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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 BASE_MEMORY_REF_COUNTED_MEMORY_H_
#define BASE_MEMORY_REF_COUNTED_MEMORY_H_
#include <stddef.h>
#include <string>
#include <vector>
#include "base/base_export.h"
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
namespace base {
// A generic interface to memory. This object is reference counted because one
// of its two subclasses own the data they carry, and we need to have
// heterogeneous containers of these two types of memory.
class BASE_EXPORT RefCountedMemory
: public base::RefCountedThreadSafe<RefCountedMemory> {
public:
// Retrieves a pointer to the beginning of the data we point to. If the data
// is empty, this will return NULL.
virtual const unsigned char* front() const = 0;
// Size of the memory pointed to.
virtual size_t size() const = 0;
// Returns true if |other| is byte for byte equal.
bool Equals(const scoped_refptr<RefCountedMemory>& other) const;
// Handy method to simplify calling front() with a reinterpret_cast.
template<typename T> const T* front_as() const {
return reinterpret_cast<const T*>(front());
}
protected:
friend class base::RefCountedThreadSafe<RefCountedMemory>;
RefCountedMemory();
virtual ~RefCountedMemory();
};
// An implementation of RefCountedMemory, where the ref counting does not
// matter.
class BASE_EXPORT RefCountedStaticMemory : public RefCountedMemory {
public:
RefCountedStaticMemory()
: data_(NULL), length_(0) {}
RefCountedStaticMemory(const void* data, size_t length)
: data_(static_cast<const unsigned char*>(length ? data : NULL)),
length_(length) {}
// Overridden from RefCountedMemory:
const unsigned char* front() const override;
size_t size() const override;
private:
~RefCountedStaticMemory() override;
const unsigned char* data_;
size_t length_;
DISALLOW_COPY_AND_ASSIGN(RefCountedStaticMemory);
};
// An implementation of RefCountedMemory, where we own the data in a vector.
class BASE_EXPORT RefCountedBytes : public RefCountedMemory {
public:
RefCountedBytes();
// Constructs a RefCountedBytes object by _copying_ from |initializer|.
explicit RefCountedBytes(const std::vector<unsigned char>& initializer);
// Constructs a RefCountedBytes object by copying |size| bytes from |p|.
RefCountedBytes(const unsigned char* p, size_t size);
// Constructs a RefCountedBytes object by performing a swap. (To non
// destructively build a RefCountedBytes, use the constructor that takes a
// vector.)
static RefCountedBytes* TakeVector(std::vector<unsigned char>* to_destroy);
// Overridden from RefCountedMemory:
const unsigned char* front() const override;
size_t size() const override;
const std::vector<unsigned char>& data() const { return data_; }
std::vector<unsigned char>& data() { return data_; }
private:
~RefCountedBytes() override;
std::vector<unsigned char> data_;
DISALLOW_COPY_AND_ASSIGN(RefCountedBytes);
};
// An implementation of RefCountedMemory, where the bytes are stored in an STL
// string. Use this if your data naturally arrives in that format.
class BASE_EXPORT RefCountedString : public RefCountedMemory {
public:
RefCountedString();
// Constructs a RefCountedString object by performing a swap. (To non
// destructively build a RefCountedString, use the default constructor and
// copy into object->data()).
static scoped_refptr<RefCountedString> TakeString(std::string* to_destroy);
// Overridden from RefCountedMemory:
const unsigned char* front() const override;
size_t size() const override;
const std::string& data() const { return data_; }
std::string& data() { return data_; }
private:
~RefCountedString() override;
std::string data_;
DISALLOW_COPY_AND_ASSIGN(RefCountedString);
};
} // namespace base
#endif // BASE_MEMORY_REF_COUNTED_MEMORY_H_
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