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29 //
30 // Author: wan@google.com (Zhanyong Wan)
31 //
32 // The Google C++ Testing Framework (Google Test)
33 //
34 // This header file defines the Message class.
35 //
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:
39 //
40 //   // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
41 //
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
44 // program!
45 
46 #ifndef GTEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
47 #define GTEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
48 
49 #include <limits>
50 
51 #include "gtest/internal/gtest-port.h"
52 
53 // Ensures that there is at least one operator<< in the global namespace.
54 // See Message& operator<<(...) below for why.
55 void operator<<(const testing::internal::Secret&, int);
56 
57 namespace testing {
58 
59 // The Message class works like an ostream repeater.
60 //
61 // Typical usage:
62 //
63 //   1. You stream a bunch of values to a Message object.
64 //      It will remember the text in a stringstream.
65 //   2. Then you stream the Message object to an ostream.
66 //      This causes the text in the Message to be streamed
67 //      to the ostream.
68 //
69 // For example;
70 //
71 //   testing::Message foo;
72 //   foo << 1 << " != " << 2;
73 //   std::cout << foo;
74 //
75 // will print "1 != 2".
76 //
77 // Message is not intended to be inherited from.  In particular, its
78 // destructor is not virtual.
79 //
80 // Note that stringstream behaves differently in gcc and in MSVC.  You
81 // can stream a NULL char pointer to it in the former, but not in the
82 // latter (it causes an access violation if you do).  The Message
83 // class hides this difference by treating a NULL char pointer as
84 // "(null)".
85 class GTEST_API_ Message {
86  private:
87   // The type of basic IO manipulators (endl, ends, and flush) for
88   // narrow streams.
89   typedef std::ostream& (*BasicNarrowIoManip)(std::ostream&);
90 
91  public:
92   // Constructs an empty Message.
93   Message();
94 
95   // Copy constructor.
Message(const Message & msg)96   Message(const Message& msg) : ss_(new ::std::stringstream) {  // NOLINT
97     *ss_ << msg.GetString();
98   }
99 
100   // Constructs a Message from a C-string.
Message(const char * str)101   explicit Message(const char* str) : ss_(new ::std::stringstream) {
102     *ss_ << str;
103   }
104 
105 #if GTEST_OS_SYMBIAN
106   // Streams a value (either a pointer or not) to this object.
107   template <typename T>
108   inline Message& operator <<(const T& value) {
109     StreamHelper(typename internal::is_pointer<T>::type(), value);
110     return *this;
111   }
112 #else
113   // Streams a non-pointer value to this object.
114   template <typename T>
115   inline Message& operator <<(const T& val) {
116     // Some libraries overload << for STL containers.  These
117     // overloads are defined in the global namespace instead of ::std.
118     //
119     // C++'s symbol lookup rule (i.e. Koenig lookup) says that these
120     // overloads are visible in either the std namespace or the global
121     // namespace, but not other namespaces, including the testing
122     // namespace which Google Test's Message class is in.
123     //
124     // To allow STL containers (and other types that has a << operator
125     // defined in the global namespace) to be used in Google Test
126     // assertions, testing::Message must access the custom << operator
127     // from the global namespace.  With this using declaration,
128     // overloads of << defined in the global namespace and those
129     // visible via Koenig lookup are both exposed in this function.
130     using ::operator <<;
131     *ss_ << val;
132     return *this;
133   }
134 
135   // Streams a pointer value to this object.
136   //
137   // This function is an overload of the previous one.  When you
138   // stream a pointer to a Message, this definition will be used as it
139   // is more specialized.  (The C++ Standard, section
140   // [temp.func.order].)  If you stream a non-pointer, then the
141   // previous definition will be used.
142   //
143   // The reason for this overload is that streaming a NULL pointer to
144   // ostream is undefined behavior.  Depending on the compiler, you
145   // may get "0", "(nil)", "(null)", or an access violation.  To
146   // ensure consistent result across compilers, we always treat NULL
147   // as "(null)".
148   template <typename T>
149   inline Message& operator <<(T* const& pointer) {  // NOLINT
150     if (pointer == NULL) {
151       *ss_ << "(null)";
152     } else {
153       *ss_ << pointer;
154     }
155     return *this;
156   }
157 #endif  // GTEST_OS_SYMBIAN
158 
159   // Since the basic IO manipulators are overloaded for both narrow
160   // and wide streams, we have to provide this specialized definition
161   // of operator <<, even though its body is the same as the
162   // templatized version above.  Without this definition, streaming
163   // endl or other basic IO manipulators to Message will confuse the
164   // compiler.
165   Message& operator <<(BasicNarrowIoManip val) {
166     *ss_ << val;
167     return *this;
168   }
169 
170   // Instead of 1/0, we want to see true/false for bool values.
171   Message& operator <<(bool b) {
172     return *this << (b ? "true" : "false");
173   }
174 
175   // These two overloads allow streaming a wide C string to a Message
176   // using the UTF-8 encoding.
177   Message& operator <<(const wchar_t* wide_c_str);
178   Message& operator <<(wchar_t* wide_c_str);
179 
180 #if GTEST_HAS_STD_WSTRING
181   // Converts the given wide string to a narrow string using the UTF-8
182   // encoding, and streams the result to this Message object.
183   Message& operator <<(const ::std::wstring& wstr);
184 #endif  // GTEST_HAS_STD_WSTRING
185 
186 #if GTEST_HAS_GLOBAL_WSTRING
187   // Converts the given wide string to a narrow string using the UTF-8
188   // encoding, and streams the result to this Message object.
189   Message& operator <<(const ::wstring& wstr);
190 #endif  // GTEST_HAS_GLOBAL_WSTRING
191 
192   // Gets the text streamed to this object so far as an std::string.
193   // Each '\0' character in the buffer is replaced with "\\0".
194   //
195   // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
196   std::string GetString() const;
197 
198  private:
199 
200 #if GTEST_OS_SYMBIAN
201   // These are needed as the Nokia Symbian Compiler cannot decide between
202   // const T& and const T* in a function template. The Nokia compiler _can_
203   // decide between class template specializations for T and T*, so a
204   // tr1::type_traits-like is_pointer works, and we can overload on that.
205   template <typename T>
StreamHelper(internal::true_type,T * pointer)206   inline void StreamHelper(internal::true_type /*is_pointer*/, T* pointer) {
207     if (pointer == NULL) {
208       *ss_ << "(null)";
209     } else {
210       *ss_ << pointer;
211     }
212   }
213   template <typename T>
StreamHelper(internal::false_type,const T & value)214   inline void StreamHelper(internal::false_type /*is_pointer*/,
215                            const T& value) {
216     // See the comments in Message& operator <<(const T&) above for why
217     // we need this using statement.
218     using ::operator <<;
219     *ss_ << value;
220   }
221 #endif  // GTEST_OS_SYMBIAN
222 
223   // We'll hold the text streamed to this object here.
224   const internal::scoped_ptr< ::std::stringstream> ss_;
225 
226   // We declare (but don't implement) this to prevent the compiler
227   // from implementing the assignment operator.
228   void operator=(const Message&);
229 };
230 
231 // Streams a Message to an ostream.
232 inline std::ostream& operator <<(std::ostream& os, const Message& sb) {
233   return os << sb.GetString();
234 }
235 
236 namespace internal {
237 
238 // Converts a streamable value to an std::string.  A NULL pointer is
239 // converted to "(null)".  When the input value is a ::string,
240 // ::std::string, ::wstring, or ::std::wstring object, each NUL
241 // character in it is replaced with "\\0".
242 template <typename T>
StreamableToString(const T & streamable)243 std::string StreamableToString(const T& streamable) {
244   return (Message() << streamable).GetString();
245 }
246 
247 }  // namespace internal
248 }  // namespace testing
249 
250 #endif  // GTEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
251