First cut of mini dart:html.

tool/input_sdk/lib/html/html_common/conversions.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+
+// Conversions for IDBKey.
+//
+// Per http://www.w3.org/TR/IndexedDB/#key-construct
+//
+// "A value is said to be a valid key if it is one of the following types: Array
+// JavaScript objects [ECMA-262], DOMString [WEBIDL], Date [ECMA-262] or float
+// [WEBIDL]. However Arrays are only valid keys if every item in the array is
+// defined and is a valid key (i.e. sparse arrays can not be valid keys) and if
+// the Array doesn't directly or indirectly contain itself. Any non-numeric
+// properties are ignored, and thus does not affect whether the Array is a valid
+// key. Additionally, if the value is of type float, it is only a valid key if
+// it is not NaN, and if the value is of type Date it is only a valid key if its
+// [[PrimitiveValue]] internal property, as defined by [ECMA-262], is not NaN."
+
+// What is required is to ensure that an Lists in the key are actually
+// JavaScript arrays, and any Dates are JavaScript Dates.
+
+// Conversions for Window.  These check if the window is the local
+// window, and if it's not, wraps or unwraps it with a secure wrapper.
+// We need to test for EventTarget here as well as it's a base type.
+// We omit an unwrapper for Window as no methods take a non-local
+// window as a parameter.
+
+part of html_common;
+
+/// Converts a Dart value into a JavaScript SerializedScriptValue.
+convertDartToNative_SerializedScriptValue(value) {
+  return convertDartToNative_PrepareForStructuredClone(value);
+}
+
+/// Since the source object may be viewed via a JavaScript event listener the
+/// original may not be modified.
+convertNativeToDart_SerializedScriptValue(object) {
+  return convertNativeToDart_AcceptStructuredClone(object, mustCopy: true);
+}
+
+
+/**
+ * Converts a Dart value into a JavaScript SerializedScriptValue.  Returns the
+ * original input or a functional 'copy'.  Does not mutate the original.
+ *
+ * The main transformation is the translation of Dart Maps are converted to
+ * JavaScript Objects.
+ *
+ * The algorithm is essentially a dry-run of the structured clone algorithm
+ * described at
+ * http://www.whatwg.org/specs/web-apps/current-work/multipage/common-dom-interfaces.html#structured-clone
+ * https://www.khronos.org/registry/typedarray/specs/latest/#9
+ *
+ * Since the result of this function is expected to be passed only to JavaScript
+ * operations that perform the structured clone algorithm which does not mutate
+ * its output, the result may share structure with the input [value].
+ */
+abstract class _StructuredClone {
+
+  // TODO(sra): Replace slots with identity hash table.
+  var values = [];
+  var copies = [];  // initially 'null', 'true' during initial DFS, then a copy.
+
+  int findSlot(value) {
+    int length = values.length;
+    for (int i = 0; i < length; i++) {
+      if (identical(values[i], value)) return i;
+    }
+    values.add(value);
+    copies.add(null);
+    return length;
+  }
+  readSlot(int i) => copies[i];
+  writeSlot(int i, x) { copies[i] = x; }
+  cleanupSlots() {}  // Will be needed if we mark objects with a property.
+  bool cloneNotRequired(object);
+  newJsMap();
+  newJsList(length);
+  void putIntoMap(map, key, value);
+
+  // Returns the input, or a clone of the input.
+  walk(e) {
+    if (e == null) return e;
+    if (e is bool) return e;
+    if (e is num) return e;
+    if (e is String) return e;
+    if (e is DateTime) {
+      return convertDartToNative_DateTime(e);
+    }
+    if (e is RegExp) {
+      // TODO(sra).
+      throw new UnimplementedError('structured clone of RegExp');
+    }
+
+    // The browser's internal structured cloning algorithm will copy certain
+    // types of object, but it will copy only its own implementations and not
+    // just any Dart implementations of the interface.
+
+    // TODO(sra): The JavaScript objects suitable for direct cloning by the
+    // structured clone algorithm could be tagged with an private interface.
+
+    if (e is File) return e;
+    if (e is Blob) return e;
+    if (e is FileList) return e;
+
+    // TODO(sra): Firefox: How to convert _TypedImageData on the other end?
+    if (e is ImageData) return e;
+    if (cloneNotRequired(e)) return e;
+
+    if (e is Map) {
+      var slot = findSlot(e);
+      var copy = readSlot(slot);
+      if (copy != null) return copy;
+      copy = newJsMap();
+      writeSlot(slot, copy);
+      e.forEach((key, value) {
+        putIntoMap(copy, key, walk(value));
+      });
+      return copy;
+    }
+
+    if (e is List) {
+      // Since a JavaScript Array is an instance of Dart List it is tempting
+      // in dart2js to avoid making a copy of the list if there is no need
+      // to copy anything reachable from the array.  However, the list may have
+      // non-native properties or methods from interceptors and such, e.g.
+      // an immutability marker. So we  had to stop doing that.
+      var slot = findSlot(e);
+      var copy = readSlot(slot);
+      if (copy != null) return copy;
+      copy = copyList(e, slot);
+      return copy;
+    }
+
+    throw new UnimplementedError('structured clone of other type');
+  }
+
+  copyList(List e, int slot) {
+    int i = 0;
+    int length = e.length;
+    var copy = newJsList(length);
+    writeSlot(slot, copy);
+    for ( ; i < length; i++) {
+      copy[i] = walk(e[i]);
+    }
+    return copy;
+  }
+
+  convertDartToNative_PrepareForStructuredClone(value) {
+    var copy = walk(value);
+    cleanupSlots();
+    return copy;
+  }
+}
+
+/**
+ * Converts a native value into a Dart object.
+ *
+ * If [mustCopy] is [:false:], may return the original input.  May mutate the
+ * original input (but will be idempotent if mutation occurs).  It is assumed
+ * that this conversion happens on native serializable script values such values
+ * from native DOM calls.
+ *
+ * [object] is the result of a structured clone operation.
+ *
+ * If necessary, JavaScript Dates are converted into Dart Dates.
+ *
+ * If [mustCopy] is [:true:], the entire object is copied and the original input
+ * is not mutated.  This should be the case where Dart and JavaScript code can
+ * access the value, for example, via multiple event listeners for
+ * MessageEvents.  Mutating the object to make it more 'Dart-like' would corrupt
+ * the value as seen from the JavaScript listeners.
+ */
+abstract class _AcceptStructuredClone {
+
+  // TODO(sra): Replace slots with identity hash table.
+  var values = [];
+  var copies = [];  // initially 'null', 'true' during initial DFS, then a copy.
+  bool mustCopy = false;
+
+  int findSlot(value) {
+    int length = values.length;
+    for (int i = 0; i < length; i++) {
+      if (identicalInJs(values[i], value)) return i;
+    }
+    values.add(value);
+    copies.add(null);
+    return length;
+  }
+
+  /// Are the two objects identical, but taking into account that two JsObject
+  /// wrappers may not be identical, but their underlying Js Object might be.
+  bool identicalInJs(a, b);
+  readSlot(int i) => copies[i];
+  writeSlot(int i, x) { copies[i] = x; }
+
+  /// Iterate over the JS properties.
+  forEachJsField(object, action);
+
+  /// Create a new Dart list of the given length. May create a native List or
+  /// a JsArray, depending if we're in Dartium or dart2js.
+  newDartList(length);
+
+  walk(e) {
+    if (e == null) return e;
+    if (e is bool) return e;
+    if (e is num) return e;
+    if (e is String) return e;
+
+    if (isJavaScriptDate(e)) {
+      return convertNativeToDart_DateTime(e);
+    }
+
+    if (isJavaScriptRegExp(e)) {
+      // TODO(sra).
+      throw new UnimplementedError('structured clone of RegExp');
+    }
+
+    if (isJavaScriptPromise(e)) {
+      return convertNativePromiseToDartFuture(e);
+    }
+
+    if (isJavaScriptSimpleObject(e)) {
+      // TODO(sra): If mustCopy is false, swizzle the prototype for one of a Map
+      // implementation that uses the properies as storage.
+      var slot = findSlot(e);
+      var copy = readSlot(slot);
+      if (copy != null) return copy;
+      copy = {};
+
+      writeSlot(slot, copy);
+      forEachJsField(e, (key, value) => copy[key] = walk(value));
+      return copy;
+    }
+
+    if (isJavaScriptArray(e)) {
+      var slot = findSlot(e);
+      var copy = readSlot(slot);
+      if (copy != null) return copy;
+
+      int length = e.length;
+      // Since a JavaScript Array is an instance of Dart List, we can modify it
+      // in-place unless we must copy.
+      copy = mustCopy ? newDartList(length) : e;
+      writeSlot(slot, copy);
+
+      for (int i = 0; i < length; i++) {
+        copy[i] = walk(e[i]);
+      }
+      return copy;
+    }
+
+    // Assume anything else is already a valid Dart object, either by having
+    // already been processed, or e.g. a clonable native class.
+    return e;
+  }
+
+  convertNativeToDart_AcceptStructuredClone(object, {mustCopy: false}) {
+    this.mustCopy = mustCopy;
+    var copy = walk(object);
+    return copy;
+  }
+}
+
+// Conversions for ContextAttributes.
+//
+// On Firefox, the returned ContextAttributes is a plain object.
+class _TypedContextAttributes implements gl.ContextAttributes {
+  bool alpha;
+  bool antialias;
+  bool depth;
+  bool premultipliedAlpha;
+  bool preserveDrawingBuffer;
+  bool stencil;
+  bool failIfMajorPerformanceCaveat;
+
+  _TypedContextAttributes(this.alpha, this.antialias, this.depth,
+      this.failIfMajorPerformanceCaveat, this.premultipliedAlpha,
+      this.preserveDrawingBuffer, this.stencil);
+}
+
+gl.ContextAttributes convertNativeToDart_ContextAttributes(
+    nativeContextAttributes) {
+  if (nativeContextAttributes is gl.ContextAttributes) {
+    return nativeContextAttributes;
+  }
+
+  // On Firefox the above test fails because ContextAttributes is a plain
+  // object so we create a _TypedContextAttributes.
+
+  return new _TypedContextAttributes(
+      JS('var', '#.alpha', nativeContextAttributes),
+      JS('var', '#.antialias', nativeContextAttributes),
+      JS('var', '#.depth', nativeContextAttributes),
+      JS('var', '#.failIfMajorPerformanceCaveat', nativeContextAttributes),
+      JS('var', '#.premultipliedAlpha', nativeContextAttributes),
+      JS('var', '#.preserveDrawingBuffer', nativeContextAttributes),
+      JS('var', '#.stencil', nativeContextAttributes));
+}
+
+// Conversions for ImageData
+//
+// On Firefox, the returned ImageData is a plain object.
+
+class _TypedImageData implements ImageData {
+  final Uint8ClampedList data;
+  final int height;
+  final int width;
+
+  _TypedImageData(this.data, this.height, this.width);
+}
+
+ImageData convertNativeToDart_ImageData(nativeImageData) {
+
+  // None of the native getters that return ImageData are declared as returning
+  // [ImageData] since that is incorrect for FireFox, which returns a plain
+  // Object.  So we need something that tells the compiler that the ImageData
+  // class has been instantiated.
+  // TODO(sra): Remove this when all the ImageData returning APIs have been
+  // annotated as returning the union ImageData + Object.
+  JS('ImageData', '0');
+
+  if (nativeImageData is ImageData) {
+
+    // Fix for Issue 16069: on IE, the `data` field is a CanvasPixelArray which
+    // has Array as the constructor property.  This interferes with finding the
+    // correct interceptor.  Fix it by overwriting the constructor property.
+    var data = nativeImageData.data;
+    if (JS('bool', '#.constructor === Array', data)) {
+      if (JS('bool', 'typeof CanvasPixelArray !== "undefined"')) {
+        JS('void', '#.constructor = CanvasPixelArray', data);
+        // This TypedArray property is missing from CanvasPixelArray.
+        JS('void', '#.BYTES_PER_ELEMENT = 1', data);
+      }
+    }
+
+    return nativeImageData;
+  }
+
+  // On Firefox the above test fails because [nativeImageData] is a plain
+  // object.  So we create a _TypedImageData.
+
+  return new _TypedImageData(
+      JS('NativeUint8ClampedList', '#.data', nativeImageData),
+      JS('var', '#.height', nativeImageData),
+      JS('var', '#.width', nativeImageData));
+}
+
+// We can get rid of this conversion if _TypedImageData implements the fields
+// with native names.
+convertDartToNative_ImageData(ImageData imageData) {
+  if (imageData is _TypedImageData) {
+    return JS('', '{data: #, height: #, width: #}',
+        imageData.data, imageData.height, imageData.width);
+  }
+  return imageData;
+}
+
+const String _serializedScriptValue =
+    'num|String|bool|'
+    'JSExtendableArray|=Object|'
+    'Blob|File|NativeByteBuffer|NativeTypedData'
+    // TODO(sra): Add Date, RegExp.
+    ;
+const annotation_Creates_SerializedScriptValue =
+    const Creates(_serializedScriptValue);
+const annotation_Returns_SerializedScriptValue =
+    const Returns(_serializedScriptValue);