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.
41 lines
1.6 KiB
Solidity
41 lines
1.6 KiB
Solidity
pragma solidity ^0.5.0;
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import "./IERC20.sol";
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import "../../math/SafeMath.sol";
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/**
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* @title SafeERC20
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* @dev Wrappers around ERC20 operations that throw on failure.
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* To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
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* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
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*/
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library SafeERC20 {
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using SafeMath for uint256;
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function safeTransfer(IERC20 token, address to, uint256 value) internal {
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require(token.transfer(to, value));
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}
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function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
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require(token.transferFrom(from, to, value));
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}
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function safeApprove(IERC20 token, address spender, uint256 value) internal {
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// safeApprove should only be called when setting an initial allowance,
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// or when resetting it to zero. To increase and decrease it, use
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// 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
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require((value == 0) || (token.allowance(msg.sender, spender) == 0));
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require(token.approve(spender, value));
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}
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function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
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uint256 newAllowance = token.allowance(address(this), spender).add(value);
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require(token.approve(spender, newAllowance));
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}
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function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
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uint256 newAllowance = token.allowance(address(this), spender).sub(value);
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require(token.approve(spender, newAllowance));
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}
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}
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