        return operator == tokenHolder ||
+            (_defaultOperators[operator] && !_revokedDefaultOperators[tokenHolder][operator]) ||
+            _operators[tokenHolder][operator];
+    }
+
+    /**
+     * @dev Mint tokens. Does not check authorization of operator
+     * @dev the caller may ckeck that operator is authorized before calling
+     * @param operator address operator requesting the operation
+     * @param to address token recipient address
+     * @param amount uint256 amount of tokens to mint
+     * @param userData bytes extra information defined by the token recipient (if any)
+     * @param operatorData bytes extra information provided by the operator (if any)
+     */
+    function _mint(
+        address operator,
+        address to,
+        uint256 amount,
+        bytes memory userData,
+        bytes memory operatorData
+    )
+    internal
+    {
+        require(to != address(0));
+        require((amount % _granularity) == 0);
+
+        // Update state variables
+        _totalSupply = _totalSupply.add(amount);
+        _balances[to] = _balances[to].add(amount);
+
+        _callTokensReceived(operator, address(0), to, amount, userData, operatorData);
+
+        emit Minted(operator, to, amount, userData, operatorData);
+    }
+
+    /**
+     * @dev Send tokens
+     * @param operator address operator requesting the transfer
+     * @param from address token holder address
+     * @param to address recipient address
+     * @param amount uint256 amount of tokens to transfer
+     * @param userData bytes extra information provided by the token holder (if any)
+     * @param operatorData bytes extra information provided by the operator (if any)
+     */
+    function _send(
+        address operator,
+        address from,
+        address to,
+        uint256 amount,
+        bytes memory userData,
+        bytes memory operatorData
+    )
+    private
+    {
+        require(from != address(0));
+        require(to != address(0));
+        require((amount % _granularity) == 0);
+
+        _callTokensToSend(operator, from, to, amount, userData, operatorData);
+
+        // Update state variables
+        _balances[from] = _balances[from].sub(amount);
+        _balances[to] = _balances[to].add(amount);
+
+        _callTokensReceived(operator, from, to, amount, userData, operatorData);
+
+        emit Sent(operator, from, to, amount, userData, operatorData);
+    }
+
+    /**
+     * @dev Burn tokens
+     * @param operator address operator requesting the operation
+     * @param from address token holder address
+     * @param amount uint256 amount of tokens to burn
+     * @param data bytes extra information provided by the token holder
+     * @param operatorData bytes extra information provided by the operator (if any)
+     */
+    function _burn(
+        address operator,
+        address from,
+        uint256 amount,
+        bytes memory data,
+        bytes memory operatorData
+    )
+    private
+    {
+        require(from != address(0));
+        require((amount % _granularity) == 0);
+
+        _callTokensToSend(operator, from, address(0), amount, data, operatorData);
+
+        // Update state variables
+        _totalSupply = _totalSupply.sub(amount);
+        _balances[from] = _balances[from].sub(amount);
+
+        emit Burned(operator, from, amount, data, operatorData);
+    }
+
+    /**
+     * @dev Call from.tokensToSend() if the interface is registered
+     * @param operator address operator requesting the transfer
+     * @param from address token holder address
+     * @param to address recipient address
+     * @param amount uint256 amount of tokens to transfer
+     * @param userData bytes extra information provided by the token holder (if any)
+     * @param operatorData bytes extra information provided by the operator (if any)
+     */
+    function _callTokensToSend(
+        address operator,
+        address from,
+        address to,
+        uint256 amount,
+        bytes memory userData,
+        bytes memory operatorData
+    )
+    private
+    {
+        address implementer = _erc1820.getInterfaceImplementer(from, TOKENS_SENDER_INTERFACE_HASH);
+        if (implementer != address(0)) {
+            IERC777Sender(implementer).tokensToSend(operator, from, to, amount, userData, operatorData);
+        }
+    }
+
+    /**
+     * @dev Call to.tokensReceived() if the interface is registered. Reverts if the recipient is a contract but
+     * tokensReceived() was not registered for the recipient
+     * @param operator address operator requesting the transfer
+     * @param from address token holder address
+     * @param to address recipient address
+     * @param amount uint256 amount of tokens to transfer
+     * @param userData bytes extra information provided by the token holder (if any)
+     * @param operatorData bytes extra information provided by the operator (if any)
+     */
+    function _callTokensReceived(
+        address operator,
+        address from,
+        address to,
+        uint256 amount,
+        bytes memory userData,
+        bytes memory operatorData
+    )
+    private
+    {
+        address implementer = _erc1820.getInterfaceImplementer(to, TOKENS_RECIPIENT_INTERFACE_HASH);
+        if (implementer != address(0)) {
+            IERC777Recipient(implementer).tokensReceived(operator, from, to, amount, userData, operatorData);
+        } else {
+            require(!to.isContract());
+        }
+    }
+}

contracts/drafts/ERC777/IERC777.sol

@@ -0,0 +1,61 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title ERC777 token interface
+ * @dev See https://eips.ethereum.org/EIPS/eip-777
+ */
+interface IERC777 {
+    function authorizeOperator(address operator) external;
+
+    function revokeOperator(address operator) external;
+
+    function send(address to, uint256 amount, bytes calldata data) external;
+
+    function operatorSend(
+        address from,
+        address to,
+        uint256 amount,
+        bytes calldata data,
+        bytes calldata operatorData
+    ) external;
+
+    function burn(uint256 amount, bytes calldata data) external;
+
+    function operatorBurn(
+        address from,
+        uint256 amount,
+        bytes calldata data,
+        bytes calldata operatorData
+    ) external;
+
+    function name() external view returns (string memory);
+
+    function symbol() external view returns (string memory);
+
+    function totalSupply() external view returns (uint256);
+
+    function balanceOf(address owner) external view returns (uint256);
+
+    function granularity() external view returns (uint256);
+
+    function defaultOperators() external view returns (address[] memory);
+
+    function isOperatorFor(address operator, address tokenHolder) external view returns (bool);
+
+    event Sent(
+        address indexed operator,
+        address indexed from,
+        address indexed to,
+        uint256 amount,
+        bytes data,
+        bytes operatorData
+    );
+
+    event Minted(address indexed operator, address indexed to, uint256 amount, bytes data, bytes operatorData);
+
+    event Burned(address indexed operator, address indexed from, uint256 amount, bytes data, bytes operatorData);
+
+    event AuthorizedOperator(address indexed operator, address indexed tokenHolder);
+
+    event RevokedOperator(address indexed operator, address indexed tokenHolder);
+}

contracts/drafts/ERC777/IERC777Recipient.sol

@@ -0,0 +1,16 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title ERC777 token recipient interface
+ * @dev See https://eips.ethereum.org/EIPS/eip-777
+ */
+interface IERC777Recipient {
+    function tokensReceived(
+        address operator,
+        address from,
+        address to,
+        uint amount,
+        bytes calldata userData,
+        bytes calldata operatorData
+    ) external;
+}

contracts/drafts/ERC777/IERC777Sender.sol

@@ -0,0 +1,16 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title ERC777 token sender interface
+ * @dev See https://eips.ethereum.org/EIPS/eip-777
+ */
+interface IERC777Sender {
+    function tokensToSend(
+        address operator,
+        address from,
+        address to,
+        uint amount,
+        bytes calldata userData,
+        bytes calldata operatorData
+    ) external;
+}

contracts/drafts/IERC1820Implementer.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title IERC1820Implementer
+ * Interface for contracts that will be registered as implementers in the ERC1820 registry.
+ * @notice For more details, see https://eips.ethereum.org/EIPS/eip-1820
+ */
+interface IERC1820Implementer {
+    /**
+     * @notice Indicates whether the contract implements the interface `interfaceHash` for the address `account` or
+     * not.
+     * @param interfaceHash keccak256 hash of the name of the interface
+     * @param account Address for which the contract will implement the interface
+     * @return ERC1820_ACCEPT_MAGIC only if the contract implements `interfaceHash` for the address `account`.
+     */
+    function canImplementInterfaceForAddress(bytes32 interfaceHash, address account) external view returns (bytes32);
+}

contracts/drafts/IERC1820Registry.sol

@@ -0,0 +1,90 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title ERC1820 Pseudo-introspection Registry Contract
+ * @author Jordi Baylina and Jacques Dafflon
+ * @notice For more details, see https://eips.ethereum.org/EIPS/eip-1820
+ */
+interface IERC1820Registry {
+    /**
+     * @notice Sets the contract which implements a specific interface for an address.
+     * Only the manager defined for that address can set it.
+     * (Each address is the manager for itself until it sets a new manager.)
+     * @param account Address for which to set the interface.
+     * (If 'account' is the zero address then 'msg.sender' is assumed.)
+     * @param interfaceHash Keccak256 hash of the name of the interface as a string.
+     * E.g., 'web3.utils.keccak256("ERC777TokensRecipient")' for the 'ERC777TokensRecipient' interface.
+     * @param implementer Contract address implementing `interfaceHash` for `account.address()`.
+     */
+    function setInterfaceImplementer(address account, bytes32 interfaceHash, address implementer) external;
+
+    /**
+     * @notice Sets `newManager.address()` as manager for `account.address()`.
+     * The new manager will be able to call 'setInterfaceImplementer' for `account.address()`.
+     * @param account Address for which to set the new manager.
+     * @param newManager Address of the new manager for `addr.address()`.
+     * (Pass '0x0' to reset the manager to `account.address()`.)
+     */
+    function setManager(address account, address newManager) external;
+
+    /**
+     *  @notice Updates the cache with whether the contract implements an ERC165 interface or not.
+     *  @param account Address of the contract for which to update the cache.
+     *  @param interfaceId ERC165 interface for which to update the cache.
+     */
+    function updateERC165Cache(address account, bytes4 interfaceId) external;
+
+    /**
+     *  @notice Get the manager of an address.
+     *  @param account Address for which to return the manager.
+     *  @return Address of the manager for a given address.
+     */
+    function getManager(address account) external view returns (address);
+
+    /**
+     *  @notice Query if an address implements an interface and through which contract.
+     *  @param account Address being queried for the implementer of an interface.
+     *  (If 'account' is the zero address then 'msg.sender' is assumed.)
+     *  @param interfaceHash Keccak256 hash of the name of the interface as a string.
+     *  E.g., 'web3.utils.keccak256("ERC777TokensRecipient")' for the 'ERC777TokensRecipient' interface.
+     *  @return The address of the contract which implements the interface `interfaceHash` for `account.address()`
+     *  or '0' if `account.address()` did not register an implementer for this interface.
+     */
+    function getInterfaceImplementer(address account, bytes32 interfaceHash) external view returns (address);
+
+    /**
+     *  @notice Checks whether a contract implements an ERC165 interface or not.
+     *  If the result is not cached a direct lookup on the contract address is performed.
+     *  If the result is not cached or the cached value is out-of-date, the cache MUST be updated manually by calling
+     *  'updateERC165Cache' with the contract address.
+     *  @param account Address of the contract to check.
+     *  @param interfaceId ERC165 interface to check.
+     *  @return True if `account.address()` implements `interfaceId`, false otherwise.
+     */
+    function implementsERC165Interface(address account, bytes4 interfaceId) external view returns (bool);
+
+    /**
+     *  @notice Checks whether a contract implements an ERC165 interface or not without using nor updating the cache.
+     *  @param account Address of the contract to check.
+     *  @param interfaceId ERC165 interface to check.
+     *  @return True if `account.address()` implements `interfaceId`, false otherwise.
+     */
+    function implementsERC165InterfaceNoCache(address account, bytes4 interfaceId) external view returns (bool);
+
+    /**
+     *  @notice Compute the keccak256 hash of an interface given its name.
+     *  @param interfaceName Name of the interface.
+     *  @return The keccak256 hash of an interface name.
+     */
+    function interfaceHash(string calldata interfaceName) external pure returns (bytes32);
+
+    /**
+     *  @notice Indicates a contract is the `implementer` of `interfaceHash` for `account`.
+     */
+    event InterfaceImplementerSet(address indexed account, bytes32 indexed interfaceHash, address indexed implementer);
+
+    /**
+     *  @notice Indicates `newManager` is the address of the new manager for `account`.
+     */
+    event ManagerChanged(address indexed account, address indexed newManager);
+}

contracts/drafts/SignatureBouncer.sol

@@ -0,0 +1,122 @@
+pragma solidity ^0.5.7;
+
+import "../access/roles/SignerRole.sol";
+import "../cryptography/ECDSA.sol";
+
+/**
+ * @title SignatureBouncer
+ * @author PhABC, Shrugs and aflesher
+ * @dev SignatureBouncer allows users to submit a signature as a permission to
+ * do an action.
+ * If the signature is from one of the authorized signer addresses, the
+ * signature is valid.
+ * Note that SignatureBouncer offers no protection against replay attacks, users
+ * must add this themselves!
+ *
+ * Signer addresses can be individual servers signing grants or different
+ * users within a decentralized club that have permission to invite other
+ * members. This technique is useful for whitelists and airdrops; instead of
+ * putting all valid addresses on-chain, simply sign a grant of the form
+ * keccak256(abi.encodePacked(`:contractAddress` + `:granteeAddress`)) using a
+ * valid signer address.
+ * Then restrict access to your crowdsale/whitelist/airdrop using the
+ * `onlyValidSignature` modifier (or implement your own using _isValidSignature).
+ * In addition to `onlyValidSignature`, `onlyValidSignatureAndMethod` and
+ * `onlyValidSignatureAndData` can be used to restrict access to only a given
+ * method or a given method with given parameters respectively.
+ * See the tests in SignatureBouncer.test.js for specific usage examples.
+ *
+ * @notice A method that uses the `onlyValidSignatureAndData` modifier must make
+ * the _signature parameter the "last" parameter. You cannot sign a message that
+ * has its own signature in it so the last 128 bytes of msg.data (which
+ * represents the length of the _signature data and the _signature data itself)
+ * is ignored when validating. Also non fixed sized parameters make constructing
+ * the data in the signature much more complex.
+ * See https://ethereum.stackexchange.com/a/50616 for more details.
+ */
+contract SignatureBouncer is SignerRole {
+    using ECDSA for bytes32;
+
+    // Function selectors are 4 bytes long, as documented in
+    // https://solidity.readthedocs.io/en/v0.4.24/abi-spec.html#function-selector
+    uint256 private constant _METHOD_ID_SIZE = 4;
+    // Signature size is 65 bytes (tightly packed v + r + s), but gets padded to 96 bytes
+    uint256 private constant _SIGNATURE_SIZE = 96;
+
+    constructor () internal {
+        // solhint-disable-previous-line no-empty-blocks
+    }
+
+    /**
+     * @dev Requires that a valid signature of a signer was provided.
+     */
+    modifier onlyValidSignature(bytes memory signature) {
+        require(_isValidSignature(msg.sender, signature), "SignatureBouncer: invalid signature for caller");
+        _;
+    }
+
+    /**
+     * @dev Requires that a valid signature with a specified method of a signer was provided.
+     */
+    modifier onlyValidSignatureAndMethod(bytes memory signature) {
+        // solhint-disable-next-line max-line-length
+        require(_isValidSignatureAndMethod(msg.sender, signature), "SignatureBouncer: invalid signature for caller and method");
+        _;
+    }
+
+    /**
+     * @dev Requires that a valid signature with a specified method and params of a signer was provided.
+     */
+    modifier onlyValidSignatureAndData(bytes memory signature) {
+        // solhint-disable-next-line max-line-length
+        require(_isValidSignatureAndData(msg.sender, signature), "SignatureBouncer: invalid signature for caller and data");
+        _;
+    }
+
+    /**
+     * @dev is the signature of `this + account` from a signer?
+     * @return bool
+     */
+    function _isValidSignature(address account, bytes memory signature) internal view returns (bool) {
+        return _isValidDataHash(keccak256(abi.encodePacked(address(this), account)), signature);
+    }
+
+    /**
+     * @dev is the signature of `this + account + methodId` from a signer?
+     * @return bool
+     */
+    function _isValidSignatureAndMethod(address account, bytes memory signature) internal view returns (bool) {
+        bytes memory data = new bytes(_METHOD_ID_SIZE);
+        for (uint i = 0; i < data.length; i++) {
+            data[i] = msg.data[i];
+        }
+        return _isValidDataHash(keccak256(abi.encodePacked(address(this), account, data)), signature);
+    }
+
+    /**
+     * @dev is the signature of `this + account + methodId + params(s)` from a signer?
+     * @notice the signature parameter of the method being validated must be the "last" parameter
+     * @return bool
+     */
+    function _isValidSignatureAndData(address account, bytes memory signature) internal view returns (bool) {
+        require(msg.data.length > _SIGNATURE_SIZE, "SignatureBouncer: data is too short");
+
+        bytes memory data = new bytes(msg.data.length - _SIGNATURE_SIZE);
+        for (uint i = 0; i < data.length; i++) {
+            data[i] = msg.data[i];
+        }
+
+        return _isValidDataHash(keccak256(abi.encodePacked(address(this), account, data)), signature);
+    }
+
+    /**
+     * @dev Internal function to convert a hash to an eth signed message
+     * and then recover the signature and check it against the signer role.
+     * @return bool
+     */
+    function _isValidDataHash(bytes32 hash, bytes memory signature) internal view returns (bool) {
+        address signer = hash.toEthSignedMessageHash().recover(signature);
+
+        return signer != address(0) && isSigner(signer);
+    }
+}

contracts/drafts/SignedSafeMath.sol

@@ -0,0 +1,60 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title SignedSafeMath
+ * @dev Signed math operations with safety checks that revert on error.
+ */
+library SignedSafeMath {
+    int256 constant private INT256_MIN = -2**255;
+
+    /**
+     * @dev Multiplies two signed integers, reverts on overflow.
+     */
+    function mul(int256 a, int256 b) internal pure returns (int256) {
+        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
+        // benefit is lost if 'b' is also tested.
+        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
+        if (a == 0) {
+            return 0;
+        }
+
+        require(!(a == -1 && b == INT256_MIN), "SignedSafeMath: multiplication overflow");
+
+        int256 c = a * b;
+        require(c / a == b, "SignedSafeMath: multiplication overflow");
+
+        return c;
+    }
+
+    /**
+     * @dev Integer division of two signed integers truncating the quotient, reverts on division by zero.
+     */
+    function div(int256 a, int256 b) internal pure returns (int256) {
+        require(b != 0, "SignedSafeMath: division by zero");
+        require(!(b == -1 && a == INT256_MIN), "SignedSafeMath: division overflow");
+
+        int256 c = a / b;
+
+        return c;
+    }
+
+    /**
+     * @dev Subtracts two signed integers, reverts on overflow.
+     */
+    function sub(int256 a, int256 b) internal pure returns (int256) {
+        int256 c = a - b;
+        require((b >= 0 && c <= a) || (b < 0 && c > a), "SignedSafeMath: subtraction overflow");
+
+        return c;
+    }
+
+    /**
+     * @dev Adds two signed integers, reverts on overflow.
+     */
+    function add(int256 a, int256 b) internal pure returns (int256) {
+        int256 c = a + b;
+        require((b >= 0 && c >= a) || (b < 0 && c < a), "SignedSafeMath: addition overflow");
+
+        return c;
+    }
+}

contracts/drafts/TokenVesting.sol

@@ -0,0 +1,174 @@
+pragma solidity ^0.5.7;
+
+import "../token/ERC20/SafeERC20.sol";
+import "../ownership/Ownable.sol";
+import "../math/SafeMath.sol";
+
+/**
+ * @title TokenVesting
+ * @dev A token holder contract that can release its token balance gradually like a
+ * typical vesting scheme, with a cliff and vesting period. Optionally revocable by the
+ * owner.
+ */
+contract TokenVesting is Ownable {
+    // The vesting schedule is time-based (i.e. using block timestamps as opposed to e.g. block numbers), and is
+    // therefore sensitive to timestamp manipulation (which is something miners can do, to a certain degree). Therefore,
+    // it is recommended to avoid using short time durations (less than a minute). Typical vesting schemes, with a
+    // cliff period of a year and a duration of four years, are safe to use.
+    // solhint-disable not-rely-on-time
+
+    using SafeMath for uint256;
+    using SafeERC20 for IERC20;
+
+    event TokensReleased(address token, uint256 amount);
+    event TokenVestingRevoked(address token);
+
+    // beneficiary of tokens after they are released
+    address private _beneficiary;
+
+    // Durations and timestamps are expressed in UNIX time, the same units as block.timestamp.
+    uint256 private _cliff;
+    uint256 private _start;
+    uint256 private _duration;
+
+    bool private _revocable;
+
+    mapping (address => uint256) private _released;
+    mapping (address => bool) private _revoked;
+
+    /**
+     * @dev Creates a vesting contract that vests its balance of any ERC20 token to the
+     * beneficiary, gradually in a linear fashion until start + duration. By then all
+     * of the balance will have vested.
+     * @param beneficiary address of the beneficiary to whom vested tokens are transferred
+     * @param cliffDuration duration in seconds of the cliff in which tokens will begin to vest
+     * @param start the time (as Unix time) at which point vesting starts
+     * @param duration duration in seconds of the period in which the tokens will vest
+     * @param revocable whether the vesting is revocable or not
+     */
+    constructor (address beneficiary, uint256 start, uint256 cliffDuration, uint256 duration, bool revocable) public {
+        require(beneficiary != address(0), "TokenVesting: beneficiary is the zero address");
+        // solhint-disable-next-line max-line-length
+        require(cliffDuration <= duration, "TokenVesting: cliff is longer than duration");
+        require(duration > 0, "TokenVesting: duration is 0");
+        // solhint-disable-next-line max-line-length
+        require(start.add(duration) > block.timestamp, "TokenVesting: final time is before current time");
+
+        _beneficiary = beneficiary;
+        _revocable = revocable;
+        _duration = duration;
+        _cliff = start.add(cliffDuration);
+        _start = start;
+    }
+
+    /**
+     * @return the beneficiary of the tokens.
+     */
+    function beneficiary() public view returns (address) {
+        return _beneficiary;
+    }
+
+    /**
+     * @return the cliff time of the token vesting.
+     */
+    function cliff() public view returns (uint256) {
+        return _cliff;
+    }
+
+    /**
+     * @return the start time of the token vesting.
+     */
+    function start() public view returns (uint256) {
+        return _start;
+    }
+
+    /**
+     * @return the duration of the token vesting.
+     */
+    function duration() public view returns (uint256) {
+        return _duration;
+    }
+
+    /**
+     * @return true if the vesting is revocable.
+     */
+    function revocable() public view returns (bool) {
+        return _revocable;
+    }
+
+    /**
+     * @return the amount of the token released.
+     */
+    function released(address token) public view returns (uint256) {
+        return _released[token];
+    }
+
+    /**
+     * @return true if the token is revoked.
+     */
+    function revoked(address token) public view returns (bool) {
+        return _revoked[token];
+    }
+
+    /**
+     * @notice Transfers vested tokens to beneficiary.
+     * @param token ERC20 token which is being vested
+     */
+    function release(IERC20 token) public {
+        uint256 unreleased = _releasableAmount(token);
+
+        require(unreleased > 0, "TokenVesting: no tokens are due");
+
+        _released[address(token)] = _released[address(token)].add(unreleased);
+
+        token.safeTransfer(_beneficiary, unreleased);
+
+        emit TokensReleased(address(token), unreleased);
+    }
+
+    /**
+     * @notice Allows the owner to revoke the vesting. Tokens already vested
+     * remain in the contract, the rest are returned to the owner.
+     * @param token ERC20 token which is being vested
+     */
+    function revoke(IERC20 token) public onlyOwner {
+        require(_revocable, "TokenVesting: cannot revoke");
+        require(!_revoked[address(token)], "TokenVesting: token already revoked");
+
+        uint256 balance = token.balanceOf(address(this));
+
+        uint256 unreleased = _releasableAmount(token);
+        uint256 refund = balance.sub(unreleased);
+
+        _revoked[address(token)] = true;
+
+        token.safeTransfer(owner(), refund);
+
+        emit TokenVestingRevoked(address(token));
+    }
+
+    /**
+     * @dev Calculates the amount that has already vested but hasn't been released yet.
+     * @param token ERC20 token which is being vested
+     */
+    function _releasableAmount(IERC20 token) private view returns (uint256) {
+        return _vestedAmount(token).sub(_released[address(token)]);
+    }
+
+    /**
+     * @dev Calculates the amount that has already vested.
+     * @param token ERC20 token which is being vested
+     */
+    function _vestedAmount(IERC20 token) private view returns (uint256) {
+        uint256 currentBalance = token.balanceOf(address(this));
+        uint256 totalBalance = currentBalance.add(_released[address(token)]);
+
+        if (block.timestamp < _cliff) {
+            return 0;
+        } else if (block.timestamp >= _start.add(_duration) || _revoked[address(token)]) {
+            return totalBalance;
+        } else {
+            return totalBalance.mul(block.timestamp.sub(_start)).div(_duration);
+        }
+    }
+}

contracts/examples/RBACWithAdmin.sol

@@ -1,66 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../ownership/rbac/RBAC.sol";
-
-
-/**
- * @title RBACWithAdmin
- * @author Matt Condon (@Shrugs)
- * @dev It's recommended that you define constants in the contract,
- * like ROLE_ADMIN below, to avoid typos.
- * @notice RBACWithAdmin is probably too expansive and powerful for your
- * application; an admin is actually able to change any address to any role
- * which is a very large API surface. It's recommended that you follow a strategy
- * of strictly defining the abilities of your roles
- * and the API-surface of your contract.
- * This is just an example for example's sake.
- */
-contract RBACWithAdmin is RBAC {
-  /**
-   * A constant role name for indicating admins.
-   */
-  string public constant ROLE_ADMIN = "admin";
-
-  /**
-   * @dev modifier to scope access to admins
-   * // reverts
-   */
-  modifier onlyAdmin()
-  {
-    checkRole(msg.sender, ROLE_ADMIN);
-    _;
-  }
-
-  /**
-   * @dev constructor. Sets msg.sender as admin by default
-   */
-  constructor()
-    public
-  {
-    addRole(msg.sender, ROLE_ADMIN);
-  }
-
-  /**
-   * @dev add a role to an address
-   * @param addr address
-   * @param roleName the name of the role
-   */
-  function adminAddRole(address addr, string roleName)
-    onlyAdmin
-    public
-  {
-    addRole(addr, roleName);
-  }
-
-  /**
-   * @dev remove a role from an address
-   * @param addr address
-   * @param roleName the name of the role
-   */
-  function adminRemoveRole(address addr, string roleName)
-    onlyAdmin
-    public
-  {
-    removeRole(addr, roleName);
-  }
-}

contracts/examples/SampleCrowdsale.sol

@@ -1,26 +1,22 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
 import "../crowdsale/validation/CappedCrowdsale.sol";
 import "../crowdsale/distribution/RefundableCrowdsale.sol";
 import "../crowdsale/emission/MintedCrowdsale.sol";
-import "../token/ERC20/MintableToken.sol";
-
+import "../token/ERC20/ERC20Mintable.sol";
+import "../token/ERC20/ERC20Detailed.sol";
 
 /**
  * @title SampleCrowdsaleToken
  * @dev Very simple ERC20 Token that can be minted.
  * It is meant to be used in a crowdsale contract.
  */
-contract SampleCrowdsaleToken is MintableToken {
-
-  // solium-disable-next-line uppercase
-  string public constant name = "Sample Crowdsale Token";
-  string public constant symbol = "SCT"; // solium-disable-line uppercase
-  uint8 public constant decimals = 18; // solium-disable-line uppercase
-
+contract SampleCrowdsaleToken is ERC20Mintable, ERC20Detailed {
+    constructor () public ERC20Detailed("Sample Crowdsale Token", "SCT", 18) {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 }
 
-
 /**
  * @title SampleCrowdsale
  * @dev This is an example of a fully fledged crowdsale.
@@ -28,34 +24,30 @@ contract SampleCrowdsaleToken is MintableToken {
  * In this example we are providing following extensions:
  * CappedCrowdsale - sets a max boundary for raised funds
  * RefundableCrowdsale - set a min goal to be reached and returns funds if it's not met
+ * MintedCrowdsale - assumes the token can be minted by the crowdsale, which does so
+ * when receiving purchases.
  *
  * After adding multiple features it's good practice to run integration tests
  * to ensure that subcontracts works together as intended.
  */
-// XXX There doesn't seem to be a way to split this line that keeps solium
-// happy. See:
-// https://github.com/duaraghav8/Solium/issues/205
-// --elopio - 2018-05-10
-// solium-disable-next-line max-len
 contract SampleCrowdsale is CappedCrowdsale, RefundableCrowdsale, MintedCrowdsale {
-
-  constructor(
-    uint256 _openingTime,
-    uint256 _closingTime,
-    uint256 _rate,
-    address _wallet,
-    uint256 _cap,
-    MintableToken _token,
-    uint256 _goal
-  )
-    public
-    Crowdsale(_rate, _wallet, _token)
-    CappedCrowdsale(_cap)
-    TimedCrowdsale(_openingTime, _closingTime)
-    RefundableCrowdsale(_goal)
-  {
-    //As goal needs to be met for a successful crowdsale
-    //the value needs to less or equal than a cap which is limit for accepted funds
-    require(_goal <= _cap);
-  }
+    constructor (
+        uint256 openingTime,
+        uint256 closingTime,
+        uint256 rate,
+        address payable wallet,
+        uint256 cap,
+        ERC20Mintable token,
+        uint256 goal
+    )
+        public
+        Crowdsale(rate, wallet, token)
+        CappedCrowdsale(cap)
+        TimedCrowdsale(openingTime, closingTime)
+        RefundableCrowdsale(goal)
+    {
+        //As goal needs to be met for a successful crowdsale
+        //the value needs to less or equal than a cap which is limit for accepted funds
+        require(goal <= cap, "SampleCrowdSale: goal is greater than cap");
+    }
 }

contracts/examples/SimpleSavingsWallet.sol

@@ -1,40 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../ownership/Heritable.sol";
-
-
-/**
- * @title SimpleSavingsWallet
- * @dev Simplest form of savings wallet whose ownership can be claimed by a heir
- * if owner dies.
- * In this example, we take a very simple savings wallet providing two operations
- * (to send and receive funds) and extend its capabilities by making it Heritable.
- * The account that creates the contract is set as owner, who has the authority to
- * choose an heir account. Heir account can reclaim the contract ownership in the
- * case that the owner dies.
- */
-contract SimpleSavingsWallet is Heritable {
-
-  event Sent(address indexed payee, uint256 amount, uint256 balance);
-  event Received(address indexed payer, uint256 amount, uint256 balance);
-
-
-  constructor(uint256 _heartbeatTimeout) Heritable(_heartbeatTimeout) public {}
-
-  /**
-   * @dev wallet can receive funds.
-   */
-  function () public payable {
-    emit Received(msg.sender, msg.value, address(this).balance);
-  }
-
-  /**
-   * @dev wallet can send funds
-   */
-  function sendTo(address payee, uint256 amount) public onlyOwner {
-    require(payee != address(0) && payee != address(this));
-    require(amount > 0);
-    payee.transfer(amount);
-    emit Sent(payee, amount, address(this).balance);
-  }
-}

contracts/examples/SimpleToken.sol

@@ -1,30 +1,22 @@
-pragma solidity ^0.4.24;
-
-
-import "../token/ERC20/StandardToken.sol";
+pragma solidity ^0.5.7;
 
+import "../token/ERC20/ERC20.sol";
+import "../token/ERC20/ERC20Detailed.sol";
 
 /**
  * @title SimpleToken
  * @dev Very simple ERC20 Token example, where all tokens are pre-assigned to the creator.
  * Note they can later distribute these tokens as they wish using `transfer` and other
- * `StandardToken` functions.
+ * `ERC20` functions.
  */
-contract SimpleToken is StandardToken {
-
-  string public constant name = "SimpleToken"; // solium-disable-line uppercase
-  string public constant symbol = "SIM"; // solium-disable-line uppercase
-  uint8 public constant decimals = 18; // solium-disable-line uppercase
-
-  uint256 public constant INITIAL_SUPPLY = 10000 * (10 ** uint256(decimals));
-
-  /**
-   * @dev Constructor that gives msg.sender all of existing tokens.
-   */
-  constructor() public {
-    totalSupply_ = INITIAL_SUPPLY;
-    balances[msg.sender] = INITIAL_SUPPLY;
-    emit Transfer(address(0), msg.sender, INITIAL_SUPPLY);
-  }
+contract SimpleToken is ERC20, ERC20Detailed {
+    uint8 public constant DECIMALS = 18;
+    uint256 public constant INITIAL_SUPPLY = 10000 * (10 ** uint256(DECIMALS));
 
+    /**
+     * @dev Constructor that gives msg.sender all of existing tokens.
+     */
+    constructor () public ERC20Detailed("SimpleToken", "SIM", DECIMALS) {
+        _mint(msg.sender, INITIAL_SUPPLY);
+    }
 }

contracts/introspection/ERC165.sol

@@ -1,20 +1,43 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
+import "./IERC165.sol";
 
 /**
  * @title ERC165
- * @dev https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
+ * @author Matt Condon (@shrugs)
+ * @dev Implements ERC165 using a lookup table.
  */
-interface ERC165 {
+contract ERC165 is IERC165 {
+    /*
+     * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
+     */
+    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
 
-  /**
-   * @notice Query if a contract implements an interface
-   * @param _interfaceId The interface identifier, as specified in ERC-165
-   * @dev Interface identification is specified in ERC-165. This function
-   * uses less than 30,000 gas.
-   */
-  function supportsInterface(bytes4 _interfaceId)
-    external
-    view
-    returns (bool);
+    /**
+     * @dev Mapping of interface ids to whether or not it's supported.
+     */
+    mapping(bytes4 => bool) private _supportedInterfaces;
+
+    /**
+     * @dev A contract implementing SupportsInterfaceWithLookup
+     * implements ERC165 itself.
+     */
+    constructor () internal {
+        _registerInterface(_INTERFACE_ID_ERC165);
+    }
+
+    /**
+     * @dev Implement supportsInterface(bytes4) using a lookup table.
+     */
+    function supportsInterface(bytes4 interfaceId) external view returns (bool) {
+        return _supportedInterfaces[interfaceId];
+    }
+
+    /**
+     * @dev Internal method for registering an interface.
+     */
+    function _registerInterface(bytes4 interfaceId) internal {
+        require(interfaceId != 0xffffffff, "ERC165: invalid interface id");
+        _supportedInterfaces[interfaceId] = true;
+    }
 }

contracts/introspection/ERC165Checker.sol

@@ -0,0 +1,122 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title ERC165Checker
+ * @dev Use `using ERC165Checker for address`; to include this library
+ * https://eips.ethereum.org/EIPS/eip-165
+ */
+library ERC165Checker {
+    // As per the EIP-165 spec, no interface should ever match 0xffffffff
+    bytes4 private constant _INTERFACE_ID_INVALID = 0xffffffff;
+
+    /*
+     * bytes4(keccak256('supportsInterface(bytes4)')) == 0x01ffc9a7
+     */
+    bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
+
+    /**
+     * @notice Query if a contract supports ERC165
+     * @param account The address of the contract to query for support of ERC165
+     * @return true if the contract at account implements ERC165
+     */
+    function _supportsERC165(address account) internal view returns (bool) {
+        // Any contract that implements ERC165 must explicitly indicate support of
+        // InterfaceId_ERC165 and explicitly indicate non-support of InterfaceId_Invalid
+        return _supportsERC165Interface(account, _INTERFACE_ID_ERC165) &&
+            !_supportsERC165Interface(account, _INTERFACE_ID_INVALID);
+    }
+
+    /**
+     * @notice Query if a contract implements an interface, also checks support of ERC165
+     * @param account The address of the contract to query for support of an interface
+     * @param interfaceId The interface identifier, as specified in ERC-165
+     * @return true if the contract at account indicates support of the interface with
+     * identifier interfaceId, false otherwise
+     * @dev Interface identification is specified in ERC-165.
+     */
+    function _supportsInterface(address account, bytes4 interfaceId) internal view returns (bool) {
+        // query support of both ERC165 as per the spec and support of _interfaceId
+        return _supportsERC165(account) &&
+            _supportsERC165Interface(account, interfaceId);
+    }
+
+    /**
+     * @notice Query if a contract implements interfaces, also checks support of ERC165
+     * @param account The address of the contract to query for support of an interface
+     * @param interfaceIds A list of interface identifiers, as specified in ERC-165
+     * @return true if the contract at account indicates support all interfaces in the
+     * interfaceIds list, false otherwise
+     * @dev Interface identification is specified in ERC-165.
+     */
+    function _supportsAllInterfaces(address account, bytes4[] memory interfaceIds) internal view returns (bool) {
+        // query support of ERC165 itself
+        if (!_supportsERC165(account)) {
+            return false;
+        }
+
+        // query support of each interface in _interfaceIds
+        for (uint256 i = 0; i < interfaceIds.length; i++) {
+            if (!_supportsERC165Interface(account, interfaceIds[i])) {
+                return false;
+            }
+        }
+
+        // all interfaces supported
+        return true;
+    }
+
+    /**
+     * @notice Query if a contract implements an interface, does not check ERC165 support
+     * @param account The address of the contract to query for support of an interface
+     * @param interfaceId The interface identifier, as specified in ERC-165
+     * @return true if the contract at account indicates support of the interface with
+     * identifier interfaceId, false otherwise
+     * @dev Assumes that account contains a contract that supports ERC165, otherwise
+     * the behavior of this method is undefined. This precondition can be checked
+     * with the `supportsERC165` method in this library.
+     * Interface identification is specified in ERC-165.
+     */
+    function _supportsERC165Interface(address account, bytes4 interfaceId) private view returns (bool) {
+        // success determines whether the staticcall succeeded and result determines
+        // whether the contract at account indicates support of _interfaceId
+        (bool success, bool result) = _callERC165SupportsInterface(account, interfaceId);
+
+        return (success && result);
+    }
+
+    /**
+     * @notice Calls the function with selector 0x01ffc9a7 (ERC165) and suppresses throw
+     * @param account The address of the contract to query for support of an interface
+     * @param interfaceId The interface identifier, as specified in ERC-165
+     * @return success true if the STATICCALL succeeded, false otherwise
+     * @return result true if the STATICCALL succeeded and the contract at account
+     * indicates support of the interface with identifier interfaceId, false otherwise
+     */
+    function _callERC165SupportsInterface(address account, bytes4 interfaceId)
+        private
+        view
+        returns (bool success, bool result)
+    {
+        bytes memory encodedParams = abi.encodeWithSelector(_INTERFACE_ID_ERC165, interfaceId);
+
+        // solhint-disable-next-line no-inline-assembly
+        assembly {
+            let encodedParams_data := add(0x20, encodedParams)
+            let encodedParams_size := mload(encodedParams)
+
+            let output := mload(0x40)    // Find empty storage location using "free memory pointer"
+            mstore(output, 0x0)
+
+            success := staticcall(
+                30000,                   // 30k gas
+                account,                 // To addr
+                encodedParams_data,
+                encodedParams_size,
+                output,
+                0x20                     // Outputs are 32 bytes long
+            )
+
+            result := mload(output)      // Load the result
+        }
+    }
+}

contracts/introspection/IERC165.sol

@@ -0,0 +1,15 @@
+pragma solidity ^0.5.7;
+
+/**
+ * @title IERC165
+ * @dev https://eips.ethereum.org/EIPS/eip-165
+ */
+interface IERC165 {
+    /**
+     * @notice Query if a contract implements an interface
+     * @param interfaceId The interface identifier, as specified in ERC-165
+     * @dev Interface identification is specified in ERC-165. This function
+     * uses less than 30,000 gas.
+     */
+    function supportsInterface(bytes4 interfaceId) external view returns (bool);
+}

contracts/introspection/SupportsInterfaceWithLookup.sol

@@ -1,53 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "./ERC165.sol";
-
-
-/**
- * @title SupportsInterfaceWithLookup
- * @author Matt Condon (@shrugs)
- * @dev Implements ERC165 using a lookup table.
- */
-contract SupportsInterfaceWithLookup is ERC165 {
-  bytes4 public constant InterfaceId_ERC165 = 0x01ffc9a7;
-  /**
-   * 0x01ffc9a7 ===
-   *   bytes4(keccak256('supportsInterface(bytes4)'))
-   */
-
-  /**
-   * @dev a mapping of interface id to whether or not it's supported
-   */
-  mapping(bytes4 => bool) internal supportedInterfaces;
-
-  /**
-   * @dev A contract implementing SupportsInterfaceWithLookup
-   * implement ERC165 itself
-   */
-  constructor()
-    public
-  {
-    _registerInterface(InterfaceId_ERC165);
-  }
-
-  /**
-   * @dev implement supportsInterface(bytes4) using a lookup table
-   */
-  function supportsInterface(bytes4 _interfaceId)
-    external
-    view
-    returns (bool)
-  {
-    return supportedInterfaces[_interfaceId];
-  }
-
-  /**
-   * @dev private method for registering an interface
-   */
-  function _registerInterface(bytes4 _interfaceId)
-    internal
-  {
-    require(_interfaceId != 0xffffffff);
-    supportedInterfaces[_interfaceId] = true;
-  }
-}

contracts/lifecycle/Destructible.sol

@@ -1,25 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-import "../ownership/Ownable.sol";
-
-
-/**
- * @title Destructible
- * @dev Base contract that can be destroyed by owner. All funds in contract will be sent to the owner.
- */
-contract Destructible is Ownable {
-
-  constructor() public payable { }
-
-  /**
-   * @dev Transfers the current balance to the owner and terminates the contract.
-   */
-  function destroy() onlyOwner public {
-    selfdestruct(owner);
-  }
-
-  function destroyAndSend(address _recipient) onlyOwner public {
-    selfdestruct(_recipient);
-  }
-}

contracts/lifecycle/Pausable.sol

@@ -1,49 +1,57 @@
-pragma solidity ^0.4.24;
-
-
-import "../ownership/Ownable.sol";
+pragma solidity ^0.5.7;
 
+import "../access/roles/PauserRole.sol";
 
 /**
  * @title Pausable
  * @dev Base contract which allows children to implement an emergency stop mechanism.
  */
-contract Pausable is Ownable {
-  event Pause();
-  event Unpause();
+contract Pausable is PauserRole {
+    event Paused(address account);
+    event Unpaused(address account);
 
-  bool public paused = false;
+    bool private _paused;
 
+    constructor () internal {
+        _paused = false;
+    }
 
-  /**
-   * @dev Modifier to make a function callable only when the contract is not paused.
-   */
-  modifier whenNotPaused() {
-    require(!paused);
-    _;
-  }
+    /**
+     * @return True if the contract is paused, false otherwise.
+     */
+    function paused() public view returns (bool) {
+        return _paused;
+    }
 
-  /**
-   * @dev Modifier to make a function callable only when the contract is paused.
-   */
-  modifier whenPaused() {
-    require(paused);
-    _;
-  }
+    /**
+     * @dev Modifier to make a function callable only when the contract is not paused.
+     */
+    modifier whenNotPaused() {
+        require(!_paused, "Pausable: paused");
+        _;
+    }
 
-  /**
-   * @dev called by the owner to pause, triggers stopped state
-   */
-  function pause() onlyOwner whenNotPaused public {
-    paused = true;
-    emit Pause();
-  }
+    /**
+     * @dev Modifier to make a function callable only when the contract is paused.
+     */
+    modifier whenPaused() {
+        require(_paused, "Pausable: not paused");
+        _;
+    }
 
-  /**
-   * @dev called by the owner to unpause, returns to normal state
-   */
-  function unpause() onlyOwner whenPaused public {
-    paused = false;
-    emit Unpause();
-  }
+    /**
+     * @dev Called by a pauser to pause, triggers stopped state.
+     */
+    function pause() public onlyPauser whenNotPaused {
+        _paused = true;
+        emit Paused(msg.sender);
+    }
+
+    /**
+     * @dev Called by a pauser to unpause, returns to normal state.
+     */
+    function unpause() public onlyPauser whenPaused {
+        _paused = false;
+        emit Unpaused(msg.sender);
+    }
 }

contracts/lifecycle/TokenDestructible.sol

@@ -1,36 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../ownership/Ownable.sol";
-import "../token/ERC20/ERC20Basic.sol";
-
-
-/**
- * @title TokenDestructible:
- * @author Remco Bloemen <remco@2π.com>
- * @dev Base contract that can be destroyed by owner. All funds in contract including
- * listed tokens will be sent to the owner.
- */
-contract TokenDestructible is Ownable {
-
-  constructor() public payable { }
-
-  /**
-   * @notice Terminate contract and refund to owner
-   * @param tokens List of addresses of ERC20 or ERC20Basic token contracts to
-   refund.
-   * @notice The called token contracts could try to re-enter this contract. Only
-   supply token contracts you trust.
-   */
-  function destroy(address[] tokens) onlyOwner public {
-
-    // Transfer tokens to owner
-    for (uint256 i = 0; i < tokens.length; i++) {
-      ERC20Basic token = ERC20Basic(tokens[i]);
-      uint256 balance = token.balanceOf(this);
-      token.transfer(owner, balance);
-    }
-
-    // Transfer Eth to owner and terminate contract
-    selfdestruct(owner);
-  }
-}

contracts/math/Math.sol

@@ -1,24 +1,31 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.7;
 
 /**
  * @title Math
- * @dev Assorted math operations
+ * @dev Assorted math operations.
  */
 library Math {
-  function max64(uint64 a, uint64 b) internal pure returns (uint64) {
-    return a >= b ? a : b;
-  }
+    /**
+     * @dev Returns the largest of two numbers.
+     */
+    function max(uint256 a, uint256 b) internal pure returns (uint256) {
+        return a >= b ? a : b;
+    }
 
-  function min64(uint64 a, uint64 b) internal pure returns (uint64) {
-    return a < b ? a : b;
-  }
+    /**
+     * @dev Returns the smallest of two numbers.
+     */
+    function min(uint256 a, uint256 b) internal pure returns (uint256) {
+        return a < b ? a : b;
+    }
 
-  function max256(uint256 a, uint256 b) internal pure returns (uint256) {
-    return a >= b ? a : b;
-  }
-
-  function min256(uint256 a, uint256 b) internal pure returns (uint256) {
-    return a < b ? a : b;
-  }
+    /**
+     * @dev Calculates the average of two numbers. Since these are integers,
+     * averages of an even and odd number cannot be represented, and will be
+     * rounded down.
+     */
+    function average(uint256 a, uint256 b) internal pure returns (uint256) {
+        // (a + b) / 2 can overflow, so we distribute
+        return (a / 2) + (b / 2) + ((a % 2 + b % 2) / 2);
+    }
 }

contracts/math/SafeMath.sol

@@ -1,52 +1,65 @@
-pragma solidity ^0.4.24;
-
+pragma solidity ^0.5.7;
 
 /**
  * @title SafeMath
- * @dev Math operations with safety checks that throw on error
+ * @dev Unsigned math operations with safety checks that revert on error.
  */
 library SafeMath {
+    /**
+     * @dev Multiplies two unsigned integers, reverts on overflow.
+     */
+    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
+        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
+        // benefit is lost if 'b' is also tested.
+        // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
+        if (a == 0) {
+            return 0;
+        }
 
-  /**
-  * @dev Multiplies two numbers, throws on overflow.
-  */
-  function mul(uint256 a, uint256 b) internal pure returns (uint256 c) {
-    // Gas optimization: this is cheaper than asserting 'a' not being zero, but the
-    // benefit is lost if 'b' is also tested.
-    // See: https://github.com/OpenZeppelin/openzeppelin-solidity/pull/522
-    if (a == 0) {
-      return 0;
+        uint256 c = a * b;
+        require(c / a == b, "SafeMath: multiplication overflow");
+
+        return c;
     }
 
-    c = a * b;
-    assert(c / a == b);
-    return c;
-  }
+    /**
+     * @dev Integer division of two unsigned integers truncating the quotient, reverts on division by zero.
+     */
+    function div(uint256 a, uint256 b) internal pure returns (uint256) {
+        // Solidity only automatically asserts when dividing by 0
+        require(b > 0, "SafeMath: division by zero");
+        uint256 c = a / b;
+        // assert(a == b * c + a % b); // There is no case in which this doesn't hold
 
-  /**
-  * @dev Integer division of two numbers, truncating the quotient.
-  */
-  function div(uint256 a, uint256 b) internal pure returns (uint256) {
-    // assert(b > 0); // Solidity automatically throws when dividing by 0
-    // uint256 c = a / b;
-    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
-    return a / b;
-  }
+        return c;
+    }
 
-  /**
-  * @dev Subtracts two numbers, throws on overflow (i.e. if subtrahend is greater than minuend).
-  */
-  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
-    assert(b <= a);
-    return a - b;
-  }
+    /**
+     * @dev Subtracts two unsigned integers, reverts on overflow (i.e. if subtrahend is greater than minuend).
+     */
+    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
+        require(b <= a, "SafeMath: subtraction overflow");
+        uint256 c = a - b;
 
-  /**
-  * @dev Adds two numbers, throws on overflow.
-  */
-  function add(uint256 a, uint256 b) internal pure returns (uint256 c) {
-    c = a + b;
-    assert(c >= a);
-    return c;
-  }
+        return c;
+    }
+
+    /**
+     * @dev Adds two unsigned integers, reverts on overflow.
+     */
+    function add(uint256 a, uint256 b) internal pure returns (uint256) {
+        uint256 c = a + b;
+        require(c >= a, "SafeMath: addition overflow");
+
+        return c;
+    }
+
+    /**
+     * @dev Divides two unsigned integers and returns the remainder (unsigned integer modulo),
+     * reverts when dividing by zero.
+     */
+    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
+        require(b != 0, "SafeMath: modulo by zero");
+        return a % b;
+    }
 }

contracts/mocks/AddressImpl.sol

@@ -0,0 +1,9 @@
+pragma solidity ^0.5.7;
+
+import "../utils/Address.sol";
+
+contract AddressImpl {
+    function isContract(address account) external view returns (bool) {
+        return Address.isContract(account);
+    }
+}

contracts/mocks/AllowanceCrowdsaleImpl.sol

@@ -1,21 +1,14 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
-import "../token/ERC20/ERC20.sol";
+import "../token/ERC20/IERC20.sol";
 import "../crowdsale/emission/AllowanceCrowdsale.sol";
 
-
 contract AllowanceCrowdsaleImpl is AllowanceCrowdsale {
-
-  constructor (
-    uint256 _rate,
-    address _wallet,
-    ERC20 _token,
-    address _tokenWallet
-  )
-    public
-    Crowdsale(_rate, _wallet, _token)
-    AllowanceCrowdsale(_tokenWallet)
-  {
-  }
-
+    constructor (uint256 rate, address payable wallet, IERC20 token, address tokenWallet)
+        public
+        Crowdsale(rate, wallet, token)
+        AllowanceCrowdsale(tokenWallet)
+    {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 }

contracts/mocks/ArraysImpl.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.5.7;
+
+import "../utils/Arrays.sol";
+
+contract ArraysImpl {
+    using Arrays for uint256[];
+
+    uint256[] private array;
+
+    constructor (uint256[] memory _array) public {
+        array = _array;
+    }
+
+    function findUpperBound(uint256 _element) external view returns (uint256) {
+        return array.findUpperBound(_element);
+    }
+}

contracts/mocks/BasicTokenMock.sol

@@ -1,15 +0,0 @@
-pragma solidity ^0.4.24;
-
-
-import "../token/ERC20/BasicToken.sol";
-
-
-// mock class using BasicToken
-contract BasicTokenMock is BasicToken {
-
-  constructor(address initialAccount, uint256 initialBalance) public {
-    balances[initialAccount] = initialBalance;
-    totalSupply_ = initialBalance;
-  }
-
-}

contracts/mocks/BouncerMock.sol

@@ -1,54 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../access/SignatureBouncer.sol";
-
-
-contract SignatureBouncerMock is SignatureBouncer {
-  function checkValidSignature(address _address, bytes _sig)
-    public
-    view
-    returns (bool)
-  {
-    return isValidSignature(_address, _sig);
-  }
-
-  function onlyWithValidSignature(bytes _sig)
-    onlyValidSignature(_sig)
-    public
-    view
-  {
-
-  }
-
-  function checkValidSignatureAndMethod(address _address, bytes _sig)
-    public
-    view
-    returns (bool)
-  {
-    return isValidSignatureAndMethod(_address, _sig);
-  }
-
-  function onlyWithValidSignatureAndMethod(bytes _sig)
-    onlyValidSignatureAndMethod(_sig)
-    public
-    view
-  {
-
-  }
-
-  function checkValidSignatureAndData(address _address, bytes _bytes, uint _val, bytes _sig)
-    public
-    view
-    returns (bool)
-  {
-    return isValidSignatureAndData(_address, _sig);
-  }
-
-  function onlyWithValidSignatureAndData(uint _val, bytes _sig)
-    onlyValidSignatureAndData(_sig)
-    public
-    view
-  {
-
-  }
-}

contracts/mocks/BurnableTokenMock.sol

@@ -1,13 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../token/ERC20/BurnableToken.sol";
-
-
-contract BurnableTokenMock is BurnableToken {
-
-  constructor(address initialAccount, uint initialBalance) public {
-    balances[initialAccount] = initialBalance;
-    totalSupply_ = initialBalance;
-  }
-
-}

contracts/mocks/CappedCrowdsaleImpl.sol

@@ -1,21 +1,14 @@
-pragma solidity ^0.4.24;
+pragma solidity ^0.5.7;
 
-import "../token/ERC20/ERC20.sol";
+import "../token/ERC20/IERC20.sol";
 import "../crowdsale/validation/CappedCrowdsale.sol";
 
-
 contract CappedCrowdsaleImpl is CappedCrowdsale {
-
-  constructor (
-    uint256 _rate,
-    address _wallet,
-    ERC20 _token,
-    uint256 _cap
-  )
-    public
-    Crowdsale(_rate, _wallet, _token)
-    CappedCrowdsale(_cap)
-  {
-  }
-
+    constructor (uint256 rate, address payable wallet, IERC20 token, uint256 cap)
+        public
+        Crowdsale(rate, wallet, token)
+        CappedCrowdsale(cap)
+    {
+        // solhint-disable-previous-line no-empty-blocks
+    }
 }

contracts/mocks/CapperRoleMock.sol

@@ -0,0 +1,18 @@
+pragma solidity ^0.5.7;
+
+import "../access/roles/CapperRole.sol";
+
+contract CapperRoleMock is CapperRole {
+    function removeCapper(address account) public {
+        _removeCapper(account);
+    }
+
+    function onlyCapperMock() public view onlyCapper {
+        // solhint-disable-previous-line no-empty-blocks
+    }
+
+    // Causes a compilation error if super._removeCapper is not internal
+    function _removeCapper(address account) internal {
+        super._removeCapper(account);
+    }
+}

contracts/mocks/ConditionalEscrowMock.sol

@@ -1,18 +1,16 @@
-pragma solidity ^0.4.24;
-
-
-import "../payment/ConditionalEscrow.sol";
+pragma solidity ^0.5.7;
 
+import "../payment/escrow/ConditionalEscrow.sol";
 
 // mock class using ConditionalEscrow
 contract ConditionalEscrowMock is ConditionalEscrow {
-  mapping(address => bool) public allowed;
+    mapping(address => bool) private _allowed;
 
-  function setAllowed(address _payee, bool _allowed) public {
-    allowed[_payee] = _allowed;
-  }
+    function setAllowed(address payee, bool allowed) public {
+        _allowed[payee] = allowed;
+    }
 
-  function withdrawalAllowed(address _payee) public view returns (bool) {
-    return allowed[_payee];
-  }
+    function withdrawalAllowed(address payee) public view returns (bool) {
+        return _allowed[payee];
+    }
 }

contracts/mocks/CountersImpl.sol

@@ -0,0 +1,21 @@
+pragma solidity ^0.5.7;
+
+import "../drafts/Counters.sol";
+
+contract CountersImpl {
+    using Counters for Counters.Counter;
+
+    Counters.Counter private _counter;
+
+    function current() public view returns (uint256) {
+        return _counter.current();
+    }
+
+    function increment() public {
+        _counter.increment();
+    }
+
+    function decrement() public {
+        _counter.decrement();
+    }
+}

contracts/mocks/CrowdsaleMock.sol

@@ -0,0 +1,9 @@
+pragma solidity ^0.5.7;
+
+import "../crowdsale/Crowdsale.sol";
+
+contract CrowdsaleMock is Crowdsale {
+    constructor (uint256 rate, address payable wallet, IERC20 token) public Crowdsale(rate, wallet, token) {
+        // solhint-disable-previous-line no-empty-blocks
+    }
+}

contracts/mocks/DetailedERC20Mock.sol

@@ -1,16 +0,0 @@
-pragma solidity ^0.4.24;
-
-import "../token/ERC20/StandardToken.sol";
-import "../token/ERC20/DetailedERC20.sol";
-
-
-contract DetailedERC20Mock is StandardToken, DetailedERC20 {
-  constructor(
-    string _name,
-    string _symbol,
-    uint8 _decimals
-  )
-    DetailedERC20(_name, _symbol, _decimals)
-    public
-  {}
-}

contracts/mocks/ECDSAMock.sol

@@ -0,0 +1,15 @@
+pragma solidity ^0.5.7;
+
+import "../cryptography/ECDSA.sol";
+
+contract ECDSAMock {
+    using ECDSA for bytes32;
+
+    function recover(bytes32 hash, bytes memory signature) public pure returns (address) {
+        return hash.recover(signature);
+    }
+
+    function toEthSignedMessageHash(bytes32 hash) public pure returns (bytes32) {
+        return hash.toEthSignedMessageHash();
+    }
+}