Remove HookReturnDelta type

.forge-snapshots/addLiquidity CA fee.snap

@@ -1 +1 @@
-329513
+329498

.forge-snapshots/addLiquidity with empty hook.snap

@@ -1 +1 @@
-284148
+284133

.forge-snapshots/poolManager bytecode size.snap

@@ -1 +1 @@
-23596
+23597

.forge-snapshots/removeLiquidity CA fee.snap

@@ -1 +1 @@
-185086
+185071

.forge-snapshots/swap CA custom curve + swap noop.snap

@@ -1 +1 @@
-135847
+135875

.forge-snapshots/swap CA fee on unspecified.snap

@@ -1 +1 @@
-184979
+185033

.forge-snapshots/swap skips hook call if hook is caller.snap

@@ -1 +1 @@
-225044
+225009

.forge-snapshots/swap with lp fee and protocol fee.snap

@@ -1 +1 @@
-181954
+181919

.forge-snapshots/update dynamic fee in before swap.snap

@@ -1 +1 @@
-160245
+160210

src/PoolManager.sol

@@ -17,7 +17,7 @@ import {ProtocolFees} from "./ProtocolFees.sol";
 import {ERC6909Claims} from "./ERC6909Claims.sol";
 import {PoolId, PoolIdLibrary} from "./types/PoolId.sol";
 import {BalanceDelta, BalanceDeltaLibrary, toBalanceDelta} from "./types/BalanceDelta.sol";
-import {HookReturnDelta} from "./types/HookReturnDelta.sol";
+import {BeforeSwapDelta} from "./types/BeforeSwapDelta.sol";
 import {Lock} from "./libraries/Lock.sol";
 import {CurrencyDelta} from "./libraries/CurrencyDelta.sol";
 import {NonZeroDeltaCount} from "./libraries/NonZeroDeltaCount.sol";
@@ -271,7 +271,7 @@ contract PoolManager is IPoolManager, ProtocolFees, NoDelegateCall, ERC6909Claim
         PoolId id = key.toId();
         _checkPoolInitialized(id);
 
-        (int256 amountToSwap, HookReturnDelta hookReturnDelta) = key.hooks.beforeSwap(key, params, hookData);
+        (int256 amountToSwap, BeforeSwapDelta beforeSwapDelta) = key.hooks.beforeSwap(key, params, hookData);
 
         // execute swap, account protocol fees, and emit swap event
         swapDelta = _swap(
@@ -286,7 +286,7 @@ contract PoolManager is IPoolManager, ProtocolFees, NoDelegateCall, ERC6909Claim
         );
 
         BalanceDelta hookDelta;
-        (swapDelta, hookDelta) = key.hooks.afterSwap(key, params, swapDelta, hookData, hookReturnDelta);
+        (swapDelta, hookDelta) = key.hooks.afterSwap(key, params, swapDelta, hookData, beforeSwapDelta);
 
         // if the hook doesnt have the flag to be able to return deltas, hookDelta will always be 0
         if (hookDelta != BalanceDeltaLibrary.ZERO_DELTA) _accountPoolBalanceDelta(key, hookDelta, address(key.hooks));

src/interfaces/IHooks.sol

@@ -4,7 +4,7 @@ pragma solidity ^0.8.24;
 import {PoolKey} from "../types/PoolKey.sol";
 import {BalanceDelta} from "../types/BalanceDelta.sol";
 import {IPoolManager} from "./IPoolManager.sol";
-import {BeforeSwapDelta} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta} from "../types/BeforeSwapDelta.sol";
 
 /// @notice The PoolManager contract decides whether to invoke specific hooks by inspecting the leading bits
 /// of the hooks contract address. For example, a 1 bit in the first bit of the address will

src/libraries/Hooks.sol

@@ -6,7 +6,7 @@ import {IHooks} from "../interfaces/IHooks.sol";
 import {SafeCast} from "../libraries/SafeCast.sol";
 import {LPFeeLibrary} from "./LPFeeLibrary.sol";
 import {BalanceDelta, toBalanceDelta, BalanceDeltaLibrary} from "../types/BalanceDelta.sol";
-import {HookReturnDelta, HookReturnDeltaLibrary} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta, BeforeSwapDeltaLibrary} from "../types/BeforeSwapDelta.sol";
 import {IPoolManager} from "../interfaces/IPoolManager.sol";
 
 /// @notice V4 decides whether to invoke specific hooks by inspecting the leading bits of the address that
@@ -17,7 +17,7 @@ library Hooks {
     using LPFeeLibrary for uint24;
     using Hooks for IHooks;
     using SafeCast for int256;
-    using HookReturnDeltaLibrary for HookReturnDelta;
+    using BeforeSwapDeltaLibrary for BeforeSwapDelta;
 
     uint256 internal constant BEFORE_INITIALIZE_FLAG = 1 << 159;
     uint256 internal constant AFTER_INITIALIZE_FLAG = 1 << 158;
@@ -139,12 +139,13 @@ library Hooks {
     /// @return delta The delta returned by the hook
     function callHookWithReturnDelta(IHooks self, bytes memory data, bool parseReturn)
         internal
-        returns (HookReturnDelta delta)
+        returns (int256 delta)
     {
         bytes memory result = callHook(self, data);
 
-        if (!parseReturn) return HookReturnDeltaLibrary.ZERO_DELTA;
-        (, delta) = abi.decode(result, (bytes4, HookReturnDelta));
+        // If this hook wasnt meant to return something, default to 0 delta
+        if (!parseReturn) return 0;
+        (, delta) = abi.decode(result, (bytes4, int256));
     }
 
     /// @notice modifier to prevent calling a hook if they initiated the action
@@ -207,20 +208,26 @@ library Hooks {
         callerDelta = delta;
         if (params.liquidityDelta > 0) {
             if (self.hasPermission(AFTER_ADD_LIQUIDITY_FLAG)) {
-                hookDelta = self.callHookWithReturnDelta(
-                    abi.encodeWithSelector(IHooks.afterAddLiquidity.selector, msg.sender, key, params, delta, hookData),
-                    self.hasPermission(AFTER_ADD_LIQUIDITY_RETURNS_DELTA_FLAG)
-                ).toBalanceDelta();
+                hookDelta = BalanceDelta.wrap(
+                    self.callHookWithReturnDelta(
+                        abi.encodeWithSelector(
+                            IHooks.afterAddLiquidity.selector, msg.sender, key, params, delta, hookData
+                        ),
+                        self.hasPermission(AFTER_ADD_LIQUIDITY_RETURNS_DELTA_FLAG)
+                    )
+                );
                 callerDelta = callerDelta - hookDelta;
             }
         } else {
             if (self.hasPermission(AFTER_REMOVE_LIQUIDITY_FLAG)) {
-                hookDelta = self.callHookWithReturnDelta(
-                    abi.encodeWithSelector(
-                        IHooks.afterRemoveLiquidity.selector, msg.sender, key, params, delta, hookData
-                    ),
-                    self.hasPermission(AFTER_REMOVE_LIQUIDITY_RETURNS_DELTA_FLAG)
-                ).toBalanceDelta();
+                hookDelta = BalanceDelta.wrap(
+                    self.callHookWithReturnDelta(
+                        abi.encodeWithSelector(
+                            IHooks.afterRemoveLiquidity.selector, msg.sender, key, params, delta, hookData
+                        ),
+                        self.hasPermission(AFTER_REMOVE_LIQUIDITY_RETURNS_DELTA_FLAG)
+                    )
+                );
                 callerDelta = callerDelta - hookDelta;
             }
         }
@@ -229,24 +236,31 @@ library Hooks {
     /// @notice calls beforeSwap hook if permissioned and validates return value
     function beforeSwap(IHooks self, PoolKey memory key, IPoolManager.SwapParams memory params, bytes calldata hookData)
         internal
-        returns (int256 amountToSwap, HookReturnDelta hookReturn)
+        returns (int256 amountToSwap, BeforeSwapDelta hookReturn)
     {
         amountToSwap = params.amountSpecified;
-        if (msg.sender == address(self)) return (amountToSwap, HookReturnDeltaLibrary.ZERO_DELTA);
+        if (msg.sender == address(self)) return (amountToSwap, BeforeSwapDeltaLibrary.ZERO_DELTA);
 
         if (self.hasPermission(BEFORE_SWAP_FLAG)) {
-            hookReturn = self.callHookWithReturnDelta(
-                abi.encodeWithSelector(IHooks.beforeSwap.selector, msg.sender, key, params, hookData),
-                self.hasPermission(BEFORE_SWAP_RETURNS_DELTA_FLAG)
+            bool canReturnDelta = self.hasPermission(BEFORE_SWAP_RETURNS_DELTA_FLAG);
+            hookReturn = BeforeSwapDelta.wrap(
+                self.callHookWithReturnDelta(
+                    abi.encodeWithSelector(IHooks.beforeSwap.selector, msg.sender, key, params, hookData),
+                    canReturnDelta
+                )
             );
-            // any return in unspecified is passed to the afterSwap hook for handling
-            int128 hookDeltaSpecified = hookReturn.getSpecifiedDelta();
-
-            // Update the swap amount according to the hook's return, and check that the swap type doesnt change (exact input/output)
-            if (hookDeltaSpecified != 0) {
-                bool exactInput = amountToSwap < 0;
-                amountToSwap += hookDeltaSpecified;
-                if (exactInput ? amountToSwap > 0 : amountToSwap < 0) revert HookDeltaExceedsSwapAmount();
+
+            // skip this logic for the case where the hook return is 0
+            if (canReturnDelta) {
+                // any return in unspecified is passed to the afterSwap hook for handling
+                int128 hookDeltaSpecified = hookReturn.getSpecifiedDelta();
+
+                // Update the swap amount according to the hook's return, and check that the swap type doesnt change (exact input/output)
+                if (hookDeltaSpecified != 0) {
+                    bool exactInput = amountToSwap < 0;
+                    amountToSwap += hookDeltaSpecified;
+                    if (exactInput ? amountToSwap > 0 : amountToSwap < 0) revert HookDeltaExceedsSwapAmount();
+                }
             }
         }
     }
@@ -258,7 +272,7 @@ library Hooks {
         IPoolManager.SwapParams memory params,
         BalanceDelta swapDelta,
         bytes calldata hookData,
-        HookReturnDelta beforeSwapHookReturn
+        BeforeSwapDelta beforeSwapHookReturn
     ) internal returns (BalanceDelta, BalanceDelta) {
         if (msg.sender == address(self)) return (swapDelta, BalanceDeltaLibrary.ZERO_DELTA);
 
@@ -269,7 +283,7 @@ library Hooks {
             hookDeltaUnspecified += self.callHookWithReturnDelta(
                 abi.encodeWithSelector(IHooks.afterSwap.selector, msg.sender, key, params, swapDelta, hookData),
                 self.hasPermission(AFTER_SWAP_RETURNS_DELTA_FLAG)
-            ).getUnspecifiedDelta();
+            ).toInt128();
         }
 
         BalanceDelta hookDelta;

src/test/BaseTestHooks.sol

@@ -4,7 +4,7 @@ pragma solidity ^0.8.24;
 import {IHooks} from "../interfaces/IHooks.sol";
 import {PoolKey} from "../types/PoolKey.sol";
 import {BalanceDelta} from "../types/BalanceDelta.sol";
-import {BeforeSwapDelta} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta} from "../types/BeforeSwapDelta.sol";
 import {IPoolManager} from "../interfaces/IPoolManager.sol";
 
 contract BaseTestHooks is IHooks {

src/test/CustomCurveHook.sol

@@ -6,7 +6,7 @@ import {SafeCast} from "../libraries/SafeCast.sol";
 import {IHooks} from "../interfaces/IHooks.sol";
 import {IPoolManager} from "../interfaces/IPoolManager.sol";
 import {PoolKey} from "../types/PoolKey.sol";
-import {BeforeSwapDelta, toBeforeSwapDelta} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta, toBeforeSwapDelta} from "../types/BeforeSwapDelta.sol";
 import {BalanceDelta} from "../types/BalanceDelta.sol";
 import {Currency} from "../types/Currency.sol";
 import {CurrencySettleTake} from "../libraries/CurrencySettleTake.sol";

src/test/DeltaReturningHook.sol

@@ -12,7 +12,7 @@ import {Currency} from "../types/Currency.sol";
 import {BaseTestHooks} from "./BaseTestHooks.sol";
 import {IERC20Minimal} from "../interfaces/external/IERC20Minimal.sol";
 import {CurrencyLibrary, Currency} from "../types/Currency.sol";
-import {BeforeSwapDelta, toBeforeSwapDelta} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta, toBeforeSwapDelta} from "../types/BeforeSwapDelta.sol";
 
 contract DeltaReturningHook is BaseTestHooks {
     using Hooks for IHooks;

src/test/DynamicFeesTestHook.sol

@@ -5,7 +5,7 @@ import {BaseTestHooks} from "./BaseTestHooks.sol";
 import {PoolKey} from "../types/PoolKey.sol";
 import {IPoolManager} from "../interfaces/IPoolManager.sol";
 import {IHooks} from "../interfaces/IHooks.sol";
-import {BeforeSwapDelta} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta} from "../types/BeforeSwapDelta.sol";
 
 contract DynamicFeesTestHook is BaseTestHooks {
     uint24 internal fee;

src/test/EmptyTestHooks.sol

@@ -6,7 +6,7 @@ import {IHooks} from "../interfaces/IHooks.sol";
 import {IPoolManager} from "../interfaces/IPoolManager.sol";
 import {PoolKey} from "../types/PoolKey.sol";
 import {BalanceDelta, BalanceDeltaLibrary} from "../types/BalanceDelta.sol";
-import {BeforeSwapDelta} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta} from "../types/BeforeSwapDelta.sol";
 
 contract EmptyTestHooks is IHooks {
     using Hooks for IHooks;

src/test/MockHooks.sol

@@ -7,7 +7,7 @@ import {IPoolManager} from "../interfaces/IPoolManager.sol";
 import {PoolKey} from "../types/PoolKey.sol";
 import {BalanceDelta, BalanceDeltaLibrary} from "../types/BalanceDelta.sol";
 import {PoolId, PoolIdLibrary} from "../types/PoolId.sol";
-import {BeforeSwapDelta} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta} from "../types/BeforeSwapDelta.sol";
 
 contract MockHooks is IHooks {
     using PoolIdLibrary for PoolKey;

src/test/SkipCallsTestHook.sol

@@ -14,7 +14,7 @@ import {PoolTestBase} from "./PoolTestBase.sol";
 import {Constants} from "../../test/utils/Constants.sol";
 import {Test} from "forge-std/Test.sol";
 import {CurrencySettleTake} from "../libraries/CurrencySettleTake.sol";
-import {BeforeSwapDelta} from "../types/HookReturnDelta.sol";
+import {BeforeSwapDelta} from "../types/BeforeSwapDelta.sol";
 
 contract SkipCallsTestHook is BaseTestHooks, Test {
     using CurrencySettleTake for Currency;

src/types/HookReturnDelta.sol → src/types/BeforeSwapDelta.sol

@@ -3,12 +3,6 @@ pragma solidity ^0.8.20;
 
 import {BalanceDelta} from "./BalanceDelta.sol";
 
-// Type used only internally to decode the different types of deltas returned by hooks
-// For afterAddLiquidity and afterRemoveLiquidity, HookReturnDelta is a BalanceDelta
-// For beforeSwap, HookReturnDelta is a BeforeSwapDelta
-// For afterSwap, HookReturnDelta is an int128 in the lower 128 bits
-type HookReturnDelta is bytes32;
-
 // Return type of the beforeSwap hook.
 // Upper 128 bits is the delta in specified tokens. Lower 128 bits is delta in unspecified tokens (to match the afterSwap hook)
 type BeforeSwapDelta is int256;
@@ -24,28 +18,20 @@ function toBeforeSwapDelta(int128 deltaSpecified, int128 deltaUnspecified)
     }
 }
 
-library HookReturnDeltaLibrary {
-    HookReturnDelta public constant ZERO_DELTA = HookReturnDelta.wrap(bytes32(0));
-
-    /// converts a HookReturnDelta type to a BalanceDelta type
-    /// returned by afterAddLiquidity and afterRemoveLiquidity
-    function toBalanceDelta(HookReturnDelta delta) internal pure returns (BalanceDelta balanceDelta) {
-        assembly {
-            balanceDelta := delta
-        }
-    }
+library BeforeSwapDeltaLibrary {
+    BeforeSwapDelta public constant ZERO_DELTA = BeforeSwapDelta.wrap(0);
 
-    /// extracts int128 from the upper 128 bits of the HookReturnDelta
+    /// extracts int128 from the upper 128 bits of the BeforeSwapDelta
     /// returned by beforeSwap
-    function getSpecifiedDelta(HookReturnDelta delta) internal pure returns (int128 deltaSpecified) {
+    function getSpecifiedDelta(BeforeSwapDelta delta) internal pure returns (int128 deltaSpecified) {
         assembly {
             deltaSpecified := shr(128, delta)
         }
     }
 
-    /// extracts int128 from the lower 128 bits of the HookReturnDelta
+    /// extracts int128 from the lower 128 bits of the BeforeSwapDelta
     /// returned by beforeSwap and afterSwap
-    function getUnspecifiedDelta(HookReturnDelta delta) internal pure returns (int128 deltaUnspecified) {
+    function getUnspecifiedDelta(BeforeSwapDelta delta) internal pure returns (int128 deltaUnspecified) {
         /// @solidity memory-safe-assembly
         assembly {
             deltaUnspecified := delta