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| 1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2010 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 #ifndef BASE_SCOPED_BSTR_WIN_H_ | 5 // TODO(brettw) remove this file when all callers are converted to using the |
| 6 #define BASE_SCOPED_BSTR_WIN_H_ | 6 // new location/namespace |
| 7 #pragma once | 7 #include "base/win/scoped_bstr.h" |
| 8 | 8 |
| 9 #include <windows.h> | 9 using base::win::ScopedBstr; |
| 10 #include <oleauto.h> | |
| 11 | |
| 12 #include "base/logging.h" | |
| 13 | |
| 14 // Manages a BSTR string pointer. | |
| 15 // The class interface is based on scoped_ptr. | |
| 16 class ScopedBstr { | |
| 17 public: | |
| 18 ScopedBstr() : bstr_(NULL) { | |
| 19 } | |
| 20 | |
| 21 // Constructor to create a new BSTR. | |
| 22 // NOTE: Do not pass a BSTR to this constructor expecting ownership to | |
| 23 // be transferred - even though it compiles! ;-) | |
| 24 explicit ScopedBstr(const wchar_t* non_bstr); | |
| 25 ~ScopedBstr(); | |
| 26 | |
| 27 // Give ScopedBstr ownership over an already allocated BSTR or NULL. | |
| 28 // If you need to allocate a new BSTR instance, use |allocate| instead. | |
| 29 void Reset(BSTR bstr = NULL); | |
| 30 | |
| 31 // Releases ownership of the BSTR to the caller. | |
| 32 BSTR Release(); | |
| 33 | |
| 34 // Creates a new BSTR from a wide string. | |
| 35 // If you already have a BSTR and want to transfer ownership to the | |
| 36 // ScopedBstr instance, call |reset| instead. | |
| 37 // Returns a pointer to the new BSTR, or NULL if allocation failed. | |
| 38 BSTR Allocate(const wchar_t* wide_str); | |
| 39 | |
| 40 // Allocates a new BSTR with the specified number of bytes. | |
| 41 // Returns a pointer to the new BSTR, or NULL if allocation failed. | |
| 42 BSTR AllocateBytes(int bytes); | |
| 43 | |
| 44 // Sets the allocated length field of the already-allocated BSTR to be | |
| 45 // |bytes|. This is useful when the BSTR was preallocated with e.g. | |
| 46 // SysAllocStringLen or SysAllocStringByteLen (call |AllocateBytes|) and | |
| 47 // then not all the bytes are being used. | |
| 48 // Note that if you want to set the length to a specific number of characters, | |
| 49 // you need to multiply by sizeof(wchar_t). Oddly, there's no public API to | |
| 50 // set the length, so we do this ourselves by hand. | |
| 51 // | |
| 52 // NOTE: The actual allocated size of the BSTR MUST be >= bytes. | |
| 53 // That responsibility is with the caller. | |
| 54 void SetByteLen(uint32 bytes); | |
| 55 | |
| 56 // Swap values of two ScopedBstr's. | |
| 57 void Swap(ScopedBstr& bstr2); | |
| 58 | |
| 59 // Retrieves the pointer address. | |
| 60 // Used to receive BSTRs as out arguments (and take ownership). | |
| 61 // The function DCHECKs on the current value being NULL. | |
| 62 // Usage: GetBstr(bstr.Receive()); | |
| 63 BSTR* Receive(); | |
| 64 | |
| 65 // Returns number of chars in the BSTR. | |
| 66 uint32 Length() const; | |
| 67 | |
| 68 // Returns the number of bytes allocated for the BSTR. | |
| 69 uint32 ByteLength() const; | |
| 70 | |
| 71 operator BSTR() const { | |
| 72 return bstr_; | |
| 73 } | |
| 74 | |
| 75 protected: | |
| 76 BSTR bstr_; | |
| 77 | |
| 78 private: | |
| 79 // Forbid comparison of ScopedBstr types. You should never have the same | |
| 80 // BSTR owned by two different scoped_ptrs. | |
| 81 bool operator==(const ScopedBstr& bstr2) const; | |
| 82 bool operator!=(const ScopedBstr& bstr2) const; | |
| 83 DISALLOW_COPY_AND_ASSIGN(ScopedBstr); | |
| 84 }; | |
| 85 | |
| 86 // Template class to generate a BSTR from a static wide string | |
| 87 // without touching the heap. Use this class via the StackBstrVar and | |
| 88 // StackBstr macros. | |
| 89 template <uint32 string_bytes> | |
| 90 class StackBstrT { | |
| 91 public: | |
| 92 // Try to stay as const as we can in an attempt to avoid someone | |
| 93 // using the class incorrectly (e.g. by supplying a variable instead | |
| 94 // of a verbatim string. We also have an assert in the constructor | |
| 95 // as an extra runtime check since the const-ness only catches one case. | |
| 96 explicit StackBstrT(const wchar_t* const str) { | |
| 97 // The BSTR API uses UINT, but we prefer uint32. | |
| 98 // Make sure we'll know about it if these types don't match. | |
| 99 COMPILE_ASSERT(sizeof(uint32) == sizeof(UINT), UintToUint32); | |
| 100 COMPILE_ASSERT(sizeof(wchar_t) == sizeof(OLECHAR), WcharToOlechar); | |
| 101 | |
| 102 // You shouldn't pass string pointers to this constructor since | |
| 103 // there's no way for the compiler to calculate the length of the | |
| 104 // string (string_bytes will be equal to pointer size in those cases). | |
| 105 DCHECK(lstrlenW(str) == (string_bytes / sizeof(bstr_.str_[0])) - 1) << | |
| 106 "not expecting a string pointer"; | |
| 107 memcpy(bstr_.str_, str, string_bytes); | |
| 108 bstr_.len_ = string_bytes - sizeof(wchar_t); | |
| 109 } | |
| 110 | |
| 111 operator BSTR() { | |
| 112 return bstr_.str_; | |
| 113 } | |
| 114 | |
| 115 protected: | |
| 116 struct BstrInternal { | |
| 117 uint32 len_; | |
| 118 wchar_t str_[string_bytes / sizeof(wchar_t)]; | |
| 119 } bstr_; | |
| 120 }; | |
| 121 | |
| 122 // Use this macro to generate an inline BSTR from a wide string. | |
| 123 // This is about 6 times faster than using the SysAllocXxx functions to | |
| 124 // allocate a BSTR and helps with keeping heap fragmentation down. | |
| 125 // Example: | |
| 126 // DoBstrStuff(StackBstr(L"This is my BSTR")); | |
| 127 // Where DoBstrStuff is: | |
| 128 // HRESULT DoBstrStuff(BSTR bstr) { ... } | |
| 129 #define StackBstr(str) \ | |
| 130 static_cast<BSTR>(StackBstrT<sizeof(str)>(str)) | |
| 131 | |
| 132 // If you need a named BSTR variable that's based on a fixed string | |
| 133 // (e.g. if the BSTR is used inside a loop or more than one place), | |
| 134 // use StackBstrVar to declare a variable. | |
| 135 // Example: | |
| 136 // StackBstrVar(L"my_property", myprop); | |
| 137 // for (int i = 0; i < objects.length(); ++i) | |
| 138 // ProcessValue(objects[i].GetProp(myprop)); // GetProp accepts BSTR | |
| 139 #define StackBstrVar(str, var) \ | |
| 140 StackBstrT<sizeof(str)> var(str) | |
| 141 | |
| 142 #endif // BASE_SCOPED_BSTR_WIN_H_ | |
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