Static Hook Fees

contracts/src/Counter.sol

@@ -1,7 +1,8 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.19;
 
-import {BaseHook} from "v4-periphery/BaseHook.sol";
+// TODO: update to v4-periphery/BaseHook.sol when its compatible
+import {BaseHook} from "./forks/BaseHook.sol";
 
 import {Hooks} from "@uniswap/v4-core/contracts/libraries/Hooks.sol";
 import {IPoolManager} from "@uniswap/v4-core/contracts/interfaces/IPoolManager.sol";
@@ -25,8 +26,8 @@ contract Counter is BaseHook {
 
     constructor(IPoolManager _poolManager) BaseHook(_poolManager) {}
 
-    function getHooksCalls() public pure override returns (Hooks.Calls memory) {
-        return Hooks.Calls({
+    function getHookPermissions() public pure override returns (Hooks.Permissions memory) {
+        return Hooks.Permissions({
             beforeInitialize: false,
             afterInitialize: false,
             beforeModifyPosition: true,
@@ -35,7 +36,8 @@ contract Counter is BaseHook {
             afterSwap: true,
             beforeDonate: false,
             afterDonate: false,
-            noOp: false
+            noOp: false,
+            accessLock: false
         });
     }
 

contracts/src/examples/FixedHookFee.sol

@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.19;
+
+// TODO: update to v4-periphery/BaseHook.sol when its compatible
+import {BaseHook} from "../forks/BaseHook.sol";
+
+import {Hooks} from "@uniswap/v4-core/contracts/libraries/Hooks.sol";
+import {IPoolManager} from "@uniswap/v4-core/contracts/interfaces/IPoolManager.sol";
+import {PoolKey} from "@uniswap/v4-core/contracts/types/PoolKey.sol";
+import {PoolId, PoolIdLibrary} from "@uniswap/v4-core/contracts/types/PoolId.sol";
+import {BalanceDelta} from "@uniswap/v4-core/contracts/types/BalanceDelta.sol";
+import {Currency, CurrencyLibrary} from "@uniswap/v4-core/contracts/types/Currency.sol";
+
+contract FixedHookFee is BaseHook {
+    using PoolIdLibrary for PoolKey;
+    using CurrencyLibrary for Currency;
+
+    uint256 public constant FIXED_HOOK_FEE = 0.0001e18;
+
+    constructor(IPoolManager _poolManager) BaseHook(_poolManager) {}
+
+    function getHookPermissions() public pure override returns (Hooks.Permissions memory) {
+        return Hooks.Permissions({
+            beforeInitialize: false,
+            afterInitialize: false,
+            beforeModifyPosition: false,
+            afterModifyPosition: false,
+            beforeSwap: true,
+            afterSwap: false,
+            beforeDonate: false,
+            afterDonate: false,
+            noOp: false,
+            accessLock: true // -- Required to take a fee -- //
+        });
+    }
+
+    function beforeSwap(address, PoolKey calldata key, IPoolManager.SwapParams calldata params, bytes calldata)
+        external
+        override
+        returns (bytes4)
+    {
+        // take a fixed fee of 0.0001 of the input token
+        params.zeroForOne
+            ? poolManager.mint(key.currency0, address(this), FIXED_HOOK_FEE)
+            : poolManager.mint(key.currency1, address(this), FIXED_HOOK_FEE);
+
+        return BaseHook.beforeSwap.selector;
+    }
+
+    /// @dev Hook fees are kept as PoolManager claims, so collecting ERC20s will require locking
+    function collectFee(address recipient, Currency currency) external returns (uint256 amount) {
+        amount = abi.decode(
+            poolManager.lock(
+                abi.encodeCall(
+                    this.handleCollectFee,
+                    (recipient, currency)
+                )
+            ),
+            (uint256)
+        );
+    }
+
+    /// @dev requires the lock pattern in order to call poolManager.burn
+    function handleCollectFee(address recipient, Currency currency) external returns (uint256 amount) {
+        // convert the fee (Claims) into ERC20 tokens
+        amount = poolManager.balanceOf(address(this), currency);
+        poolManager.burn(currency, amount);
+
+        // direct claims (the tokens) to the recipient
+        poolManager.take(currency, recipient, amount);
+    }
+}

contracts/src/examples/NoOpSwap.sol

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.20;
 
-import {BaseHook} from "v4-periphery/BaseHook.sol";
+import {BaseHook} from "../forks/BaseHook.sol";
 
 import {Hooks} from "@uniswap/v4-core/contracts/libraries/Hooks.sol";
 import {IPoolManager} from "@uniswap/v4-core/contracts/interfaces/IPoolManager.sol";
@@ -22,8 +22,8 @@ contract NoOpSwap is BaseHook {
 
     constructor(IPoolManager _poolManager) BaseHook(_poolManager) {}
 
-    function getHooksCalls() public pure override returns (Hooks.Calls memory) {
-        return Hooks.Calls({
+    function getHookPermissions() public pure override returns (Hooks.Permissions memory) {
+        return Hooks.Permissions({
             beforeInitialize: false,
             afterInitialize: false,
             beforeModifyPosition: false,
@@ -32,7 +32,8 @@ contract NoOpSwap is BaseHook {
             afterSwap: true,
             beforeDonate: false,
             afterDonate: false,
-            noOp: true
+            noOp: true,
+            accessLock: false
         });
     }
 

contracts/src/forks/BaseHook.sol

@@ -0,0 +1,130 @@
+// NOTE: ----------------------------------------------------------------------------------------------- //
+// December 1, 2023:                                                                                     //
+//   Recent v4-core changes are uncompatible with an outdated v4-periphery/BaseHook.sol                  //
+//   This is a *temporary* fix until v4-periphery is updated.                                            //
+// ----------------------------------------------------------------------------------------------------- //
+
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity ^0.8.19;
+
+import {Hooks} from "@uniswap/v4-core/contracts/libraries/Hooks.sol";
+import {IPoolManager} from "@uniswap/v4-core/contracts/interfaces/IPoolManager.sol";
+import {IHooks} from "@uniswap/v4-core/contracts/interfaces/IHooks.sol";
+import {BalanceDelta} from "@uniswap/v4-core/contracts/types/BalanceDelta.sol";
+import {PoolKey} from "@uniswap/v4-core/contracts/types/PoolKey.sol";
+
+abstract contract BaseHook is IHooks {
+    error NotPoolManager();
+    error NotSelf();
+    error InvalidPool();
+    error LockFailure();
+    error HookNotImplemented();
+
+    /// @notice The address of the pool manager
+    IPoolManager public immutable poolManager;
+
+    constructor(IPoolManager _poolManager) {
+        poolManager = _poolManager;
+        validateHookPermissions(this);
+    }
+
+    /// @dev Only the pool manager may call this function
+    modifier poolManagerOnly() {
+        if (msg.sender != address(poolManager)) revert NotPoolManager();
+        _;
+    }
+
+    /// @dev Only this address may call this function
+    modifier selfOnly() {
+        if (msg.sender != address(this)) revert NotSelf();
+        _;
+    }
+
+    /// @dev Only pools with hooks set to this contract may call this function
+    modifier onlyValidPools(IHooks hooks) {
+        if (hooks != this) revert InvalidPool();
+        _;
+    }
+
+    function getHookPermissions() public pure virtual returns (Hooks.Permissions memory);
+
+    // this function is virtual so that we can override it during testing,
+    // which allows us to deploy an implementation to any address
+    // and then etch the bytecode into the correct address
+    function validateHookPermissions(BaseHook _this) internal pure virtual {
+        Hooks.validateHookPermissions(_this, getHookPermissions());
+    }
+
+    function lockAcquired(bytes calldata data) external virtual poolManagerOnly returns (bytes memory) {
+        (bool success, bytes memory returnData) = address(this).call(data);
+        if (success) return returnData;
+        if (returnData.length == 0) revert LockFailure();
+        // if the call failed, bubble up the reason
+        /// @solidity memory-safe-assembly
+        assembly {
+            revert(add(returnData, 32), mload(returnData))
+        }
+    }
+
+    function beforeInitialize(address, PoolKey calldata, uint160, bytes calldata) external virtual returns (bytes4) {
+        revert HookNotImplemented();
+    }
+
+    function afterInitialize(address, PoolKey calldata, uint160, int24, bytes calldata)
+        external
+        virtual
+        returns (bytes4)
+    {
+        revert HookNotImplemented();
+    }
+
+    function beforeModifyPosition(address, PoolKey calldata, IPoolManager.ModifyPositionParams calldata, bytes calldata)
+        external
+        virtual
+        returns (bytes4)
+    {
+        revert HookNotImplemented();
+    }
+
+    function afterModifyPosition(
+        address,
+        PoolKey calldata,
+        IPoolManager.ModifyPositionParams calldata,
+        BalanceDelta,
+        bytes calldata
+    ) external virtual returns (bytes4) {
+        revert HookNotImplemented();
+    }
+
+    function beforeSwap(address, PoolKey calldata, IPoolManager.SwapParams calldata, bytes calldata)
+        external
+        virtual
+        returns (bytes4)
+    {
+        revert HookNotImplemented();
+    }
+
+    function afterSwap(address, PoolKey calldata, IPoolManager.SwapParams calldata, BalanceDelta, bytes calldata)
+        external
+        virtual
+        returns (bytes4)
+    {
+        revert HookNotImplemented();
+    }
+
+    function beforeDonate(address, PoolKey calldata, uint256, uint256, bytes calldata)
+        external
+        virtual
+        returns (bytes4)
+    {
+        revert HookNotImplemented();
+    }
+
+    function afterDonate(address, PoolKey calldata, uint256, uint256, bytes calldata)
+        external
+        virtual
+        returns (bytes4)
+    {
+        revert HookNotImplemented();
+    }
+}

contracts/test/examples/FixedHookFee.t.sol

@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.19;
+
+import "forge-std/Test.sol";
+import {IHooks} from "@uniswap/v4-core/contracts/interfaces/IHooks.sol";
+import {Hooks} from "@uniswap/v4-core/contracts/libraries/Hooks.sol";
+import {TickMath} from "@uniswap/v4-core/contracts/libraries/TickMath.sol";
+import {IPoolManager} from "@uniswap/v4-core/contracts/interfaces/IPoolManager.sol";
+import {PoolKey} from "@uniswap/v4-core/contracts/types/PoolKey.sol";
+import {BalanceDelta} from "@uniswap/v4-core/contracts/types/BalanceDelta.sol";
+import {PoolId, PoolIdLibrary} from "@uniswap/v4-core/contracts/types/PoolId.sol";
+import {Constants} from "@uniswap/v4-core/contracts/../test/utils/Constants.sol";
+import {CurrencyLibrary, Currency} from "@uniswap/v4-core/contracts/types/Currency.sol";
+import {HookTest} from "../utils/HookTest.sol";
+import {FixedHookFee} from "../../src/examples/FixedHookFee.sol";
+import {HookMiner} from "../utils/HookMiner.sol";
+
+contract FixedHookFeeTest is HookTest {
+    using PoolIdLibrary for PoolKey;
+    using CurrencyLibrary for Currency;
+
+    FixedHookFee hook;
+    PoolKey poolKey;
+    PoolId poolId;
+
+    address alice = makeAddr("alice");
+
+    function setUp() public {
+        // creates the pool manager, test tokens, and other utility routers
+        HookTest.initHookTestEnv();
+
+        // Deploy the hook to an address with the correct flags
+        uint160 flags = uint160(Hooks.BEFORE_SWAP_FLAG | Hooks.ACCESS_LOCK_FLAG);
+        (address hookAddress, bytes32 salt) =
+            HookMiner.find(address(this), flags, type(FixedHookFee).creationCode, abi.encode(address(manager)));
+        hook = new FixedHookFee{salt: salt}(IPoolManager(address(manager)));
+        require(address(hook) == hookAddress, "FixedHookFeeTest: hook address mismatch");
+
+        // Create the pool
+        poolKey = PoolKey(Currency.wrap(address(token0)), Currency.wrap(address(token1)), 3000, 60, IHooks(hook));
+        poolId = poolKey.toId();
+        initializeRouter.initialize(poolKey, Constants.SQRT_RATIO_1_1, ZERO_BYTES);
+
+        // Provide liquidity to the pool
+        modifyPositionRouter.modifyPosition(poolKey, IPoolManager.ModifyPositionParams(-60, 60, 10 ether), ZERO_BYTES);
+        modifyPositionRouter.modifyPosition(poolKey, IPoolManager.ModifyPositionParams(-120, 120, 10 ether), ZERO_BYTES);
+        modifyPositionRouter.modifyPosition(
+            poolKey,
+            IPoolManager.ModifyPositionParams(TickMath.minUsableTick(60), TickMath.maxUsableTick(60), 10_000 ether),
+            ZERO_BYTES
+        );
+    }
+
+    function test_hookFee() public {
+        uint256 balanceBefore = token0.balanceOf(address(this));
+        // Perform a test swap //
+        int256 amount = 1e18;
+        bool zeroForOne = true;
+        swap(poolKey, amount, zeroForOne, ZERO_BYTES);
+        // ------------------- //
+        uint256 balanceAfter = token0.balanceOf(address(this));
+
+        // swapper paid for the fixed hook fee
+        assertEq(balanceBefore - balanceAfter, uint256(amount) + hook.FIXED_HOOK_FEE());
+
+        // collect the hook fees
+        assertEq(token0.balanceOf(alice), 0);
+        hook.collectFee(alice, Currency.wrap(address(token0)));
+        assertEq(token0.balanceOf(alice), hook.FIXED_HOOK_FEE());
+    }
+}

src/keywords.json

@@ -21,6 +21,13 @@
     "swap",
     "skip swap"
   ],
+  "/fees/fixed-hook-fee": [
+    "hook",
+    "hooks",
+    "fee",
+    "static fee",
+    "hook fee"
+  ],
   "/create-liquidity": [
     "liquidity",
     "LP",

src/nav.ts

@@ -32,7 +32,12 @@ export const HOOK_ROUTES: Route[] = [
   }
 ]
 
-const HACK_ROUTES: Route[] = []
+const FEE_ROUTES: Route[] = [
+  {
+    path: "fixed-hook-fee",
+    title: "Static Hook Fee"
+  }
+]
 
 export const TEST_ROUTES: Route[] = []
 
@@ -53,13 +58,13 @@ export const ROUTES_BY_CATEGORY = [
       path: `/hooks/${route.path}`,
     })),
   },
-  // {
-  //   title: "Hacks",
-  //   routes: HACK_ROUTES.map((route) => ({
-  //     ...route,
-  //     path: `/hacks/${route.path}`,
-  //   })),
-  // },
+  {
+    title: "Fees",
+    routes: FEE_ROUTES.map((route) => ({
+      ...route,
+      path: `/fees/${route.path}`,
+    })),
+  },
   // {
   //   title: "Tests",
   //   routes: TEST_ROUTES.map((route) => ({