lib/html/src/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.

// Patch file for the dart:isolate library.

/********************************************************
  Inserted from lib/isolate/serialization.dart
 ********************************************************/

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);
    if (x is SendPortSync) return visitSendPortSync(x);

    // Overridable fallback.
    return visitObject(x);
  }

  abstract visitPrimitive(x);
  abstract visitList(List x);
  abstract visitMap(Map x);
  abstract visitSendPort(SendPort x);
  abstract visitSendPortSync(SendPortSync x);

  visitObject(Object x) {
    // TODO(floitsch): make this a real exception. (which one)?
    throw "Message serialization: Illegal value $x passed";
  }

  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);
      default: return deserializeObject(x);
    }
  }

  _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);

  deserializeObject(List x) {
    // TODO(floitsch): Use real exception (which one?).
    throw "Unexpected serialized object";
  }
}