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// Copyright (c) 2011 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_WIN_SCOPED_BSTR_H_
#define BASE_WIN_SCOPED_BSTR_H_
#include <windows.h>
#include <oleauto.h>
#include <stddef.h>
#include "base/base_export.h"
#include "base/logging.h"
#include "base/macros.h"
#include "base/strings/string16.h"
namespace base {
namespace win {
// Manages a BSTR string pointer.
// The class interface is based on scoped_ptr.
class BASE_EXPORT ScopedBstr {
public:
ScopedBstr() : bstr_(NULL) {
}
// Constructor to create a new BSTR.
//
// NOTE: Do not pass a BSTR to this constructor expecting ownership to
// be transferred - even though it compiles! ;-)
explicit ScopedBstr(const char16* non_bstr);
~ScopedBstr();
// Give ScopedBstr ownership over an already allocated BSTR or NULL.
// If you need to allocate a new BSTR instance, use |allocate| instead.
void Reset(BSTR bstr = NULL);
// Releases ownership of the BSTR to the caller.
BSTR Release();
// Creates a new BSTR from a 16-bit C-style string.
//
// If you already have a BSTR and want to transfer ownership to the
// ScopedBstr instance, call |reset| instead.
//
// Returns a pointer to the new BSTR, or NULL if allocation failed.
BSTR Allocate(const char16* str);
// Allocates a new BSTR with the specified number of bytes.
// Returns a pointer to the new BSTR, or NULL if allocation failed.
BSTR AllocateBytes(size_t bytes);
// Sets the allocated length field of the already-allocated BSTR to be
// |bytes|. This is useful when the BSTR was preallocated with e.g.
// SysAllocStringLen or SysAllocStringByteLen (call |AllocateBytes|) and then
// not all the bytes are being used.
//
// Note that if you want to set the length to a specific number of
// characters, you need to multiply by sizeof(wchar_t). Oddly, there's no
// public API to set the length, so we do this ourselves by hand.
//
// NOTE: The actual allocated size of the BSTR MUST be >= bytes. That
// responsibility is with the caller.
void SetByteLen(size_t bytes);
// Swap values of two ScopedBstr's.
void Swap(ScopedBstr& bstr2);
// Retrieves the pointer address.
// Used to receive BSTRs as out arguments (and take ownership).
// The function DCHECKs on the current value being NULL.
// Usage: GetBstr(bstr.Receive());
BSTR* Receive();
// Returns number of chars in the BSTR.
size_t Length() const;
// Returns the number of bytes allocated for the BSTR.
size_t ByteLength() const;
operator BSTR() const {
return bstr_;
}
protected:
BSTR bstr_;
private:
// Forbid comparison of ScopedBstr types. You should never have the same
// BSTR owned by two different scoped_ptrs.
bool operator==(const ScopedBstr& bstr2) const;
bool operator!=(const ScopedBstr& bstr2) const;
DISALLOW_COPY_AND_ASSIGN(ScopedBstr);
};
} // namespace win
} // namespace base
#endif // BASE_WIN_SCOPED_BSTR_H_
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