50 lines
1.1 KiB
Solidity
50 lines
1.1 KiB
Solidity
pragma solidity ^0.4.24;
|
|
|
|
import "./IERC20.sol";
|
|
import "../../math/SafeMath.sol";
|
|
|
|
/**
|
|
* @title SafeERC20
|
|
* @dev Wrappers around ERC20 operations that throw on failure.
|
|
* To use this library you can add a `using SafeERC20 for ERC20;` statement to your contract,
|
|
* which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
|
|
*/
|
|
library SafeERC20 {
|
|
using SafeMath for uint256;
|
|
|
|
function safeTransfer(IERC20 token, address to, uint256 value) internal {
|
|
require(token.transfer(to, value));
|
|
}
|
|
|
|
function safeApprove(
|
|
IERC20 token,
|
|
address spender,
|
|
uint256 value
|
|
)
|
|
internal
|
|
{
|
|
require((value == 0) || (token.allowance(msg.sender, spender) == 0));
|
|
require(token.approve(spender, value));
|
|
}
|
|
|
|
function safeIncreaseAllowance(
|
|
IERC20 token,
|
|
address spender,
|
|
uint256 addedValue
|
|
)
|
|
internal
|
|
{
|
|
require(token.increaseAllowance(spender, addedValue));
|
|
}
|
|
|
|
function safeDecreaseAllowance(
|
|
IERC20 token,
|
|
address spender,
|
|
uint256 subtractedValue
|
|
)
|
|
internal
|
|
{
|
|
require(token.decreaseAllowance(spender, subtractedValue));
|
|
}
|
|
}
|