changes for 0.3.9

lib/mixins_meta.dart

Index: lib/mixins_meta.dart
diff --git a/lib/mixins_meta.dart b/lib/mixins_meta.dart
new file mode 100644
index 0000000000000000000000000000000000000000..6284c169a1bbd367683b913f9078a94e3f4be8ca
--- /dev/null
+++ b/lib/mixins_meta.dart
@@ -0,0 +1,84 @@
+// 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.
+
+/// Provides metadata about mixins to dart-protoc-plugin.
+/// (Experimental API; subject to change.)
+library protobuf.mixins.meta;
+
+/// Entry point called by dart-protoc-plugin.
+PbMixin findMixin(String name) {
+  for (var m in _exportedMixins) {
+    if (m.name == name) {
+      return m;
+    }
+  }
+  return null; // not found
+}
+
+/// PbMixin contains the metadata needed by dart-protoc-plugin to apply a mixin.
+///
+/// The mixin can be applied to a message using the options in dart_options.proto.

[Søren Gjesse, 2015/06/23 06:49:56]

Long line.

[skybrian, 2015/06/24 18:39:04]

Done.

+/// Only one mixin can be applied to each message, but that mixin can depend on
+/// another mixin, recursively, similar to single inheritance.
+class PbMixin {
+
+  /// The Dart symbol to be imported into the .pb.dart file.

[Søren Gjesse, 2015/06/23 06:49:56]

Maybe be more explicit in this comment that this is the class name of the actual
mixin.

[skybrian, 2015/06/24 18:39:04]

Done.

+  final String name;
+
+  /// The name of the file that the .pb.dart file should import the symbol from.
+  final String importFrom;
+
+  /// Another mixin to apply ahead of this one, or null for none.
+  final PbMixin parent;
+
+  /// Names that shouldn't be used by properties in the generated child class.
+  /// May be null if the mixin doesn't reserve any new names.
+  final List<String> reservedNames;
+
+  const PbMixin._raw(this.name,
+      {this.importFrom, this.parent, this.reservedNames});
+
+  /// Returns the mixin and its ancestors, in the order they should be applied.
+  Iterable<PbMixin> findMixinsToApply() {
+    var result = [this];
+    for (var p = parent; p != null; p = p.parent) {
+      result.add(p);
+    }
+    return result.reversed;
+  }
+
+  /// Returns all the reserved names, including from ancestor mixins.
+  Iterable<String> findReservedNames() {
+    var names = new Set<String>();
+    for (var m = this; m != null; m = m.parent) {
+      if (m.reservedNames != null) {
+        names.addAll(m.reservedNames);
+      }
+    }
+    return names;
+  }
+}
+
+/// The mixins that findMixin() can return.
+const _exportedMixins = const [_pbMapMixin];
+
+const _pbMapMixin = const PbMixin._raw("PbMapMixin",
+    importFrom: "package:protobuf/src/protobuf/mixins/map_mixin.dart",
+    parent: _mapMixin);
+
+const _mapMixin = const PbMixin._raw("MapMixin",

[Søren Gjesse, 2015/06/23 06:49:56]

This mixin is in this registry because it is required by PbMapMixin. However it
cannot be a primary mixin (or at least is not intended to be as it does not work
on its own). Should there be a boolean flag here to indicate that this is not a
primary mixin so that the protoc plugin can fail if this is the only mixin used.

Of course getting into this situation require "mis-configuration" of the prats
of the protoc-plugin that are currently hard-coded.

[skybrian, 2015/06/24 18:39:03]

I'm relying on _exportedMixins to indicate whether a Mixin class is "public".
Since MapMixin is not listed there, findMixin will return null and the protoc
plugin will report that the mixin isn't found if someone attempts to use it in a
 .proto file.

We could make the error message better by using a flag like you suggest, but
I'm going to skip that for now.

+    importFrom: "dart:collection",
+    reservedNames: const [
+  'addAll',
+  'containsKey',
+  'containsValue',
+  'forEach',
+  'putIfAbsent',
+  'remove',
+  'isEmpty',
+  'isNotEmpty',
+  'keys',
+  'length',
+  'values',
+]);