Add ERC-6909 implementations

src/interfaces/IERC6909.sol

@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.8.30;
+
+/// @title ERC-6909 Minimal Multi-Token Interface
+/// @notice Interface for ERC-6909 multi-token contracts with custom errors.
+interface IERC6909 {
+    /// @notice Thrown when the sender has insufficient balance.
+    error ERC6909InsufficientBalance(address _sender, uint256 _balance, uint256 _needed, uint256 _id);
+
+    /// @notice Thrown when the spender has insufficient allowance.
+    error ERC6909InsufficientAllowance(address _spender, uint256 _allowance, uint256 _needed, uint256 _id);
+
+    /// @notice Thrown when the approver address is invalid.
+    error ERC6909InvalidApprover(address _approver);
+
+    /// @notice Thrown when the receiver address is invalid.
+    error ERC6909InvalidReceiver(address _receiver);
+
+    /// @notice Thrown when the sender address is invalid.
+    error ERC6909InvalidSender(address _sender);
+
+    /// @notice Thrown when the spender address is invalid.
+    error ERC6909InvalidSpender(address _spender);
+
+    /// @notice Emitted when a transfer occurs.
+    event Transfer(
+        address _caller, address indexed _sender, address indexed _receiver, uint256 indexed _id, uint256 _amount
+    );
+
+    /// @notice Emitted when an operator is set.
+    event OperatorSet(address indexed _owner, address indexed _spender, bool _approved);
+
+    /// @notice Emitted when an approval occurs.
+    event Approval(address indexed _owner, address indexed _spender, uint256 indexed _id, uint256 _amount);
+
+    /// @notice Owner balance of an id.
+    /// @param _owner The address of the owner.
+    /// @param _id The id of the token.
+    /// @return The balance of the token.
+    function balanceOf(address _owner, uint256 _id) external view returns (uint256);
+
+    /// @notice Spender allowance of an id.
+    /// @param _owner The address of the owner.
+    /// @param _spender The address of the spender.
+    /// @param _id The id of the token.
+    /// @return The allowance of the token.
+    function allowance(address _owner, address _spender, uint256 _id) external view returns (uint256);
+
+    /// @notice Checks if a spender is approved by an owner as an operator.
+    /// @param _owner The address of the owner.
+    /// @param _spender The address of the spender.
+    /// @return The approval status.
+    function isOperator(address _owner, address _spender) external view returns (bool);
+
+    /// @notice Approves an amount of an id to a spender.
+    /// @param _spender The address of the spender.
+    /// @param _id The id of the token.
+    /// @param _amount The amount of the token.
+    /// @return Whether the approval succeeded.
+    function approve(address _spender, uint256 _id, uint256 _amount) external returns (bool);
+
+    /// @notice Sets or removes a spender as an operator for the caller.
+    /// @param _spender The address of the spender.
+    /// @param _approved The approval status.
+    /// @return Whether the operator update succeeded.
+    function setOperator(address _spender, bool _approved) external returns (bool);
+
+    /// @notice Transfers an amount of an id from the caller to a receiver.
+    /// @param _receiver The address of the receiver.
+    /// @param _id The id of the token.
+    /// @param _amount The amount of the token.
+    /// @return Whether the transfer succeeded.
+    function transfer(address _receiver, uint256 _id, uint256 _amount) external returns (bool);
+
+    /// @notice Transfers an amount of an id from a sender to a receiver.
+    /// @param _sender The address of the sender.
+    /// @param _receiver The address of the receiver.
+    /// @param _id The id of the token.
+    /// @param _amount The amount of the token.
+    /// @return Whether the transfer succeeded.
+    function transferFrom(address _sender, address _receiver, uint256 _id, uint256 _amount) external returns (bool);
+}

src/token/ERC6909/ERC6909/ERC6909Facet.sol

@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: MIT
+pragma solidity >=0.8.30;
+
+/// @title ERC-6909 Minimal Multi-Token Interface
+/// @notice A complete, dependency-free ERC-6909 implementation using the diamond storage pattern.
+contract ERC6909Facet {
+    /// @notice Thrown when the sender has insufficient balance.
+    error ERC6909InsufficientBalance(address _sender, uint256 _balance, uint256 _needed, uint256 _id);
+
+    /// @notice Thrown when the spender has insufficient allowance.
+    error ERC6909InsufficientAllowance(address _spender, uint256 _allowance, uint256 _needed, uint256 _id);
+
+    /// @notice Thrown when the receiver address is invalid.
+    error ERC6909InvalidReceiver(address _receiver);
+
+    /// @notice Thrown when the sender address is invalid.
+    error ERC6909InvalidSender(address _sender);
+
+    /// @notice Thrown when the spender address is invalid.
+    error ERC6909InvalidSpender(address _spender);
+
+    /// @notice Emitted when a transfer occurs.
+    event Transfer(
+        address _caller, address indexed _sender, address indexed _receiver, uint256 indexed _id, uint256 _amount
+    );
+
+    /// @notice Emitted when an operator is set.
+    event OperatorSet(address indexed _owner, address indexed _spender, bool _approved);
+
+    /// @notice Emitted when an approval occurs.
+    event Approval(address indexed _owner, address indexed _spender, uint256 indexed _id, uint256 _amount);
+
+    /// @dev Storage position determined by the keccak256 hash of the diamond storage identifier.
+    bytes32 constant STORAGE_POSITION = keccak256("compose.erc6909");
+
+    /// @custom:storage-location erc8042:compose.erc6909
+    struct ERC6909Storage {
+        mapping(address owner => mapping(uint256 id => uint256 amount)) balanceOf;
+        mapping(address owner => mapping(address spender => mapping(uint256 id => uint256 amount))) allowance;
+        mapping(address owner => mapping(address spender => bool)) isOperator;
+    }
+
+    /// @notice Returns a pointer to the ERC-6909 storage struct.
+    /// @dev Uses inline assembly to access the storage slot defined by STORAGE_POSITION.
+    /// @return s The ERC6909Storage struct in storage.
+    function getStorage() internal pure returns (ERC6909Storage storage s) {
+        bytes32 position = STORAGE_POSITION;
+        assembly {
+            s.slot := position
+        }
+    }
+
+    /// @notice Owner balance of an id.
+    /// @param _owner The address of the owner.
+    /// @param _id The id of the token.
+    /// @return The balance of the token.
+    function balanceOf(address _owner, uint256 _id) external view returns (uint256) {
+        return getStorage().balanceOf[_owner][_id];
+    }
+
+    /// @notice Spender allowance of an id.
+    /// @param _owner The address of the owner.
+    /// @param _spender The address of the spender.
+    /// @param _id The id of the token.
+    /// @return The allowance of the token.
+    function allowance(address _owner, address _spender, uint256 _id) external view returns (uint256) {
+        return getStorage().allowance[_owner][_spender][_id];
+    }
+
+    /// @notice Checks if a spender is approved by an owner as an operator.
+    /// @param _owner The address of the owner.
+    /// @param _spender The address of the spender.
+    /// @return The approval status.
+    function isOperator(address _owner, address _spender) external view returns (bool) {
+        return getStorage().isOperator[_owner][_spender];
+    }
+
+    /// @notice Transfers an amount of an id from the caller to a receiver.
+    /// @param _receiver The address of the receiver.
+    /// @param _id The id of the token.
+    /// @param _amount The amount of the token.
+    /// @return Whether the transfer succeeded.
+    function transfer(address _receiver, uint256 _id, uint256 _amount) external returns (bool) {
+        if (_receiver == address(0)) {
+            revert ERC6909InvalidReceiver(address(0));
+        }
+
+        ERC6909Storage storage s = getStorage();
+
+        uint256 fromBalance = s.balanceOf[msg.sender][_id];
+
+        if (fromBalance < _amount) {
+            revert ERC6909InsufficientBalance(msg.sender, fromBalance, _amount, _id);
+        }
+
+        unchecked {
+            s.balanceOf[msg.sender][_id] = fromBalance - _amount;
+        }
+
+        s.balanceOf[_receiver][_id] += _amount;
+
+        emit Transfer(msg.sender, msg.sender, _receiver, _id, _amount);
+
+        return true;
+    }
+
+    /// @notice Transfers an amount of an id from a sender to a receiver.
+    /// @param _sender The address of the sender.
+    /// @param _receiver The address of the receiver.
+    /// @param _id The id of the token.
+    /// @param _amount The amount of the token.
+    /// @return Whether the transfer succeeded.
+    function transferFrom(address _sender, address _receiver, uint256 _id, uint256 _amount) external returns (bool) {
+        if (_sender == address(0)) {
+            revert ERC6909InvalidSender(address(0));
+        }
+
+        if (_receiver == address(0)) {
+            revert ERC6909InvalidReceiver(address(0));
+        }
+
+        ERC6909Storage storage s = getStorage();
+
+        if (msg.sender != _sender && !s.isOperator[_sender][msg.sender]) {
+            uint256 currentAllowance = s.allowance[_sender][msg.sender][_id];
+            if (currentAllowance < type(uint256).max) {
+                if (currentAllowance < _amount) {
+                    revert ERC6909InsufficientAllowance(msg.sender, currentAllowance, _amount, _id);
+                }
+                unchecked {
+                    s.allowance[_sender][msg.sender][_id] = currentAllowance - _amount;
+                }
+            }
+        }
+
+        uint256 fromBalance = s.balanceOf[_sender][_id];
+        if (fromBalance < _amount) {
+            revert ERC6909InsufficientBalance(_sender, fromBalance, _amount, _id);
+        }
+        unchecked {
+            s.balanceOf[_sender][_id] = fromBalance - _amount;
+        }
+
+        s.balanceOf[_receiver][_id] += _amount;
+
+        emit Transfer(msg.sender, _sender, _receiver, _id, _amount);
+
+        return true;
+    }
+
+    /// @notice Approves an amount of an id to a spender.
+    /// @param _spender The address of the spender.
+    /// @param _id The id of the token.
+    /// @param _amount The amount of the token.
+    /// @return Whether the approval succeeded.
+    function approve(address _spender, uint256 _id, uint256 _amount) external returns (bool) {
+        if (_spender == address(0)) {
+            revert ERC6909InvalidSpender(address(0));
+        }
+
+        ERC6909Storage storage s = getStorage();
+
+        s.allowance[msg.sender][_spender][_id] = _amount;
+
+        emit Approval(msg.sender, _spender, _id, _amount);
+
+        return true;
+    }
+
+    /// @notice Sets or removes a spender as an operator for the caller.
+    /// @param _spender The address of the spender.
+    /// @param _approved The approval status.
+    /// @return Whether the operator update succeeded.
+    function setOperator(address _spender, bool _approved) external returns (bool) {
+        if (_spender == address(0)) {
+            revert ERC6909InvalidSpender(address(0));
+        }
+
+        ERC6909Storage storage s = getStorage();
+
+        s.isOperator[msg.sender][_spender] = _approved;
+
+        emit OperatorSet(msg.sender, _spender, _approved);
+
+        return true;
+    }
+}