Initial support for generating client and server stubs for Dart.

lib/service_generator.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 protoc;
+
+class ServiceGenerator extends ProtobufContainer {
+  final String classname;
+  final String fqname;
+
+  final ProtobufContainer _parent;
+  final GenerationContext _context;
+  final ServiceDescriptorProto _descriptor;
+  final List<MethodDescriptorProto> _methodDescriptors;
+
+  ServiceGenerator(ServiceDescriptorProto descriptor, ProtobufContainer parent,
+      this._context)
+      : _descriptor = descriptor,
+        _parent = parent,
+        classname = descriptor.name,
+        fqname = (parent == null || parent.fqname == null)
+            ? descriptor.name
+            : (parent.fqname == '.'
+                ? '.${descriptor.name}'

[skybrian, 2015/06/24 16:16:30]

This calculation is a bit messy. Perhaps move it to a _getFullName() function,
and then you can use early returns instead of nested ?:.

+                : '${parent.fqname}.${descriptor.name}'),
+        _methodDescriptors = descriptor.method {
+    _context.register(this);
+  }
+
+  String get package => _parent.package;
+
+  String _simpleType(String typename) {
+    return typename.substring(typename.lastIndexOf('.') + 1);
+  }
+
+  void generate(IndentingWriter out) {
+    out.addBlock(
+        'abstract class ${classname}ServiceBase extends GeneratedService {',
+        '}', () {
+      for (MethodDescriptorProto m in _methodDescriptors) {
+        out.println('Future<${_simpleType(m.outputType)}> ${m.name}('
+            'ServerContext ctx, ${_simpleType(m.inputType)} request);');
+      }
+      out.println();
+      out.addBlock(
+          'Future<List<int>> handleCall(ServerContext ctx, String method, '

[skybrian, 2015/06/24 16:16:30]

We should make this handle JSON and binary on the server side too, which seems
tricky.

One way would be to change List<int> to dynamic for both request and response,
and also pass in two methods:

typedef DeserializeFunc(request, GeneratedMessage msg);

typedef SerializeFunc(GeneratedMessage msg, response);

That seems awkward, so another way would be to use a GeneratedMessage for both
request and response, but then we need another method for the caller to use to
create the request:

GeneratedMessage createRequest(String method);

Future<GeneratedMessage> handleCall(ServerContext ctx, String method,
GeneratedMessage request);

+          'List<int> requestBytes) async {', '}', () {
+        for (MethodDescriptorProto m in _methodDescriptors) {
+          out.addBlock('if (method == \'${m.name}\') {', '} else ', () {

[skybrian, 2015/06/24 16:16:30]

Not a big deal, but it seems like a switch statement would be nicer.

+            out.println('var request = new ${_simpleType(m.inputType)}'
+                '.fromBuffer(requestBytes);');
+            out.println('var result = await ${m.name}(ctx, request);');
+            out.println('return result.writeToBuffer();');
+          }, endWithNewline: false);
+        }
+        out.addBlock('{', '}', () {
+          out.println('throw \'Unknown method: \$method\';');

[skybrian, 2015/06/24 16:16:30]

make this an ArgumentError?

+        });
+      });
+    });
+    out.println();
+  }
+}