Multi CurrencyDeltas Library (#245)

* i might just be insane * additional assertion * fix pseudorandom seeding * do not bound seed * pr feedback
Uniswap · Aug 2, 2024 · fff8413 · fff8413
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diff --git a/src/libraries/CurrencyDeltas.sol b/src/libraries/CurrencyDeltas.sol
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.21;
+
+import {IPoolManager} from "@uniswap/v4-core/src/interfaces/IPoolManager.sol";
+import {Currency} from "@uniswap/v4-core/src/types/Currency.sol";
+import {BalanceDelta, toBalanceDelta} from "@uniswap/v4-core/src/types/BalanceDelta.sol";
+import {SafeCast} from "@uniswap/v4-core/src/libraries/SafeCast.sol";
+
+/// @title Currency Deltas
+/// @notice Fetch two currency deltas in a single call
+library CurrencyDeltas {
+    using SafeCast for int256;
+
+    /// @notice Get the current delta for a caller in the two given currencies
+    /// @param _caller The address of the caller
+    /// @param currency0 The currency to lookup the delta
+    /// @param currency1 The other currency to lookup the delta
+    /// @return BalanceDelta The delta of the two currencies packed
+    /// amount0 corresponding to currency0 and amount1 corresponding to currency1
+    function currencyDeltas(IPoolManager manager, address _caller, Currency currency0, Currency currency1)
+        internal
+        view
+        returns (BalanceDelta)
+    {
+        bytes32 tloadSlot0;
+        bytes32 tloadSlot1;
+        assembly {
+            mstore(0, _caller)
+            mstore(32, currency0)
+            tloadSlot0 := keccak256(0, 64)
+
+            mstore(0, _caller)
+            mstore(32, currency1)
+            tloadSlot1 := keccak256(0, 64)
+        }
+        bytes32[] memory slots = new bytes32[](2);
+        slots[0] = tloadSlot0;
+        slots[1] = tloadSlot1;
+        bytes32[] memory result = manager.exttload(slots);
+        return toBalanceDelta(int256(uint256(result[0])).toInt128(), int256(uint256(result[1])).toInt128());
+    }
+}
diff --git a/test/libraries/CurrencyDeltas.t.sol b/test/libraries/CurrencyDeltas.t.sol
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.24;
+
+import "forge-std/Test.sol";
+import {IERC20} from "forge-std/interfaces/IERC20.sol";
+import {IPoolManager} from "@uniswap/v4-core/src/interfaces/IPoolManager.sol";
+import {BalanceDelta} from "@uniswap/v4-core/src/types/BalanceDelta.sol";
+import {Currency, CurrencyLibrary} from "@uniswap/v4-core/src/types/Currency.sol";
+import {StateLibrary} from "@uniswap/v4-core/src/libraries/StateLibrary.sol";
+import {Deployers} from "@uniswap/v4-core/test/utils/Deployers.sol";
+
+import {MockCurrencyDeltaReader} from "../mocks/MockCurrencyDeltaReader.sol";
+
+contract CurrencyDeltasTest is Test, Deployers {
+    using CurrencyLibrary for Currency;
+
+    MockCurrencyDeltaReader reader;
+
+    function setUp() public {
+        deployFreshManagerAndRouters();
+        deployMintAndApprove2Currencies();
+
+        reader = new MockCurrencyDeltaReader(manager);
+
+        IERC20 token0 = IERC20(Currency.unwrap(currency0));
+        IERC20 token1 = IERC20(Currency.unwrap(currency1));
+
+        token0.approve(address(reader), type(uint256).max);
+        token1.approve(address(reader), type(uint256).max);
+
+        // send tokens to PoolManager so tests can .take()
+        token0.transfer(address(manager), 1_000_000e18);
+        token1.transfer(address(manager), 1_000_000e18);
+
+        // convert some ERC20s into ERC6909
+        claimsRouter.deposit(currency0, address(this), 1_000_000e18);
+        claimsRouter.deposit(currency1, address(this), 1_000_000e18);
+        manager.approve(address(reader), currency0.toId(), type(uint256).max);
+        manager.approve(address(reader), currency1.toId(), type(uint256).max);
+    }
+
+    function test_fuzz_currencyDeltas(uint8 depth, uint256 seed, uint128 amount0, uint128 amount1) public {
+        int128 delta0Expected = 0;
+        int128 delta1Expected = 0;
+
+        bytes[] memory calls = new bytes[](depth);
+        for (uint256 i = 0; i < depth; i++) {
+            amount0 = uint128(bound(amount0, 1, 100e18));
+            amount1 = uint128(bound(amount1, 1, 100e18));
+            uint256 _seed = seed % (i + 1);
+            if (_seed % 8 == 0) {
+                calls[i] = abi.encodeWithSelector(MockCurrencyDeltaReader.settle.selector, currency0, amount0);
+                delta0Expected += int128(amount0);
+            } else if (_seed % 8 == 1) {
+                calls[i] = abi.encodeWithSelector(MockCurrencyDeltaReader.settle.selector, currency1, amount1);
+                delta1Expected += int128(amount1);
+            } else if (_seed % 8 == 2) {
+                calls[i] = abi.encodeWithSelector(MockCurrencyDeltaReader.burn.selector, currency0, amount0);
+                delta0Expected += int128(amount0);
+            } else if (_seed % 8 == 3) {
+                calls[i] = abi.encodeWithSelector(MockCurrencyDeltaReader.burn.selector, currency1, amount1);
+                delta1Expected += int128(amount1);
+            } else if (_seed % 8 == 4) {
+                calls[i] = abi.encodeWithSelector(MockCurrencyDeltaReader.take.selector, currency0, amount0);
+                delta0Expected -= int128(amount0);
+            } else if (_seed % 8 == 5) {
+                calls[i] = abi.encodeWithSelector(MockCurrencyDeltaReader.take.selector, currency1, amount1);
+                delta1Expected -= int128(amount1);
+            } else if (_seed % 8 == 6) {
+                calls[i] = abi.encodeWithSelector(MockCurrencyDeltaReader.mint.selector, currency0, amount0);
+                delta0Expected -= int128(amount0);
+            } else if (_seed % 8 == 7) {
+                calls[i] = abi.encodeWithSelector(MockCurrencyDeltaReader.mint.selector, currency1, amount1);
+                delta1Expected -= int128(amount1);
+            }
+        }
+
+        BalanceDelta delta = reader.execute(calls, currency0, currency1);
+        assertEq(delta.amount0(), delta0Expected);
+        assertEq(delta.amount1(), delta1Expected);
+    }
+}
diff --git a/test/mocks/MockCurrencyDeltaReader.sol b/test/mocks/MockCurrencyDeltaReader.sol
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.24;
+
+import {IPoolManager} from "@uniswap/v4-core/src/interfaces/IPoolManager.sol";
+import {BalanceDelta} from "@uniswap/v4-core/src/types/BalanceDelta.sol";
+import {Currency} from "@uniswap/v4-core/src/types/Currency.sol";
+import {TransientStateLibrary} from "@uniswap/v4-core/src/libraries/TransientStateLibrary.sol";
+import {Deployers} from "@uniswap/v4-core/test/utils/Deployers.sol";
+import {CurrencySettler} from "@uniswap/v4-core/test/utils/CurrencySettler.sol";
+
+import {CurrencyDeltas} from "../../src/libraries/CurrencyDeltas.sol";
+
+/// @dev A minimal helper strictly for testing
+contract MockCurrencyDeltaReader {
+    using TransientStateLibrary for IPoolManager;
+    using CurrencyDeltas for IPoolManager;
+    using CurrencySettler for Currency;
+
+    IPoolManager public poolManager;
+
+    address sender;
+
+    constructor(IPoolManager _poolManager) {
+        poolManager = _poolManager;
+    }
+
+    /// @param calls an array of abi.encodeWithSelector
+    function execute(bytes[] calldata calls, Currency currency0, Currency currency1) external returns (BalanceDelta) {
+        sender = msg.sender;
+        return abi.decode(poolManager.unlock(abi.encode(calls, currency0, currency1)), (BalanceDelta));
+    }
+
+    function unlockCallback(bytes calldata data) external returns (bytes memory) {
+        (bytes[] memory calls, Currency currency0, Currency currency1) = abi.decode(data, (bytes[], Currency, Currency));
+        for (uint256 i; i < calls.length; i++) {
+            (bool success,) = address(this).call(calls[i]);
+            if (!success) revert("CurrencyDeltaReader");
+        }
+
+        BalanceDelta delta = poolManager.currencyDeltas(address(this), currency0, currency1);
+        int256 delta0 = poolManager.currencyDelta(address(this), currency0);
+        int256 delta1 = poolManager.currencyDelta(address(this), currency1);
+
+        // confirm agreement between currencyDeltas and single-read currencyDelta
+        require(delta.amount0() == int128(delta0), "CurrencyDeltaReader: delta0");
+        require(delta.amount1() == int128(delta1), "CurrencyDeltaReader: delta1");
+
+        // close deltas
+        if (delta.amount0() < 0) currency0.settle(poolManager, sender, uint256(-int256(delta.amount0())), false);
+        if (delta.amount1() < 0) currency1.settle(poolManager, sender, uint256(-int256(delta.amount1())), false);
+        if (delta.amount0() > 0) currency0.take(poolManager, sender, uint256(int256(delta.amount0())), false);
+        if (delta.amount1() > 0) currency1.take(poolManager, sender, uint256(int256(delta.amount1())), false);
+        return abi.encode(delta);
+    }
+
+    function settle(Currency currency, uint256 amount) external {
+        currency.settle(poolManager, sender, amount, false);
+    }
+
+    function burn(Currency currency, uint256 amount) external {
+        currency.settle(poolManager, sender, amount, true);
+    }
+
+    function take(Currency currency, uint256 amount) external {
+        currency.take(poolManager, sender, amount, false);
+    }
+
+    function mint(Currency currency, uint256 amount) external {
+        currency.take(poolManager, sender, amount, true);
+    }
+}