be5ed7364b
* Now compiling in a separate directory using truffle 5. * Ported to 0.5.1, now compiling using 0.5.1. * test now also compiles using the truffle 5 hack. * Downgraded to 0.5.0. * Sorted scripts. * Cleaned up the compile script a bit.
25 lines
873 B
Solidity
25 lines
873 B
Solidity
pragma solidity ^0.5.0;
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/**
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* @title Counter
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* @author Matt Condon (@shrugs)
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* @dev Provides an incrementing uint256 id acquired by the `Counter#next` getter.
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* Use this for issuing ERC721 ids or keeping track of request ids, anything you want, really.
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*
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* Include with `using Counter for Counter.Counter;`
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* @notice Does not allow an Id of 0, which is popularly used to signify a null state in solidity.
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* Does not protect from overflows, but if you have 2^256 ids, you have other problems.
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* (But actually, it's generally impossible to increment a counter this many times, energy wise
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* so it's not something you have to worry about.)
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*/
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library Counter {
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struct Counter {
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uint256 current; // default: 0
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}
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function next(Counter storage index) internal returns (uint256) {
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index.current += 1;
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return index.current;
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}
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}
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