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// 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_CPP_EXTENSIONS_OUTPUT_TRAITS_H_
#define PPAPI_CPP_EXTENSIONS_OUTPUT_TRAITS_H_
#include <vector>
#include "ppapi/c/pp_var.h"
#include "ppapi/cpp/extensions/from_var_converter.h"
#include "ppapi/cpp/logging.h"
#include "ppapi/cpp/pass_ref.h"
#include "ppapi/cpp/var.h"
namespace pp {
namespace ext {
namespace internal {
// Base class for all those types within the pp::ext namespace that are used
// with CompletionCallbackWithOutput. This class doesn't do anything itself,
// but it affects the behavior of CallbackOutputTraits for all its subclasses.
//
// TODO(yzshen): Within pp::ext, basic types such as std::string or double may
// be used with CompletionCallbackWithOutput as well. This approach doesn't
// work for them. One way is to refactor CallbackOutputTraits to consider not
// only the output C++ object type, but also the output parameter type that the
// C interface uses. And then we can remove this class.
class OutputObjectBase {
};
template <class T>
class VarOutputAdapterWithStorage {
public:
VarOutputAdapterWithStorage() : pp_var_(PP_MakeUndefined()) {
}
~VarOutputAdapterWithStorage() {
PP_DCHECK(pp_var_.type == PP_VARTYPE_UNDEFINED);
}
PP_Var& pp_var() { return pp_var_; }
T& output() {
converter_.Set(PASS_REF, pp_var_);
pp_var_ = PP_MakeUndefined();
return converter_.value();
}
private:
PP_Var pp_var_;
FromVarConverter<T> converter_;
// Disallow copying and assignment.
VarOutputAdapterWithStorage(const VarOutputAdapterWithStorage<T>&);
VarOutputAdapterWithStorage<T>& operator=(
const VarOutputAdapterWithStorage<T>&);
};
template <class T>
struct ExtensionsCallbackOutputTraits {
typedef PP_Var* APIArgType;
typedef VarOutputAdapterWithStorage<T> StorageType;
static inline APIArgType StorageToAPIArg(StorageType& t) {
return &t.pp_var();
}
// This must be called exactly once to consume the one PP_Var reference
// assigned to us by the browser.
static inline T& StorageToPluginArg(StorageType& t) {
return t.output();
}
};
// This class provides storage for a PP_Var and a vector of objects which are
// of type T. The PP_Var is used as an output parameter to recevie an array var
// from the browser. Each element in the array var is converted to a T object,
// using FromVarConverter, and stores in the vector.
template <class T>
class ArrayVarOutputAdapterWithStorage {
public:
ArrayVarOutputAdapterWithStorage() : pp_var_(PP_MakeUndefined()) {
}
~ArrayVarOutputAdapterWithStorage() {
PP_DCHECK(pp_var_.type == PP_VARTYPE_UNDEFINED);
}
PP_Var& pp_var() { return pp_var_; }
std::vector<T>& output() {
PP_DCHECK(output_storage_.empty());
// TODO(yzshen): Add support for ArrayVar and read the contents from
// |pp_var_| and put into |output_storage_|.
Var auto_release(PASS_REF, pp_var_);
pp_var_ = PP_MakeUndefined();
return output_storage_;
}
private:
PP_Var pp_var_;
std::vector<T> output_storage_;
// Disallow copying and assignment.
ArrayVarOutputAdapterWithStorage(const ArrayVarOutputAdapterWithStorage<T>&);
ArrayVarOutputAdapterWithStorage<T>& operator=(
const ArrayVarOutputAdapterWithStorage<T>&);
};
template <class T>
struct ExtensionsVectorCallbackOutputTraits {
typedef PP_Var* APIArgType;
typedef ArrayVarOutputAdapterWithStorage<T> StorageType;
static inline APIArgType StorageToAPIArg(StorageType& t) {
return &t.pp_var();
}
// This must be called exactly once to consume the one PP_Var reference
// assigned to us by the browser.
static inline std::vector<T>& StorageToPluginArg(StorageType& t) {
return t.output();
}
};
} // namespace internal
} // namespace ext
} // namespace pp
#endif // PPAPI_CPP_EXTENSIONS_OUTPUT_TRAITS_H_
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