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