✨ Add convenience equality check (#1160)

Vectorized · Nov 9, 2024 · a3d6a97 · a3d6a97
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diff --git a/src/utils/EfficientHashLib.sol b/src/utils/EfficientHashLib.sol
@@ -360,6 +360,26 @@ library EfficientHashLib {
         }
     }
 
+    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
+    /*                      EQUALITY CHECKS                       */
+    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
+
+    /// @dev Returns `a == abi.decode(b, (bytes32))`.
+    function eq(bytes32 a, bytes memory b) internal pure returns (bool result) {
+        /// @solidity memory-safe-assembly
+        assembly {
+            result := and(eq(0x20, mload(b)), eq(a, mload(add(b, 0x20))))
+        }
+    }
+
+    /// @dev Returns `abi.decode(a, (bytes32)) == a`.
+    function eq(bytes memory a, bytes32 b) internal pure returns (bool result) {
+        /// @solidity memory-safe-assembly
+        assembly {
+            result := and(eq(0x20, mload(a)), eq(b, mload(add(a, 0x20))))
+        }
+    }
+
     /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
     /*               BYTE SLICE HASHING OPERATIONS                */
     /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/

diff --git a/test/EfficientHashLib.t.sol b/test/EfficientHashLib.t.sol
@@ -140,4 +140,25 @@ contract EfficientHashLibTest is SoladyTest {
     function testEfficientHashBytesSlice() public {
         this.testEfficientHashBytesSlice(bytes32(0), "0123456789");
     }
+
+    function testEfficientHashEq(bytes32 a, uint256 n) public {
+        bytes memory b = abi.encode(a);
+        bytes memory s = abi.encode(a);
+        /// @solidity memory-safe-assembly
+        assembly {
+            mstore(s, mod(n, 0x20))
+        }
+        assertTrue(EfficientHashLib.eq(a, b));
+        assertTrue(EfficientHashLib.eq(b, a));
+        assertFalse(EfficientHashLib.eq(a, s));
+        assertFalse(EfficientHashLib.eq(s, a));
+    }
+
+    function testEfficientHashEq() public {
+        bytes32 a = 0x123456789a123456789a123456789a123456789a123456789a123456789a1234;
+        bytes memory b = hex"123456789a123456789a123456789a123456789a123456789a123456789a1234";
+        assertTrue(EfficientHashLib.eq(a, b));
+        // The following costs approximately 90 more gas:
+        // `assertTrue(a == abi.decode(b, (bytes32)))`;
+    }
 }