Support user generated custom native JS classes.

sdk/lib/js/dart2js/js_dart2js.dart

 // Copyright (c) 2013, 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.
 
 /**
  * Support for interoperating with JavaScript.
  *
  * This library provides access to JavaScript objects from Dart, allowing
  * Dart code to get and set properties, and call methods of JavaScript objects
  * and invoke JavaScript functions. The library takes care of converting
@@ skipping 74 matching lines @@
  *
  *     var jsArray = new JsObject.jsify([1, 2, 3]);
  */
 library dart.js;
 
 import 'dart:html' show Blob, Event, ImageData, Node, Window;
 import 'dart:collection' show HashMap, ListMixin;
 import 'dart:indexed_db' show KeyRange;
 import 'dart:typed_data' show TypedData;
 
-import 'dart:_foreign_helper' show JS, DART_CLOSURE_TO_JS;
-import 'dart:_interceptors' show JavaScriptObject, UnknownJavaScriptObject;
-import 'dart:_js_helper' show Primitives, convertDartClosureToJS,
-    getIsolateAffinityTag;
+import 'dart:_foreign_helper' show JS, JS_CONST, DART_CLOSURE_TO_JS;
+import 'dart:_interceptors'
+    show JavaScriptObject, UnknownJavaScriptObject, DART_CLOSURE_PROPERTY_NAME;
+import 'dart:_js_helper'
+    show Primitives, convertDartClosureToJS, getIsolateAffinityTag;
+
+export 'dart:_interceptors' show JavaScriptObject;
 
 final JsObject context = _wrapToDart(JS('', 'self'));
 
 _convertDartFunction(Function f, {bool captureThis: false}) {
-  return JS('',
-    'function(_call, f, captureThis) {'
-      'return function() {'
-        'return _call(f, captureThis, this, '
-            'Array.prototype.slice.apply(arguments));'
-      '}'
-    '}(#, #, #)', DART_CLOSURE_TO_JS(_callDartFunction), f, captureThis);
+  return JS(
+      '',
+      '''
+        function(_call, f, captureThis) {
+          return function() {
+            return _call(f, captureThis, this,
+                Array.prototype.slice.apply(arguments));
+          }
+        }(#, #, #)
+      ''',
+      DART_CLOSURE_TO_JS(_callDartFunction),
+      f,
+      captureThis);
 }
 
 _callDartFunction(callback, bool captureThis, self, List arguments) {
   if (captureThis) {
     arguments = [self]..addAll(arguments);
   }
   var dartArgs = new List.from(arguments.map(_convertToDart));
   return _convertToJS(Function.apply(callback, dartArgs));
 }
 
@@ skipping 85 matching lines @@
    *
    * Use this constructor only if you wish to get access to JavaScript
    * properties attached to a browser host object, such as a Node or Blob, that
    * is normally automatically converted into a native Dart object.
    *
    * An exception will be thrown if [object] either is `null` or has the type
    * `bool`, `num`, or `String`.
    */
   factory JsObject.fromBrowserObject(object) {
     if (object is num || object is String || object is bool || object == null) {
-      throw new ArgumentError(
-        "object cannot be a num, string, bool, or null");
+      throw new ArgumentError("object cannot be a num, string, bool, or null");
     }
     return _wrapToDart(_convertToJS(object));
   }
 
   /**
    * Recursively converts a JSON-like collection of Dart objects to a
    * collection of JavaScript objects and returns a [JsObject] proxy to it.
    *
    * [object] must be a [Map] or [Iterable], the contents of which are also
    * converted. Maps and Iterables are copied to a new JavaScript object.
@@ skipping 33 matching lines @@
 
     return _convert(data);
   }
 
   /**
    * Returns the value associated with [property] from the proxied JavaScript
    * object.
    *
    * The type of [property] must be either [String] or [num].
    */
-  dynamic operator[](property) {
+  dynamic operator [](property) {
     if (property is! String && property is! num) {
       throw new ArgumentError("property is not a String or num");
     }
     return _convertToDart(JS('', '#[#]', _jsObject, property));
   }
 
   /**
    * Sets the value associated with [property] on the proxied JavaScript
    * object.
    *
    * The type of [property] must be either [String] or [num].
    */
-  operator[]=(property, value) {
+  operator []=(property, value) {
     if (property is! String && property is! num) {
       throw new ArgumentError("property is not a String or num");
     }
     JS('', '#[#]=#', _jsObject, property, _convertToJS(value));
   }
 
   int get hashCode => 0;
 
-  bool operator==(other) => other is JsObject &&
-      JS('bool', '# === #', _jsObject, other._jsObject);
+  bool operator ==(other) =>
+      other is JsObject && JS('bool', '# === #', _jsObject, other._jsObject);
 
   /**
    * Returns `true` if the JavaScript object contains the specified property
    * either directly or though its prototype chain.
    *
    * This is the equivalent of the `in` operator in JavaScript.
    */
   bool hasProperty(property) {
     if (property is! String && property is! num) {
       throw new ArgumentError("property is not a String or num");
@@ skipping 21 matching lines @@
   bool instanceof(JsFunction type) {
     return JS('bool', '# instanceof #', _jsObject, _convertToJS(type));
   }
 
   /**
    * Returns the result of the JavaScript objects `toString` method.
    */
   String toString() {
     try {
       return JS('String', 'String(#)', _jsObject);
-    } catch(e) {
+    } catch (e) {
       return super.toString();
     }
   }
 
   /**
    * Calls [method] on the JavaScript object with the arguments [args] and
    * returns the result.
    *
    * The type of [method] must be either [String] or [num].
    */
   dynamic callMethod(method, [List args]) {
     if (method is! String && method is! num) {
       throw new ArgumentError("method is not a String or num");
     }
-    return _convertToDart(JS('', '#[#].apply(#, #)', _jsObject, method,
+    return _convertToDart(JS(
+        '',
+        '#[#].apply(#, #)',
+        _jsObject,
+        method,
         _jsObject,
         args == null ? null : new List.from(args.map(_convertToJS))));
   }
 }
 
 /**
  * Proxies a JavaScript Function object.
  */
 class JsFunction extends JsObject {
-
   /**
    * Returns a [JsFunction] that captures its 'this' binding and calls [f]
    * with the value of this passed as the first argument.
    */
   factory JsFunction.withThis(Function f) {
     var jsFunc = _convertDartFunction(f, captureThis: true);
     return new JsFunction._fromJs(jsFunc);
   }
 
   JsFunction._fromJs(jsObject) : super._fromJs(jsObject);
 
   /**
    * Invokes the JavaScript function with arguments [args]. If [thisArg] is
    * supplied it is the value of `this` for the invocation.
    */
-  dynamic apply(List args, { thisArg }) =>
-      _convertToDart(JS('', '#.apply(#, #)', _jsObject,
-          _convertToJS(thisArg),
-          args == null ? null : new List.from(args.map(_convertToJS))));
+  dynamic apply(List args, {thisArg}) => _convertToDart(JS(
+      '',
+      '#.apply(#, #)',
+      _jsObject,
+      _convertToJS(thisArg),
+      args == null ? null : new List.from(args.map(_convertToJS))));
 }
 
 /**
  * A [List] that proxies a JavaScript array.
  */
 class JsArray<E> extends JsObject with ListMixin<E> {
-
   /**
    * Creates a new JavaScript array.
    */
   JsArray() : super._fromJs([]);
 
   /**
    * Creates a new JavaScript array and initializes it to the contents of
    * [other].
    */
   JsArray.from(Iterable<E> other)
@@ skipping 45 matching lines @@
   int get length {
     // Check the length honours the List contract.
     var len = JS('', '#.length', _jsObject);
     // JavaScript arrays have lengths which are unsigned 32-bit integers.
     if (JS('bool', 'typeof # === "number" && (# >>> 0) === #', len, len, len)) {
       return JS('int', '#', len);
     }
     throw new StateError('Bad JsArray length');
   }
 
-  set length(int length) { super['length'] = length; }
-
+  void set length(int length) {
+    super['length'] = length;
+  }
 
   // Methods overriden for better performance
 
   void add(E value) {
     callMethod('push', [value]);
   }
 
   void addAll(Iterable<E> iterable) {
     var list = (JS('bool', '# instanceof Array', iterable))
         ? iterable
@@ skipping 32 matching lines @@
 
   void sort([int compare(E a, E b)]) {
     // Note: arr.sort(null) is a type error in FF
     callMethod('sort', compare == null ? [] : [compare]);
   }
 }
 
 // property added to a Dart object referencing its JS-side DartObject proxy
 final String _DART_OBJECT_PROPERTY_NAME =
     getIsolateAffinityTag(r'_$dart_dartObject');
-final String _DART_CLOSURE_PROPERTY_NAME =
-    getIsolateAffinityTag(r'_$dart_dartClosure');
 
 // property added to a JS object referencing its Dart-side JsObject proxy
 const _JS_OBJECT_PROPERTY_NAME = r'_$dart_jsObject';
 const _JS_FUNCTION_PROPERTY_NAME = r'$dart_jsFunction';
+const _JS_FUNCTION_PROPERTY_NAME_CAPTURE_THIS = r'_$dart_jsFunctionCaptureThis';
 
 bool _defineProperty(o, String name, value) {
   try {
     if (_isExtensible(o) &&
         // TODO(ahe): Calling _hasOwnProperty to work around
         // https://code.google.com/p/dart/issues/detail?id=21331.
         !_hasOwnProperty(o, name)) {
       JS('void', 'Object.defineProperty(#, #, { value: #})', o, name, value);
       return true;
     }
@@ skipping 26 matching lines @@
 dynamic _convertToJS(dynamic o) {
   // Note: we don't write `if (o == null) return null;` to make sure dart2js
   // doesn't convert `return null;` into `return;` (which would make `null` be
   // `undefined` in Javascprit). See dartbug.com/20305 for details.
   if (o == null || o is String || o is num || o is bool) {
     return o;
   }
   if (o is JsObject) {
     return o._jsObject;
   }
-  if (o is Blob || o is Event || o is KeyRange || o is ImageData || o is Node ||
-      o is TypedData || o is Window) {
+  if (o is Blob ||
+      o is Event ||
+      o is KeyRange ||
+      o is ImageData ||
+      o is Node ||
+      o is TypedData ||
+      o is Window) {
     return o;
   }
   if (o is DateTime) {
     return Primitives.lazyAsJsDate(o);
   }
   if (o is Function) {
     return _getJsProxy(o, _JS_FUNCTION_PROPERTY_NAME, (o) {
       var jsFunction = _convertDartFunction(o);
       // set a property on the JS closure referencing the Dart closure
-      _defineProperty(jsFunction, _DART_CLOSURE_PROPERTY_NAME, o);
+      _defineProperty(jsFunction, DART_CLOSURE_PROPERTY_NAME, o);
       return jsFunction;
     });
   }
   var ctor = _dartProxyCtor;
-  return _getJsProxy(o, _JS_OBJECT_PROPERTY_NAME,
-      (o) => JS('', 'new #(#)', ctor, o));
+  return _getJsProxy(
+      o, _JS_OBJECT_PROPERTY_NAME, (o) => JS('', 'new #(#)', ctor, o));
 }
 
 Object _getJsProxy(o, String propertyName, createProxy(o)) {
   var jsProxy = _getOwnProperty(o, propertyName);
   if (jsProxy == null) {
     jsProxy = createProxy(o);
     _defineProperty(o, propertyName, jsProxy);
   }
   return jsProxy;
 }
 
 // converts a Dart object to a reference to a native JS object
 // which might be a DartObject JS->Dart proxy
 Object _convertToDart(o) {
   if (JS('bool', '# == null', o) ||
       JS('bool', 'typeof # == "string"', o) ||
       JS('bool', 'typeof # == "number"', o) ||
       JS('bool', 'typeof # == "boolean"', o)) {
     return o;
-  } else if (_isLocalObject(o)
-      && (o is Blob || o is Event || o is KeyRange || o is ImageData
-      || o is Node || o is TypedData || o is Window)) {
+  } else if (_isLocalObject(o) &&
+      (o is Blob ||
+          o is Event ||
+          o is KeyRange ||
+          o is ImageData ||
+          o is Node ||
+          o is TypedData ||
+          o is Window)) {
     // long line: dart2js doesn't allow string concatenation in the JS() form
     return JS('Blob|Event|KeyRange|ImageData|Node|TypedData|Window', '#', o);
   } else if (JS('bool', '# instanceof Date', o)) {
     var ms = JS('num', '#.getTime()', o);
     return new DateTime.fromMillisecondsSinceEpoch(ms);
   } else if (JS('bool', '#.constructor === #', o, _dartProxyCtor)) {
     return JS('', '#.o', o);
   } else {
     return _wrapToDart(o);
   }
 }
 
 JsObject _wrapToDart(o) {
   if (JS('bool', 'typeof # == "function"', o)) {
-    return _getDartProxy(o, _DART_CLOSURE_PROPERTY_NAME,
-        (o) => new JsFunction._fromJs(o));
+    return _getDartProxy(
+        o, DART_CLOSURE_PROPERTY_NAME, (o) => new JsFunction._fromJs(o));
   }
   if (JS('bool', '# instanceof Array', o)) {
-    return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
-        (o) => new JsArray._fromJs(o));
+    return _getDartProxy(
+        o, _DART_OBJECT_PROPERTY_NAME, (o) => new JsArray._fromJs(o));
   }
-  return _getDartProxy(o, _DART_OBJECT_PROPERTY_NAME,
-      (o) => new JsObject._fromJs(o));
+  return _getDartProxy(
+      o, _DART_OBJECT_PROPERTY_NAME, (o) => new JsObject._fromJs(o));
 }
 
 Object _getDartProxy(o, String propertyName, createProxy(o)) {
   var dartProxy = _getOwnProperty(o, propertyName);
   // Temporary fix for dartbug.com/15193
   // In some cases it's possible to see a JavaScript object that
   // came from a different context and was previously proxied to
   // Dart in that context. The JS object will have a cached proxy
   // but it won't be a valid Dart object in this context.
   // For now we throw away the cached proxy, but we should be able
   // to cache proxies from multiple JS contexts and Dart isolates.
   if (dartProxy == null || !_isLocalObject(o)) {
     dartProxy = createProxy(o);
     _defineProperty(o, propertyName, dartProxy);
   }
   return dartProxy;
 }
+
+// Start of methods for new style Dart-JS interop.

[Siggi Cherem (dart-lang), 2015/10/06 22:38:02]

nit: maybe add a // ---------------------------------------------- :)

[Jacob, 2015/10/13 01:19:24]

Done.

+
+const _UNDEFINED = const JS_CONST('void 0');
+
+// TODO(jacobr): this method is a hack to work around the lack of proper dart
+// support for varargs methods.
+List _stripUndefinedArgs(List args) =>
+    args.takeWhile((i) => JS('bool', '# !== #', i, _UNDEFINED)).toList();

[sra1, 2015/10/06 21:42:17]

could also use
JS('bool', 'typeof # != "undefined"', i)

[Jacob, 2015/10/13 01:19:24]

done. is that faster?

+
+class _JavaScriptFunctionHack implements Function {
+  call(
+      [a = _UNDEFINED,
+      b = _UNDEFINED,
+      c = _UNDEFINED,
+      d = _UNDEFINED,
+      e = _UNDEFINED,
+      f = _UNDEFINED,
+      g = _UNDEFINED,
+      h = _UNDEFINED,
+      i = _UNDEFINED,
+      j = _UNDEFINED]) {
+    // Exceedingly slow default implementation.
+    return JS('', '#.apply(null, #)', this,
+        _stripUndefinedArgs([a, b, c, d, e, f, g, h, i, j]));
+  }
+}
+
+void _copyOwnProperties(src, dest) {
+  JS(
+      '',

[Siggi Cherem (dart-lang), 2015/10/06 22:38:02]

eeek - maybe file a dartfmt bug, this format seems very odd to me, maybe because
the function name is short. I'd prefer:
JS('', r'''
       ...
     ''', src, dest);

[Jacob, 2015/10/13 01:19:24]

i think the existing is easier to read although less dense.
I find it annoying that with the other option, the first '' is 1 character off
from the '''

+      r'''
+        (function(src, dest) {
+          var properties = Object.getOwnPropertyNames(src);
+          for (var i = 0, len = properties.length; i < len; i++) {
+            var name = properties[i];
+            dest[name] = src[name];
+          }
+        })(#, #)
+      ''',
+      src,
+      dest);
+}
+
+// TODO(jacobr): remove this method. So far it appears that specifying the list
+// of registered types in Dart2Js has significant negative code size
+// implications so it is better to specify usage purely based on which
+// libraries are imported. Remove after Dartium is modified to function without
+// requiring this method.
+void registerJsInterfaces([List<Type> types]) {

[Siggi Cherem (dart-lang), 2015/10/06 22:38:02]

I thought you said this was no longer used?

[Jacob, 2015/10/13 01:19:24]

I need a home for the fnProto munging.
We also need to figure out what the solution is for cross frames.
Perhaps this method needs to be
allowInteropOnFrame(Window window)
?

[Siggi Cherem (dart-lang), 2015/10/13 02:08:52]

sounds good - btw, this code disappeared, did it move somewhere else?

[Jacob, 2015/10/13 03:10:42]

Yep. I now generate the .call$N methods through the correct (i think) in
js_interop_analysis.dart 
see buildJsInteropBootstrap

+  // No need to actually register in Dart2JS.
+  var fnHackProto = JS('', '#.__proto__', new _JavaScriptFunctionHack());
+  var fnProto = JS('', 'Function.prototype');
+  _copyOwnProperties(fnHackProto, fnProto);
+  // Add optimized call methods for small numbers of arguments.
+  if (JS('bool', r'#.hasOwnProperty("call$0") ', fnHackProto)) {
+    JS('', r'#.call$0 = function() { return this(); }', fnProto);
+    JS('', r'#.call$1 = function(a) { return this(a); }', fnProto);
+    JS('', r'#.call$2 = function(a, b) { return this(a, b); }', fnProto);
+    JS('', r'#.call$3 = function(a, b, c) { return this(a, b, c); }', fnProto);
+    JS('', r'#.call$4 = function(a, b, c, d) { return this(a, b, c, d); }',
+        fnProto);
+  } else {
+    if (!JS('bool', r'#.hasOwnProperty("$0") ', fnHackProto)) {
+      throw 'Internal error. Unexpected minified output';
+    }
+    JS('', r'#.$0 = function() { return this(); }', fnProto);
+    JS('', r'#.$1 = function(a) { return this(a); }', fnProto);
+    JS('', r'#.$2 = function(a, b) { return this(a, b); }', fnProto);
+    JS('', r'#.$3 = function(a, b, c) { return this(a, b, c); }', fnProto);
+    JS('', r'#.$4 = function(a, b, c, d) { return this(a, b, c, d); }',
+        fnProto);
+  }
+}
+
+_convertDartFunctionFast(Function f) {
+  var existing = JS('', '#.#', f, _JS_FUNCTION_PROPERTY_NAME);
+  if (existing != null) return existing;
+  var ret = JS(
+      '',
+      '''
+        function(_call, f) {
+          return function() {
+            return _call(f, Array.prototype.slice.apply(arguments));

[sra1, 2015/10/06 21:42:17]

.apply -> .call ?

Add small targeted test for this.

[Jacob, 2015/10/13 01:19:24]

I have tests for this.
Array.prototype.slice.apply is just a cargo cult JS tactic to convert Arguments
to a valid Array. I did a double take when I saw it originally. Notice that
_convertDartFunction
is using the same pattern. 
If there is a faster pattern I can switch to it.

+          }
+        }(#, #)
+      ''',
+      DART_CLOSURE_TO_JS(_callDartFunctionFast),
+      f);
+  JS('', '#.# = #', ret, DART_CLOSURE_PROPERTY_NAME, f);
+  JS('', '#.# = #', f, _JS_FUNCTION_PROPERTY_NAME, ret);
+  return ret;
+}
+
+_convertDartFunctionFastCaptureThis(Function f) {
+  var existing = JS('', '#.#', f, _JS_FUNCTION_PROPERTY_NAME_CAPTURE_THIS);
+  if (existing != null) return existing;
+  var ret = JS(
+      '',
+      '''
+        function(_call, f) {
+          return function() {
+            return _call(f, this,Array.prototype.slice.apply(arguments));

[sra1, 2015/10/06 21:42:17]

'this,' -> 'this, '

.apply -> .call ?

Add test for this path.

[Jacob, 2015/10/13 01:19:24]

see comment for previous case.

+          }
+        }(#, #)
+      ''',
+      DART_CLOSURE_TO_JS(_callDartFunctionFastCaptureThis),
+      f);
+  JS('', '#.# = #', ret, DART_CLOSURE_PROPERTY_NAME, f);
+  JS('', '#.# = #', f, _JS_FUNCTION_PROPERTY_NAME_CAPTURE_THIS, ret);
+  return ret;
+}
+
+_callDartFunctionFast(callback, List arguments) {
+  return Function.apply(callback, arguments);
+}
+
+_callDartFunctionFastCaptureThis(callback, self, List arguments) {
+  return _convertToJS(Function.apply(callback, [self]..addAll(arguments)));
+}
+
+Function allowInterop(Function f) {
+  if (JS('bool', 'typeof(#) == "function"', f)) {
+    // Already supports interop, just use the existing function.
+    return f;
+  } else {
+    return _convertDartFunctionFast(f);
+  }
+}
+
+Function allowInteropCaptureThis(Function f) {
+  if (JS('bool', 'typeof(#) == "function"', f)) {
+    // Behavior when the function is already a JS function is unspecified.
+    throw new ArgumentError(
+        "Function is already a JS function so cannot capture this.");
+    return f;
+  } else {
+    return _convertDartFunctionFastCaptureThis(f);
+  }
+}