Refactor the message serialization code a bit so we can start playing with it for JS interop purpos…

lib/isolate/serialization.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.
+
+class _MessageTraverserVisitedMap {
+
+  operator[](var object) => null;
+  void operator[]=(var object, var info) { }
+
+  void reset() { }
+  void cleanup() { }
+
+}
+
+/** Abstract visitor for dart objects that can be sent as isolate messages. */
+class _MessageTraverser {
+
+  _MessageTraverserVisitedMap _visited;
+  _MessageTraverser() : _visited = new _MessageTraverserVisitedMap();
+
+  /** Visitor's entry point. */
+  traverse(var x) {
+    if (isPrimitive(x)) return visitPrimitive(x);
+    _visited.reset();
+    var result;
+    try {
+      result = _dispatch(x);
+    } finally {
+      _visited.cleanup();
+    }
+    return result;
+  }
+
+  _dispatch(var x) {
+    if (isPrimitive(x)) return visitPrimitive(x);
+    if (x is List) return visitList(x);
+    if (x is Map) return visitMap(x);
+    if (x is SendPort) return visitSendPort(x);
+
+    // TODO(floitsch): make this a real exception. (which one)?
+    throw "Message serialization: Illegal value $x passed";
+  }
+
+  abstract visitPrimitive(x);
+  abstract visitList(List x);
+  abstract visitMap(Map x);
+  abstract visitSendPort(SendPort x);
+
+  static bool isPrimitive(x) {
+    return (x === null) || (x is String) || (x is num) || (x is bool);
+  }
+}
+
+
+/** A visitor that recursively copies a message. */
+class _Copier extends _MessageTraverser {
+
+  visitPrimitive(x) => x;
+
+  List visitList(List list) {
+    List copy = _visited[list];
+    if (copy !== null) return copy;
+
+    int len = list.length;
+
+    // TODO(floitsch): we loose the generic type of the List.
+    copy = new List(len);
+    _visited[list] = copy;
+    for (int i = 0; i < len; i++) {
+      copy[i] = _dispatch(list[i]);
+    }
+    return copy;
+  }
+
+  Map visitMap(Map map) {
+    Map copy = _visited[map];
+    if (copy !== null) return copy;
+
+    // TODO(floitsch): we loose the generic type of the map.
+    copy = new Map();
+    _visited[map] = copy;
+    map.forEach((key, val) {
+      copy[_dispatch(key)] = _dispatch(val);
+    });
+    return copy;
+  }
+
+}
+
+/** Visitor that serializes a message as a JSON array. */
+class _Serializer extends _MessageTraverser {
+  int _nextFreeRefId = 0;
+
+  visitPrimitive(x) => x;
+
+  visitList(List list) {
+    int copyId = _visited[list];
+    if (copyId !== null) return ['ref', copyId];
+
+    int id = _nextFreeRefId++;
+    _visited[list] = id;
+    var jsArray = _serializeList(list);
+    // TODO(floitsch): we are losing the generic type.
+    return ['list', id, jsArray];
+  }
+
+  visitMap(Map map) {
+    int copyId = _visited[map];
+    if (copyId !== null) return ['ref', copyId];
+
+    int id = _nextFreeRefId++;
+    _visited[map] = id;
+    var keys = _serializeList(map.getKeys());
+    var values = _serializeList(map.getValues());
+    // TODO(floitsch): we are losing the generic type.
+    return ['map', id, keys, values];
+  }
+
+  _serializeList(List list) {
+    int len = list.length;
+    var result = new List(len);
+    for (int i = 0; i < len; i++) {
+      result[i] = _dispatch(list[i]);
+    }
+    return result;
+  }
+}
+
+/** Deserializes arrays created with [_Serializer]. */
+class _Deserializer {
+  Map<int, Dynamic> _deserialized;
+
+  _Deserializer();
+
+  static bool isPrimitive(x) {
+    return (x === null) || (x is String) || (x is num) || (x is bool);
+  }
+
+  deserialize(x) {
+    if (isPrimitive(x)) return x;
+    // TODO(floitsch): this should be new HashMap<int, var|Dynamic>()
+    _deserialized = new HashMap();
+    return _deserializeHelper(x);
+  }
+
+  _deserializeHelper(x) {
+    if (isPrimitive(x)) return x;
+    assert(x is List);
+    switch (x[0]) {
+      case 'ref': return _deserializeRef(x);
+      case 'list': return _deserializeList(x);
+      case 'map': return _deserializeMap(x);
+      case 'sendport': return deserializeSendPort(x);
+      // TODO(floitsch): Use real exception (which one?).
+      default: throw "Unexpected serialized object";
+    }
+  }
+
+  _deserializeRef(List x) {
+    int id = x[1];
+    var result = _deserialized[id];
+    assert(result !== null);
+    return result;
+  }
+
+  List _deserializeList(List x) {
+    int id = x[1];
+    // We rely on the fact that Dart-lists are directly mapped to Js-arrays.
+    List dartList = x[2];
+    _deserialized[id] = dartList;
+    int len = dartList.length;
+    for (int i = 0; i < len; i++) {
+      dartList[i] = _deserializeHelper(dartList[i]);
+    }
+    return dartList;
+  }
+
+  Map _deserializeMap(List x) {
+    Map result = new Map();
+    int id = x[1];
+    _deserialized[id] = result;
+    List keys = x[2];
+    List values = x[3];
+    int len = keys.length;
+    assert(len == values.length);
+    for (int i = 0; i < len; i++) {
+      var key = _deserializeHelper(keys[i]);
+      var value = _deserializeHelper(values[i]);
+      result[key] = value;
+    }
+    return result;
+  }
+
+  abstract deserializeSendPort(List x);
+
+}