changes for 0.3.9

lib/src/protobuf/map_mixin.dart

+// Copyright (c) 2015, 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.
+
+part of protobuf;
+
+// Used by the protoc plugin to avoid name conflicts.
+// TODO: extract names automatically somehow?
+const PbMapMixin_reservedNames = const [
+  'addAll', 'containsKey', 'containsValue', 'forEach', 'putIfAbsent',
+  'remove', 'isEmpty', 'isNotEmpty', 'keys', 'length', 'values',
+  'getMapValue', 'mustGetMapValue', 'setMapValue'
+];
+
+/// A PbMapMixin provides an experimental implementation of the

[Siggi Cherem (dart-lang), 2015/06/22 19:45:37]

since your new protoc is more pluggable, I wonder if it's possible to take this
out of this package, and provide it to protoc externally.

The main challenge I see is how to provide the list of reserved names to protoc.
For that one option could be to provide the list of names on a flag. Another
idea is to use a second isolate to load the definition of the mixin, and use
mirrors to extract the required names.

Thoughts?

[skybrian, 2015/06/22 21:53:50]

I'd like to keep it in the open source code as an example.
Yes, I'd like to relax the restrictions on mixins, but that's trickier and I
need to get something out soon, so I'm going to leave it as a followup.

[Siggi Cherem (dart-lang), 2015/06/22 22:22:25]

Totally, we could still include an example in the protoc repo (e.g. an example
folder).

Long term, I would prefer if this mixin is not baked into this package. Since
the idea is for others to be able to provide their own mixin, it would be nice
to show how to do so without having to modify this library (which is hard for
people to do).

+/// Map interface for a GeneratedMessage.
+///
+/// This mixin is enabled via an option in
+/// dart_options.proto in dart-protoc-plugin.
+class PbMapMixin implements Map<String, dynamic> {

[Søren Gjesse, 2015/06/22 07:25:01]

Just for context here. Is this supposed to replace/simplify the code generated
for the map interface by the Dart protoc plugin?

[skybrian, 2015/06/22 21:53:50]

Yes.

+
+  // GeneratedMessage properties and methods used by this mixin.
+
+  BuilderInfo info_;
+  void clear();
+  int getTagNumber(String fieldName);
+  getField(int tagNumber);
+  void setField(int tagNumber, var value, [int fieldType = null]);
+
+  @override
+  operator [] (key) {
+    if (key is !String) return null;
+    var tag = getTagNumber(key);
+    if (tag == null) return null;
+    return getField(tag);
+  }
+
+  @override
+  operator []= (String key, val) {
+    var tag = getTagNumber(key);
+    if (tag == null) {
+      throw new ArgumentError(
+          "field '${key}' not found in ${info_.messageName}");
+    }
+    setField(tag, val);
+  }
+
+  @override
+  get keys => info_.byName.keys;
+
+  @override
+  bool containsKey(Object key) => info_.byName.containsKey(key);
+
+  @override
+  get length => info_.byName.length;
+
+  @override
+  remove(key) {
+    throw new UnsupportedError(
+        "remove() not supported by ${info_.messageName}");
+  }
+
+  // methods copied from MapMixin (since mixins cannot mix in other mixins).

[Søren Gjesse, 2015/06/22 07:25:01]

Could another option be that whenever PbMapMixin is used as a mixin MapMixin has
to be used as well?

[skybrian, 2015/06/22 21:53:50]

Good idea. I can implement a simple form of inheritance without much trouble.

+
+  @override
+  void forEach(void action(String key, value)) {
+    for (String key in keys) {
+      action(key, this[key]);
+    }
+  }
+
+  @override
+  void addAll(Map<String, dynamic> other) {
+    for (String key in other.keys) {
+      this[key] = other[key];
+    }
+  }
+
+  @override
+  bool containsValue(value) {
+    for (String key in keys) {
+      if (this[key] == value) return true;
+    }
+    return false;
+  }
+
+  @override
+  putIfAbsent(String key, ifAbsent()) {
+    if (keys.contains(key)) {
+      return this[key];
+    }
+    return this[key] = ifAbsent();
+  }
+
+  bool get isEmpty => keys.isEmpty;
+  bool get isNotEmpty => keys.isNotEmpty;
+  Iterable get values => new _PbMapMixinValues(this);
+}
+
+class _PbMapMixinValues extends Iterable {
+  final PbMapMixin _map;
+  _PbMapMixinValues(this._map);
+
+  int get length => _map.length;
+  bool get isEmpty => _map.isEmpty;
+  bool get isNotEmpty => _map.isNotEmpty;
+  get first => _map[_map.keys.first];
+  get single => _map[_map.keys.single];
+  get last => _map[_map.keys.last];
+
+  Iterator get iterator => new _PbMapMixinValueIterator(_map);
+}
+
+class _PbMapMixinValueIterator implements Iterator {
+  final Iterator _keys;
+  final PbMapMixin _map;
+  var _current = null;
+
+  _PbMapMixinValueIterator(PbMapMixin map) : 
+      _map = map,
+      _keys = map.keys.iterator;
+
+  bool moveNext() {
+    if (_keys.moveNext()) {
+      _current = _map[_keys.current];
+      return true;
+    }
+    _current = null;
+    return false;
+  }
+
+  get current => _current;
+}