add EVMUtils contract

cadence/contracts/utils/EVMUtils.cdc

@@ -0,0 +1,51 @@
+import "EVM"
+
+/// Contract containing EVM-related utility methods
+///
+access(all) contract EVMUtils {
+    /// Returns an EVMAddress as a hex string without a 0x prefix
+    ///
+    /// @param address: The EVMAddress to convert to a hex string
+    ///
+    /// @return The hex string representation of the EVMAddress without 0x prefix
+    ///
+    // TODO: Remove once EVMAddress.toString() is available
+    access(all)
+    view fun getEVMAddressAsHexString(address: EVM.EVMAddress): String {
+        let bytes = address.bytes
+        // Iterating & appending to an array is not allowed in a `view` method and this method must be `view` for
+        // certain use cases in the bridge contracts - namely for emitting values in pre- & post-conditions
+        let addressBytes: [UInt8] = [
+            bytes[0], bytes[1], bytes[2], bytes[3],
+            bytes[4], bytes[5], bytes[6], bytes[7],
+            bytes[8], bytes[9], bytes[10], bytes[11],
+            bytes[12], bytes[13], bytes[14], bytes[15],
+            bytes[16], bytes[17], bytes[18], bytes[19]
+        ]
+        return String.encodeHex(addressBytes)
+    }
+
+    /// Returns an EVMAddress as a hex string without a 0x prefix, truncating the string's last 20 bytes if exceeded
+    ///
+    /// @param address: The hex string to convert to an EVMAddress without the 0x prefix
+    ///
+    /// @return The EVMAddress representation of the hex string
+    ///
+    access(all)
+    fun getEVMAddressFromHexString(address: String): EVM.EVMAddress? {
+        if address.length != 40 {
+            return nil
+        }
+        var addressBytes: [UInt8] = address.decodeHex()
+        if addressBytes.length != 20 {
+            return nil
+        }
+        return EVM.EVMAddress(bytes: [
+            addressBytes[0], addressBytes[1], addressBytes[2], addressBytes[3],
+            addressBytes[4], addressBytes[5], addressBytes[6], addressBytes[7],
+            addressBytes[8], addressBytes[9], addressBytes[10], addressBytes[11],
+            addressBytes[12], addressBytes[13], addressBytes[14], addressBytes[15],
+            addressBytes[16], addressBytes[17], addressBytes[18], addressBytes[19]
+        ])
+    }
+}