Release v2.0.1

Fix SafeERC20.safeApprove bug

(cherry picked from commit 3111291b4a)

.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

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

.eslintrc

@@ -0,0 +1,55 @@
+{
+  "extends" : [
+    "standard",
+    "plugin:promise/recommended"
+  ],
+  "plugins": [
+    "promise"
+  ],
+  "env": {
+    "browser" : true,
+    "node"    : true,
+    "mocha"   : true,
+    "jest"    : true
+  },
+  "globals" : {
+    "artifacts": false,
+    "contract": false,
+    "assert": false,
+    "web3": false
+  },
+  "rules": {
+
+    // Strict mode
+    "strict": ["error", "global"],
+
+    // Code style
+    "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"],
+
+    "promise/always-return": "off",
+    "promise/avoid-new": "off",
+  }
+}

.gitattributes

@@ -0,0 +1 @@
+*.sol linguist-language=Solidity

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,34 @@
+## 🎉 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/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,17 @@
+<!-- 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. -->
+
+Fixes #
+
+# 🚀 Description
+
+<!-- 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:fix`).

.gitignore

@@ -1,7 +1,39 @@
 *.swp
 *.swo
-node_modules/
+
+# Logs
+logs
+*.log
+
+# Runtime data
+pids
+*.pid
+*.seed
+allFiredEvents
+scTopics
+
+# Coverage directory used by tools like istanbul
+coverage
+coverage.json
+coverageEnv
+
+# node-waf configuration
+.lock-wscript
+
+# Dependency directory
+node_modules
+
+# Debug log from npm
+npm-debug.log
+
+# local env variables
+.env
+
+# truffle build directory
 build/
+
+# lol macs
 .DS_Store/
-/coverage
-coverage.json
+
+# truffle
+.node-xmlhttprequest-*

.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

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

.solcover.js

@@ -0,0 +1,9 @@
+module.exports = {
+    norpc: true,
+    testCommand: 'node --max-old-space-size=4096 ../node_modules/.bin/truffle test --network coverage',
+    compileCommand: 'node --max-old-space-size=4096 ../node_modules/.bin/truffle compile --network coverage',
+    skipFiles: [
+        'lifecycle/Migrations.sol',
+        'mocks'
+    ]
+}

.soliumignore

@@ -1 +1 @@
-node_modules
+node_modules

.soliumrc.json

@@ -1,22 +1,21 @@
 {
-  "custom-rules-filename": null,
+  "extends": "solium:all",
+  "plugins": ["security"],
   "rules": {
-    "imports-on-top": true,
-    "variable-declarations": true,
-    "array-declarations": true,
-    "operator-whitespace": true,
-    "lbrace": true,
-    "mixedcase": false,
-    "camelcase": true,
-    "uppercase": true,
-    "no-with": true,
-    "no-empty-blocks": true,
-    "no-unused-vars": true,
-    "double-quotes": true,
-    "blank-lines": true,
-    "indentation": true,
-    "whitespace": true,
-    "deprecated-suicide": true,
-    "pragma-on-top": true
+    "blank-lines": "off",
+    "error-reason": "off",
+    "indentation": ["error", 2],
+    "lbrace": "off",
+    "linebreak-style": ["error", "unix"],
+    "max-len": ["error", 79],
+    "no-constant": ["error"],
+    "no-empty-blocks": "off",
+    "quotes": ["error", "double"],
+    "uppercase": "off",
+    "visibility-first": "error",
+
+    "security/enforce-explicit-visibility": ["error"],
+    "security/no-block-members": ["warning"],
+    "security/no-inline-assembly": ["warning"]
   }
 }

.travis.yml

@@ -3,10 +3,54 @@ sudo: false
 group: beta
 language: node_js
 node_js:
-  - "6"
-before_install:
-  - npm install truffle@3.1.9 -g
-  - npm i -g ethereumjs-testrpc
-script:
-  - testrpc > /dev/null &
-  - truffle test
+  - "8"
+
+cache:
+  directories:
+    - node_modules
+
+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
+  include:
+    # Run the unit test suite three times in parallel.
+    # The first one gets results faster and is the only one required to pass.
+    # The second one generates the coverage report.
+    # The third one is to keep us informed about possible issues with the
+    # upcoming solidity release.
+    - stage: tests
+      name: "unit tests"
+      script: npm run test
+    - stage: tests
+      name: "unit tests with coverage"
+      script: npm run test
+      env: SOLIDITY_COVERAGE=true
+    - stage: tests
+      name: "unit tests with solc nightly"
+      script: npm run test
+      env: SOLC_NIGHTLY=true
+    # solidity and javascript style tests.
+    - stage: tests
+      name: "static tests"
+      script: npm run lint
+    - stage: update docs
+      if: tag =~ ^v[0-9]+\.[0-9]+\.[0-9]+$
+      addons:
+        apt:
+          packages:
+            - curl
+      script:
+        - ./scripts/ci/trigger_docs_update "${TRAVIS_TAG}"
+
+notifications:
+  slack:
+    rooms:
+      - secure: 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
+    on_success: change
+    on_failure: always
+    on_pull_requests: false

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.

CONTRIBUTING.md

@@ -1,107 +1,58 @@
-Contributing to Zeppelin
+Contributing to OpenZeppelin
 =======
 
-## Design Guidelines
+We really appreciate and value contributions to OpenZeppelin. Please take 5' to review the items listed below to make sure that your contributions are merged as soon as possible. 
 
-These are some global design goals in Zeppelin.
+## Contribution guidelines
 
-### D0 - Security in Depth
-We strive to provide secure, tested, audited code. To achieve this, we need to match intention with function. Thus, documentation, code clarity, community review and security discussions are fundamental.
+Smart contracts manage value and are highly vulnerable to errors and attacks. We have very strict guidelines, please make sure to review them: ["Contribution guidelines wiki entry"](https://github.com/OpenZeppelin/openzeppelin-solidity/wiki/Contribution-guidelines).
 
-### D1 - Simple and Modular
-Simpler code means easier audits, and better understanding of what each component does. We look for small files, small contracts, and small functions. If you can separate a contract into two independent functionalities you should probably do it.
+## Creating Pull Requests (PRs)
 
-### D2 - Naming Matters
+As a contributor, you are expected to fork this repository, work on your own fork and then submit pull requests. The pull requests will be reviewed and eventually merged into the main repo. See ["Fork-a-Repo"](https://help.github.com/articles/fork-a-repo/) for how this works.
 
-We take our time with picking names. Code is going to be written once, and read hundreds of times. Renaming for clarity is encouraged.
+*IMPORTANT* 
+* Please see ["Git flow wiki entry"](https://github.com/OpenZeppelin/openzeppelin-solidity/wiki/Git-flow) for understanding how to use branches in this repository.
 
-### D3 - Tests
+## A typical workflow
 
-Write tests for all your code. We encourage Test Driven Development so we know when our code is right. Even though not all code in the repository is tested at the moment, we aim to test every line of code in the future.
+1) Make sure your fork is up to date with the main repository:
 
-### D4 - Check preconditions and post-conditions
+```
+cd openzeppelin-solidity
+git remote add upstream https://github.com/OpenZeppelin/openzeppelin-solidity.git
+git fetch upstream
+git pull --rebase upstream master
+```
+NOTE: The directory `openzeppelin-solidity` represents your fork's local copy.
 
-A very important way to prevent vulnerabilities is to catch a contract’s inconsistent state as early as possible. This is why we want functions to check pre- and post-conditions for executing its logic. When writing code, ask yourself what you are expecting to be true before and after the function runs, and express it in code.
-
-### D5 - Code Consistency
-
-Consistency on the way classes are used is paramount to an easier understanding of the library. The codebase should be as unified as possible. Read existing code and get inspired before you write your own. Follow the style guidelines. Don’t hesitate to ask for help on how to best write a specific piece of code.
-
-### D6 - Regular Audits
-Following good programming practices is a way to reduce the risk of vulnerabilities, but professional code audits are still needed. We will perform regular code audits on major releases, and hire security professionals to provide independent review.
-
-## Style Guidelines
-
-The design guidelines have quite a high abstraction level. These style guidelines are more concrete and easier to apply, and also more opinionated.
-
-### General
-
-#### G0 - Default to Solidity's official style guide.
-
-Follow the official Solidity style guide: http://solidity.readthedocs.io/en/latest/style-guide.html
-
-#### G1 - No Magic Constants
-
-Avoid constants in the code as much as possible. Magic strings are also magic constants.
-
-#### G2 - Code that Fails Early
-
-We ask our code to fail as soon as possible when an unexpected input was provided or unexpected state was found.
-
-#### G3 - Internal Amounts Must be Signed Integers and Represent the Smallest Units.
-
-Avoid representation errors by always dealing with weis when handling ether. GUIs can convert to more human-friendly representations. Use Signed Integers (int) to prevent underflow problems.
-
-
-### Testing
-
-#### T1 - Tests Must be Written Elegantly
-
-Style guidelines are not relaxed for tests. Tests are a good way to show how to use the library, and maintaining them is extremely necessary.
-
-Don't write long tests, write helper functions to make them be as short and concise as possible (they should take just a few lines each), and use good variable names.
-
-#### T2 - Tests Must not be Random
-
-Inputs for tests should not be generated randomly. Accounts used to create test contracts are an exception, those can be random. Also, the type and structure of outputs should be checked.
-
-
-### Documentation
-
-TODO
-
-## Pull Request Workflow
-
-Our workflow is based on GitHub's pull requests. We use feature branches, prepended with: `test`, `feature`, `fix`, `refactor`, or `remove` according to the change the branch introduces. Some examples for such branches are:
-```sh
-git checkout -b test/some-module
-git checkout -b feature/some-new-stuff
-git checkout -b fix/some-bug
-git checkout -b remove/some-file
+2) Branch out from `master` into `fix/some-bug-#123`:
+(Postfixing #123 will associate your PR with the issue #123 and make everyone's life easier =D)
+```
+git checkout -b fix/some-bug-#123
 ```
 
-We expect pull requests to be rebased to the master branch before merging:
-```sh
-git remote add zep git@github.com:OpenZeppelin/zeppelin-solidity.git
-git pull --rebase zep master
+3) Make your changes, add your files, commit and push to your fork.
+
+```
+git add SomeFile.js
+git commit "Fix some bug #123"
+git push origin fix/some-bug-#123
 ```
 
-Note that we require rebasing your branch instead of merging it, for commit readability reasons.
+4) Go to [github.com/OpenZeppelin/openzeppelin-solidity](https://github.com/OpenZeppelin/zeppelin-solidity) in your web browser and issue a new pull request.
 
-After that, you can push the changes to your fork, by doing:
-```sh
-git push origin your_branch_name
-git push origin feature/some-new-stuff
-git push origin fix/some-bug
-```
+*IMPORTANT* Read the PR template very carefully and make sure to follow all the instructions. These instructions 
+refer to some very important conditions that your PR must meet in order to be accepted, such as making sure that all tests pass, JS linting tests pass, solidity linting tests pass, etc.
 
-Finally go to [github.com/OpenZeppelin/zeppelin-solidity](https://github.com/OpenZeppelin/zeppelin-solidity) in your web browser and issue a new pull request.
+5) Maintainers will review your code and possibly ask for changes before your code is pulled in to the main repository. We'll check that all tests pass, review the coding style, and check for general code correctness. If everything is OK, we'll merge your pull request and your code will be part of OpenZeppelin.
 
-Main contributors will review your code and possibly ask for changes before your code is pulled in to the main repository.  We'll check that all tests pass, review the coding style, and check for general code correctness. If everything is OK, we'll merge your pull request and your code will be part of Zeppelin.
+*IMPORTANT* Please pay attention to the maintainer's feedback, since its a necessary step to keep up with the standards OpenZeppelin attains to.
 
-If you have any questions feel free to post them to
-[github.com/OpenZeppelin/zeppelin-solidity/issues](https://github.com/OpenZeppelin/zeppelin-solidity/issues).
+## All set!
 
-Finally, if you're looking to collaborate and want to find easy tasks to start, [look at the issues we marked as easy](https://github.com/OpenZeppelin/zeppelin-solidity/labels/easy).
+If you have any questions feel free to post them to github.com/OpenZeppelin/openzeppelin-solidity/issues.
+
+Finally, if you're looking to collaborate and want to find easy tasks to start, look at the issues we marked as ["Good first issue"](https://github.com/OpenZeppelin/openzeppelin-solidity/labels/good%20first%20issue).
 
 Thanks for your time and code!

LICENSE

@@ -5,18 +5,18 @@ Copyright (c) 2016 Smart Contract Solutions, Inc.
 Permission is hereby granted, free of charge, to any person obtaining
 a copy of this software and associated documentation files (the
 "Software"), to deal in the Software without restriction, including
-without limitation the rights to use, copy, modify, merge, publish, 
+without limitation the rights to use, copy, modify, merge, publish,
 distribute, sublicense, and/or sell copies of the Software, and to
-permit persons to whom the Software is furnished to do so, subject to 
+permit persons to whom the Software is furnished to do so, subject to
 the following conditions:
 
 The above copyright notice and this permission notice shall be included
 in all copies or substantial portions of the Software.
 
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 
-OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
-MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. 
-IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 
-CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, 
-TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE 
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -1,77 +1,58 @@
-# Zeppelin Solidity
-[![NPM Package](https://img.shields.io/npm/v/zeppelin-solidity.svg?style=flat-square)](https://www.npmjs.org/package/zeppelin-solidity)
-[![Build Status](https://img.shields.io/travis/OpenZeppelin/zeppelin-solidity.svg?branch=master&style=flat-square)](https://travis-ci.org/OpenZeppelin/zeppelin-solidity)
+# <img src="logo.png" alt="OpenZeppelin" width="400px">
 
-OpenZeppelin is a library for writing secure [Smart Contracts](https://en.wikipedia.org/wiki/Smart_contract) on Ethereum.
+[![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)
 
-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](http://solidity.readthedocs.io/en/develop/).
+**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.
 
-> 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).
+## Install
 
-## Getting Started
-
-OpenZeppelin integrates with [Truffle](https://github.com/ConsenSys/truffle), an Ethereum development environment. Please install Truffle and initialize your project with `truffle init`.
-
-```sh
-npm install -g truffle@beta
-mkdir myproject && cd myproject
-truffle init
+```
+npm install openzeppelin-solidity
 ```
 
-To install the OpenZeppelin library, run:
-```sh
-npm install zeppelin-solidity
-```
+## Usage
 
-After that, you'll get all the library's contracts in the `node_modules/zeppelin-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.
 
-```js
-import 'zeppelin-solidity/contracts/ownership/Ownable.sol';
+```solidity
+pragma solidity ^0.4.24;
 
-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 {
+  }
 }
 ```
 
+> You need an ethereum development framework for the above import statements to work! Check out these guides for [Truffle] or [Embark].
+
+On our site you will find a few [guides] to learn about the diferent 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 Slack][Slack].
 
 ## 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?
+Please report any security issues you find to security@openzeppelin.org.
 
-- Read documentation: http://zeppelin-solidity.readthedocs.io/en/latest/
-
-- Ask for help and follow progress at: https://slack.openzeppelin.org/
-
-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/zeppelin-solidity/issues
-- Contribution guidelines: https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/CONTRIBUTING.md
-
-## Collaborating organizations and audits by OpenZeppelin
-- [Golem](https://golem.network/)
-- [Mediachain](http://www.mediachain.io/)
-- [Truffle](http://truffleframework.com/)
-- [Firstblood](http://firstblood.io/)
-- [Rootstock](http://www.rsk.co/)
-- [Consensys](https://consensys.net/)
-- [DigixGlobal](https://www.dgx.io/)
-- [Coinfund](https://coinfund.io/)
-- [DemocracyEarth](http://democracy.earth/)
-- [Signatura](https://signatura.co/)
-- [Ether.camp](http://www.ether.camp/)
-- [Aragon](https://aragon.one/)
-- [Wings](https://wings.ai/)
-
-among others...
+## Contribute
 
+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/zeppelin-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
+[Slack]: https://slack.openzeppelin.org
+[Zeppelin]: https://zeppelin.solutions
+[contribution guide]: CONTRIBUTING.md
+[Truffle]: https://truffleframework.com/docs/truffle/quickstart
+[Embark]: https://embark.status.im/docs/quick_start.html

RELEASING.md

@@ -0,0 +1,96 @@
+# 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.
+
+```
+npm publish --tag next
+```
+
+Publish the release notes on GitHub and ask our community manager to announce the release candidate on at least Slack and 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
+```
+
+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 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.
+
+```
+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.

audit/ZeppelinAudit.md

@@ -5,7 +5,7 @@ Authored by Dennis Peterson and Peter Vessenes
 
 # Introduction
 
-Zeppelin requested that New Alchemy perform an audit of the contracts in their OpenZeppelin library. The OpenZeppelin contracts are a set of contracts intended to be a safe building block for a variety of uses by parties that may not be as sophisticated as the OpenZeppelin team. It is a design goal that the contracts be deployable safely and "as-is". 
+Zeppelin requested that New Alchemy perform an audit of the contracts in their OpenZeppelin library. The OpenZeppelin contracts are a set of contracts intended to be a safe building block for a variety of uses by parties that may not be as sophisticated as the OpenZeppelin team. It is a design goal that the contracts be deployable safely and "as-is".
 
 The contracts are hosted at:
 
@@ -22,9 +22,9 @@ The audit makes no statements or warrantees about utility of the code, safety of
 
 # Executive Summary
 
-Overall the OpenZeppelin codebase is of reasonably high quality -- it is clean, modular and follows best practices throughout. 
+Overall the OpenZeppelin codebase is of reasonably high quality -- it is clean, modular and follows best practices throughout.
 
-It is still in flux as a codebase, and needs better documentation per file as to expected behavior and future plans. It probably needs more comprehensive and aggressive tests written by people less nice than the current OpenZeppelin team. 
+It is still in flux as a codebase, and needs better documentation per file as to expected behavior and future plans. It probably needs more comprehensive and aggressive tests written by people less nice than the current OpenZeppelin team.
 
 We identified two critical errors and one moderate issue, and would not recommend this commit hash for public use until these bugs are remedied.
 
@@ -34,12 +34,12 @@ The repository includes a set of Truffle unit tests, a requirement and best prac
 
 ## Big Picture: Is This A Worthwhile Project?
 
-As soon as a developer touches OpenZeppelin contracts, they will modify something, leaving them in an un-audited state. We do not recommend developers deploy any unaudited code to the Blockchain if it will handle money, information or other things of value. 
+As soon as a developer touches OpenZeppelin contracts, they will modify something, leaving them in an un-audited state. We do not recommend developers deploy any unaudited code to the Blockchain if it will handle money, information or other things of value.
 
 > "In accordance with Unix philosophy, Perl gives you enough rope to hang yourself"
 > --Larry Wall
 
-We think this is an incredibly worthwhile project -- aided by the high code quality. Creating a framework that can be easily extended helps increase the average code quality on the Blockchain by charting a course for developers and encouraging containment of modifications to certain sections. 
+We think this is an incredibly worthwhile project -- aided by the high code quality. Creating a framework that can be easily extended helps increase the average code quality on the Blockchain by charting a course for developers and encouraging containment of modifications to certain sections.
 
 > "Rust: The language that makes you take the safety off before shooting yourself in the foot"
 > -- (@mbrubeck)
@@ -48,7 +48,7 @@ We think much more could be done here, and recommend the OpenZeppelin team keep
 
 ## Solidity Version Updates Recommended
 
-Most of the code uses Solidity 0.4.8, but some files under `Ownership` are marked 0.4.0. These should be updated.
+Most of the code uses Solidity 0.4.11, but some files under `Ownership` are marked 0.4.0. These should be updated.
 
 Solidity 0.4.10 will add several features which could be useful in these contracts:
 
@@ -65,7 +65,7 @@ In general we prefer `throw` in our code audits, because it is simpler -- it's l
 
 In the OpenZeppelin contracts, both styles are used in different parts of the codebase. `SimpleToken` transfers throw upon failure, while the full ERC20 token returns `false`. Some modifiers `throw`, others just wrap the function body in a conditional, effectively allowing the function to return false if the condition is not met.
 
-We don't love this, and would usually recommend you stick with one style or the other throughout the codebase. 
+We don't love this, and would usually recommend you stick with one style or the other throughout the codebase.
 
 In at least one case, these different techniques are combined cleverly (see the Multisig comments, line 65). As a set of contracts intended for general use, we recommend you either strive for more consistency or document explicit design criteria that govern which techniques are used where.
 
@@ -77,19 +77,19 @@ Note that it may be impossible to use either one in all situations. For example,
 CrowdsaleToken.sol has no provision for withdrawing the raised ether. We *strongly* recommend a standard `withdraw` function be added. There is no scenario in which someone should deploy this contract as is, whether for testing or live.
 
 ## Recursive Call in MultisigWallet
-Line 45 of `MultisigWallet.sol` checks if the amount being sent by `execute` is under a daily limit. 
+Line 45 of `MultisigWallet.sol` checks if the amount being sent by `execute` is under a daily limit.
 
-This function can only be called by the "Owner". As a first angle of attack, it's worth asking what will happen if the multisig wallet owners reset the daily limit by approving a call to `resetSpentToday`. 
+This function can only be called by the "Owner". As a first angle of attack, it's worth asking what will happen if the multisig wallet owners reset the daily limit by approving a call to `resetSpentToday`.
 
 If a chain of calls can be constructed in which the owner confirms the `resetSpentToday` function and then withdraws through `execute` in a recursive call, the contract can be drained. In fact, this could be done without a recursive call, just through repeated `execute` calls alternating with the `confirm` calls.
 
-We are still working through the confirmation protocol in `Shareable.sol`, but we are not convinced that this is impossible, in fact it looks possible. The flexibility any shared owner has in being able to revoke confirmation later is another worrisome angle of approach even if some simple patches are included. 
+We are still working through the confirmation protocol in `Shareable.sol`, but we are not convinced that this is impossible, in fact it looks possible. The flexibility any shared owner has in being able to revoke confirmation later is another worrisome angle of approach even if some simple patches are included.
 
 This bug has a number of causes that need to be addressed:
 
-1. `resetSpentToday` and `confirm` together do not limit the days on which the function can be called or (it appears) the number of times it can be called. 
-1. Once a call has been confirmed and `execute`d it appears that it can be re-executed. This is not good. 
-3. `confirmandCheck` doesn't seem to have logic about whether or not the function in question has been called. 
+1. `resetSpentToday` and `confirm` together do not limit the days on which the function can be called or (it appears) the number of times it can be called.
+1. Once a call has been confirmed and `execute`d it appears that it can be re-executed. This is not good.
+3. `confirmandCheck` doesn't seem to have logic about whether or not the function in question has been called.
 4. Even if it did, `revoke` would need updates and logic to deal with revocation requests after a function call had been completed.
 
 We do not recommend using the MultisigWallet until these issues are fixed.
@@ -97,9 +97,9 @@ We do not recommend using the MultisigWallet until these issues are fixed.
 # Moderate to Minor Issues
 
 ## PullPayment
-PullPayment.sol needs some work. It has no explicit provision for cancelling a payment. This would be desirable in a number of scenarios; consider a payee losing their wallet, or giving a griefing address, or just an address that requires more than the default gas offered by `send`. 
+PullPayment.sol needs some work. It has no explicit provision for cancelling a payment. This would be desirable in a number of scenarios; consider a payee losing their wallet, or giving a griefing address, or just an address that requires more than the default gas offered by `send`.
 
-`asyncSend` has no overflow checking. This is a bad plan. We recommend overflow and underflow checking at the layer closest to the data manipulation. 
+`asyncSend` has no overflow checking. This is a bad plan. We recommend overflow and underflow checking at the layer closest to the data manipulation.
 
 `asyncSend` allows more balance to be queued up for sending than the contract holds. This is probably a bad idea, or at the very least should be called something different. If the intent is to allow this, it should have provisions for dealing with race conditions between competing `withdrawPayments` calls.
 
@@ -107,7 +107,7 @@ It would be nice to see how many payments are pending. This would imply a bit of
 
 ## Shareable Contract
 
-We do not believe the `Shareable.sol` contract is ready for primetime. It is missing functions, and as written may be vulnerable to a reordering attack -- an attack in which a miner or other party "racing" with a smart contract participant inserts their own information into a list or mapping. 
+We do not believe the `Shareable.sol` contract is ready for primetime. It is missing functions, and as written may be vulnerable to a reordering attack -- an attack in which a miner or other party "racing" with a smart contract participant inserts their own information into a list or mapping.
 
 The confirmation and revocation code needs to be looked over with a very careful eye imagining extraordinarily bad behavior by shared owners before this contract can be called safe.
 
@@ -129,7 +129,7 @@ I presume that the goal of this contract is to allow and annotate a migration to
 
 ### Pausable
 
-We like these pauses! Note that these allow significant griefing potential by owners, and that this might not be obvious to participants in smart contracts using the OpenZeppelin framework. We would recommend that additional sample logic be added to for instance the TokenContract showing safer use of the pause and resume functions. In particular, we would recommend a timelock after which anyone could unpause the contract. 
+We like these pauses! Note that these allow significant griefing potential by owners, and that this might not be obvious to participants in smart contracts using the OpenZeppelin framework. We would recommend that additional sample logic be added to for instance the TokenContract showing safer use of the pause and resume functions. In particular, we would recommend a timelock after which anyone could unpause the contract.
 
 The modifers use the pattern `if(bool){_;}`. This is fine for functions that return false upon failure, but could be problematic for functions expected to throw upon failure. See our comments above on standardizing on `throw` or `return(false)`.
 
@@ -163,7 +163,7 @@ Line 34: "this contract only has six types of events"...actually only two.
 
 Line 61: Why is `ownerIndex` keyed by addresses hashed to `uint`s? Why not use the addresses directly, so `ownerIndex` is less obscure, and so there's stronger typing?
 
-Line 62: Do not love `++i) ... owners[2+ i]`. Makes me do math, which is not what I want to do. I want to not have to do math. 
+Line 62: Do not love `++i) ... owners[2+ i]`. Makes me do math, which is not what I want to do. I want to not have to do math.
 
 There should probably be a function for adding a new operation, so the developer doesn't have to work directly with the internal data. (This would make the multisig contract even shorter.)
 
@@ -171,7 +171,7 @@ There's a `revoke` function but not a `propose` function that we can see.
 
 Beware reordering. If `propose` allows the user to choose a bytes string for their proposal, bad things(TM) will happen as currently written.
 
-	
+
 ### Multisig
 
 Just an interface. Note it allows changing an owner address, but not changing the number of owners. This is somewhat limiting but also simplifies implementation.
@@ -184,9 +184,9 @@ Safe from reentrance attack since ether send is at the end, plus it uses `.send(
 
 There's an argument to be made that `.call.value()` is a better option *if* you're sure that it will be done after all state updates, since `.send` will fail if the recipient has an expensive fallback function. However, in the context of a function meant to be embedded in other contracts, it's probably better to use `.send`. One possible compromise is to add a function which allows only the owner to send ether via `.call.value`.
 
-If you don't use `call.value` you should implement a `cancel` function in case some value is pending here. 
+If you don't use `call.value` you should implement a `cancel` function in case some value is pending here.
 
-Line 14: 
+Line 14:
 Doesn't use safeAdd. Although it appears that payout amounts can only be increased, in fact the payer could lower the payout as much as desired via overflow. Also, the payer could add a large non-overflowing amount, causing the payment to exceed the contract balance and therefore fail when withdraw is attempted.
 
 Recommendation: track the sum of non-withdrawn asyncSends, and don't allow a new one which exceeds the leftover balance. If it's ever desirable to make payments revocable, it should be done explicitly.
@@ -195,7 +195,7 @@ Recommendation: track the sum of non-withdrawn asyncSends, and don't allow a new
 
 ### ERC20
 
-Standard ERC20 interface only. 
+Standard ERC20 interface only.
 
 There's a security hole in the standard, reported at Edcon: `approve` does not protect against race conditions and simply replaces the current value. An approved spender could wait for the owner to call `approve` again, then attempt to spend the old limit before the new limit is applied. If successful, this attacker could successfully spend the sum of both limits.
 
@@ -208,11 +208,11 @@ https://drive.google.com/file/d/0ByMtMw2hul0EN3NCaVFHSFdxRzA/view
 
 ### ERC20Basic
 
-Simpler interface skipping the Approve function. Note this departs from ERC20 in another way: transfer throws instead of returning false. 
+Simpler interface skipping the Approve function. Note this departs from ERC20 in another way: transfer throws instead of returning false.
 
 ### BasicToken
 
-Uses `SafeSub` and `SafeMath`, so transfer `throw`s instead of returning false. This complies with ERC20Basic but not the actual ERC20 standard. 
+Uses `SafeSub` and `SafeMath`, so transfer `throw`s instead of returning false. This complies with ERC20Basic but not the actual ERC20 standard.
 
 ### StandardToken
 
@@ -234,10 +234,10 @@ Note: an alternative pattern is a mint() function which is only callable from a
 
 ### VestedToken
 
-Lines 23, 27: 
-Functions `transfer()` and `transferFrom()` have a modifier canTransfer which throws if not enough tokens are available. However, transfer() returns a boolean success. Inconsistent treatment of failure conditions may cause problems for other contracts using the token. (Note that transferableTokens() relies on safeSub(), so will also throw if there's insufficient balance.) 
+Lines 23, 27:
+Functions `transfer()` and `transferFrom()` have a modifier canTransfer which throws if not enough tokens are available. However, transfer() returns a boolean success. Inconsistent treatment of failure conditions may cause problems for other contracts using the token. (Note that transferableTokens() relies on safeSub(), so will also throw if there's insufficient balance.)
 
-Line 64: 
+Line 64:
 Delete not actually necessary since the value is overwritten in the next line anyway.
 
 ## Root level
@@ -255,7 +255,7 @@ The modifier `limitedDaily` calls `underLimit`, which both checks that the spend
 Lines 4, 11:
 Comment claims that `DayLimit` is multiowned, and Shareable is imported, but DayLimit does not actually inherit from Shareable. The intent may be for child contracts to inherit from Shareable (as Multisig does); in this case the import should be removed and the comment altered.
 
-Line 46: 
+Line 46:
 Manual overflow check instead of using safeAdd. Since this is called from a function that throws upon failure anyway, there's no real downside to using safeAdd.
 
 ### LimitBalance
@@ -264,19 +264,19 @@ No issues.
 
 ### MultisigWallet
 
-Lines 28, 76, 80: 
+Lines 28, 76, 80:
 `kill`, `setDailyLimit`, and `resetSpentToday` only happen with multisig approval, and hashes for these actions are logged by Shareable. However, they should probably post their own events for easy reading.
 
-Line 45: 
+Line 45:
 This call to underLimit will reduce the daily limit, and then either throw or return 0. So in this case there's no danger that the limit will be reduced without the operation going through.
 
-Line 65: 
+Line 65:
 Shareable's onlyManyOwners will take the user's confirmation, and execute the function body if and only if enough users have confirmed. Whole thing throws if the send fails, which will roll back the confirmation. Confirm returns false if not enough have confirmed yet, true if the whole thing succeeds, and throws only in the exceptional circumstance that the designated transaction unexpectedly fails. Elegant design.
 
-Line 68: 
+Line 68:
 Throw here is good but note this function can fail either by returning false or by throwing.
 
-Line 92: 
+Line 92:
 A bit odd to split `clearPending()` between this contract and Shareable. However this does allow contracts inheriting from Shareable to use custom structs for pending transactions.
 
 

contracts/.npmignore

@@ -0,0 +1,2 @@
+mocks
+examples

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/Bounty.sol

@@ -1,78 +0,0 @@
-pragma solidity ^0.4.8;
-
-
-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 recieve funds, if they haven't already been claimed.
-   */
-  function() payable {
-    if (claimed) {
-      throw;
-    }
-  }
-
-  /**
-   * @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() returns(Target) {
-    Target target = Target(deployContract());
-    researchers[target] = msg.sender;
-    TargetCreated(target);
-    return target;
-  }
-
-  /**
-   * @dev Internal function to deploy the target contract.
-   * @return A target contract address
-   */
-  function deployContract() internal returns(address);
-
-  /**
-   * @dev Sends the contract funds to the researcher that proved the contract is broken.
-   * @param target contract
-   */
-  function claim(Target target) {
-    address researcher = researchers[target];
-    if (researcher == 0) {
-      throw;
-    }
-    // Check Target contract invariants
-    if (target.checkInvariant()) {
-      throw;
-    }
-    asyncSend(researcher, this.balance);
-    claimed = true;
-  }
-
-}
-
-
-/**
- * @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() returns(bool);
-}

contracts/DayLimit.sol

@@ -1,75 +0,0 @@
-pragma solidity ^0.4.8;
-
-/**
- * @title DayLimit
- * @dev Base contract that enables methods to be protected by placing a linear limit (specifiable)
- * on a particular resource per calendar day. Is multiowned to allow the limit to be altered.
- */
-contract DayLimit {
-
-  uint public dailyLimit;
-  uint public spentToday;
-  uint public lastDay;
-
-  /**
-   * @dev Constructor that sets the passed value as a dailyLimit.
-   * @param _limit Uint to represent the daily limit.
-   */
-  function DayLimit(uint _limit) {
-    dailyLimit = _limit;
-    lastDay = today();
-  }
-
-  /**
-   * @dev sets the daily limit. Does not alter the amount already spent today.
-   * @param _newLimit Uint to represent the new limit.
-   */
-  function _setDailyLimit(uint _newLimit) internal {
-    dailyLimit = _newLimit;
-  }
-
-  /**
-   * @dev Resets the amount already spent today.
-   */
-  function _resetSpentToday() internal {
-    spentToday = 0;
-  }
-
-  /**
-   * @dev Checks to see if there is enough resource to spend today. If true, the resource may be expended.
-   * @param _value Uint representing the amount of resource to spend.
-   * @return A boolean that is True if the resource was spended and false otherwise.
-   */
-  function underLimit(uint _value) internal returns (bool) {
-    // reset the spend limit if we're on a different day to last time.
-    if (today() > lastDay) {
-      spentToday = 0;
-      lastDay = today();
-    }
-    // check to see if there's enough left - if so, subtract and return true.
-    // overflow protection                    // dailyLimit check
-    if (spentToday + _value >= spentToday && spentToday + _value <= dailyLimit) {
-      spentToday += _value;
-      return true;
-    }
-    return false;
-  }
-
-  /**
-   * @dev Private function to determine today's index
-   * @return Uint of today's index.
-   */
-  function today() private constant returns (uint) {
-    return now / 1 days;
-  }
-
-  /**
-   * @dev Simple modifier for daily limit.
-   */
-  modifier limitedDaily(uint _value) {
-    if (!underLimit(_value)) {
-      throw;
-    }
-    _;
-  }
-}

contracts/LimitBalance.sol

@@ -1,33 +0,0 @@
-pragma solidity ^0.4.8;
-
-
-/**
- * @title LimitBalance
- * @dev Simple contract to limit the balance of child contract.
- * @dev Note this doesn't prevent other contracts to send funds by using selfdestruct(address);
- * @dev See: https://github.com/ConsenSys/smart-contract-best-practices#remember-that-ether-can-be-forcibly-sent-to-an-account
- */
-contract LimitBalance {
-
-  uint public limit;
-
-  /**
-   * @dev Constructor that sets the passed value as a limit. 
-   * @param _limit Uint to represent the limit.
-   */
-  function LimitBalance(uint _limit) {
-    limit = _limit;
-  }
-
-  /**
-   * @dev Checks if limit was reached. Case true, it throws.
-   */
-  modifier limitedPayable() {
-    if (this.balance > limit) {
-      throw;
-    }
-    _;
-
-  }
-
-}

contracts/MultisigWallet.sol

@@ -1,127 +0,0 @@
-pragma solidity ^0.4.8;
-
-
-import "./ownership/Multisig.sol";
-import "./ownership/Shareable.sol";
-import "./DayLimit.sol";
-
-
-/**
- * MultisigWallet
- * Usage:
- *     bytes32 h = Wallet(w).from(oneOwner).execute(to, value, data);
- *     Wallet(w).from(anotherOwner).confirm(h);
- */
-contract MultisigWallet is Multisig, Shareable, DayLimit {
-
-  struct Transaction {
-    address to;
-    uint value;
-    bytes data;
-  }
-
-  /**
-   * Constructor, sets the owners addresses, number of approvals required, and daily spending limit
-   * @param _owners A list of owners.
-   * @param _required The amount required for a transaction to be approved.
-   */
-  function MultisigWallet(address[] _owners, uint _required, uint _daylimit)       
-    Shareable(_owners, _required)        
-    DayLimit(_daylimit) { }
-
-  /** 
-   * @dev destroys the contract sending everything to `_to`. 
-   */
-  function destroy(address _to) onlymanyowners(keccak256(msg.data)) external {
-    selfdestruct(_to);
-  }
-
-  /** 
-   * @dev Fallback function, receives value and emits a deposit event. 
-   */
-  function() payable {
-    // just being sent some cash?
-    if (msg.value > 0)
-      Deposit(msg.sender, msg.value);
-  }
-
-  /**
-   * @dev Outside-visible transaction entry point. Executes transaction immediately if below daily 
-   * spending limit. If not, goes into multisig process. We provide a hash on return to allow the 
-   * sender to provide shortcuts for the other confirmations (allowing them to avoid replicating 
-   * the _to, _value, and _data arguments). They still get the option of using them if they want, 
-   * anyways.
-   * @param _to The receiver address
-   * @param _value The value to send
-   * @param _data The data part of the transaction
-   */
-  function execute(address _to, uint _value, bytes _data) external onlyOwner returns (bytes32 _r) {
-    // first, take the opportunity to check that we're under the daily limit.
-    if (underLimit(_value)) {
-      SingleTransact(msg.sender, _value, _to, _data);
-      // yes - just execute the call.
-      if (!_to.call.value(_value)(_data)) {
-        throw;
-      }
-      return 0;
-    }
-    // determine our operation hash.
-    _r = keccak256(msg.data, block.number);
-    if (!confirm(_r) && txs[_r].to == 0) {
-      txs[_r].to = _to;
-      txs[_r].value = _value;
-      txs[_r].data = _data;
-      ConfirmationNeeded(_r, msg.sender, _value, _to, _data);
-    }
-  }
-
-  /**
-   * @dev Confirm a transaction by providing just the hash. We use the previous transactions map, 
-   * txs, in order to determine the body of the transaction from the hash provided.
-   * @param _h The transaction hash to approve.
-   */
-  function confirm(bytes32 _h) onlymanyowners(_h) returns (bool) {
-    if (txs[_h].to != 0) {
-      if (!txs[_h].to.call.value(txs[_h].value)(txs[_h].data)) {
-        throw;
-      }
-      MultiTransact(msg.sender, _h, txs[_h].value, txs[_h].to, txs[_h].data);
-      delete txs[_h];
-      return true;
-    }
-  }
-
-  /** 
-   * @dev Updates the daily limit value. 
-   * @param _newLimit 
-   */
-  function setDailyLimit(uint _newLimit) onlymanyowners(keccak256(msg.data)) external {
-    _setDailyLimit(_newLimit);
-  }
-
-  /** 
-   * @dev Resets the value spent to enable more spending
-   */
-  function resetSpentToday() onlymanyowners(keccak256(msg.data)) external {
-    _resetSpentToday();
-  }
-
-
-  // INTERNAL METHODS
-  /** 
-   * @dev Clears the list of transactions pending approval.
-   */
-  function clearPending() internal {
-    uint length = pendingsIndex.length;
-    for (uint i = 0; i < length; ++i) {
-      delete txs[pendingsIndex[i]];
-    }
-    super.clearPending();
-  }
-
-
-  // FIELDS
-
-  // pending transactions we have at present.
-  mapping (bytes32 => Transaction) txs;
-}

contracts/ReentrancyGuard.sol

@@ -1,34 +0,0 @@
-pragma solidity ^0.4.8;
-
-/**
- * @title Helps contracts guard agains rentrancy 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 rentrancy_lock = 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() {
-    if(rentrancy_lock == false) {
-      rentrancy_lock = true;
-      _;
-      rentrancy_lock = false;
-    } else {
-      throw;
-    }
-  }
-
-}

contracts/SafeMath.sol

@@ -1,53 +0,0 @@
-pragma solidity ^0.4.8;
-
-
-/**
- * Math operations with safety checks
- */
-library SafeMath {
-  function mul(uint a, uint b) internal returns (uint) {
-    uint c = a * b;
-    assert(a == 0 || c / a == b);
-    return c;
-  }
-
-  function div(uint a, uint b) internal returns (uint) {
-    // assert(b > 0); // Solidity automatically throws when dividing by 0
-    uint c = a / b;
-    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
-    return c;
-  }
-
-  function sub(uint a, uint b) internal returns (uint) {
-    assert(b <= a);
-    return a - b;
-  }
-
-  function add(uint a, uint b) internal returns (uint) {
-    uint c = a + b;
-    assert(c >= a);
-    return c;
-  }
-
-  function max64(uint64 a, uint64 b) internal constant returns (uint64) {
-    return a >= b ? a : b;
-  }
-
-  function min64(uint64 a, uint64 b) internal constant returns (uint64) {
-    return a < b ? a : b;
-  }
-
-  function max256(uint256 a, uint256 b) internal constant returns (uint256) {
-    return a >= b ? a : b;
-  }
-
-  function min256(uint256 a, uint256 b) internal constant returns (uint256) {
-    return a < b ? a : b;
-  }
-
-  function assert(bool assertion) internal {
-    if (!assertion) {
-      throw;
-    }
-  }
-}

contracts/access/Roles.sol

@@ -0,0 +1,44 @@
+pragma solidity ^0.4.24;
+
+/**
+ * @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(account != address(0));
+    require(!has(role, account));
+
+    role.bearer[account] = true;
+  }
+
+  /**
+   * @dev remove an account's access to this role
+   */
+  function remove(Role storage role, address account) internal {
+    require(account != address(0));
+    require(has(role, account));
+
+    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));
+    return role.bearer[account];
+  }
+}

contracts/access/roles/CapperRole.sol

@@ -0,0 +1,43 @@
+pragma solidity ^0.4.24;
+
+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));
+    _;
+  }
+
+  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 ^0.4.24;
+
+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));
+    _;
+  }
+
+  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 ^0.4.24;
+
+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));
+    _;
+  }
+
+  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 ^0.4.24;
+
+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));
+    _;
+  }
+
+  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/crowdsale/Crowdsale.sol

@@ -0,0 +1,241 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/IERC20.sol";
+import "../math/SafeMath.sol";
+import "../token/ERC20/SafeERC20.sol";
+import "../utils/ReentrancyGuard.sol";
+
+/**
+ * @title Crowdsale
+ * @dev Crowdsale is a base contract for managing a token crowdsale,
+ * 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 / overridden.
+ * The internal interface conforms the extensible and modifiable surface of crowdsales. Override
+ * the methods to add functionality. Consider using 'super' where appropriate to concatenate
+ * behavior.
+ */
+contract Crowdsale is ReentrancyGuard {
+  using SafeMath for uint256;
+  using SafeERC20 for IERC20;
+
+  // The token being sold
+  IERC20 private _token;
+
+  // Address where funds are collected
+  address 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 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 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 TokensPurchased(
+    address indexed purchaser,
+    address indexed beneficiary,
+    uint256 value,
+    uint256 amount
+  );
+
+  /**
+   * @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 wallet, IERC20 token) internal {
+    require(rate > 0);
+    require(wallet != address(0));
+    require(token != address(0));
+
+    _rate = rate;
+    _wallet = wallet;
+    _token = token;
+  }
+
+  // -----------------------------------------
+  // Crowdsale external interface
+  // -----------------------------------------
+
+  /**
+   * @dev fallback function ***DO NOT OVERRIDE***
+   * Note that other contracts will transfer fund 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);
+  }
+
+  /**
+   * @return the token being sold.
+   */
+  function token() public view returns(IERC20) {
+    return _token;
+  }
+
+  /**
+   * @return the address where funds are collected.
+   */
+  function wallet() public view returns(address) {
+    return _wallet;
+  }
+
+  /**
+   * @return the number of token units a buyer gets per wei.
+   */
+  function rate() public view returns(uint256) {
+    return _rate;
+  }
+
+  /**
+   * @return the amount of wei raised.
+   */
+  function weiRaised() public view returns (uint256) {
+    return _weiRaised;
+  }
+
+  /**
+   * @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);
+
+    // calculate token amount to be created
+    uint256 tokens = _getTokenAmount(weiAmount);
+
+    // update state
+    _weiRaised = _weiRaised.add(weiAmount);
+
+    _processPurchase(beneficiary, tokens);
+    emit TokensPurchased(
+      msg.sender,
+      beneficiary,
+      weiAmount,
+      tokens
+    );
+
+    _updatePurchasingState(beneficiary, weiAmount);
+
+    _forwardFunds();
+    _postValidatePurchase(beneficiary, weiAmount);
+  }
+
+  // -----------------------------------------
+  // Internal interface (extensible)
+  // -----------------------------------------
+
+  /**
+   * @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));
+    require(weiAmount != 0);
+  }
+
+  /**
+   * @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
+  {
+    // optional override
+  }
+
+  /**
+   * @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 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 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 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/distribution/FinalizableCrowdsale.sol

@@ -0,0 +1,50 @@
+pragma solidity ^0.4.24;
+
+import "../../math/SafeMath.sol";
+import "../validation/TimedCrowdsale.sol";
+
+/**
+ * @title FinalizableCrowdsale
+ * @dev Extension of Crowdsale with a one-off finalization action, where one
+ * can do extra work after finishing.
+ */
+contract FinalizableCrowdsale is TimedCrowdsale {
+  using SafeMath for uint256;
+
+  bool private _finalized;
+
+  event CrowdsaleFinalized();
+
+  constructor() internal {
+    _finalized = false;
+  }
+
+  /**
+   * @return true if the crowdsale is finalized, false otherwise.
+   */
+  function finalized() public view returns (bool) {
+    return _finalized;
+  }
+
+  /**
+   * @dev Must be called after crowdsale ends, to do some extra finalization
+   * work. Calls the contract's finalization function.
+   */
+  function finalize() public {
+    require(!_finalized);
+    require(hasClosed());
+
+    _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 {
+  }
+}

contracts/crowdsale/distribution/PostDeliveryCrowdsale.sol

@@ -0,0 +1,50 @@
+pragma solidity ^0.4.24;
+
+import "../validation/TimedCrowdsale.sol";
+import "../../math/SafeMath.sol";
+
+/**
+ * @title PostDeliveryCrowdsale
+ * @dev Crowdsale that locks tokens from withdrawal until it ends.
+ */
+contract PostDeliveryCrowdsale is TimedCrowdsale {
+  using SafeMath for uint256;
+
+  mapping(address => uint256) private _balances;
+
+  constructor() internal {}
+
+  /**
+   * @dev Withdraw tokens only after crowdsale ends.
+   * @param beneficiary Whose tokens will be withdrawn.
+   */
+  function withdrawTokens(address beneficiary) public {
+    require(hasClosed());
+    uint256 amount = _balances[beneficiary];
+    require(amount > 0);
+    _balances[beneficiary] = 0;
+    _deliverTokens(beneficiary, amount);
+  }
+
+  /**
+   * @return the balance of an account.
+   */
+  function balanceOf(address account) public view returns(uint256) {
+    return _balances[account];
+  }
+
+  /**
+   * @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);
+  }
+
+}

contracts/crowdsale/distribution/RefundableCrowdsale.sol

@@ -0,0 +1,91 @@
+pragma solidity ^0.4.24;
+
+import "../../math/SafeMath.sol";
+import "./FinalizableCrowdsale.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.
+ * WARNING: 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. There are many possible ways to avoid this, like making the
+ * the crowdsale inherit from PostDeliveryCrowdsale, or imposing 
+ * restrictions on token trading until the crowdsale is finalized.
+ * This is being discussed in 
+ * https://github.com/OpenZeppelin/openzeppelin-solidity/issues/877
+ * This contract will be updated when we agree on a general solution
+ * for this problem.
+ */
+contract RefundableCrowdsale is FinalizableCrowdsale {
+  using SafeMath for uint256;
+
+  // 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;
+
+  /**
+   * @dev Constructor, creates RefundEscrow.
+   * @param goal Funding goal
+   */
+  constructor(uint256 goal) internal {
+    require(goal > 0);
+    _escrow = new RefundEscrow(wallet());
+    _goal = goal;
+  }
+
+  /**
+   * @return minimum amount of funds to be raised in wei.
+   */
+  function goal() public view returns(uint256) {
+    return _goal;
+  }
+
+  /**
+   * @dev Investors can claim refunds here if crowdsale is unsuccessful
+   * @param beneficiary Whose refund will be claimed.
+   */
+  function claimRefund(address beneficiary) public {
+    require(finalized());
+    require(!goalReached());
+
+    _escrow.withdraw(beneficiary);
+  }
+
+  /**
+   * @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/emission/AllowanceCrowdsale.sol

@@ -0,0 +1,59 @@
+pragma solidity ^0.4.24;
+
+import "../Crowdsale.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 IERC20;
+
+  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) internal {
+    require(tokenWallet != address(0));
+    _tokenWallet = tokenWallet;
+  }
+
+  /**
+   * @return the address of the wallet that will hold the tokens.
+   */
+  function tokenWallet() public view returns(address) {
+    return _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 Math.min(
+      token().balanceOf(_tokenWallet),
+      token().allowance(_tokenWallet, 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

@@ -0,0 +1,29 @@
+pragma solidity ^0.4.24;
+
+import "../Crowdsale.sol";
+import "../../token/ERC20/ERC20Mintable.sol";
+
+/**
+ * @title MintedCrowdsale
+ * @dev Extension of Crowdsale contract whose tokens are minted in each purchase.
+ * Token ownership should be transferred to MintedCrowdsale for minting.
+ */
+contract MintedCrowdsale is Crowdsale {
+  constructor() internal {}
+
+  /**
+   * @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));
+  }
+}

contracts/crowdsale/price/IncreasingPriceCrowdsale.sol

@@ -0,0 +1,81 @@
+pragma solidity ^0.4.24;
+
+import "../validation/TimedCrowdsale.sol";
+import "../../math/SafeMath.sol";
+
+/**
+ * @title IncreasingPriceCrowdsale
+ * @dev Extension of Crowdsale contract that increases the price of tokens linearly in time.
+ * Note that what should be provided to the constructor is the initial and final _rates_, that is,
+ * 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;
+
+  uint256 private _initialRate;
+  uint256 private _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) internal {
+    require(finalRate > 0);
+    require(initialRate > finalRate);
+    _initialRate = initialRate;
+    _finalRate = finalRate;
+  }
+
+  /**
+   * The base rate function is overridden to revert, since this crowdsale doens't use it, and
+   * all calls to it are a mistake.
+   */
+  function rate() public view returns(uint256) {
+    revert();
+  }
+
+  /**
+   * @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;
+    }
+
+    // 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));
+  }
+
+  /**
+   * @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

@@ -0,0 +1,55 @@
+pragma solidity ^0.4.24;
+
+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;
+
+  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) internal {
+    require(cap > 0);
+    _cap = cap;
+  }
+
+  /**
+   * @return the cap of the crowdsale.
+   */
+  function cap() public view returns(uint256) {
+    return _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);
+  }
+
+}

contracts/crowdsale/validation/IndividuallyCappedCrowdsale.sol

@@ -0,0 +1,81 @@
+pragma solidity ^0.4.24;
+
+import "../../math/SafeMath.sol";
+import "../Crowdsale.sol";
+import "../../access/roles/CapperRole.sol";
+
+/**
+ * @title IndividuallyCappedCrowdsale
+ * @dev Crowdsale with per-beneficiary caps.
+ */
+contract IndividuallyCappedCrowdsale is Crowdsale, CapperRole {
+  using SafeMath for uint256;
+
+  mapping(address => uint256) private _contributions;
+  mapping(address => uint256) private _caps;
+
+  constructor() internal {}
+
+  /**
+   * @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 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 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 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);
+    require(
+      _contributions[beneficiary].add(weiAmount) <= _caps[beneficiary]);
+  }
+
+  /**
+   * @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/TimedCrowdsale.sol

@@ -0,0 +1,85 @@
+pragma solidity ^0.4.24;
+
+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;
+
+  uint256 private _openingTime;
+  uint256 private _closingTime;
+
+  /**
+   * @dev Reverts if not in crowdsale time range.
+   */
+  modifier onlyWhileOpen {
+    require(isOpen());
+    _;
+  }
+
+  /**
+   * @dev Constructor, takes crowdsale opening and closing times.
+   * @param openingTime Crowdsale opening time
+   * @param closingTime Crowdsale closing time
+   */
+  constructor(uint256 openingTime, uint256 closingTime) internal {
+    // solium-disable-next-line security/no-block-members
+    require(openingTime >= block.timestamp);
+    require(closingTime > openingTime);
+
+    _openingTime = openingTime;
+    _closingTime = closingTime;
+  }
+
+  /**
+   * @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) {
+    // solium-disable-next-line security/no-block-members
+    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) {
+    // solium-disable-next-line security/no-block-members
+    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);
+  }
+
+}

contracts/cryptography/ECDSA.sol

@@ -0,0 +1,71 @@
+pragma solidity ^0.4.24;
+
+/**
+ * @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 signature)
+    internal
+    pure
+    returns (address)
+  {
+    bytes32 r;
+    bytes32 s;
+    uint8 v;
+
+    // Check the signature length
+    if (signature.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(signature, 0x20))
+      s := mload(add(signature, 0x40))
+      v := byte(0, mload(add(signature, 0x60)))
+    }
+
+    // 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/cryptography/MerkleProof.sol

@@ -0,0 +1,42 @@
+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 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[] 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/Counter.sol

@@ -0,0 +1,28 @@
+pragma solidity ^0.4.24;
+
+/**
+ * @title Counter
+ * @author Matt Condon (@shrugs)
+ * @dev Provides an incrementing uint256 id acquired by the `Counter#next` getter.
+ * Use this for issuing ERC721 ids or keeping track of request ids, anything you want, really.
+ *
+ * Include with `using Counter for Counter.Counter;`
+ * @notice Does not allow an Id of 0, which is popularly used to signify a null state in solidity.
+ * Does not protect from overflows, but if you have 2^256 ids, you have other problems.
+ * (But actually, it's generally impossible to increment a counter this many times, energy wise
+ * so it's not something you have to worry about.)
+ */
+library Counter {
+
+  struct Counter {
+    uint256 current; // default: 0
+  }
+
+  function next(Counter storage index)
+    internal
+    returns (uint256)
+  {
+    index.current += 1;
+    return index.current;
+  }
+}

contracts/drafts/ERC1046/TokenMetadata.sol

@@ -0,0 +1,27 @@
+pragma solidity ^0.4.24;
+
+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
+ * @dev TODO - update https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/token/ERC721/IERC721.sol#L17 when 1046 is finalized
+ */
+contract ERC20TokenMetadata is IERC20 {
+  function tokenURI() external view returns (string);
+}
+
+contract ERC20WithMetadata is ERC20TokenMetadata {
+  string private _tokenURI;
+
+  constructor(string tokenURI)
+    public
+  {
+    _tokenURI = tokenURI;
+  }
+
+  function tokenURI() external view returns (string) {
+    return _tokenURI;
+  }
+}

contracts/drafts/ERC20Migrator.sol

@@ -0,0 +1,100 @@
+pragma solidity ^0.4.24;
+
+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 transfered 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(legacyToken != address(0));
+    _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(_newToken == address(0));
+    require(newToken != address(0));
+    require(newToken.isMinter(this));
+
+    _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 {
+    _legacyToken.safeTransferFrom(account, 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, this);
+    uint256 amount = Math.min(balance, allowance);
+    migrate(account, amount);
+  }
+}

contracts/drafts/SignatureBouncer.sol

@@ -0,0 +1,146 @@
+pragma solidity ^0.4.24;
+
+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 _signaature 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 {}
+
+  /**
+   * @dev requires that a valid signature of a signer was provided
+   */
+  modifier onlyValidSignature(bytes signature)
+  {
+    require(_isValidSignature(msg.sender, signature));
+    _;
+  }
+
+  /**
+   * @dev requires that a valid signature with a specifed method of a signer was provided
+   */
+  modifier onlyValidSignatureAndMethod(bytes signature)
+  {
+    require(_isValidSignatureAndMethod(msg.sender, signature));
+    _;
+  }
+
+  /**
+   * @dev requires that a valid signature with a specifed method and params of a signer was provided
+   */
+  modifier onlyValidSignatureAndData(bytes signature)
+  {
+    require(_isValidSignatureAndData(msg.sender, signature));
+    _;
+  }
+
+  /**
+   * @dev is the signature of `this + sender` from a signer?
+   * @return bool
+   */
+  function _isValidSignature(address account, bytes signature)
+    internal
+    view
+    returns (bool)
+  {
+    return _isValidDataHash(
+      keccak256(abi.encodePacked(address(this), account)),
+      signature
+    );
+  }
+
+  /**
+   * @dev is the signature of `this + sender + methodId` from a signer?
+   * @return bool
+   */
+  function _isValidSignatureAndMethod(address account, bytes 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 + sender + 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 signature)
+    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), 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 signature)
+    internal
+    view
+    returns (bool)
+  {
+    address signer = hash
+      .toEthSignedMessageHash()
+      .recover(signature);
+
+    return signer != address(0) && isSigner(signer);
+  }
+}

contracts/drafts/TokenVesting.sol

@@ -0,0 +1,175 @@
+/* solium-disable security/no-block-members */
+
+pragma solidity ^0.4.24;
+
+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 {
+  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;
+
+  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));
+    require(cliffDuration <= duration);
+    require(duration > 0);
+    require(start.add(duration) > block.timestamp);
+
+    _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);
+
+    _released[token] = _released[token].add(unreleased);
+
+    token.safeTransfer(_beneficiary, unreleased);
+
+    emit TokensReleased(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);
+    require(!_revoked[token]);
+
+    uint256 balance = token.balanceOf(address(this));
+
+    uint256 unreleased = _releasableAmount(token);
+    uint256 refund = balance.sub(unreleased);
+
+    _revoked[token] = true;
+
+    token.safeTransfer(owner(), refund);
+
+    emit TokenVestingRevoked(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[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(this);
+    uint256 totalBalance = currentBalance.add(_released[token]);
+
+    if (block.timestamp < _cliff) {
+      return 0;
+    } else if (block.timestamp >= _start.add(_duration) || _revoked[token]) {
+      return totalBalance;
+    } else {
+      return totalBalance.mul(block.timestamp.sub(_start)).div(_duration);
+    }
+  }
+}

contracts/examples/SampleCrowdsale.sol

@@ -0,0 +1,57 @@
+pragma solidity ^0.4.24;
+
+import "../crowdsale/validation/CappedCrowdsale.sol";
+import "../crowdsale/distribution/RefundableCrowdsale.sol";
+import "../crowdsale/emission/MintedCrowdsale.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 ERC20Mintable, ERC20Detailed {
+  constructor() public ERC20Detailed("Sample Crowdsale Token", "SCT", 18) {}
+}
+
+/**
+ * @title SampleCrowdsale
+ * @dev This is an example of a fully fledged crowdsale.
+ * The way to add new features to a base crowdsale is by multiple inheritance.
+ * 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,
+    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);
+  }
+}

contracts/examples/SimpleToken.sol

@@ -0,0 +1,26 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/ERC20.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
+ * `ERC20` functions.
+ */
+contract SimpleToken is ERC20 {
+
+  string public constant name = "SimpleToken";
+  string public constant symbol = "SIM";
+  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 {
+    _mint(msg.sender, INITIAL_SUPPLY);
+  }
+
+}

contracts/introspection/ERC165.sol

@@ -0,0 +1,53 @@
+pragma solidity ^0.4.24;
+
+import "./IERC165.sol";
+
+/**
+ * @title ERC165
+ * @author Matt Condon (@shrugs)
+ * @dev Implements ERC165 using a lookup table.
+ */
+contract ERC165 is IERC165 {
+
+  bytes4 private 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) private _supportedInterfaces;
+
+  /**
+   * @dev A contract implementing SupportsInterfaceWithLookup
+   * implement ERC165 itself
+   */
+  constructor()
+    internal
+  {
+    _registerInterface(_InterfaceId_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);
+    _supportedInterfaces[interfaceId] = true;
+  }
+}

contracts/introspection/ERC165Checker.sol

@@ -0,0 +1,146 @@
+pragma solidity ^0.4.24;
+
+/**
+ * @title ERC165Checker
+ * @dev Use `using ERC165Checker for address`; to include this library
+ * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
+ */
+library ERC165Checker {
+  // As per the EIP-165 spec, no interface should ever match 0xffffffff
+  bytes4 private constant _InterfaceId_Invalid = 0xffffffff;
+
+  bytes4 private constant _InterfaceId_ERC165 = 0x01ffc9a7;
+  /**
+   * 0x01ffc9a7 ===
+   *   bytes4(keccak256('supportsInterface(bytes4)'))
+   */
+
+  /**
+   * @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, _InterfaceId_ERC165) &&
+      !_supportsERC165Interface(account, _InterfaceId_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[] 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(
+      _InterfaceId_ERC165,
+      interfaceId
+    );
+
+    // solium-disable-next-line security/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 +1,19 @@
+pragma solidity ^0.4.24;
+
+/**
+ * @title IERC165
+ * @dev https://github.com/ethereum/EIPs/blob/master/EIPS/eip-165.md
+ */
+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/lifecycle/Destructible.sol

@@ -1,23 +0,0 @@
-pragma solidity ^0.4.8;
-
-
-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 {
-
-  /**
-   * @dev Transfers the current balance to the owner and terminates the contract. 
-   */
-  function destroy() onlyOwner {
-    selfdestruct(owner);
-  }
-
-  function destroyAndSend(address _recipient) onlyOwner {
-    selfdestruct(_recipient);
-  }
-}

contracts/lifecycle/Migrations.sol

@@ -1,21 +0,0 @@
-pragma solidity ^0.4.8;
-
-
-import '../ownership/Ownable.sol';
-
-/**
- * @title Migrations
- * @dev This is a truffle contract, needed for truffle integration, not meant for use by Zeppelin users.
- */
-contract Migrations is Ownable {
-  uint public lastCompletedMigration;
-
-  function setCompleted(uint completed) onlyOwner {
-    lastCompletedMigration = completed;
-  }
-
-  function upgrade(address newAddress) onlyOwner {
-    Migrations upgraded = Migrations(newAddress);
-    upgraded.setCompleted(lastCompletedMigration);
-  }
-}

contracts/lifecycle/Pausable.sol

@@ -1,51 +1,57 @@
-pragma solidity ^0.4.8;
-
-
-import "../ownership/Ownable.sol";
+pragma solidity ^0.4.24;
 
+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 allow actions only when the contract IS 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 not paused.
    */
   modifier whenNotPaused() {
-    if (paused) throw;
+    require(!_paused);
     _;
   }
 
   /**
-   * @dev modifier to allow actions only when the contract IS NOT paused
+   * @dev Modifier to make a function callable only when the contract is paused.
    */
-  modifier whenPaused {
-    if (!paused) throw;
+  modifier whenPaused() {
+    require(_paused);
     _;
   }
 
   /**
    * @dev called by the owner to pause, triggers stopped state
    */
-  function pause() onlyOwner whenNotPaused returns (bool) {
-    paused = true;
-    Pause();
-    return true;
+  function pause() public onlyPauser whenNotPaused {
+    _paused = true;
+    emit Paused(msg.sender);
   }
 
   /**
    * @dev called by the owner to unpause, returns to normal state
    */
-  function unpause() onlyOwner whenPaused returns (bool) {
-    paused = false;
-    Unpause();
-    return true;
+  function unpause() public onlyPauser whenPaused {
+    _paused = false;
+    emit Unpaused(msg.sender);
   }
 }

contracts/lifecycle/TokenDestructible.sol

@@ -1,34 +0,0 @@
-pragma solidity ^0.4.8;
-
-
-import "../ownership/Ownable.sol";
-import "../token/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 {
-
-  /** 
-   * @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 {
-
-    // Transfer tokens to owner
-    for(uint 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

@@ -0,0 +1,31 @@
+pragma solidity ^0.4.24;
+
+/**
+ * @title Math
+ * @dev Assorted math operations
+ */
+library Math {
+  /**
+  * @dev Returns the largest of two numbers.
+  */
+  function max(uint256 a, uint256 b) internal pure returns (uint256) {
+    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;
+  }
+
+  /**
+  * @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

@@ -0,0 +1,65 @@
+pragma solidity ^0.4.24;
+
+/**
+ * @title SafeMath
+ * @dev Math operations with safety checks that revert on error
+ */
+library SafeMath {
+
+  /**
+  * @dev Multiplies two numbers, 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;
+    }
+
+    uint256 c = a * b;
+    require(c / a == b);
+
+    return c;
+  }
+
+  /**
+  * @dev Integer division of two numbers truncating the quotient, reverts on division by zero.
+  */
+  function div(uint256 a, uint256 b) internal pure returns (uint256) {
+    require(b > 0); // Solidity only automatically asserts 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 c;
+  }
+
+  /**
+  * @dev Subtracts two numbers, reverts on overflow (i.e. if subtrahend is greater than minuend).
+  */
+  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
+    require(b <= a);
+    uint256 c = a - b;
+
+    return c;
+  }
+
+  /**
+  * @dev Adds two numbers, reverts on overflow.
+  */
+  function add(uint256 a, uint256 b) internal pure returns (uint256) {
+    uint256 c = a + b;
+    require(c >= a);
+
+    return c;
+  }
+
+  /**
+  * @dev Divides two numbers 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);
+    return a % b;
+  }
+}

contracts/mocks/AddressImpl.sol

@@ -0,0 +1,14 @@
+pragma solidity ^0.4.24;
+
+import "../utils/Address.sol";
+
+contract AddressImpl {
+  function isContract(address account)
+    external
+    view
+    returns (bool)
+  {
+    return Address.isContract(account); 
+  }
+  
+}

contracts/mocks/AllowanceCrowdsaleImpl.sol

@@ -0,0 +1,20 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/IERC20.sol";
+import "../crowdsale/emission/AllowanceCrowdsale.sol";
+
+contract AllowanceCrowdsaleImpl is AllowanceCrowdsale {
+
+  constructor (
+    uint256 rate,
+    address wallet,
+    IERC20 token,
+    address tokenWallet
+  )
+    public
+    Crowdsale(rate, wallet, token)
+    AllowanceCrowdsale(tokenWallet)
+  {
+  }
+
+}

contracts/mocks/ArraysImpl.sol

@@ -0,0 +1,18 @@
+pragma solidity ^0.4.24;
+
+import "../utils/Arrays.sol";
+
+contract ArraysImpl {
+
+  using Arrays for uint256[];
+
+  uint256[] private array;
+
+  constructor(uint256[] _array) public {
+    array = _array;
+  }
+
+  function findUpperBound(uint256 _element) external view returns (uint256) {
+    return array.findUpperBound(_element);
+  }
+}

contracts/mocks/CappedCrowdsaleImpl.sol

@@ -0,0 +1,20 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/IERC20.sol";
+import "../crowdsale/validation/CappedCrowdsale.sol";
+
+contract CappedCrowdsaleImpl is CappedCrowdsale {
+
+  constructor (
+    uint256 rate,
+    address wallet,
+    IERC20 token,
+    uint256 cap
+  )
+    public
+    Crowdsale(rate, wallet, token)
+    CappedCrowdsale(cap)
+  {
+  }
+
+}

contracts/mocks/CapperRoleMock.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.4.24;
+
+import "../access/roles/CapperRole.sol";
+
+contract CapperRoleMock is CapperRole {
+  function removeCapper(address account) public {
+    _removeCapper(account);
+  }
+
+  function onlyCapperMock() public view onlyCapper {
+  }
+
+  // Causes a compilation error if super._removeCapper is not internal
+  function _removeCapper(address account) internal {
+    super._removeCapper(account);
+  }
+}

contracts/mocks/ConditionalEscrowMock.sol

@@ -0,0 +1,16 @@
+pragma solidity ^0.4.24;
+
+import "../payment/escrow/ConditionalEscrow.sol";
+
+// mock class using ConditionalEscrow
+contract ConditionalEscrowMock is ConditionalEscrow {
+  mapping(address => bool) private _allowed;
+
+  function setAllowed(address payee, bool allowed) public {
+    _allowed[payee] = allowed;
+  }
+
+  function withdrawalAllowed(address payee) public view returns (bool) {
+    return _allowed[payee];
+  }
+}

contracts/mocks/CounterImpl.sol

@@ -0,0 +1,20 @@
+pragma solidity ^0.4.24;
+
+import "../drafts/Counter.sol";
+
+contract CounterImpl {
+  using Counter for Counter.Counter;
+
+  uint256 public theId;
+
+  // use whatever key you want to track your counters
+  mapping(string => Counter.Counter) private _counters;
+
+  function doThing(string key)
+    public
+    returns (uint256)
+  {
+    theId = _counters[key].next();
+    return theId;
+  }
+}

contracts/mocks/CrowdsaleMock.sol

@@ -0,0 +1,9 @@
+pragma solidity ^0.4.24;
+
+import "../crowdsale/Crowdsale.sol";
+
+contract CrowdsaleMock is Crowdsale {
+  constructor(uint256 rate, address wallet, IERC20 token) public
+    Crowdsale(rate, wallet, token) {
+  }
+}

contracts/mocks/DetailedERC20Mock.sol

@@ -0,0 +1,15 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/ERC20.sol";
+import "../token/ERC20/ERC20Detailed.sol";
+
+contract ERC20DetailedMock is ERC20, ERC20Detailed {
+  constructor(
+    string name,
+    string symbol,
+    uint8 decimals
+  )
+    ERC20Detailed(name, symbol, decimals)
+    public
+  {}
+}

contracts/mocks/ECDSAMock.sol

@@ -0,0 +1,23 @@
+pragma solidity ^0.4.24;
+
+import "../cryptography/ECDSA.sol";
+
+contract ECDSAMock {
+  using ECDSA for bytes32;
+
+  function recover(bytes32 hash, bytes signature)
+    public
+    pure
+    returns (address)
+  {
+    return hash.recover(signature);
+  }
+
+  function toEthSignedMessageHash(bytes32 hash)
+    public
+    pure
+    returns (bytes32)
+  {
+    return hash.toEthSignedMessageHash();
+  }
+}

contracts/mocks/ERC165/ERC165InterfacesSupported.sol

@@ -0,0 +1,66 @@
+pragma solidity ^0.4.24;
+
+import "../../introspection/IERC165.sol";
+
+/**
+ * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-214.md#specification
+ * > Any attempts to make state-changing operations inside an execution instance with STATIC set to true will instead throw an exception.
+ * > These operations include [...], LOG0, LOG1, LOG2, [...]
+ *
+ * therefore, because this contract is staticcall'd we need to not emit events (which is how solidity-coverage works)
+ * solidity-coverage ignores the /mocks folder, so we duplicate its implementation here to avoid instrumenting it
+ */
+contract SupportsInterfaceWithLookupMock is IERC165 {
+
+  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) private _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;
+  }
+}
+
+contract ERC165InterfacesSupported is SupportsInterfaceWithLookupMock {
+  constructor (bytes4[] interfaceIds)
+    public
+  {
+    for (uint256 i = 0; i < interfaceIds.length; i++) {
+      _registerInterface(interfaceIds[i]);
+    }
+  }
+}

contracts/mocks/ERC165/ERC165NotSupported.sol

@@ -0,0 +1,5 @@
+pragma solidity ^0.4.24;
+
+contract ERC165NotSupported {
+
+}

contracts/mocks/ERC165CheckerMock.sol

@@ -0,0 +1,31 @@
+pragma solidity ^0.4.24;
+
+import "../introspection/ERC165Checker.sol";
+
+contract ERC165CheckerMock {
+  using ERC165Checker for address;
+
+  function supportsERC165(address account)
+    public
+    view
+    returns (bool)
+  {
+    return account._supportsERC165();
+  }
+
+  function supportsInterface(address account, bytes4 interfaceId)
+    public
+    view
+    returns (bool)
+  {
+    return account._supportsInterface(interfaceId);
+  }
+
+  function supportsAllInterfaces(address account, bytes4[] interfaceIds)
+    public
+    view
+    returns (bool)
+  {
+    return account._supportsAllInterfaces(interfaceIds);
+  }
+}

contracts/mocks/ERC165Mock.sol

@@ -0,0 +1,11 @@
+pragma solidity ^0.4.24;
+
+import "../introspection/ERC165.sol";
+
+contract ERC165Mock is ERC165 {
+  function registerInterface(bytes4 interfaceId)
+    public
+  {
+    _registerInterface(interfaceId);
+  }
+}

contracts/mocks/ERC20BurnableMock.sol

@@ -0,0 +1,11 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/ERC20Burnable.sol";
+
+contract ERC20BurnableMock is ERC20Burnable {
+
+  constructor(address initialAccount, uint256 initialBalance) public {
+    _mint(initialAccount, initialBalance);
+  }
+
+}

contracts/mocks/ERC20MintableMock.sol

@@ -0,0 +1,7 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/ERC20Mintable.sol";
+import "./MinterRoleMock.sol";
+
+contract ERC20MintableMock is ERC20Mintable, MinterRoleMock {
+}

contracts/mocks/ERC20Mock.sol

@@ -0,0 +1,24 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/ERC20.sol";
+
+// mock class using ERC20
+contract ERC20Mock is ERC20 {
+
+  constructor(address initialAccount, uint256 initialBalance) public {
+    _mint(initialAccount, initialBalance);
+  }
+
+  function mint(address account, uint256 amount) public {
+    _mint(account, amount);
+  }
+
+  function burn(address account, uint256 amount) public {
+    _burn(account, amount);
+  }
+
+  function burnFrom(address account, uint256 amount) public {
+    _burnFrom(account, amount);
+  }
+
+}

contracts/mocks/ERC20PausableMock.sol

@@ -0,0 +1,13 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/ERC20Pausable.sol";
+import "./PauserRoleMock.sol";
+
+// mock class using ERC20Pausable
+contract ERC20PausableMock is ERC20Pausable, PauserRoleMock {
+
+  constructor(address initialAccount, uint initialBalance) public {
+    _mint(initialAccount, initialBalance);
+  }
+
+}

contracts/mocks/ERC20WithMetadataMock.sol

@@ -0,0 +1,11 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/ERC20.sol";
+import "../drafts/ERC1046/TokenMetadata.sol";
+
+contract ERC20WithMetadataMock is ERC20, ERC20WithMetadata {
+  constructor(string tokenURI) public
+    ERC20WithMetadata(tokenURI)
+  {
+  }
+}

contracts/mocks/ERC721FullMock.sol

@@ -0,0 +1,32 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC721/ERC721Full.sol";
+import "../token/ERC721/ERC721Mintable.sol";
+import "../token/ERC721/ERC721MetadataMintable.sol";
+import "../token/ERC721/ERC721Burnable.sol";
+
+/**
+ * @title ERC721FullMock
+ * This mock just provides a public mint and burn functions for testing purposes,
+ * and a public setter for metadata URI
+ */
+contract ERC721FullMock
+  is ERC721Full, ERC721Mintable, ERC721MetadataMintable, ERC721Burnable {
+
+  constructor(string name, string symbol) public
+    ERC721Mintable()
+    ERC721Full(name, symbol)
+  {}
+
+  function exists(uint256 tokenId) public view returns (bool) {
+    return _exists(tokenId);
+  }
+
+  function setTokenURI(uint256 tokenId, string uri) public {
+    _setTokenURI(tokenId, uri);
+  }
+
+  function removeTokenFrom(address from, uint256 tokenId) public {
+    _removeTokenFrom(from, tokenId);
+  }
+}

contracts/mocks/ERC721MintableBurnableImpl.sol

@@ -0,0 +1,20 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC721/ERC721Full.sol";
+import "../token/ERC721/ERC721Mintable.sol";
+import "../token/ERC721/ERC721MetadataMintable.sol";
+import "../token/ERC721/ERC721Burnable.sol";
+
+/**
+ * @title ERC721MintableBurnableImpl
+ */
+contract ERC721MintableBurnableImpl
+  is ERC721Full, ERC721Mintable, ERC721MetadataMintable, ERC721Burnable {
+
+  constructor()
+    ERC721Mintable()
+    ERC721Full("Test", "TEST")
+    public
+  {
+  }
+}

contracts/mocks/ERC721Mock.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC721/ERC721.sol";
+
+/**
+ * @title ERC721Mock
+ * This mock just provides a public mint and burn functions for testing purposes
+ */
+contract ERC721Mock is ERC721 {
+  function mint(address to, uint256 tokenId) public {
+    _mint(to, tokenId);
+  }
+
+  function burn(uint256 tokenId) public {
+    _burn(ownerOf(tokenId), tokenId);
+  }
+}

contracts/mocks/ERC721PausableMock.sol

@@ -0,0 +1,22 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC721/ERC721Pausable.sol";
+import "./PauserRoleMock.sol";
+
+/**
+ * @title ERC721PausableMock
+ * This mock just provides a public mint, burn and exists functions for testing purposes
+ */
+contract ERC721PausableMock is ERC721Pausable, PauserRoleMock {
+  function mint(address to, uint256 tokenId) public {
+    super._mint(to, tokenId);
+  }
+
+  function burn(uint256 tokenId) public {
+    super._burn(ownerOf(tokenId), tokenId);
+  }
+
+  function exists(uint256 tokenId) public view returns (bool) {
+    return super._exists(tokenId);
+  }
+}

contracts/mocks/ERC721ReceiverMock.sol

@@ -0,0 +1,41 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC721/IERC721Receiver.sol";
+
+contract ERC721ReceiverMock is IERC721Receiver {
+  bytes4 private _retval;
+  bool private _reverts;
+
+  event Received(
+    address operator,
+    address from,
+    uint256 tokenId,
+    bytes data,
+    uint256 gas
+  );
+
+  constructor(bytes4 retval, bool reverts) public {
+    _retval = retval;
+    _reverts = reverts;
+  }
+
+  function onERC721Received(
+    address operator,
+    address from,
+    uint256 tokenId,
+    bytes data
+  )
+    public
+    returns(bytes4)
+  {
+    require(!_reverts);
+    emit Received(
+      operator,
+      from,
+      tokenId,
+      data,
+      gasleft() // msg.gas was deprecated in solidityv0.4.21
+    );
+    return _retval;
+  }
+}

contracts/mocks/EventEmitter.sol

@@ -0,0 +1,62 @@
+pragma solidity ^0.4.24;
+
+contract EventEmitter {
+  event Argumentless();
+  event ShortUint(uint8 value);
+  event ShortInt(int8 value);
+  event LongUint(uint256 value);
+  event LongInt(int256 value);
+  event Address(address value);
+  event Boolean(bool value);
+  event String(string value);
+  event LongUintBooleanString(
+    uint256 uintValue,
+    bool booleanValue,
+    string stringValue
+  );
+
+  function emitArgumentless() public {
+    emit Argumentless();
+  }
+
+  function emitShortUint(uint8 value) public {
+    emit ShortUint(value);
+  }
+
+  function emitShortInt(int8 value) public {
+    emit ShortInt(value);
+  }
+
+  function emitLongUint(uint256 value) public {
+    emit LongUint(value);
+  }
+
+  function emitLongInt(int256 value) public {
+    emit LongInt(value);
+  }
+
+  function emitAddress(address value) public {
+    emit Address(value);
+  }
+
+  function emitBoolean(bool value) public {
+    emit Boolean(value);
+  }
+
+  function emitString(string value) public {
+    emit String(value);
+  }
+
+  function emitLongUintBooleanString(
+    uint256 uintValue,
+    bool booleanValue,
+    string stringValue)
+  public {
+    emit LongUintBooleanString(uintValue, booleanValue, stringValue);
+  }
+
+  function emitLongUintAndBoolean(uint256 uintValue, bool boolValue) public {
+    emit LongUint(uintValue);
+    emit Boolean(boolValue);
+  }
+}

contracts/mocks/FinalizableCrowdsaleImpl.sol

@@ -0,0 +1,21 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/IERC20.sol";
+import "../crowdsale/distribution/FinalizableCrowdsale.sol";
+
+contract FinalizableCrowdsaleImpl is FinalizableCrowdsale {
+
+  constructor (
+    uint256 openingTime,
+    uint256 closingTime,
+    uint256 rate,
+    address wallet,
+    IERC20 token
+  )
+    public
+    Crowdsale(rate, wallet, token)
+    TimedCrowdsale(openingTime, closingTime)
+  {
+  }
+
+}

contracts/mocks/IncreasingPriceCrowdsaleImpl.sol

@@ -0,0 +1,23 @@
+pragma solidity ^0.4.24;
+
+import "../crowdsale/price/IncreasingPriceCrowdsale.sol";
+import "../math/SafeMath.sol";
+
+contract IncreasingPriceCrowdsaleImpl is IncreasingPriceCrowdsale {
+
+  constructor (
+    uint256 openingTime,
+    uint256 closingTime,
+    address wallet,
+    IERC20 token,
+    uint256 initialRate,
+    uint256 finalRate
+  )
+    public
+    Crowdsale(initialRate, wallet, token)
+    TimedCrowdsale(openingTime, closingTime)
+    IncreasingPriceCrowdsale(initialRate, finalRate)
+  {
+  }
+
+}

contracts/mocks/IndividuallyCappedCrowdsaleImpl.sol

@@ -0,0 +1,19 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/IERC20.sol";
+import "../crowdsale/validation/IndividuallyCappedCrowdsale.sol";
+import "./CapperRoleMock.sol";
+
+contract IndividuallyCappedCrowdsaleImpl
+  is IndividuallyCappedCrowdsale, CapperRoleMock {
+
+  constructor(
+    uint256 rate,
+    address wallet,
+    IERC20 token
+  )
+    public
+    Crowdsale(rate, wallet, token)
+  {
+  }
+}

contracts/mocks/MathMock.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.4.24;
+
+import "../math/Math.sol";
+
+contract MathMock {
+  function max(uint256 a, uint256 b) public pure returns (uint256) {
+    return Math.max(a, b);
+  }
+
+  function min(uint256 a, uint256 b) public pure returns (uint256) {
+    return Math.min(a, b);
+  }
+
+  function average(uint256 a, uint256 b) public pure returns (uint256) {
+    return Math.average(a, b);
+  }
+}

contracts/mocks/MerkleProofWrapper.sol

@@ -0,0 +1,18 @@
+pragma solidity ^0.4.24;
+
+import { MerkleProof } from "../cryptography/MerkleProof.sol";
+
+contract MerkleProofWrapper {
+
+  function verify(
+    bytes32[] proof,
+    bytes32 root,
+    bytes32 leaf
+  )
+    public
+    pure
+    returns (bool)
+  {
+    return MerkleProof.verify(proof, root, leaf);
+  }
+}

contracts/mocks/MintedCrowdsaleImpl.sol

@@ -0,0 +1,18 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/ERC20Mintable.sol";
+import "../crowdsale/emission/MintedCrowdsale.sol";
+
+contract MintedCrowdsaleImpl is MintedCrowdsale {
+
+  constructor (
+    uint256 rate,
+    address wallet,
+    ERC20Mintable token
+  )
+    public
+    Crowdsale(rate, wallet, token)
+  {
+  }
+
+}

contracts/mocks/MinterRoleMock.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.4.24;
+
+import "../access/roles/MinterRole.sol";
+
+contract MinterRoleMock is MinterRole {
+  function removeMinter(address account) public {
+    _removeMinter(account);
+  }
+
+  function onlyMinterMock() public view onlyMinter {
+  }
+
+  // Causes a compilation error if super._removeMinter is not internal
+  function _removeMinter(address account) internal {
+    super._removeMinter(account);
+  }
+}

contracts/mocks/OwnableMock.sol

@@ -0,0 +1,6 @@
+pragma solidity ^0.4.24;
+
+import "../ownership/Ownable.sol";
+
+contract OwnableMock is Ownable {
+}

contracts/mocks/PausableMock.sol

@@ -1,15 +1,14 @@
-pragma solidity ^0.4.8;
-
-
-import '../../contracts/lifecycle/Pausable.sol';
+pragma solidity ^0.4.24;
 
+import "../lifecycle/Pausable.sol";
+import "./PauserRoleMock.sol";
 
 // mock class using Pausable
-contract PausableMock is Pausable {
+contract PausableMock is Pausable, PauserRoleMock {
   bool public drasticMeasureTaken;
-  uint public count;
+  uint256 public count;
 
-  function PausableMock() {
+  constructor() public {
     drasticMeasureTaken = false;
     count = 0;
   }

contracts/mocks/PauserRoleMock.sol

@@ -0,0 +1,17 @@
+pragma solidity ^0.4.24;
+
+import "../access/roles/PauserRole.sol";
+
+contract PauserRoleMock is PauserRole {
+  function removePauser(address account) public {
+    _removePauser(account);
+  }
+
+  function onlyPauserMock() public view onlyPauser {
+  }
+
+  // Causes a compilation error if super._removePauser is not internal
+  function _removePauser(address account) internal {
+    super._removePauser(account);
+  }
+}

contracts/mocks/PostDeliveryCrowdsaleImpl.sol

@@ -0,0 +1,21 @@
+pragma solidity ^0.4.24;
+
+import "../token/ERC20/IERC20.sol";
+import "../crowdsale/distribution/PostDeliveryCrowdsale.sol";
+
+contract PostDeliveryCrowdsaleImpl is PostDeliveryCrowdsale {
+
+  constructor (
+    uint256 openingTime,
+    uint256 closingTime,
+    uint256 rate,
+    address wallet,
+    IERC20 token
+  )
+    public
+    TimedCrowdsale(openingTime, closingTime)
+    Crowdsale(rate, wallet, token)
+  {
+  }
+
+}

contracts/mocks/PullPaymentMock.sol

@@ -0,0 +1,15 @@
+pragma solidity ^0.4.24;
+
+import "../payment/PullPayment.sol";
+
+// mock class using PullPayment
+contract PullPaymentMock is PullPayment {
+
+  constructor() public payable { }
+
+  // test helper function to call asyncTransfer
+  function callTransfer(address dest, uint256 amount) public {
+    _asyncTransfer(dest, amount);
+  }
+
+}