// SPDX-License-Identifier: AGPL-3.0-onlypragmasolidity >=0.8.0;/// @notice Modern and gas efficient ERC20 + EIP-2612 implementation./// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/tokens/ERC20.sol)/// @author Modified from Uniswap (https://github.com/Uniswap/uniswap-v2-core/blob/master/contracts/UniswapV2ERC20.sol)/// @dev Do not manually set balances without updating totalSupply, as the sum of all user balances must not exceed it.abstractcontractERC20{
/*//////////////////////////////////////////////////////////////
EVENTS
//////////////////////////////////////////////////////////////*/eventTransfer(addressindexedfrom, addressindexed to, uint256 amount);
eventApproval(addressindexed owner, addressindexed spender, uint256 amount);
/*//////////////////////////////////////////////////////////////
METADATA STORAGE
//////////////////////////////////////////////////////////////*/stringpublic name;
stringpublic symbol;
uint8publicimmutable decimals;
/*//////////////////////////////////////////////////////////////
ERC20 STORAGE
//////////////////////////////////////////////////////////////*/uint256public totalSupply;
mapping(address=>uint256) public balanceOf;
mapping(address=>mapping(address=>uint256)) public allowance;
/*//////////////////////////////////////////////////////////////
EIP-2612 STORAGE
//////////////////////////////////////////////////////////////*/uint256internalimmutable INITIAL_CHAIN_ID;
bytes32internalimmutable INITIAL_DOMAIN_SEPARATOR;
mapping(address=>uint256) public nonces;
/*//////////////////////////////////////////////////////////////
CONSTRUCTOR
//////////////////////////////////////////////////////////////*/constructor(stringmemory _name,
stringmemory _symbol,
uint8 _decimals
) {
name = _name;
symbol = _symbol;
decimals = _decimals;
INITIAL_CHAIN_ID =block.chainid;
INITIAL_DOMAIN_SEPARATOR = computeDomainSeparator();
}
/*//////////////////////////////////////////////////////////////
ERC20 LOGIC
//////////////////////////////////////////////////////////////*/functionapprove(address spender, uint256 amount) publicvirtualreturns (bool) {
allowance[msg.sender][spender] = amount;
emit Approval(msg.sender, spender, amount);
returntrue;
}
functiontransfer(address to, uint256 amount) publicvirtualreturns (bool) {
balanceOf[msg.sender] -= amount;
// Cannot overflow because the sum of all user// balances can't exceed the max uint256 value.unchecked {
balanceOf[to] += amount;
}
emit Transfer(msg.sender, to, amount);
returntrue;
}
functiontransferFrom(addressfrom,
address to,
uint256 amount
) publicvirtualreturns (bool) {
uint256 allowed = allowance[from][msg.sender]; // Saves gas for limited approvals.if (allowed !=type(uint256).max) allowance[from][msg.sender] = allowed - amount;
balanceOf[from] -= amount;
// Cannot overflow because the sum of all user// balances can't exceed the max uint256 value.unchecked {
balanceOf[to] += amount;
}
emit Transfer(from, to, amount);
returntrue;
}
/*//////////////////////////////////////////////////////////////
EIP-2612 LOGIC
//////////////////////////////////////////////////////////////*/functionpermit(address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) publicvirtual{
require(deadline >=block.timestamp, "PERMIT_DEADLINE_EXPIRED");
// Unchecked because the only math done is incrementing// the owner's nonce which cannot realistically overflow.unchecked {
address recoveredAddress =ecrecover(
keccak256(
abi.encodePacked(
"\x19\x01",
DOMAIN_SEPARATOR(),
keccak256(
abi.encode(
keccak256(
"Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)"
),
owner,
spender,
value,
nonces[owner]++,
deadline
)
)
)
),
v,
r,
s
);
require(recoveredAddress !=address(0) && recoveredAddress == owner, "INVALID_SIGNER");
allowance[recoveredAddress][spender] = value;
}
emit Approval(owner, spender, value);
}
functionDOMAIN_SEPARATOR() publicviewvirtualreturns (bytes32) {
returnblock.chainid== INITIAL_CHAIN_ID ? INITIAL_DOMAIN_SEPARATOR : computeDomainSeparator();
}
functioncomputeDomainSeparator() internalviewvirtualreturns (bytes32) {
returnkeccak256(
abi.encode(
keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
keccak256(bytes(name)),
keccak256("1"),
block.chainid,
address(this)
)
);
}
/*//////////////////////////////////////////////////////////////
INTERNAL MINT/BURN LOGIC
//////////////////////////////////////////////////////////////*/function_mint(address to, uint256 amount) internalvirtual{
totalSupply += amount;
// Cannot overflow because the sum of all user// balances can't exceed the max uint256 value.unchecked {
balanceOf[to] += amount;
}
emit Transfer(address(0), to, amount);
}
function_burn(addressfrom, uint256 amount) internalvirtual{
balanceOf[from] -= amount;
// Cannot underflow because a user's balance// will never be larger than the total supply.unchecked {
totalSupply -= amount;
}
emit Transfer(from, address(0), amount);
}
}
Contract Source Code
File 4 of 6: IERC20.sol
// SPDX-License-Identifier: MITpragmasolidity >=0.6.2;/// @dev Interface of the ERC20 standard as defined in the EIP./// @dev This includes the optional name, symbol, and decimals metadata.interfaceIERC20{
/// @dev Emitted when `value` tokens are moved from one account (`from`) to another (`to`).eventTransfer(addressindexedfrom, addressindexed to, uint256 value);
/// @dev Emitted when the allowance of a `spender` for an `owner` is set, where `value`/// is the new allowance.eventApproval(addressindexed owner, addressindexed spender, uint256 value);
/// @notice Returns the amount of tokens in existence.functiontotalSupply() externalviewreturns (uint256);
/// @notice Returns the amount of tokens owned by `account`.functionbalanceOf(address account) externalviewreturns (uint256);
/// @notice Moves `amount` tokens from the caller's account to `to`.functiontransfer(address to, uint256 amount) externalreturns (bool);
/// @notice Returns the remaining number of tokens that `spender` is allowed/// to spend on behalf of `owner`functionallowance(address owner, address spender) externalviewreturns (uint256);
/// @notice Sets `amount` as the allowance of `spender` over the caller's tokens./// @dev Be aware of front-running risks: https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729functionapprove(address spender, uint256 amount) externalreturns (bool);
/// @notice Moves `amount` tokens from `from` to `to` using the allowance mechanism./// `amount` is then deducted from the caller's allowance.functiontransferFrom(addressfrom, address to, uint256 amount) externalreturns (bool);
/// @notice Returns the name of the token.functionname() externalviewreturns (stringmemory);
/// @notice Returns the symbol of the token.functionsymbol() externalviewreturns (stringmemory);
/// @notice Returns the decimals places of the token.functiondecimals() externalviewreturns (uint8);
}
// SPDX-License-Identifier: AGPL-3.0-onlypragmasolidity >=0.8.0;import {ERC20} from"../tokens/ERC20.sol";
/// @notice Safe ETH and ERC20 transfer library that gracefully handles missing return values./// @author Solmate (https://github.com/transmissions11/solmate/blob/main/src/utils/SafeTransferLib.sol)/// @dev Use with caution! Some functions in this library knowingly create dirty bits at the destination of the free memory pointer.librarySafeTransferLib{
/*//////////////////////////////////////////////////////////////
ETH OPERATIONS
//////////////////////////////////////////////////////////////*/functionsafeTransferETH(address to, uint256 amount) internal{
bool success;
/// @solidity memory-safe-assemblyassembly {
// Transfer the ETH and store if it succeeded or not.
success :=call(gas(), to, amount, 0, 0, 0, 0)
}
require(success, "ETH_TRANSFER_FAILED");
}
/*//////////////////////////////////////////////////////////////
ERC20 OPERATIONS
//////////////////////////////////////////////////////////////*/functionsafeTransferFrom(
ERC20 token,
addressfrom,
address to,
uint256 amount
) internal{
bool success;
/// @solidity memory-safe-assemblyassembly {
// Get a pointer to some free memory.let freeMemoryPointer :=mload(0x40)
// Write the abi-encoded calldata into memory, beginning with the function selector.mstore(freeMemoryPointer, 0x23b872dd00000000000000000000000000000000000000000000000000000000)
mstore(add(freeMemoryPointer, 4), and(from, 0xffffffffffffffffffffffffffffffffffffffff)) // Append and mask the "from" argument.mstore(add(freeMemoryPointer, 36), and(to, 0xffffffffffffffffffffffffffffffffffffffff)) // Append and mask the "to" argument.mstore(add(freeMemoryPointer, 68), amount) // Append the "amount" argument. Masking not required as it's a full 32 byte type.// We use 100 because the length of our calldata totals up like so: 4 + 32 * 3.// We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
success :=call(gas(), token, 0, freeMemoryPointer, 100, 0, 32)
// Set success to whether the call reverted, if not we check it either// returned exactly 1 (can't just be non-zero data), or had no return data and token has code.ifand(iszero(and(eq(mload(0), 1), gt(returndatasize(), 31))), success) {
success :=iszero(or(iszero(extcodesize(token)), returndatasize()))
}
}
require(success, "TRANSFER_FROM_FAILED");
}
functionsafeTransfer(
ERC20 token,
address to,
uint256 amount
) internal{
bool success;
/// @solidity memory-safe-assemblyassembly {
// Get a pointer to some free memory.let freeMemoryPointer :=mload(0x40)
// Write the abi-encoded calldata into memory, beginning with the function selector.mstore(freeMemoryPointer, 0xa9059cbb00000000000000000000000000000000000000000000000000000000)
mstore(add(freeMemoryPointer, 4), and(to, 0xffffffffffffffffffffffffffffffffffffffff)) // Append and mask the "to" argument.mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument. Masking not required as it's a full 32 byte type.// We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.// We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
success :=call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
// Set success to whether the call reverted, if not we check it either// returned exactly 1 (can't just be non-zero data), or had no return data and token has code.ifand(iszero(and(eq(mload(0), 1), gt(returndatasize(), 31))), success) {
success :=iszero(or(iszero(extcodesize(token)), returndatasize()))
}
}
require(success, "TRANSFER_FAILED");
}
functionsafeApprove(
ERC20 token,
address to,
uint256 amount
) internal{
bool success;
/// @solidity memory-safe-assemblyassembly {
// Get a pointer to some free memory.let freeMemoryPointer :=mload(0x40)
// Write the abi-encoded calldata into memory, beginning with the function selector.mstore(freeMemoryPointer, 0x095ea7b300000000000000000000000000000000000000000000000000000000)
mstore(add(freeMemoryPointer, 4), and(to, 0xffffffffffffffffffffffffffffffffffffffff)) // Append and mask the "to" argument.mstore(add(freeMemoryPointer, 36), amount) // Append the "amount" argument. Masking not required as it's a full 32 byte type.// We use 68 because the length of our calldata totals up like so: 4 + 32 * 2.// We use 0 and 32 to copy up to 32 bytes of return data into the scratch space.
success :=call(gas(), token, 0, freeMemoryPointer, 68, 0, 32)
// Set success to whether the call reverted, if not we check it either// returned exactly 1 (can't just be non-zero data), or had no return data and token has code.ifand(iszero(and(eq(mload(0), 1), gt(returndatasize(), 31))), success) {
success :=iszero(or(iszero(extcodesize(token)), returndatasize()))
}
}
require(success, "APPROVE_FAILED");
}
}