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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef BASE_WIN_SCOPED_BSTR_H_ | |
6 #define BASE_WIN_SCOPED_BSTR_H_ | |
7 | |
8 #include <windows.h> | |
9 #include <oleauto.h> | |
10 | |
11 #include "base/base_export.h" | |
12 #include "base/logging.h" | |
13 #include "base/strings/string16.h" | |
14 | |
15 namespace base { | |
16 namespace win { | |
17 | |
18 // Manages a BSTR string pointer. | |
19 // The class interface is based on scoped_ptr. | |
20 class BASE_EXPORT ScopedBstr { | |
21 public: | |
22 ScopedBstr() : bstr_(NULL) { | |
23 } | |
24 | |
25 // Constructor to create a new BSTR. | |
26 // | |
27 // NOTE: Do not pass a BSTR to this constructor expecting ownership to | |
28 // be transferred - even though it compiles! ;-) | |
29 explicit ScopedBstr(const char16* non_bstr); | |
30 ~ScopedBstr(); | |
31 | |
32 // Give ScopedBstr ownership over an already allocated BSTR or NULL. | |
33 // If you need to allocate a new BSTR instance, use |allocate| instead. | |
34 void Reset(BSTR bstr = NULL); | |
35 | |
36 // Releases ownership of the BSTR to the caller. | |
37 BSTR Release(); | |
38 | |
39 // Creates a new BSTR from a 16-bit C-style string. | |
40 // | |
41 // If you already have a BSTR and want to transfer ownership to the | |
42 // ScopedBstr instance, call |reset| instead. | |
43 // | |
44 // Returns a pointer to the new BSTR, or NULL if allocation failed. | |
45 BSTR Allocate(const char16* str); | |
46 | |
47 // Allocates a new BSTR with the specified number of bytes. | |
48 // Returns a pointer to the new BSTR, or NULL if allocation failed. | |
49 BSTR AllocateBytes(size_t bytes); | |
50 | |
51 // Sets the allocated length field of the already-allocated BSTR to be | |
52 // |bytes|. This is useful when the BSTR was preallocated with e.g. | |
53 // SysAllocStringLen or SysAllocStringByteLen (call |AllocateBytes|) and then | |
54 // not all the bytes are being used. | |
55 // | |
56 // Note that if you want to set the length to a specific number of | |
57 // characters, you need to multiply by sizeof(wchar_t). Oddly, there's no | |
58 // public API to set the length, so we do this ourselves by hand. | |
59 // | |
60 // NOTE: The actual allocated size of the BSTR MUST be >= bytes. That | |
61 // responsibility is with the caller. | |
62 void SetByteLen(size_t bytes); | |
63 | |
64 // Swap values of two ScopedBstr's. | |
65 void Swap(ScopedBstr& bstr2); | |
66 | |
67 // Retrieves the pointer address. | |
68 // Used to receive BSTRs as out arguments (and take ownership). | |
69 // The function DCHECKs on the current value being NULL. | |
70 // Usage: GetBstr(bstr.Receive()); | |
71 BSTR* Receive(); | |
72 | |
73 // Returns number of chars in the BSTR. | |
74 size_t Length() const; | |
75 | |
76 // Returns the number of bytes allocated for the BSTR. | |
77 size_t ByteLength() const; | |
78 | |
79 operator BSTR() const { | |
80 return bstr_; | |
81 } | |
82 | |
83 protected: | |
84 BSTR bstr_; | |
85 | |
86 private: | |
87 // Forbid comparison of ScopedBstr types. You should never have the same | |
88 // BSTR owned by two different scoped_ptrs. | |
89 bool operator==(const ScopedBstr& bstr2) const; | |
90 bool operator!=(const ScopedBstr& bstr2) const; | |
91 DISALLOW_COPY_AND_ASSIGN(ScopedBstr); | |
92 }; | |
93 | |
94 } // namespace win | |
95 } // namespace base | |
96 | |
97 #endif // BASE_WIN_SCOPED_BSTR_H_ | |
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