PURR

purrcoin

Token

Market Cap

$1.00

Price

—

Token

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Contract

This contract's source code is verified!

Contract Metadata

Compiler

0.8.20+commit.a1b79de6

Language

Solidity

Contract Source Code

File 1 of 4: ERC20.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/// @notice Simple ERC20 + EIP-2612 implementation.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/tokens/ERC20.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/tokens/ERC20.sol)
/// @author Modified from OpenZeppelin (https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC20/ERC20.sol)
///
/// @dev Note:
/// - The ERC20 standard allows minting and transferring to and from the zero address,
///   minting and transferring zero tokens, as well as self-approvals.
///   For performance, this implementation WILL NOT revert for such actions.
///   Please add any checks with overrides if desired.
/// - The `permit` function uses the ecrecover precompile (0x1).
///
/// If you are overriding:
/// - NEVER violate the ERC20 invariant:
///   the total sum of all balances must be equal to `totalSupply()`.
/// - Check that the overridden function is actually used in the function you want to
///   change the behavior of. Much of the code has been manually inlined for performance.
abstract contract ERC20 {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                       CUSTOM ERRORS                        */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The total supply has overflowed.
    error TotalSupplyOverflow();

    /// @dev The allowance has overflowed.
    error AllowanceOverflow();

    /// @dev The allowance has underflowed.
    error AllowanceUnderflow();

    /// @dev Insufficient balance.
    error InsufficientBalance();

    /// @dev Insufficient allowance.
    error InsufficientAllowance();

    /// @dev The permit is invalid.
    error InvalidPermit();

    /// @dev The permit has expired.
    error PermitExpired();

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                           EVENTS                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Emitted when `amount` tokens is transferred from `from` to `to`.
    event Transfer(address indexed from, address indexed to, uint256 amount);

    /// @dev Emitted when `amount` tokens is approved by `owner` to be used by `spender`.
    event Approval(address indexed owner, address indexed spender, uint256 amount);

    /// @dev `keccak256(bytes("Transfer(address,address,uint256)"))`.
    uint256 private constant _TRANSFER_EVENT_SIGNATURE =
        0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

    /// @dev `keccak256(bytes("Approval(address,address,uint256)"))`.
    uint256 private constant _APPROVAL_EVENT_SIGNATURE =
        0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                          STORAGE                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The storage slot for the total supply.
    uint256 private constant _TOTAL_SUPPLY_SLOT = 0x05345cdf77eb68f44c;

    /// @dev The balance slot of `owner` is given by:
    /// ```
    ///     mstore(0x0c, _BALANCE_SLOT_SEED)
    ///     mstore(0x00, owner)
    ///     let balanceSlot := keccak256(0x0c, 0x20)
    /// ```
    uint256 private constant _BALANCE_SLOT_SEED = 0x87a211a2;

    /// @dev The allowance slot of (`owner`, `spender`) is given by:
    /// ```
    ///     mstore(0x20, spender)
    ///     mstore(0x0c, _ALLOWANCE_SLOT_SEED)
    ///     mstore(0x00, owner)
    ///     let allowanceSlot := keccak256(0x0c, 0x34)
    /// ```
    uint256 private constant _ALLOWANCE_SLOT_SEED = 0x7f5e9f20;

    /// @dev The nonce slot of `owner` is given by:
    /// ```
    ///     mstore(0x0c, _NONCES_SLOT_SEED)
    ///     mstore(0x00, owner)
    ///     let nonceSlot := keccak256(0x0c, 0x20)
    /// ```
    uint256 private constant _NONCES_SLOT_SEED = 0x38377508;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         CONSTANTS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev `(_NONCES_SLOT_SEED << 16) | 0x1901`.
    uint256 private constant _NONCES_SLOT_SEED_WITH_SIGNATURE_PREFIX = 0x383775081901;

    /// @dev `keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)")`.
    bytes32 private constant _DOMAIN_TYPEHASH =
        0x8b73c3c69bb8fe3d512ecc4cf759cc79239f7b179b0ffacaa9a75d522b39400f;

    /// @dev `keccak256("1")`.
    bytes32 private constant _VERSION_HASH =
        0xc89efdaa54c0f20c7adf612882df0950f5a951637e0307cdcb4c672f298b8bc6;

    /// @dev `keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)")`.
    bytes32 private constant _PERMIT_TYPEHASH =
        0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                       ERC20 METADATA                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the name of the token.
    function name() public view virtual returns (string memory);

    /// @dev Returns the symbol of the token.
    function symbol() public view virtual returns (string memory);

    /// @dev Returns the decimals places of the token.
    function decimals() public view virtual returns (uint8) {
        return 18;
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                           ERC20                            */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the amount of tokens in existence.
    function totalSupply() public view virtual returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := sload(_TOTAL_SUPPLY_SLOT)
        }
    }

    /// @dev Returns the amount of tokens owned by `owner`.
    function balanceOf(address owner) public view virtual returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x0c, _BALANCE_SLOT_SEED)
            mstore(0x00, owner)
            result := sload(keccak256(0x0c, 0x20))
        }
    }

    /// @dev Returns the amount of tokens that `spender` can spend on behalf of `owner`.
    function allowance(address owner, address spender)
        public
        view
        virtual
        returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x20, spender)
            mstore(0x0c, _ALLOWANCE_SLOT_SEED)
            mstore(0x00, owner)
            result := sload(keccak256(0x0c, 0x34))
        }
    }

    /// @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
    ///
    /// Emits a {Approval} event.
    function approve(address spender, uint256 amount) public virtual returns (bool) {
        /// @solidity memory-safe-assembly
        assembly {
            // Compute the allowance slot and store the amount.
            mstore(0x20, spender)
            mstore(0x0c, _ALLOWANCE_SLOT_SEED)
            mstore(0x00, caller())
            sstore(keccak256(0x0c, 0x34), amount)
            // Emit the {Approval} event.
            mstore(0x00, amount)
            log3(0x00, 0x20, _APPROVAL_EVENT_SIGNATURE, caller(), shr(96, mload(0x2c)))
        }
        return true;
    }

    /// @dev Transfer `amount` tokens from the caller to `to`.
    ///
    /// Requirements:
    /// - `from` must at least have `amount`.
    ///
    /// Emits a {Transfer} event.
    function transfer(address to, uint256 amount) public virtual returns (bool) {
        _beforeTokenTransfer(msg.sender, to, amount);
        /// @solidity memory-safe-assembly
        assembly {
            // Compute the balance slot and load its value.
            mstore(0x0c, _BALANCE_SLOT_SEED)
            mstore(0x00, caller())
            let fromBalanceSlot := keccak256(0x0c, 0x20)
            let fromBalance := sload(fromBalanceSlot)
            // Revert if insufficient balance.
            if gt(amount, fromBalance) {
                mstore(0x00, 0xf4d678b8) // `InsufficientBalance()`.
                revert(0x1c, 0x04)
            }
            // Subtract and store the updated balance.
            sstore(fromBalanceSlot, sub(fromBalance, amount))
            // Compute the balance slot of `to`.
            mstore(0x00, to)
            let toBalanceSlot := keccak256(0x0c, 0x20)
            // Add and store the updated balance of `to`.
            // Will not overflow because the sum of all user balances
            // cannot exceed the maximum uint256 value.
            sstore(toBalanceSlot, add(sload(toBalanceSlot), amount))
            // Emit the {Transfer} event.
            mstore(0x20, amount)
            log3(0x20, 0x20, _TRANSFER_EVENT_SIGNATURE, caller(), shr(96, mload(0x0c)))
        }
        _afterTokenTransfer(msg.sender, to, amount);
        return true;
    }

    /// @dev Transfers `amount` tokens from `from` to `to`.
    ///
    /// Note: Does not update the allowance if it is the maximum uint256 value.
    ///
    /// Requirements:
    /// - `from` must at least have `amount`.
    /// - The caller must have at least `amount` of allowance to transfer the tokens of `from`.
    ///
    /// Emits a {Transfer} event.
    function transferFrom(address from, address to, uint256 amount) public virtual returns (bool) {
        _beforeTokenTransfer(from, to, amount);
        /// @solidity memory-safe-assembly
        assembly {
            let from_ := shl(96, from)
            // Compute the allowance slot and load its value.
            mstore(0x20, caller())
            mstore(0x0c, or(from_, _ALLOWANCE_SLOT_SEED))
            let allowanceSlot := keccak256(0x0c, 0x34)
            let allowance_ := sload(allowanceSlot)
            // If the allowance is not the maximum uint256 value.
            if add(allowance_, 1) {
                // Revert if the amount to be transferred exceeds the allowance.
                if gt(amount, allowance_) {
                    mstore(0x00, 0x13be252b) // `InsufficientAllowance()`.
                    revert(0x1c, 0x04)
                }
                // Subtract and store the updated allowance.
                sstore(allowanceSlot, sub(allowance_, amount))
            }
            // Compute the balance slot and load its value.
            mstore(0x0c, or(from_, _BALANCE_SLOT_SEED))
            let fromBalanceSlot := keccak256(0x0c, 0x20)
            let fromBalance := sload(fromBalanceSlot)
            // Revert if insufficient balance.
            if gt(amount, fromBalance) {
                mstore(0x00, 0xf4d678b8) // `InsufficientBalance()`.
                revert(0x1c, 0x04)
            }
            // Subtract and store the updated balance.
            sstore(fromBalanceSlot, sub(fromBalance, amount))
            // Compute the balance slot of `to`.
            mstore(0x00, to)
            let toBalanceSlot := keccak256(0x0c, 0x20)
            // Add and store the updated balance of `to`.
            // Will not overflow because the sum of all user balances
            // cannot exceed the maximum uint256 value.
            sstore(toBalanceSlot, add(sload(toBalanceSlot), amount))
            // Emit the {Transfer} event.
            mstore(0x20, amount)
            log3(0x20, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, from_), shr(96, mload(0x0c)))
        }
        _afterTokenTransfer(from, to, amount);
        return true;
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                          EIP-2612                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev For more performance, override to return the constant value
    /// of `keccak256(bytes(name()))` if `name()` will never change.
    function _constantNameHash() internal view virtual returns (bytes32 result) {}

    /// @dev Returns the current nonce for `owner`.
    /// This value is used to compute the signature for EIP-2612 permit.
    function nonces(address owner) public view virtual returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            // Compute the nonce slot and load its value.
            mstore(0x0c, _NONCES_SLOT_SEED)
            mstore(0x00, owner)
            result := sload(keccak256(0x0c, 0x20))
        }
    }

    /// @dev Sets `value` as the allowance of `spender` over the tokens of `owner`,
    /// authorized by a signed approval by `owner`.
    ///
    /// Emits a {Approval} event.
    function permit(
        address owner,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) public virtual {
        bytes32 nameHash = _constantNameHash();
        //  We simply calculate it on-the-fly to allow for cases where the `name` may change.
        if (nameHash == bytes32(0)) nameHash = keccak256(bytes(name()));
        /// @solidity memory-safe-assembly
        assembly {
            // Revert if the block timestamp is greater than `deadline`.
            if gt(timestamp(), deadline) {
                mstore(0x00, 0x1a15a3cc) // `PermitExpired()`.
                revert(0x1c, 0x04)
            }
            let m := mload(0x40) // Grab the free memory pointer.
            // Clean the upper 96 bits.
            owner := shr(96, shl(96, owner))
            spender := shr(96, shl(96, spender))
            // Compute the nonce slot and load its value.
            mstore(0x0e, _NONCES_SLOT_SEED_WITH_SIGNATURE_PREFIX)
            mstore(0x00, owner)
            let nonceSlot := keccak256(0x0c, 0x20)
            let nonceValue := sload(nonceSlot)
            // Prepare the domain separator.
            mstore(m, _DOMAIN_TYPEHASH)
            mstore(add(m, 0x20), nameHash)
            mstore(add(m, 0x40), _VERSION_HASH)
            mstore(add(m, 0x60), chainid())
            mstore(add(m, 0x80), address())
            mstore(0x2e, keccak256(m, 0xa0))
            // Prepare the struct hash.
            mstore(m, _PERMIT_TYPEHASH)
            mstore(add(m, 0x20), owner)
            mstore(add(m, 0x40), spender)
            mstore(add(m, 0x60), value)
            mstore(add(m, 0x80), nonceValue)
            mstore(add(m, 0xa0), deadline)
            mstore(0x4e, keccak256(m, 0xc0))
            // Prepare the ecrecover calldata.
            mstore(0x00, keccak256(0x2c, 0x42))
            mstore(0x20, and(0xff, v))
            mstore(0x40, r)
            mstore(0x60, s)
            let t := staticcall(gas(), 1, 0, 0x80, 0x20, 0x20)
            // If the ecrecover fails, the returndatasize will be 0x00,
            // `owner` will be checked if it equals the hash at 0x00,
            // which evaluates to false (i.e. 0), and we will revert.
            // If the ecrecover succeeds, the returndatasize will be 0x20,
            // `owner` will be compared against the returned address at 0x20.
            if iszero(eq(mload(returndatasize()), owner)) {
                mstore(0x00, 0xddafbaef) // `InvalidPermit()`.
                revert(0x1c, 0x04)
            }
            // Increment and store the updated nonce.
            sstore(nonceSlot, add(nonceValue, t)) // `t` is 1 if ecrecover succeeds.
            // Compute the allowance slot and store the value.
            // The `owner` is already at slot 0x20.
            mstore(0x40, or(shl(160, _ALLOWANCE_SLOT_SEED), spender))
            sstore(keccak256(0x2c, 0x34), value)
            // Emit the {Approval} event.
            log3(add(m, 0x60), 0x20, _APPROVAL_EVENT_SIGNATURE, owner, spender)
            mstore(0x40, m) // Restore the free memory pointer.
            mstore(0x60, 0) // Restore the zero pointer.
        }
    }

    /// @dev Returns the EIP-712 domain separator for the EIP-2612 permit.
    function DOMAIN_SEPARATOR() public view virtual returns (bytes32 result) {
        bytes32 nameHash = _constantNameHash();
        //  We simply calculate it on-the-fly to allow for cases where the `name` may change.
        if (nameHash == bytes32(0)) nameHash = keccak256(bytes(name()));
        /// @solidity memory-safe-assembly
        assembly {
            let m := mload(0x40) // Grab the free memory pointer.
            mstore(m, _DOMAIN_TYPEHASH)
            mstore(add(m, 0x20), nameHash)
            mstore(add(m, 0x40), _VERSION_HASH)
            mstore(add(m, 0x60), chainid())
            mstore(add(m, 0x80), address())
            result := keccak256(m, 0xa0)
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  INTERNAL MINT FUNCTIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Mints `amount` tokens to `to`, increasing the total supply.
    ///
    /// Emits a {Transfer} event.
    function _mint(address to, uint256 amount) internal virtual {
        _beforeTokenTransfer(address(0), to, amount);
        /// @solidity memory-safe-assembly
        assembly {
            let totalSupplyBefore := sload(_TOTAL_SUPPLY_SLOT)
            let totalSupplyAfter := add(totalSupplyBefore, amount)
            // Revert if the total supply overflows.
            if lt(totalSupplyAfter, totalSupplyBefore) {
                mstore(0x00, 0xe5cfe957) // `TotalSupplyOverflow()`.
                revert(0x1c, 0x04)
            }
            // Store the updated total supply.
            sstore(_TOTAL_SUPPLY_SLOT, totalSupplyAfter)
            // Compute the balance slot and load its value.
            mstore(0x0c, _BALANCE_SLOT_SEED)
            mstore(0x00, to)
            let toBalanceSlot := keccak256(0x0c, 0x20)
            // Add and store the updated balance.
            sstore(toBalanceSlot, add(sload(toBalanceSlot), amount))
            // Emit the {Transfer} event.
            mstore(0x20, amount)
            log3(0x20, 0x20, _TRANSFER_EVENT_SIGNATURE, 0, shr(96, mload(0x0c)))
        }
        _afterTokenTransfer(address(0), to, amount);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  INTERNAL BURN FUNCTIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Burns `amount` tokens from `from`, reducing the total supply.
    ///
    /// Emits a {Transfer} event.
    function _burn(address from, uint256 amount) internal virtual {
        _beforeTokenTransfer(from, address(0), amount);
        /// @solidity memory-safe-assembly
        assembly {
            // Compute the balance slot and load its value.
            mstore(0x0c, _BALANCE_SLOT_SEED)
            mstore(0x00, from)
            let fromBalanceSlot := keccak256(0x0c, 0x20)
            let fromBalance := sload(fromBalanceSlot)
            // Revert if insufficient balance.
            if gt(amount, fromBalance) {
                mstore(0x00, 0xf4d678b8) // `InsufficientBalance()`.
                revert(0x1c, 0x04)
            }
            // Subtract and store the updated balance.
            sstore(fromBalanceSlot, sub(fromBalance, amount))
            // Subtract and store the updated total supply.
            sstore(_TOTAL_SUPPLY_SLOT, sub(sload(_TOTAL_SUPPLY_SLOT), amount))
            // Emit the {Transfer} event.
            mstore(0x00, amount)
            log3(0x00, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, shl(96, from)), 0)
        }
        _afterTokenTransfer(from, address(0), amount);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                INTERNAL TRANSFER FUNCTIONS                 */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Moves `amount` of tokens from `from` to `to`.
    function _transfer(address from, address to, uint256 amount) internal virtual {
        _beforeTokenTransfer(from, to, amount);
        /// @solidity memory-safe-assembly
        assembly {
            let from_ := shl(96, from)
            // Compute the balance slot and load its value.
            mstore(0x0c, or(from_, _BALANCE_SLOT_SEED))
            let fromBalanceSlot := keccak256(0x0c, 0x20)
            let fromBalance := sload(fromBalanceSlot)
            // Revert if insufficient balance.
            if gt(amount, fromBalance) {
                mstore(0x00, 0xf4d678b8) // `InsufficientBalance()`.
                revert(0x1c, 0x04)
            }
            // Subtract and store the updated balance.
            sstore(fromBalanceSlot, sub(fromBalance, amount))
            // Compute the balance slot of `to`.
            mstore(0x00, to)
            let toBalanceSlot := keccak256(0x0c, 0x20)
            // Add and store the updated balance of `to`.
            // Will not overflow because the sum of all user balances
            // cannot exceed the maximum uint256 value.
            sstore(toBalanceSlot, add(sload(toBalanceSlot), amount))
            // Emit the {Transfer} event.
            mstore(0x20, amount)
            log3(0x20, 0x20, _TRANSFER_EVENT_SIGNATURE, shr(96, from_), shr(96, mload(0x0c)))
        }
        _afterTokenTransfer(from, to, amount);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                INTERNAL ALLOWANCE FUNCTIONS                */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Updates the allowance of `owner` for `spender` based on spent `amount`.
    function _spendAllowance(address owner, address spender, uint256 amount) internal virtual {
        /// @solidity memory-safe-assembly
        assembly {
            // Compute the allowance slot and load its value.
            mstore(0x20, spender)
            mstore(0x0c, _ALLOWANCE_SLOT_SEED)
            mstore(0x00, owner)
            let allowanceSlot := keccak256(0x0c, 0x34)
            let allowance_ := sload(allowanceSlot)
            // If the allowance is not the maximum uint256 value.
            if add(allowance_, 1) {
                // Revert if the amount to be transferred exceeds the allowance.
                if gt(amount, allowance_) {
                    mstore(0x00, 0x13be252b) // `InsufficientAllowance()`.
                    revert(0x1c, 0x04)
                }
                // Subtract and store the updated allowance.
                sstore(allowanceSlot, sub(allowance_, amount))
            }
        }
    }

    /// @dev Sets `amount` as the allowance of `spender` over the tokens of `owner`.
    ///
    /// Emits a {Approval} event.
    function _approve(address owner, address spender, uint256 amount) internal virtual {
        /// @solidity memory-safe-assembly
        assembly {
            let owner_ := shl(96, owner)
            // Compute the allowance slot and store the amount.
            mstore(0x20, spender)
            mstore(0x0c, or(owner_, _ALLOWANCE_SLOT_SEED))
            sstore(keccak256(0x0c, 0x34), amount)
            // Emit the {Approval} event.
            mstore(0x00, amount)
            log3(0x00, 0x20, _APPROVAL_EVENT_SIGNATURE, shr(96, owner_), shr(96, mload(0x2c)))
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     HOOKS TO OVERRIDE                      */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Hook that is called before any transfer of tokens.
    /// This includes minting and burning.
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual {}

    /// @dev Hook that is called after any transfer of tokens.
    /// This includes minting and burning.
    function _afterTokenTransfer(address from, address to, uint256 amount) internal virtual {}
}

Contract Source Code

File 2 of 4: ERC721.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/// @notice Simple ERC721 implementation with storage hitchhiking.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/tokens/ERC721.sol)
/// @author Modified from Solmate (https://github.com/transmissions11/solmate/blob/main/src/tokens/ERC721.sol)
/// @author Modified from OpenZeppelin (https://github.com/OpenZeppelin/openzeppelin-contracts/tree/master/contracts/token/ERC721/ERC721.sol)
///
/// @dev Note:
/// - The ERC721 standard allows for self-approvals.
///   For performance, this implementation WILL NOT revert for such actions.
///   Please add any checks with overrides if desired.
/// - For performance, methods are made payable where permitted by the ERC721 standard.
/// - The `safeTransfer` functions use the identity precompile (0x4)
///   to copy memory internally.
///
/// If you are overriding:
/// - NEVER violate the ERC721 invariant:
///   the balance of an owner MUST always be equal to their number of ownership slots.
///   The transfer functions do not have an underflow guard for user token balances.
/// - Make sure all variables written to storage are properly cleaned
//    (e.g. the bool value for `isApprovedForAll` MUST be either 1 or 0 under the hood).
/// - Check that the overridden function is actually used in the function you want to
///   change the behavior of. Much of the code has been manually inlined for performance.
abstract contract ERC721 {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         CONSTANTS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev An account can hold up to 4294967295 tokens.
    uint256 internal constant _MAX_ACCOUNT_BALANCE = 0xffffffff;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                       CUSTOM ERRORS                        */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Only the token owner or an approved account can manage the token.
    error NotOwnerNorApproved();

    /// @dev The token does not exist.
    error TokenDoesNotExist();

    /// @dev The token already exists.
    error TokenAlreadyExists();

    /// @dev Cannot query the balance for the zero address.
    error BalanceQueryForZeroAddress();

    /// @dev Cannot mint or transfer to the zero address.
    error TransferToZeroAddress();

    /// @dev The token must be owned by `from`.
    error TransferFromIncorrectOwner();

    /// @dev The recipient's balance has overflowed.
    error AccountBalanceOverflow();

    /// @dev Cannot safely transfer to a contract that does not implement
    /// the ERC721Receiver interface.
    error TransferToNonERC721ReceiverImplementer();

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                           EVENTS                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Emitted when token `id` is transferred from `from` to `to`.
    event Transfer(address indexed from, address indexed to, uint256 indexed id);

    /// @dev Emitted when `owner` enables `account` to manage the `id` token.
    event Approval(address indexed owner, address indexed account, uint256 indexed id);

    /// @dev Emitted when `owner` enables or disables `operator` to manage all of their tokens.
    event ApprovalForAll(address indexed owner, address indexed operator, bool isApproved);

    /// @dev `keccak256(bytes("Transfer(address,address,uint256)"))`.
    uint256 private constant _TRANSFER_EVENT_SIGNATURE =
        0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef;

    /// @dev `keccak256(bytes("Approval(address,address,uint256)"))`.
    uint256 private constant _APPROVAL_EVENT_SIGNATURE =
        0x8c5be1e5ebec7d5bd14f71427d1e84f3dd0314c0f7b2291e5b200ac8c7c3b925;

    /// @dev `keccak256(bytes("ApprovalForAll(address,address,bool)"))`.
    uint256 private constant _APPROVAL_FOR_ALL_EVENT_SIGNATURE =
        0x17307eab39ab6107e8899845ad3d59bd9653f200f220920489ca2b5937696c31;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                          STORAGE                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The ownership data slot of `id` is given by:
    /// ```
    ///     mstore(0x00, id)
    ///     mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
    ///     let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
    /// ```
    /// Bits Layout:
    /// - [0..159]   `addr`
    /// - [160..255] `extraData`
    ///
    /// The approved address slot is given by: `add(1, ownershipSlot)`.
    ///
    /// See: https://notes.ethereum.org/%40vbuterin/verkle_tree_eip
    ///
    /// The balance slot of `owner` is given by:
    /// ```
    ///     mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
    ///     mstore(0x00, owner)
    ///     let balanceSlot := keccak256(0x0c, 0x1c)
    /// ```
    /// Bits Layout:
    /// - [0..31]   `balance`
    /// - [32..255] `aux`
    ///
    /// The `operator` approval slot of `owner` is given by:
    /// ```
    ///     mstore(0x1c, or(_ERC721_MASTER_SLOT_SEED, operator))
    ///     mstore(0x00, owner)
    ///     let operatorApprovalSlot := keccak256(0x0c, 0x30)
    /// ```
    uint256 private constant _ERC721_MASTER_SLOT_SEED = 0x7d8825530a5a2e7a << 192;

    /// @dev Pre-shifted and pre-masked constant.
    uint256 private constant _ERC721_MASTER_SLOT_SEED_MASKED = 0x0a5a2e7a00000000;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                      ERC721 METADATA                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the token collection name.
    function name() public view virtual returns (string memory);

    /// @dev Returns the token collection symbol.
    function symbol() public view virtual returns (string memory);

    /// @dev Returns the Uniform Resource Identifier (URI) for token `id`.
    function tokenURI(uint256 id) public view virtual returns (string memory);

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                           ERC721                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the owner of token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function ownerOf(uint256 id) public view virtual returns (address result) {
        result = _ownerOf(id);
        /// @solidity memory-safe-assembly
        assembly {
            if iszero(result) {
                mstore(0x00, 0xceea21b6) // `TokenDoesNotExist()`.
                revert(0x1c, 0x04)
            }
        }
    }

    /// @dev Returns the number of tokens owned by `owner`.
    ///
    /// Requirements:
    /// - `owner` must not be the zero address.
    function balanceOf(address owner) public view virtual returns (uint256 result) {
        /// @solidity memory-safe-assembly
        assembly {
            // Revert if the `owner` is the zero address.
            if iszero(owner) {
                mstore(0x00, 0x8f4eb604) // `BalanceQueryForZeroAddress()`.
                revert(0x1c, 0x04)
            }
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            mstore(0x00, owner)
            result := and(sload(keccak256(0x0c, 0x1c)), _MAX_ACCOUNT_BALANCE)
        }
    }

    /// @dev Returns the account approved to manage token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function getApproved(uint256 id) public view virtual returns (address result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, id)
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
            if iszero(shl(96, sload(ownershipSlot))) {
                mstore(0x00, 0xceea21b6) // `TokenDoesNotExist()`.
                revert(0x1c, 0x04)
            }
            result := sload(add(1, ownershipSlot))
        }
    }

    /// @dev Sets `account` as the approved account to manage token `id`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    /// - The caller must be the owner of the token,
    ///   or an approved operator for the token owner.
    ///
    /// Emits an {Approval} event.
    function approve(address account, uint256 id) public payable virtual {
        _approve(msg.sender, account, id);
    }

    /// @dev Returns whether `operator` is approved to manage the tokens of `owner`.
    function isApprovedForAll(address owner, address operator)
        public
        view
        virtual
        returns (bool result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x1c, operator)
            mstore(0x08, _ERC721_MASTER_SLOT_SEED_MASKED)
            mstore(0x00, owner)
            result := sload(keccak256(0x0c, 0x30))
        }
    }

    /// @dev Sets whether `operator` is approved to manage the tokens of the caller.
    ///
    /// Emits an {ApprovalForAll} event.
    function setApprovalForAll(address operator, bool isApproved) public virtual {
        /// @solidity memory-safe-assembly
        assembly {
            // Convert to 0 or 1.
            isApproved := iszero(iszero(isApproved))
            // Update the `isApproved` for (`msg.sender`, `operator`).
            mstore(0x1c, operator)
            mstore(0x08, _ERC721_MASTER_SLOT_SEED_MASKED)
            mstore(0x00, caller())
            sstore(keccak256(0x0c, 0x30), isApproved)
            // Emit the {ApprovalForAll} event.
            mstore(0x00, isApproved)
            // forgefmt: disable-next-item
            log3(0x00, 0x20, _APPROVAL_FOR_ALL_EVENT_SIGNATURE, caller(), shr(96, shl(96, operator)))
        }
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function transferFrom(address from, address to, uint256 id) public payable virtual {
        _beforeTokenTransfer(from, to, id);
        /// @solidity memory-safe-assembly
        assembly {
            // Clear the upper 96 bits.
            let bitmaskAddress := shr(96, not(0))
            from := and(bitmaskAddress, from)
            to := and(bitmaskAddress, to)
            // Load the ownership data.
            mstore(0x00, id)
            mstore(0x1c, or(_ERC721_MASTER_SLOT_SEED, caller()))
            let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
            let ownershipPacked := sload(ownershipSlot)
            let owner := and(bitmaskAddress, ownershipPacked)
            // Revert if the token does not exist, or if `from` is not the owner.
            if iszero(mul(owner, eq(owner, from))) {
                // `TokenDoesNotExist()`, `TransferFromIncorrectOwner()`.
                mstore(shl(2, iszero(owner)), 0xceea21b6a1148100)
                revert(0x1c, 0x04)
            }
            // Load, check, and update the token approval.
            {
                mstore(0x00, from)
                let approvedAddress := sload(add(1, ownershipSlot))
                // Revert if the caller is not the owner, nor approved.
                if iszero(or(eq(caller(), from), eq(caller(), approvedAddress))) {
                    if iszero(sload(keccak256(0x0c, 0x30))) {
                        mstore(0x00, 0x4b6e7f18) // `NotOwnerNorApproved()`.
                        revert(0x1c, 0x04)
                    }
                }
                // Delete the approved address if any.
                if approvedAddress { sstore(add(1, ownershipSlot), 0) }
            }
            // Update with the new owner.
            sstore(ownershipSlot, xor(ownershipPacked, xor(from, to)))
            // Decrement the balance of `from`.
            {
                let fromBalanceSlot := keccak256(0x0c, 0x1c)
                sstore(fromBalanceSlot, sub(sload(fromBalanceSlot), 1))
            }
            // Increment the balance of `to`.
            {
                mstore(0x00, to)
                let toBalanceSlot := keccak256(0x0c, 0x1c)
                let toBalanceSlotPacked := add(sload(toBalanceSlot), 1)
                // Revert if `to` is the zero address, or if the account balance overflows.
                if iszero(mul(to, and(toBalanceSlotPacked, _MAX_ACCOUNT_BALANCE))) {
                    // `TransferToZeroAddress()`, `AccountBalanceOverflow()`.
                    mstore(shl(2, iszero(to)), 0xea553b3401336cea)
                    revert(0x1c, 0x04)
                }
                sstore(toBalanceSlot, toBalanceSlotPacked)
            }
            // Emit the {Transfer} event.
            log4(codesize(), 0x00, _TRANSFER_EVENT_SIGNATURE, from, to, id)
        }
        _afterTokenTransfer(from, to, id);
    }

    /// @dev Equivalent to `safeTransferFrom(from, to, id, "")`.
    function safeTransferFrom(address from, address to, uint256 id) public payable virtual {
        transferFrom(from, to, id);
        if (_hasCode(to)) _checkOnERC721Received(from, to, id, "");
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    /// - If `to` refers to a smart contract, it must implement
    ///   {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
    ///
    /// Emits a {Transfer} event.
    function safeTransferFrom(address from, address to, uint256 id, bytes calldata data)
        public
        payable
        virtual
    {
        transferFrom(from, to, id);
        if (_hasCode(to)) _checkOnERC721Received(from, to, id, data);
    }

    /// @dev Returns true if this contract implements the interface defined by `interfaceId`.
    /// See: https://eips.ethereum.org/EIPS/eip-165
    /// This function call must use less than 30000 gas.
    function supportsInterface(bytes4 interfaceId) public view virtual returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            let s := shr(224, interfaceId)
            // ERC165: 0x01ffc9a7, ERC721: 0x80ac58cd, ERC721Metadata: 0x5b5e139f.
            result := or(or(eq(s, 0x01ffc9a7), eq(s, 0x80ac58cd)), eq(s, 0x5b5e139f))
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  INTERNAL QUERY FUNCTIONS                  */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns if token `id` exists.
    function _exists(uint256 id) internal view virtual returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, id)
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            result := iszero(iszero(shl(96, sload(add(id, add(id, keccak256(0x00, 0x20)))))))
        }
    }

    /// @dev Returns the owner of token `id`.
    /// Returns the zero address instead of reverting if the token does not exist.
    function _ownerOf(uint256 id) internal view virtual returns (address result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, id)
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            result := shr(96, shl(96, sload(add(id, add(id, keccak256(0x00, 0x20))))))
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*            INTERNAL DATA HITCHHIKING FUNCTIONS             */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    // For performance, no events are emitted for the hitchhiking setters.
    // Please emit your own events if required.

    /// @dev Returns the auxiliary data for `owner`.
    /// Minting, transferring, burning the tokens of `owner` will not change the auxiliary data.
    /// Auxiliary data can be set for any address, even if it does not have any tokens.
    function _getAux(address owner) internal view virtual returns (uint224 result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            mstore(0x00, owner)
            result := shr(32, sload(keccak256(0x0c, 0x1c)))
        }
    }

    /// @dev Set the auxiliary data for `owner` to `value`.
    /// Minting, transferring, burning the tokens of `owner` will not change the auxiliary data.
    /// Auxiliary data can be set for any address, even if it does not have any tokens.
    function _setAux(address owner, uint224 value) internal virtual {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            mstore(0x00, owner)
            let balanceSlot := keccak256(0x0c, 0x1c)
            let packed := sload(balanceSlot)
            sstore(balanceSlot, xor(packed, shl(32, xor(value, shr(32, packed)))))
        }
    }

    /// @dev Returns the extra data for token `id`.
    /// Minting, transferring, burning a token will not change the extra data.
    /// The extra data can be set on a non-existent token.
    function _getExtraData(uint256 id) internal view virtual returns (uint96 result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, id)
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            result := shr(160, sload(add(id, add(id, keccak256(0x00, 0x20)))))
        }
    }

    /// @dev Sets the extra data for token `id` to `value`.
    /// Minting, transferring, burning a token will not change the extra data.
    /// The extra data can be set on a non-existent token.
    function _setExtraData(uint256 id, uint96 value) internal virtual {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, id)
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
            let packed := sload(ownershipSlot)
            sstore(ownershipSlot, xor(packed, shl(160, xor(value, shr(160, packed)))))
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  INTERNAL MINT FUNCTIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Mints token `id` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must not exist.
    /// - `to` cannot be the zero address.
    ///
    /// Emits a {Transfer} event.
    function _mint(address to, uint256 id) internal virtual {
        _beforeTokenTransfer(address(0), to, id);
        /// @solidity memory-safe-assembly
        assembly {
            // Clear the upper 96 bits.
            to := shr(96, shl(96, to))
            // Load the ownership data.
            mstore(0x00, id)
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
            let ownershipPacked := sload(ownershipSlot)
            // Revert if the token already exists.
            if shl(96, ownershipPacked) {
                mstore(0x00, 0xc991cbb1) // `TokenAlreadyExists()`.
                revert(0x1c, 0x04)
            }
            // Update with the owner.
            sstore(ownershipSlot, or(ownershipPacked, to))
            // Increment the balance of the owner.
            {
                mstore(0x00, to)
                let balanceSlot := keccak256(0x0c, 0x1c)
                let balanceSlotPacked := add(sload(balanceSlot), 1)
                // Revert if `to` is the zero address, or if the account balance overflows.
                if iszero(mul(to, and(balanceSlotPacked, _MAX_ACCOUNT_BALANCE))) {
                    // `TransferToZeroAddress()`, `AccountBalanceOverflow()`.
                    mstore(shl(2, iszero(to)), 0xea553b3401336cea)
                    revert(0x1c, 0x04)
                }
                sstore(balanceSlot, balanceSlotPacked)
            }
            // Emit the {Transfer} event.
            log4(codesize(), 0x00, _TRANSFER_EVENT_SIGNATURE, 0, to, id)
        }
        _afterTokenTransfer(address(0), to, id);
    }

    /// @dev Mints token `id` to `to`, and updates the extra data for token `id` to `value`.
    /// Does NOT check if token `id` already exists (assumes `id` is auto-incrementing).
    ///
    /// Requirements:
    ///
    /// - `to` cannot be the zero address.
    ///
    /// Emits a {Transfer} event.
    function _mintAndSetExtraDataUnchecked(address to, uint256 id, uint96 value) internal virtual {
        _beforeTokenTransfer(address(0), to, id);
        /// @solidity memory-safe-assembly
        assembly {
            // Clear the upper 96 bits.
            to := shr(96, shl(96, to))
            // Update with the owner and extra data.
            mstore(0x00, id)
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            sstore(add(id, add(id, keccak256(0x00, 0x20))), or(shl(160, value), to))
            // Increment the balance of the owner.
            {
                mstore(0x00, to)
                let balanceSlot := keccak256(0x0c, 0x1c)
                let balanceSlotPacked := add(sload(balanceSlot), 1)
                // Revert if `to` is the zero address, or if the account balance overflows.
                if iszero(mul(to, and(balanceSlotPacked, _MAX_ACCOUNT_BALANCE))) {
                    // `TransferToZeroAddress()`, `AccountBalanceOverflow()`.
                    mstore(shl(2, iszero(to)), 0xea553b3401336cea)
                    revert(0x1c, 0x04)
                }
                sstore(balanceSlot, balanceSlotPacked)
            }
            // Emit the {Transfer} event.
            log4(codesize(), 0x00, _TRANSFER_EVENT_SIGNATURE, 0, to, id)
        }
        _afterTokenTransfer(address(0), to, id);
    }

    /// @dev Equivalent to `_safeMint(to, id, "")`.
    function _safeMint(address to, uint256 id) internal virtual {
        _safeMint(to, id, "");
    }

    /// @dev Mints token `id` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must not exist.
    /// - `to` cannot be the zero address.
    /// - If `to` refers to a smart contract, it must implement
    ///   {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
    ///
    /// Emits a {Transfer} event.
    function _safeMint(address to, uint256 id, bytes memory data) internal virtual {
        _mint(to, id);
        if (_hasCode(to)) _checkOnERC721Received(address(0), to, id, data);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  INTERNAL BURN FUNCTIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Equivalent to `_burn(address(0), id)`.
    function _burn(uint256 id) internal virtual {
        _burn(address(0), id);
    }

    /// @dev Destroys token `id`, using `by`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - If `by` is not the zero address,
    ///   it must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function _burn(address by, uint256 id) internal virtual {
        address owner = ownerOf(id);
        _beforeTokenTransfer(owner, address(0), id);
        /// @solidity memory-safe-assembly
        assembly {
            // Clear the upper 96 bits.
            by := shr(96, shl(96, by))
            // Load the ownership data.
            mstore(0x00, id)
            mstore(0x1c, or(_ERC721_MASTER_SLOT_SEED, by))
            let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
            let ownershipPacked := sload(ownershipSlot)
            // Reload the owner in case it is changed in `_beforeTokenTransfer`.
            owner := shr(96, shl(96, ownershipPacked))
            // Revert if the token does not exist.
            if iszero(owner) {
                mstore(0x00, 0xceea21b6) // `TokenDoesNotExist()`.
                revert(0x1c, 0x04)
            }
            // Load and check the token approval.
            {
                mstore(0x00, owner)
                let approvedAddress := sload(add(1, ownershipSlot))
                // If `by` is not the zero address, do the authorization check.
                // Revert if the `by` is not the owner, nor approved.
                if iszero(or(iszero(by), or(eq(by, owner), eq(by, approvedAddress)))) {
                    if iszero(sload(keccak256(0x0c, 0x30))) {
                        mstore(0x00, 0x4b6e7f18) // `NotOwnerNorApproved()`.
                        revert(0x1c, 0x04)
                    }
                }
                // Delete the approved address if any.
                if approvedAddress { sstore(add(1, ownershipSlot), 0) }
            }
            // Clear the owner.
            sstore(ownershipSlot, xor(ownershipPacked, owner))
            // Decrement the balance of `owner`.
            {
                let balanceSlot := keccak256(0x0c, 0x1c)
                sstore(balanceSlot, sub(sload(balanceSlot), 1))
            }
            // Emit the {Transfer} event.
            log4(codesize(), 0x00, _TRANSFER_EVENT_SIGNATURE, owner, 0, id)
        }
        _afterTokenTransfer(owner, address(0), id);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                INTERNAL APPROVAL FUNCTIONS                 */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns whether `account` is the owner of token `id`, or is approved to manage it.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    function _isApprovedOrOwner(address account, uint256 id)
        internal
        view
        virtual
        returns (bool result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            result := 1
            // Clear the upper 96 bits.
            account := shr(96, shl(96, account))
            // Load the ownership data.
            mstore(0x00, id)
            mstore(0x1c, or(_ERC721_MASTER_SLOT_SEED, account))
            let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
            let owner := shr(96, shl(96, sload(ownershipSlot)))
            // Revert if the token does not exist.
            if iszero(owner) {
                mstore(0x00, 0xceea21b6) // `TokenDoesNotExist()`.
                revert(0x1c, 0x04)
            }
            // Check if `account` is the `owner`.
            if iszero(eq(account, owner)) {
                mstore(0x00, owner)
                // Check if `account` is approved to manage the token.
                if iszero(sload(keccak256(0x0c, 0x30))) {
                    result := eq(account, sload(add(1, ownershipSlot)))
                }
            }
        }
    }

    /// @dev Returns the account approved to manage token `id`.
    /// Returns the zero address instead of reverting if the token does not exist.
    function _getApproved(uint256 id) internal view virtual returns (address result) {
        /// @solidity memory-safe-assembly
        assembly {
            mstore(0x00, id)
            mstore(0x1c, _ERC721_MASTER_SLOT_SEED)
            result := sload(add(1, add(id, add(id, keccak256(0x00, 0x20)))))
        }
    }

    /// @dev Equivalent to `_approve(address(0), account, id)`.
    function _approve(address account, uint256 id) internal virtual {
        _approve(address(0), account, id);
    }

    /// @dev Sets `account` as the approved account to manage token `id`, using `by`.
    ///
    /// Requirements:
    /// - Token `id` must exist.
    /// - If `by` is not the zero address, `by` must be the owner
    ///   or an approved operator for the token owner.
    ///
    /// Emits a {Approval} event.
    function _approve(address by, address account, uint256 id) internal virtual {
        assembly {
            // Clear the upper 96 bits.
            let bitmaskAddress := shr(96, not(0))
            account := and(bitmaskAddress, account)
            by := and(bitmaskAddress, by)
            // Load the owner of the token.
            mstore(0x00, id)
            mstore(0x1c, or(_ERC721_MASTER_SLOT_SEED, by))
            let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
            let owner := and(bitmaskAddress, sload(ownershipSlot))
            // Revert if the token does not exist.
            if iszero(owner) {
                mstore(0x00, 0xceea21b6) // `TokenDoesNotExist()`.
                revert(0x1c, 0x04)
            }
            // If `by` is not the zero address, do the authorization check.
            // Revert if `by` is not the owner, nor approved.
            if iszero(or(iszero(by), eq(by, owner))) {
                mstore(0x00, owner)
                if iszero(sload(keccak256(0x0c, 0x30))) {
                    mstore(0x00, 0x4b6e7f18) // `NotOwnerNorApproved()`.
                    revert(0x1c, 0x04)
                }
            }
            // Sets `account` as the approved account to manage `id`.
            sstore(add(1, ownershipSlot), account)
            // Emit the {Approval} event.
            log4(codesize(), 0x00, _APPROVAL_EVENT_SIGNATURE, owner, account, id)
        }
    }

    /// @dev Approve or remove the `operator` as an operator for `by`,
    /// without authorization checks.
    ///
    /// Emits an {ApprovalForAll} event.
    function _setApprovalForAll(address by, address operator, bool isApproved) internal virtual {
        /// @solidity memory-safe-assembly
        assembly {
            // Clear the upper 96 bits.
            by := shr(96, shl(96, by))
            operator := shr(96, shl(96, operator))
            // Convert to 0 or 1.
            isApproved := iszero(iszero(isApproved))
            // Update the `isApproved` for (`by`, `operator`).
            mstore(0x1c, or(_ERC721_MASTER_SLOT_SEED, operator))
            mstore(0x00, by)
            sstore(keccak256(0x0c, 0x30), isApproved)
            // Emit the {ApprovalForAll} event.
            mstore(0x00, isApproved)
            log3(0x00, 0x20, _APPROVAL_FOR_ALL_EVENT_SIGNATURE, by, operator)
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                INTERNAL TRANSFER FUNCTIONS                 */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Equivalent to `_transfer(address(0), from, to, id)`.
    function _transfer(address from, address to, uint256 id) internal virtual {
        _transfer(address(0), from, to, id);
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - If `by` is not the zero address,
    ///   it must be the owner of the token, or be approved to manage the token.
    ///
    /// Emits a {Transfer} event.
    function _transfer(address by, address from, address to, uint256 id) internal virtual {
        _beforeTokenTransfer(from, to, id);
        /// @solidity memory-safe-assembly
        assembly {
            // Clear the upper 96 bits.
            let bitmaskAddress := shr(96, not(0))
            from := and(bitmaskAddress, from)
            to := and(bitmaskAddress, to)
            by := and(bitmaskAddress, by)
            // Load the ownership data.
            mstore(0x00, id)
            mstore(0x1c, or(_ERC721_MASTER_SLOT_SEED, by))
            let ownershipSlot := add(id, add(id, keccak256(0x00, 0x20)))
            let ownershipPacked := sload(ownershipSlot)
            let owner := and(bitmaskAddress, ownershipPacked)
            // Revert if the token does not exist, or if `from` is not the owner.
            if iszero(mul(owner, eq(owner, from))) {
                // `TokenDoesNotExist()`, `TransferFromIncorrectOwner()`.
                mstore(shl(2, iszero(owner)), 0xceea21b6a1148100)
                revert(0x1c, 0x04)
            }
            // Load, check, and update the token approval.
            {
                mstore(0x00, from)
                let approvedAddress := sload(add(1, ownershipSlot))
                // If `by` is not the zero address, do the authorization check.
                // Revert if the `by` is not the owner, nor approved.
                if iszero(or(iszero(by), or(eq(by, from), eq(by, approvedAddress)))) {
                    if iszero(sload(keccak256(0x0c, 0x30))) {
                        mstore(0x00, 0x4b6e7f18) // `NotOwnerNorApproved()`.
                        revert(0x1c, 0x04)
                    }
                }
                // Delete the approved address if any.
                if approvedAddress { sstore(add(1, ownershipSlot), 0) }
            }
            // Update with the new owner.
            sstore(ownershipSlot, xor(ownershipPacked, xor(from, to)))
            // Decrement the balance of `from`.
            {
                let fromBalanceSlot := keccak256(0x0c, 0x1c)
                sstore(fromBalanceSlot, sub(sload(fromBalanceSlot), 1))
            }
            // Increment the balance of `to`.
            {
                mstore(0x00, to)
                let toBalanceSlot := keccak256(0x0c, 0x1c)
                let toBalanceSlotPacked := add(sload(toBalanceSlot), 1)
                // Revert if `to` is the zero address, or if the account balance overflows.
                if iszero(mul(to, and(toBalanceSlotPacked, _MAX_ACCOUNT_BALANCE))) {
                    // `TransferToZeroAddress()`, `AccountBalanceOverflow()`.
                    mstore(shl(2, iszero(to)), 0xea553b3401336cea)
                    revert(0x1c, 0x04)
                }
                sstore(toBalanceSlot, toBalanceSlotPacked)
            }
            // Emit the {Transfer} event.
            log4(codesize(), 0x00, _TRANSFER_EVENT_SIGNATURE, from, to, id)
        }
        _afterTokenTransfer(from, to, id);
    }

    /// @dev Equivalent to `_safeTransfer(from, to, id, "")`.
    function _safeTransfer(address from, address to, uint256 id) internal virtual {
        _safeTransfer(from, to, id, "");
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - The caller must be the owner of the token, or be approved to manage the token.
    /// - If `to` refers to a smart contract, it must implement
    ///   {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
    ///
    /// Emits a {Transfer} event.
    function _safeTransfer(address from, address to, uint256 id, bytes memory data)
        internal
        virtual
    {
        _transfer(address(0), from, to, id);
        if (_hasCode(to)) _checkOnERC721Received(from, to, id, data);
    }

    /// @dev Equivalent to `_safeTransfer(by, from, to, id, "")`.
    function _safeTransfer(address by, address from, address to, uint256 id) internal virtual {
        _safeTransfer(by, from, to, id, "");
    }

    /// @dev Transfers token `id` from `from` to `to`.
    ///
    /// Requirements:
    ///
    /// - Token `id` must exist.
    /// - `from` must be the owner of the token.
    /// - `to` cannot be the zero address.
    /// - If `by` is not the zero address,
    ///   it must be the owner of the token, or be approved to manage the token.
    /// - If `to` refers to a smart contract, it must implement
    ///   {IERC721Receiver-onERC721Received}, which is called upon a safe transfer.
    ///
    /// Emits a {Transfer} event.
    function _safeTransfer(address by, address from, address to, uint256 id, bytes memory data)
        internal
        virtual
    {
        _transfer(by, from, to, id);
        if (_hasCode(to)) _checkOnERC721Received(from, to, id, data);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                    HOOKS FOR OVERRIDING                    */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Hook that is called before any token transfers, including minting and burning.
    function _beforeTokenTransfer(address from, address to, uint256 id) internal virtual {}

    /// @dev Hook that is called after any token transfers, including minting and burning.
    function _afterTokenTransfer(address from, address to, uint256 id) internal virtual {}

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                      PRIVATE HELPERS                       */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns if `a` has bytecode of non-zero length.
    function _hasCode(address a) private view returns (bool result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := extcodesize(a) // Can handle dirty upper bits.
        }
    }

    /// @dev Perform a call to invoke {IERC721Receiver-onERC721Received} on `to`.
    /// Reverts if the target does not support the function correctly.
    function _checkOnERC721Received(address from, address to, uint256 id, bytes memory data)
        private
    {
        /// @solidity memory-safe-assembly
        assembly {
            // Prepare the calldata.
            let m := mload(0x40)
            let onERC721ReceivedSelector := 0x150b7a02
            mstore(m, onERC721ReceivedSelector)
            mstore(add(m, 0x20), caller()) // The `operator`, which is always `msg.sender`.
            mstore(add(m, 0x40), shr(96, shl(96, from)))
            mstore(add(m, 0x60), id)
            mstore(add(m, 0x80), 0x80)
            let n := mload(data)
            mstore(add(m, 0xa0), n)
            if n { pop(staticcall(gas(), 4, add(data, 0x20), n, add(m, 0xc0), n)) }
            // Revert if the call reverts.
            if iszero(call(gas(), to, 0, add(m, 0x1c), add(n, 0xa4), m, 0x20)) {
                if returndatasize() {
                    // Bubble up the revert if the call reverts.
                    returndatacopy(m, 0x00, returndatasize())
                    revert(m, returndatasize())
                }
            }
            // Load the returndata and compare it.
            if iszero(eq(mload(m), shl(224, onERC721ReceivedSelector))) {
                mstore(0x00, 0xd1a57ed6) // `TransferToNonERC721ReceiverImplementer()`.
                revert(0x1c, 0x04)
            }
        }
    }
}

Contract Source Code

File 3 of 4: Ownable.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

/// @notice Simple single owner authorization mixin.
/// @author Solady (https://github.com/vectorized/solady/blob/main/src/auth/Ownable.sol)
///
/// @dev Note:
/// This implementation does NOT auto-initialize the owner to `msg.sender`.
/// You MUST call the `_initializeOwner` in the constructor / initializer.
///
/// While the ownable portion follows
/// [EIP-173](https://eips.ethereum.org/EIPS/eip-173) for compatibility,
/// the nomenclature for the 2-step ownership handover may be unique to this codebase.
abstract contract Ownable {
    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                       CUSTOM ERRORS                        */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The caller is not authorized to call the function.
    error Unauthorized();

    /// @dev The `newOwner` cannot be the zero address.
    error NewOwnerIsZeroAddress();

    /// @dev The `pendingOwner` does not have a valid handover request.
    error NoHandoverRequest();

    /// @dev Cannot double-initialize.
    error AlreadyInitialized();

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                           EVENTS                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The ownership is transferred from `oldOwner` to `newOwner`.
    /// This event is intentionally kept the same as OpenZeppelin's Ownable to be
    /// compatible with indexers and [EIP-173](https://eips.ethereum.org/EIPS/eip-173),
    /// despite it not being as lightweight as a single argument event.
    event OwnershipTransferred(address indexed oldOwner, address indexed newOwner);

    /// @dev An ownership handover to `pendingOwner` has been requested.
    event OwnershipHandoverRequested(address indexed pendingOwner);

    /// @dev The ownership handover to `pendingOwner` has been canceled.
    event OwnershipHandoverCanceled(address indexed pendingOwner);

    /// @dev `keccak256(bytes("OwnershipTransferred(address,address)"))`.
    uint256 private constant _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE =
        0x8be0079c531659141344cd1fd0a4f28419497f9722a3daafe3b4186f6b6457e0;

    /// @dev `keccak256(bytes("OwnershipHandoverRequested(address)"))`.
    uint256 private constant _OWNERSHIP_HANDOVER_REQUESTED_EVENT_SIGNATURE =
        0xdbf36a107da19e49527a7176a1babf963b4b0ff8cde35ee35d6cd8f1f9ac7e1d;

    /// @dev `keccak256(bytes("OwnershipHandoverCanceled(address)"))`.
    uint256 private constant _OWNERSHIP_HANDOVER_CANCELED_EVENT_SIGNATURE =
        0xfa7b8eab7da67f412cc9575ed43464468f9bfbae89d1675917346ca6d8fe3c92;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                          STORAGE                           */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev The owner slot is given by:
    /// `bytes32(~uint256(uint32(bytes4(keccak256("_OWNER_SLOT_NOT")))))`.
    /// It is intentionally chosen to be a high value
    /// to avoid collision with lower slots.
    /// The choice of manual storage layout is to enable compatibility
    /// with both regular and upgradeable contracts.
    bytes32 internal constant _OWNER_SLOT =
        0xffffffffffffffffffffffffffffffffffffffffffffffffffffffff74873927;

    /// The ownership handover slot of `newOwner` is given by:
    /// ```
    ///     mstore(0x00, or(shl(96, user), _HANDOVER_SLOT_SEED))
    ///     let handoverSlot := keccak256(0x00, 0x20)
    /// ```
    /// It stores the expiry timestamp of the two-step ownership handover.
    uint256 private constant _HANDOVER_SLOT_SEED = 0x389a75e1;

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                     INTERNAL FUNCTIONS                     */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Override to return true to make `_initializeOwner` prevent double-initialization.
    function _guardInitializeOwner() internal pure virtual returns (bool guard) {}

    /// @dev Initializes the owner directly without authorization guard.
    /// This function must be called upon initialization,
    /// regardless of whether the contract is upgradeable or not.
    /// This is to enable generalization to both regular and upgradeable contracts,
    /// and to save gas in case the initial owner is not the caller.
    /// For performance reasons, this function will not check if there
    /// is an existing owner.
    function _initializeOwner(address newOwner) internal virtual {
        if (_guardInitializeOwner()) {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
                if sload(ownerSlot) {
                    mstore(0x00, 0x0dc149f0) // `AlreadyInitialized()`.
                    revert(0x1c, 0x04)
                }
                // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
                // Store the new value.
                sstore(ownerSlot, or(newOwner, shl(255, iszero(newOwner))))
                // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, 0, newOwner)
            }
        } else {
            /// @solidity memory-safe-assembly
            assembly {
                // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
                // Store the new value.
                sstore(_OWNER_SLOT, newOwner)
                // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, 0, newOwner)
            }
        }
    }

    /// @dev Sets the owner directly without authorization guard.
    function _setOwner(address newOwner) internal virtual {
        if (_guardInitializeOwner()) {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
                // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
                // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, sload(ownerSlot), newOwner)
                // Store the new value.
                sstore(ownerSlot, or(newOwner, shl(255, iszero(newOwner))))
            }
        } else {
            /// @solidity memory-safe-assembly
            assembly {
                let ownerSlot := _OWNER_SLOT
                // Clean the upper 96 bits.
                newOwner := shr(96, shl(96, newOwner))
                // Emit the {OwnershipTransferred} event.
                log3(0, 0, _OWNERSHIP_TRANSFERRED_EVENT_SIGNATURE, sload(ownerSlot), newOwner)
                // Store the new value.
                sstore(ownerSlot, newOwner)
            }
        }
    }

    /// @dev Throws if the sender is not the owner.
    function _checkOwner() internal view virtual {
        /// @solidity memory-safe-assembly
        assembly {
            // If the caller is not the stored owner, revert.
            if iszero(eq(caller(), sload(_OWNER_SLOT))) {
                mstore(0x00, 0x82b42900) // `Unauthorized()`.
                revert(0x1c, 0x04)
            }
        }
    }

    /// @dev Returns how long a two-step ownership handover is valid for in seconds.
    /// Override to return a different value if needed.
    /// Made internal to conserve bytecode. Wrap it in a public function if needed.
    function _ownershipHandoverValidFor() internal view virtual returns (uint64) {
        return 48 * 3600;
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                  PUBLIC UPDATE FUNCTIONS                   */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Allows the owner to transfer the ownership to `newOwner`.
    function transferOwnership(address newOwner) public payable virtual onlyOwner {
        /// @solidity memory-safe-assembly
        assembly {
            if iszero(shl(96, newOwner)) {
                mstore(0x00, 0x7448fbae) // `NewOwnerIsZeroAddress()`.
                revert(0x1c, 0x04)
            }
        }
        _setOwner(newOwner);
    }

    /// @dev Allows the owner to renounce their ownership.
    function renounceOwnership() public payable virtual onlyOwner {
        _setOwner(address(0));
    }

    /// @dev Request a two-step ownership handover to the caller.
    /// The request will automatically expire in 48 hours (172800 seconds) by default.
    function requestOwnershipHandover() public payable virtual {
        unchecked {
            uint256 expires = block.timestamp + _ownershipHandoverValidFor();
            /// @solidity memory-safe-assembly
            assembly {
                // Compute and set the handover slot to `expires`.
                mstore(0x0c, _HANDOVER_SLOT_SEED)
                mstore(0x00, caller())
                sstore(keccak256(0x0c, 0x20), expires)
                // Emit the {OwnershipHandoverRequested} event.
                log2(0, 0, _OWNERSHIP_HANDOVER_REQUESTED_EVENT_SIGNATURE, caller())
            }
        }
    }

    /// @dev Cancels the two-step ownership handover to the caller, if any.
    function cancelOwnershipHandover() public payable virtual {
        /// @solidity memory-safe-assembly
        assembly {
            // Compute and set the handover slot to 0.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, caller())
            sstore(keccak256(0x0c, 0x20), 0)
            // Emit the {OwnershipHandoverCanceled} event.
            log2(0, 0, _OWNERSHIP_HANDOVER_CANCELED_EVENT_SIGNATURE, caller())
        }
    }

    /// @dev Allows the owner to complete the two-step ownership handover to `pendingOwner`.
    /// Reverts if there is no existing ownership handover requested by `pendingOwner`.
    function completeOwnershipHandover(address pendingOwner) public payable virtual onlyOwner {
        /// @solidity memory-safe-assembly
        assembly {
            // Compute and set the handover slot to 0.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, pendingOwner)
            let handoverSlot := keccak256(0x0c, 0x20)
            // If the handover does not exist, or has expired.
            if gt(timestamp(), sload(handoverSlot)) {
                mstore(0x00, 0x6f5e8818) // `NoHandoverRequest()`.
                revert(0x1c, 0x04)
            }
            // Set the handover slot to 0.
            sstore(handoverSlot, 0)
        }
        _setOwner(pendingOwner);
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                   PUBLIC READ FUNCTIONS                    */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Returns the owner of the contract.
    function owner() public view virtual returns (address result) {
        /// @solidity memory-safe-assembly
        assembly {
            result := sload(_OWNER_SLOT)
        }
    }

    /// @dev Returns the expiry timestamp for the two-step ownership handover to `pendingOwner`.
    function ownershipHandoverExpiresAt(address pendingOwner)
        public
        view
        virtual
        returns (uint256 result)
    {
        /// @solidity memory-safe-assembly
        assembly {
            // Compute the handover slot.
            mstore(0x0c, _HANDOVER_SLOT_SEED)
            mstore(0x00, pendingOwner)
            // Load the handover slot.
            result := sload(keccak256(0x0c, 0x20))
        }
    }

    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
    /*                         MODIFIERS                          */
    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

    /// @dev Marks a function as only callable by the owner.
    modifier onlyOwner() virtual {
        _checkOwner();
        _;
    }
}

Contract Source Code

File 4 of 4: Purrcoin.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.20;

/*
                                                  
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              'c;.  ;x;.....,:::,. ox.            
             ,l,    ,ko::::coo,    ld.            
            'o;     .,;.    ';;:;,cl'             
          .::.                  .ckc              
         .cc.                     .ll.            
         lx.                       .c:.           
         lx.                        ,d'           
         lx.                        ,d'           
         lx.                        ,d'           
         ;o,                        ,d'           
          'l,                      ,l;            
          .oOo.                   'l:             
         ;0WMWOl:,.            .':;.              
         'xNMWKc.,::::;.      .lxoc:::::::::::::::
          .xNMMO,  ...'l;       ..................
           .kWMM0;     'lo,        .cccccccccccccc
            'kWMW0,     'll;.       ..''''...'..''
             .xWMW0,      ,d;       .:lddccccccccc
              .xNMWO;.     .,:'       .;l:..      
               ;XMMMXl.      'l;        .cc.      

                        $PURR
            tg: https://t.me/purrcoinonbase
             website: https://megapurrs.com
        twitter: https://twitter.com/VirtualAlaska

*/

import "solady/src/tokens/ERC20.sol";
import "solady/src/tokens/ERC721.sol";
import "solady/src/auth/Ownable.sol";

contract Purrcoin is ERC20, Ownable {
    error TradingNotOpen();
    error NoMoreTokens();

    uint256 MAX_SUPPLY = 1_000_000_000 * 1 ether;

    modifier onlyNFT() {
        require(msg.sender == MegapurrsNFT, "CanOnlyBeCalledByNFT");
        _;
    }

    address feeReceiver;
    address signatory;
    address MegapurrsNFT;
    address uniswapPair;

    uint8 taxedBlocks = 20;
    uint256 tax = 25;

    uint256 startBlock;

    bool public isTradingOpen = false;

    constructor() ERC20() {
        _initializeOwner(msg.sender);
        _mint(msg.sender, (MAX_SUPPLY * 80) / 100);
        feeReceiver = msg.sender;
    }

    function _beforeTokenTransfer(
        address from,
        address to,
        uint256 amount
    ) internal view override {
        if (!isTradingOpen) {
            if (to != owner() && from != owner() && from != address(0)) {
                revert TradingNotOpen();
            }
        }
    }

    function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal override {
        if (
            isTradingOpen &&
            block.number < (startBlock + taxedBlocks) &&
            (from == uniswapPair || to == uniswapPair)
        ) {
            uint256 taxAmount = (amount * tax) / 100;
            super._transfer(from, to, amount - taxAmount);
            super._transfer(from, feeReceiver, taxAmount);
            return;
        }
        super._transfer(from, to, amount);
    }

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public override returns (bool) {
        if (
            isTradingOpen &&
            block.number < (startBlock + taxedBlocks) &&
            (from == uniswapPair || to == uniswapPair)
        ) {
            uint256 taxAmount = (amount * tax) / 100;
            super.transferFrom(from, to, amount - taxAmount);
            super.transferFrom(from, feeReceiver, taxAmount);
            return true;
        }
        return super.transferFrom(from, to, amount);
    }

    function transfer(
        address to,
        uint256 amount
    ) public override returns (bool) {
        if (
            isTradingOpen &&
            block.number < (startBlock + taxedBlocks) &&
            (msg.sender == uniswapPair || to == uniswapPair)
        ) {
            uint256 taxAmount = (amount * tax) / 100;
            super.transfer(to, amount - taxAmount);
            super.transfer(feeReceiver, taxAmount);
            return true;
        }
        return super.transfer(to, amount);
    }

    function enableTrading(address pair, address receiver) external onlyOwner {
        isTradingOpen = true;
        startBlock = block.number;
        uniswapPair = pair;
        feeReceiver = receiver;
    }

    function mintByNFT(uint256 amount, address to) public onlyNFT {
        if (totalSupply() + (amount * (20_000 * 1 ether)) > MAX_SUPPLY) {
            revert NoMoreTokens();
        }
        _mint(to, amount * (20_000 * 1 ether));
    }

    function name() public pure override returns (string memory) {
        return "PURR";
    }

    function symbol() public pure override returns (string memory) {
        return "purrcoin";
    }

    function setUniswapPair(address pair) external onlyOwner {
        uniswapPair = pair;
    }

    function setSignatory(address signer) external onlyOwner {
        signatory = signer;
    }

    function setMegapurrsNFT(address nft) external onlyOwner {
        MegapurrsNFT = nft;
    }

    function setFeeReceiver(address fees) external onlyOwner {
        feeReceiver = fees;
    }

    function mintRemainingTokens() external onlyOwner {
        _mint(msg.sender, MAX_SUPPLY - totalSupply());
    }
}

Settings

{
  "compilationTarget": {
    "contracts/Purrcoin.sol": "Purrcoin"
  },
  "evmVersion": "paris",
  "libraries": {},
  "metadata": {
    "bytecodeHash": "ipfs"
  },
  "optimizer": {
    "enabled": false,
    "runs": 200
  },
  "remappings": []
}

ABI

[{"inputs":[],"stateMutability":"nonpayable","type":"constructor"},{"inputs":[],"name":"AllowanceOverflow","type":"error"},{"inputs":[],"name":"AllowanceUnderflow","type":"error"},{"inputs":[],"name":"AlreadyInitialized","type":"error"},{"inputs":[],"name":"InsufficientAllowance","type":"error"},{"inputs":[],"name":"InsufficientBalance","type":"error"},{"inputs":[],"name":"InvalidPermit","type":"error"},{"inputs":[],"name":"NewOwnerIsZeroAddress","type":"error"},{"inputs":[],"name":"NoHandoverRequest","type":"error"},{"inputs":[],"name":"NoMoreTokens","type":"error"},{"inputs":[],"name":"PermitExpired","type":"error"},{"inputs":[],"name":"TotalSupplyOverflow","type":"error"},{"inputs":[],"name":"TradingNotOpen","type":"error"},{"inputs":[],"name":"Unauthorized","type":"error"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"owner","type":"address"},{"indexed":true,"internalType":"address","name":"spender","type":"address"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"Approval","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"pendingOwner","type":"address"}],"name":"OwnershipHandoverCanceled","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"pendingOwner","type":"address"}],"name":"OwnershipHandoverRequested","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"oldOwner","type":"address"},{"indexed":true,"internalType":"address","name":"newOwner","type":"address"}],"name":"OwnershipTransferred","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"internalType":"address","name":"from","type":"address"},{"indexed":true,"internalType":"address","name":"to","type":"address"},{"indexed":false,"internalType":"uint256","name":"amount","type":"uint256"}],"name":"Transfer","type":"event"},{"inputs":[],"name":"DOMAIN_SEPARATOR","outputs":[{"internalType":"bytes32","name":"result","type":"bytes32"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"address","name":"spender","type":"address"}],"name":"allowance","outputs":[{"internalType":"uint256","name":"result","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"approve","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"result","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"cancelOwnershipHandover","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"pendingOwner","type":"address"}],"name":"completeOwnershipHandover","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"decimals","outputs":[{"internalType":"uint8","name":"","type":"uint8"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"pair","type":"address"},{"internalType":"address","name":"receiver","type":"address"}],"name":"enableTrading","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"isTradingOpen","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"uint256","name":"amount","type":"uint256"},{"internalType":"address","name":"to","type":"address"}],"name":"mintByNFT","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"mintRemainingTokens","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"name","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"pure","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"}],"name":"nonces","outputs":[{"internalType":"uint256","name":"result","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"owner","outputs":[{"internalType":"address","name":"result","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"pendingOwner","type":"address"}],"name":"ownershipHandoverExpiresAt","outputs":[{"internalType":"uint256","name":"result","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"owner","type":"address"},{"internalType":"address","name":"spender","type":"address"},{"internalType":"uint256","name":"value","type":"uint256"},{"internalType":"uint256","name":"deadline","type":"uint256"},{"internalType":"uint8","name":"v","type":"uint8"},{"internalType":"bytes32","name":"r","type":"bytes32"},{"internalType":"bytes32","name":"s","type":"bytes32"}],"name":"permit","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"renounceOwnership","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[],"name":"requestOwnershipHandover","outputs":[],"stateMutability":"payable","type":"function"},{"inputs":[{"internalType":"address","name":"fees","type":"address"}],"name":"setFeeReceiver","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"nft","type":"address"}],"name":"setMegapurrsNFT","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"signer","type":"address"}],"name":"setSignatory","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"pair","type":"address"}],"name":"setUniswapPair","outputs":[],"stateMutability":"nonpayable","type":"function"},{"inputs":[],"name":"symbol","outputs":[{"internalType":"string","name":"","type":"string"}],"stateMutability":"pure","type":"function"},{"inputs":[],"name":"totalSupply","outputs":[{"internalType":"uint256","name":"result","type":"uint256"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"transfer","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"from","type":"address"},{"internalType":"address","name":"to","type":"address"},{"internalType":"uint256","name":"amount","type":"uint256"}],"name":"transferFrom","outputs":[{"internalType":"bool","name":"","type":"bool"}],"stateMutability":"nonpayable","type":"function"},{"inputs":[{"internalType":"address","name":"newOwner","type":"address"}],"name":"transferOwnership","outputs":[],"stateMutability":"payable","type":"function"}]