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// Copyright (c) 2012 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_ARRAY_WRITER_H_
#define PPAPI_SHARED_IMPL_ARRAY_WRITER_H_
#include <string.h>
#include <vector>
#include "base/memory/ref_counted.h"
#include "ppapi/c/pp_array_output.h"
#include "ppapi/c/pp_resource.h"
#include "ppapi/c/pp_var.h"
#include "ppapi/shared_impl/ppapi_shared_export.h"
namespace ppapi {
class Resource;
// Holds a PP_ArrayWriter and provides helper functions for writing arrays
// to it. It also handles 0-initialization of the raw C struct and attempts
// to prevent you from writing the array twice.
class PPAPI_SHARED_EXPORT ArrayWriter {
public:
ArrayWriter(); // Creates an is_null() object
ArrayWriter(const PP_ArrayOutput& output);
~ArrayWriter();
bool is_valid() const { return !!pp_array_output_.GetDataBuffer; }
bool is_null() const { return !is_valid(); }
void set_pp_array_output(const PP_ArrayOutput& output) {
pp_array_output_ = output;
}
// Sets the array output back to its is_null() state.
void Reset();
// Copies the given vector of data to the plugin output array.
//
// Returns true on success, false if the plugin reported allocation failure.
// In either case, the object will become is_null() immediately after the
// call since one output function should only be issued once.
//
// THIS IS DESIGNED FOR POD ONLY. For the case of resources, for example, we
// want to transfer a reference only on success. Likewise, if you have a
// structure of PP_Vars or a struct that contains a PP_Resource, we need to
// make sure that the right thing happens with the ref on success and failure.
template<typename T>
bool StoreVector(const std::vector<T>& input) {
// Always call the alloc function, even on 0 array size.
void* dest = pp_array_output_.GetDataBuffer(
pp_array_output_.user_data,
static_cast<uint32_t>(input.size()),
sizeof(T));
// Regardless of success, we clear the output to prevent future calls on
// this same output object.
Reset();
if (input.empty())
return true; // Allow plugin to return NULL on 0 elements.
if (!dest)
return false;
memcpy(dest, &input[0], sizeof(T) * input.size());
return true;
}
// Stores the given vector of resources as PP_Resources to the output vector,
// adding one reference to each.
//
// On failure this returns false, nothing will be copied, and the resource
// refcounts will be unchanged. In either case, the object will become
// is_null() immediately after the call since one output function should only
// be issued once.
//
// Note: potentially this could be a template in case you have a vector of
// FileRef objects, for example. However, this saves code since there's only
// one instantiation and is sufficient for now.
bool StoreResourceVector(
const std::vector< scoped_refptr<Resource> >& input);
// Like the above version but takes an array of AddRed'ed PP_Resources. On
// storage failure, this will release each resource.
bool StoreResourceVector(const std::vector<PP_Resource>& input);
private:
PP_ArrayOutput pp_array_output_;
DISALLOW_COPY_AND_ASSIGN(ArrayWriter);
};
} // namespace ppapi
#endif // PPAPI_SHARED_IMPL_ARRAY_WRITER_H_
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