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OptimismMintableERC20.sol
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OptimismMintableERC20.sol
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// SPDX-License-Identifier: MIT
pragma solidity 0.8.15;
import { ERC20 } from "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import { IERC165 } from "@openzeppelin/contracts/utils/introspection/IERC165.sol";
import { ILegacyMintableERC20, IOptimismMintableERC20 } from "./IOptimismMintableERC20.sol";
import { Semver } from "../universal/Semver.sol";
/**
* @title OptimismMintableERC20
* @notice OptimismMintableERC20 is a standard extension of the base ERC20 token contract designed
* to allow the StandardBridge contracts to mint and burn tokens. This makes it possible to
* use an OptimismMintablERC20 as the L2 representation of an L1 token, or vice-versa.
* Designed to be backwards compatible with the older StandardL2ERC20 token which was only
* meant for use on L2.
*/
contract OptimismMintableERC20 is IOptimismMintableERC20, ILegacyMintableERC20, ERC20, Semver {
/**
* @notice Address of the corresponding version of this token on the remote chain.
*/
address public immutable REMOTE_TOKEN;
/**
* @notice Address of the StandardBridge on this network.
*/
address public immutable BRIDGE;
/**
* @notice Emitted whenever tokens are minted for an account.
*
* @param account Address of the account tokens are being minted for.
* @param amount Amount of tokens minted.
*/
event Mint(address indexed account, uint256 amount);
/**
* @notice Emitted whenever tokens are burned from an account.
*
* @param account Address of the account tokens are being burned from.
* @param amount Amount of tokens burned.
*/
event Burn(address indexed account, uint256 amount);
/**
* @notice A modifier that only allows the bridge to call
*/
modifier onlyBridge() {
require(msg.sender == BRIDGE, "OptimismMintableERC20: only bridge can mint and burn");
_;
}
/**
* @custom:semver 1.0.0
*
* @param _bridge Address of the L2 standard bridge.
* @param _remoteToken Address of the corresponding L1 token.
* @param _name ERC20 name.
* @param _symbol ERC20 symbol.
*/
constructor(
address _bridge,
address _remoteToken,
string memory _name,
string memory _symbol
) ERC20(_name, _symbol) Semver(1, 0, 0) {
REMOTE_TOKEN = _remoteToken;
BRIDGE = _bridge;
}
/**
* @notice Allows the StandardBridge on this network to mint tokens.
*
* @param _to Address to mint tokens to.
* @param _amount Amount of tokens to mint.
*/
function mint(address _to, uint256 _amount)
external
virtual
override(IOptimismMintableERC20, ILegacyMintableERC20)
onlyBridge
{
_mint(_to, _amount);
emit Mint(_to, _amount);
}
/**
* @notice Allows the StandardBridge on this network to burn tokens.
*
* @param _from Address to burn tokens from.
* @param _amount Amount of tokens to burn.
*/
function burn(address _from, uint256 _amount)
external
virtual
override(IOptimismMintableERC20, ILegacyMintableERC20)
onlyBridge
{
_burn(_from, _amount);
emit Burn(_from, _amount);
}
/**
* @notice ERC165 interface check function.
*
* @param _interfaceId Interface ID to check.
*
* @return Whether or not the interface is supported by this contract.
*/
function supportsInterface(bytes4 _interfaceId) external pure returns (bool) {
bytes4 iface1 = type(IERC165).interfaceId;
// Interface corresponding to the legacy L2StandardERC20.
bytes4 iface2 = type(ILegacyMintableERC20).interfaceId;
// Interface corresponding to the updated OptimismMintableERC20 (this contract).
bytes4 iface3 = type(IOptimismMintableERC20).interfaceId;
return _interfaceId == iface1 || _interfaceId == iface2 || _interfaceId == iface3;
}
/**
* @custom:legacy
* @notice Legacy getter for the remote token. Use REMOTE_TOKEN going forward.
*/
function l1Token() public view returns (address) {
return REMOTE_TOKEN;
}
/**
* @custom:legacy
* @notice Legacy getter for the bridge. Use BRIDGE going forward.
*/
function l2Bridge() public view returns (address) {
return BRIDGE;
}
/**
* @custom:legacy
* @notice Legacy getter for REMOTE_TOKEN.
*/
function remoteToken() public view returns (address) {
return REMOTE_TOKEN;
}
/**
* @custom:legacy
* @notice Legacy getter for BRIDGE.
*/
function bridge() public view returns (address) {
return BRIDGE;
}
}