Add JavaScriptFoundationCompat module to provide utilities to interact Foundation types

Benchmarks/Package.swift

@@ -10,7 +10,10 @@ let package = Package(
     targets: [
         .executableTarget(
             name: "Benchmarks",
-            dependencies: ["JavaScriptKit"],
+            dependencies: [
+                "JavaScriptKit",
+                .product(name: "JavaScriptFoundationCompat", package: "JavaScriptKit"),
+            ],
             exclude: ["Generated/JavaScript", "bridge-js.d.ts"],
             swiftSettings: [
                 .enableExperimentalFeature("Extern")

Benchmarks/Sources/Benchmarks.swift

@@ -1,4 +1,6 @@
 import JavaScriptKit
+import JavaScriptFoundationCompat
+import Foundation
 
 class Benchmark {
     init(_ title: String) {
@@ -75,4 +77,22 @@ class Benchmark {
             }
         }
     }
+
+    do {
+        let conversion = Benchmark("Conversion")
+        let data = Data(repeating: 0, count: 10_000)
+        conversion.testSuite("Data to JSTypedArray") {
+            for _ in 0..<1_000_000 {
+                _ = data.jsTypedArray
+            }
+        }
+
+        let uint8Array = data.jsTypedArray
+
+        conversion.testSuite("JSTypedArray to Data") {
+            for _ in 0..<1_000_000 {
+                _ = Data.construct(from: uint8Array)
+            }
+        }
+    }
 }

Package.swift

@@ -21,6 +21,7 @@ let package = Package(
         .library(name: "JavaScriptKit", targets: ["JavaScriptKit"]),
         .library(name: "JavaScriptEventLoop", targets: ["JavaScriptEventLoop"]),
         .library(name: "JavaScriptBigIntSupport", targets: ["JavaScriptBigIntSupport"]),
+        .library(name: "JavaScriptFoundationCompat", targets: ["JavaScriptFoundationCompat"]),
         .library(name: "JavaScriptEventLoopTestSupport", targets: ["JavaScriptEventLoopTestSupport"]),
         .plugin(name: "PackageToJS", targets: ["PackageToJS"]),
         .plugin(name: "BridgeJS", targets: ["BridgeJS"]),
@@ -106,6 +107,18 @@ let package = Package(
                 "JavaScriptEventLoopTestSupport",
             ]
         ),
+        .target(
+            name: "JavaScriptFoundationCompat",
+            dependencies: [
+                "JavaScriptKit"
+            ]
+        ),
+        .testTarget(
+            name: "JavaScriptFoundationCompatTests",
+            dependencies: [
+                "JavaScriptFoundationCompat"
+            ]
+        ),
         .plugin(
             name: "PackageToJS",
             capability: .command(

Sources/JavaScriptFoundationCompat/Data+JSValue.swift

@@ -0,0 +1,42 @@
+import Foundation
+import JavaScriptKit
+
+/// Data <-> Uint8Array conversion. The conversion is lossless and copies the bytes at most once per conversion
+extension Data: ConvertibleToJSValue, ConstructibleFromJSValue {
+    /// Convert a Data to a JSTypedArray<UInt8>.
+    ///
+    /// - Returns: A Uint8Array that contains the bytes of the Data.
+    public var jsTypedArray: JSTypedArray<UInt8> {
+        self.withUnsafeBytes { buffer in
+            return JSTypedArray<UInt8>(buffer: buffer.bindMemory(to: UInt8.self))
+        }
+    }
+
+    /// Convert a Data to a JSValue.
+    ///
+    /// - Returns: A JSValue that contains the bytes of the Data as a Uint8Array.
+    public var jsValue: JSValue { jsTypedArray.jsValue }
+
+    /// Construct a Data from a JSTypedArray<UInt8>.
+    public static func construct(from uint8Array: JSTypedArray<UInt8>) -> Data? {
+        // First, allocate the data storage
+        var data = Data(count: uint8Array.lengthInBytes)
+        // Then, copy the byte contents into the Data buffer
+        data.withUnsafeMutableBytes { destinationBuffer in
+            uint8Array.copyMemory(to: destinationBuffer.bindMemory(to: UInt8.self))
+        }
+        return data
+    }
+
+    /// Construct a Data from a JSValue.
+    ///
+    /// - Parameter jsValue: The JSValue to construct a Data from.
+    /// - Returns: A Data, if the JSValue is a Uint8Array.
+    public static func construct(from jsValue: JSValue) -> Data? {
+        guard let uint8Array = JSTypedArray<UInt8>(from: jsValue) else {
+            // If the JSValue is not a Uint8Array, fail.
+            return nil
+        }
+        return construct(from: uint8Array)
+    }
+}

Tests/JavaScriptFoundationCompatTests/Data+JSValueTests.swift

@@ -0,0 +1,55 @@
+import XCTest
+import Foundation
+import JavaScriptFoundationCompat
+import JavaScriptKit
+
+final class DataJSValueTests: XCTestCase {
+    func testDataToJSValue() {
+        let data = Data([0x00, 0x01, 0x02, 0x03])
+        let jsValue = data.jsValue
+
+        let uint8Array = JSTypedArray<UInt8>(from: jsValue)
+        XCTAssertEqual(uint8Array?.lengthInBytes, 4)
+        XCTAssertEqual(uint8Array?[0], 0x00)
+        XCTAssertEqual(uint8Array?[1], 0x01)
+        XCTAssertEqual(uint8Array?[2], 0x02)
+        XCTAssertEqual(uint8Array?[3], 0x03)
+    }
+
+    func testJSValueToData() {
+        let jsValue = JSTypedArray<UInt8>([0x00, 0x01, 0x02, 0x03]).jsValue
+        let data = Data.construct(from: jsValue)
+        XCTAssertEqual(data, Data([0x00, 0x01, 0x02, 0x03]))
+    }
+
+    func testDataToJSValue_withLargeData() {
+        let data = Data(repeating: 0x00, count: 1024 * 1024)
+        let jsValue = data.jsValue
+        let uint8Array = JSTypedArray<UInt8>(from: jsValue)
+        XCTAssertEqual(uint8Array?.lengthInBytes, 1024 * 1024)
+    }
+
+    func testJSValueToData_withLargeData() {
+        let jsValue = JSTypedArray<UInt8>(Array(repeating: 0x00, count: 1024 * 1024)).jsValue
+        let data = Data.construct(from: jsValue)
+        XCTAssertEqual(data?.count, 1024 * 1024)
+    }
+
+    func testDataToJSValue_withEmptyData() {
+        let data = Data()
+        let jsValue = data.jsValue
+        let uint8Array = JSTypedArray<UInt8>(from: jsValue)
+        XCTAssertEqual(uint8Array?.lengthInBytes, 0)
+    }
+
+    func testJSValueToData_withEmptyData() {
+        let jsValue = JSTypedArray<UInt8>([]).jsValue
+        let data = Data.construct(from: jsValue)
+        XCTAssertEqual(data, Data())
+    }
+
+    func testJSValueToData_withInvalidJSValue() {
+        let data = Data.construct(from: JSObject().jsValue)
+        XCTAssertNil(data)
+    }
+}