3318b91697
* feat: add AutoIncrementing contract * feat: allow multiple counters per instance * fix: some linting errors * feat: use recommended implementaiton * fix: remove .only in tests * fix: PR notes * fix: add note about incrementing counter
30 lines
939 B
Solidity
30 lines
939 B
Solidity
pragma solidity ^0.4.24;
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/**
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* @title AutoIncrementing
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* @author Matt Condon (@shrugs)
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* @dev Provides an auto-incrementing uint256 id acquired by the `Counter#nextId` getter.
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* Use this for issuing ERC721Token ids or keeping track of request ids, anything you want, really.
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*
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* Include with `using AutoIncrementing for AutoIncrementing.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 AutoIncrementing {
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struct Counter {
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uint256 prevId; // default: 0
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}
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function nextId(Counter storage _counter)
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internal
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returns (uint256)
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{
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_counter.prevId = _counter.prevId + 1;
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return _counter.prevId;
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}
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}
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