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30 // Author: wan@google.com (Zhanyong Wan)
32 // The Google C++ Testing Framework (Google Test)
34 // This header file defines the Message class.
36 // IMPORTANT NOTE: Due to limitation of the C++ language, we have to
37 // leave some internal implementation details in this header file.
38 // They are clearly marked by comments like this:
40 // // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
42 // Such code is NOT meant to be used by a user directly, and is subject
43 // to CHANGE WITHOUT NOTICE. Therefore DO NOT DEPEND ON IT in a user
46 #ifndef GTEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
47 #define GTEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
51 #include "gtest/internal/gtest-port.h"
52 #include "gtest/internal/custom/raw-ostream.h"
54 // Ensures that there is at least one operator<< in the global namespace.
55 // See Message& operator<<(...) below for why.
56 void operator<<(const testing::internal::Secret
&, int);
60 // The Message class works like an ostream repeater.
64 // 1. You stream a bunch of values to a Message object.
65 // It will remember the text in a stringstream.
66 // 2. Then you stream the Message object to an ostream.
67 // This causes the text in the Message to be streamed
72 // testing::Message foo;
73 // foo << 1 << " != " << 2;
76 // will print "1 != 2".
78 // Message is not intended to be inherited from. In particular, its
79 // destructor is not virtual.
81 // Note that stringstream behaves differently in gcc and in MSVC. You
82 // can stream a NULL char pointer to it in the former, but not in the
83 // latter (it causes an access violation if you do). The Message
84 // class hides this difference by treating a NULL char pointer as
86 class GTEST_API_ Message
{
88 // The type of basic IO manipulators (endl, ends, and flush) for
90 typedef std::ostream
& (*BasicNarrowIoManip
)(std::ostream
&);
93 // Constructs an empty Message.
97 Message(const Message
& msg
) : ss_(new ::std::stringstream
) { // NOLINT
98 *ss_
<< msg
.GetString();
101 // Constructs a Message from a C-string.
102 explicit Message(const char* str
) : ss_(new ::std::stringstream
) {
107 // Streams a value (either a pointer or not) to this object.
108 template <typename T
>
109 inline Message
& operator <<(const T
& value
) {
110 StreamHelper(typename
internal::is_pointer
<T
>::type(), value
);
114 // Streams a non-pointer value to this object.
115 template <typename T
>
116 inline Message
& operator <<(const T
& val
) {
117 // Some libraries overload << for STL containers. These
118 // overloads are defined in the global namespace instead of ::std.
120 // C++'s symbol lookup rule (i.e. Koenig lookup) says that these
121 // overloads are visible in either the std namespace or the global
122 // namespace, but not other namespaces, including the testing
123 // namespace which Google Test's Message class is in.
125 // To allow STL containers (and other types that has a << operator
126 // defined in the global namespace) to be used in Google Test
127 // assertions, testing::Message must access the custom << operator
128 // from the global namespace. With this using declaration,
129 // overloads of << defined in the global namespace and those
130 // visible via Koenig lookup are both exposed in this function.
132 *ss_
<< llvm_gtest::printable(val
);
136 // Streams a pointer value to this object.
138 // This function is an overload of the previous one. When you
139 // stream a pointer to a Message, this definition will be used as it
140 // is more specialized. (The C++ Standard, section
141 // [temp.func.order].) If you stream a non-pointer, then the
142 // previous definition will be used.
144 // The reason for this overload is that streaming a NULL pointer to
145 // ostream is undefined behavior. Depending on the compiler, you
146 // may get "0", "(nil)", "(null)", or an access violation. To
147 // ensure consistent result across compilers, we always treat NULL
149 template <typename T
>
150 inline Message
& operator <<(T
* const& pointer
) { // NOLINT
151 if (pointer
== NULL
) {
154 *ss_
<< llvm_gtest::printable(pointer
);
158 #endif // GTEST_OS_SYMBIAN
160 // Since the basic IO manipulators are overloaded for both narrow
161 // and wide streams, we have to provide this specialized definition
162 // of operator <<, even though its body is the same as the
163 // templatized version above. Without this definition, streaming
164 // endl or other basic IO manipulators to Message will confuse the
166 Message
& operator <<(BasicNarrowIoManip val
) {
171 // Instead of 1/0, we want to see true/false for bool values.
172 Message
& operator <<(bool b
) {
173 return *this << (b
? "true" : "false");
176 // These two overloads allow streaming a wide C string to a Message
177 // using the UTF-8 encoding.
178 Message
& operator <<(const wchar_t* wide_c_str
);
179 Message
& operator <<(wchar_t* wide_c_str
);
181 #if GTEST_HAS_STD_WSTRING
182 // Converts the given wide string to a narrow string using the UTF-8
183 // encoding, and streams the result to this Message object.
184 Message
& operator <<(const ::std::wstring
& wstr
);
185 #endif // GTEST_HAS_STD_WSTRING
187 #if GTEST_HAS_GLOBAL_WSTRING
188 // Converts the given wide string to a narrow string using the UTF-8
189 // encoding, and streams the result to this Message object.
190 Message
& operator <<(const ::wstring
& wstr
);
191 #endif // GTEST_HAS_GLOBAL_WSTRING
193 // Gets the text streamed to this object so far as an std::string.
194 // Each '\0' character in the buffer is replaced with "\\0".
196 // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
197 std::string
GetString() const;
202 // These are needed as the Nokia Symbian Compiler cannot decide between
203 // const T& and const T* in a function template. The Nokia compiler _can_
204 // decide between class template specializations for T and T*, so a
205 // tr1::type_traits-like is_pointer works, and we can overload on that.
206 template <typename T
>
207 inline void StreamHelper(internal::true_type
/*is_pointer*/, T
* pointer
) {
208 if (pointer
== NULL
) {
214 template <typename T
>
215 inline void StreamHelper(internal::false_type
/*is_pointer*/,
217 // See the comments in Message& operator <<(const T&) above for why
218 // we need this using statement.
222 #endif // GTEST_OS_SYMBIAN
224 // We'll hold the text streamed to this object here.
225 const internal::scoped_ptr
< ::std::stringstream
> ss_
;
227 // We declare (but don't implement) this to prevent the compiler
228 // from implementing the assignment operator.
229 void operator=(const Message
&);
232 // Streams a Message to an ostream.
233 inline std::ostream
& operator <<(std::ostream
& os
, const Message
& sb
) {
234 return os
<< sb
.GetString();
239 // Converts a streamable value to an std::string. A NULL pointer is
240 // converted to "(null)". When the input value is a ::string,
241 // ::std::string, ::wstring, or ::std::wstring object, each NUL
242 // character in it is replaced with "\\0".
243 template <typename T
>
244 std::string
StreamableToString(const T
& streamable
) {
245 return (Message() << streamable
).GetString();
248 } // namespace internal
249 } // namespace testing
251 #endif // GTEST_INCLUDE_GTEST_GTEST_MESSAGE_H_