Mojo JS Bindings: add support for associative arrays (Mojo map type)

mojo/public/interfaces/bindings/tests/test_structs.mojom

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import "mojo/public/interfaces/bindings/tests/rect.mojom"
 
 [JavaPackage="org.chromium.mojo.bindings.test.mojom.test_structs"]
 module mojo.test {
 
 struct NamedRegion {
@@ skipping 90 matching lines @@
   const int32 TEN_TOO = EType.E2;
   EType f0 = E0; // 0
   EType f1 = E1; // 1
   EType f2 = E2; // 10
   EType f3 = E3; // 10
   EType f4 = E4; // 11
   int32 f5 = TEN;
   int32 f6 = ALSO_TEN;
 };
 
+// Used to verify that all possible Map key field types can be encoded and

[yzshen1, 2014/10/15 05:58:02]

int64 and uint64? :)

[hansmuller, 2014/10/15 21:45:46]

JS can't really encode 64 bit integers properly but testing 64 bit keys with
smaller values is OK. I will add that.

+// decoded successfully.
+
+struct MapFields {
+  map<bool, bool> f0;
+  map<int8, int8> f1;
+  map<uint8, uint8> f2;
+  map<int16, int16> f3;
+  map<uint16, uint16> f4;
+  map<int32, int32> f5;
+  map<uint32, uint32> f6;
+  map<float, float> f7;
+  map<double, double> f8;
+  map<string, string> f9;

[qsr, 2014/10/15 13:03:40]

Do you want to test with structs, arrays and map as values?

[hansmuller, 2014/10/15 21:45:46]

This test was just intended to verify that all possible key types worked. I've
renamed the mojom type and etc to MapKeyTypes to make it a teeny bit clearer.

I've also added a unit test for the value types you suggested. I had to leave
the following fields out for now, since the C++ bindings don't generate code
that will compile for them yet:

  // map<string, map<string, string>> f3;
  // map<string, array<map<string, string>>> f4;
  // map<string, Rect?> f5;
 

[yzshen1, 2014/10/15 22:22:13]

(Out of curiosity) I thought the C++ bindings should work? what are the
problems?

[hansmuller, 2014/10/16 20:11:04]

-  The first two fail in the cpp parser:
  File
"/builds/dev/src/mojo/public/tools/bindings/generators/mojom_cpp_generator.py",
line 117, in GetCppArrayArgWrapperType
    return _kind_to_cpp_type[kind]
KeyError: <mojom.generate.module.Kind object at 0x2d641d0>


- The third one generates code that doesn't compile:
struct MapSerializer;
       ^
../../mojo/public/cpp/bindings/lib/map_serialization.h:99:19: error: implicit
instantiation of undefined template
'mojo::internal::MapSerializer<mojo::InlinedStructPtr<mojo::test::Rect>,
mojo::test::internal::Rect_Data *, true>'
        internal::MapSerializer<MapValue, DataValue>::GetItemSize(

+};
+
 }