Add PPB_VarDictionary_Dev support - part 1.

ppapi/shared_impl/dictionary_var.h

+// Copyright (c) 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.
+
+#ifndef PPAPI_SHARED_IMPL_DICTIONARY_VAR_H_
+#define PPAPI_SHARED_IMPL_DICTIONARY_VAR_H_
+
+#include <map>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "ppapi/c/pp_var.h"
+#include "ppapi/shared_impl/ppapi_shared_export.h"
+#include "ppapi/shared_impl/scoped_pp_var.h"
+#include "ppapi/shared_impl/var.h"
+
+namespace ppapi {
+
+class PPAPI_SHARED_EXPORT DictionaryVar : public Var {
+ public:
+  typedef std::map<std::string, ScopedPPVar> KeyValueMap;
+
+  DictionaryVar();
+
+  // Helper function that converts a PP_Var to a DictionaryVar. This will
+  // return NULL if the PP_Var is not of type PP_VARTYPE_DICTIONARY or the
+  // dictionary cannot be found from the var tracker.
+  static DictionaryVar* FromPPVar(const PP_Var& var);
+
+  // Var overrides.
+  virtual DictionaryVar* AsDictionaryVar() OVERRIDE;
+  virtual PP_VarType GetType() const OVERRIDE;
+
+  // The returned PP_Var has been added ref on behalf of the caller.

[dmichael (off chromium), 2013/03/05 22:01:03]

nit: wording is a little akward (maybe just make it match what you do for Array
as Raymes suggested)

[yzshen1, 2013/03/14 05:38:21]

Done. Yeah, it sounds better that way.
On 2013/03/05 22:01:03, dmichael wrote:

+  PP_Var Get(const PP_Var& key) const;
+  PP_Bool Set(const PP_Var& key, const PP_Var& value);
+  void Delete(const PP_Var& key);
+  PP_Bool HasKey(const PP_Var& key) const;
+  // The returned PP_Var has been added ref on behalf of the caller.

[dmichael (off chromium), 2013/03/05 22:01:03]

ditto, and please make it plural (returned PP_Vars, etc)

[yzshen1, 2013/03/14 05:38:21]

Done changing it to "had a ref added on behalf of the caller."

(I may be wrong since I am not a native speaker, but better to ask.)
I thought usually we use the singular form in this case. For example, this is a
comment from another file:
  // Creates a PP_Var corresponding to this object. The return value will have
  // one reference addrefed on behalf of the caller.
  PP_Var GetPPVar();

On 2013/03/05 22:01:03, dmichael wrote:

[dmichael (off chromium), 2013/03/15 17:35:48]

Sorry, I had the array ref-counts on the brain. You're right.

+  PP_Var GetKeys() const;
+
+  // Returns false and keeps the dictionary unchanged if |key| is not a valid
+  // UTF-8 string.
+  bool SetWithStringKey(const std::string& utf8_key, const PP_Var& value);
+  void DeleteWithStringKey(const std::string& utf8_key);
+
+  const KeyValueMap& key_value_map() const {
+    return key_value_map_;
+  }
+
+ protected:
+  virtual ~DictionaryVar();
+
+ private:
+  KeyValueMap key_value_map_;

[dmichael (off chromium), 2013/03/05 22:01:03]

So I take it you're not worrying about making it work in v8 yet? If you were, I
would expect a separate host implementation. Alternately, we can do the
conversion for the purposes of Messaging at the point a message comes in or goes
out...  but that will sacrifice a bit of performance.

As we discussed over IM before, I think it's fine to leave out messaging support
for now. But I think we need to support messaging before taking Array/Dictionary
out of Dev.

[yzshen1, 2013/03/14 05:38:21]

Correct. I haven't done that part.
I think at least this implementation is needed for the plugin side. So I decided
to implement it first.
Right.
I don't think we need to access the same struct from the both sides, so a
copy-and-convert approach should be okay (but may be inefficient, as you have
pointed out).
Agreed!

+
+  DISALLOW_COPY_AND_ASSIGN(DictionaryVar);
+};
+
+}  // namespace ppapi
+
+#endif  // PPAPI_SHARED_IMPL_DICTIONARY_VAR_H_