SelfPermit.sol

// SPDX-License-Identifier: AGPL-3.0
pragma solidity >=0.5.0;

import {ERC20} from "solmate/tokens/ERC20.sol";

/// @title Self Permit
/// @notice Functionality to call permit on any EIP-2612-compliant token for use in the route
/// @dev These functions are expected to be embedded in multicalls to allow EOAs to approve a contract and call a function
/// that requires an approval in a single transaction.
abstract contract SelfPermit {
    function selfPermit(
        ERC20 token,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public payable {
        token.permit(msg.sender, address(this), value, deadline, v, r, s);
    }

    function selfPermitIfNecessary(
        ERC20 token,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external payable {
        if (token.allowance(msg.sender, address(this)) < value)
            selfPermit(token, value, deadline, v, r, s);
    }
}