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29
30// The Google C++ Testing and Mocking Framework (Google Test)
31//
32// This header file defines the Message class.
33//
34// IMPORTANT NOTE: Due to limitation of the C++ language, we have to
35// leave some internal implementation details in this header file.
36// They are clearly marked by comments like this:
37//
38// // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
39//
40// Such code is NOT meant to be used by a user directly, and is subject
41// to CHANGE WITHOUT NOTICE. Therefore DO NOT DEPEND ON IT in a user
42// program!
43
44// IWYU pragma: private, include "gtest/gtest.h"
45// IWYU pragma: friend gtest/.*
46// IWYU pragma: friend gmock/.*
47
48#ifndef GOOGLETEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
49#define GOOGLETEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
50
51#include <limits>
52#include <memory>
53#include <ostream>
54#include <sstream>
55#include <string>
56
57#include "gtest/internal/gtest-port.h"
58
59GTEST_DISABLE_MSC_WARNINGS_PUSH_(4251 \
60/* class A needs to have dll-interface to be used by clients of class B */)
61
62// Ensures that there is at least one operator<< in the global namespace.
63// See Message& operator<<(...) below for why.
64void operator<<(const testing::internal::Secret&, int);
65
66namespace testing {
67
68// The Message class works like an ostream repeater.
69//
70// Typical usage:
71//
72// 1. You stream a bunch of values to a Message object.
73// It will remember the text in a stringstream.
74// 2. Then you stream the Message object to an ostream.
75// This causes the text in the Message to be streamed
76// to the ostream.
77//
78// For example;
79//
80// testing::Message foo;
81// foo << 1 << " != " << 2;
82// std::cout << foo;
83//
84// will print "1 != 2".
85//
86// Message is not intended to be inherited from. In particular, its
87// destructor is not virtual.
88//
89// Note that stringstream behaves differently in gcc and in MSVC. You
90// can stream a NULL char pointer to it in the former, but not in the
91// latter (it causes an access violation if you do). The Message
92// class hides this difference by treating a NULL char pointer as
93// "(null)".
94class GTEST_API_ Message {
95 private:
96 // The type of basic IO manipulators (endl, ends, and flush) for
97 // narrow streams.
98 typedef std::ostream& (*BasicNarrowIoManip)(std::ostream&);
99
100 public:
101 // Constructs an empty Message.
102 Message();
103
104 // Copy constructor.
105 Message(const Message& msg) : ss_(new ::std::stringstream) { // NOLINT
106 *ss_ << msg.GetString();
107 }
108
109 // Constructs a Message from a C-string.
110 explicit Message(const char* str) : ss_(new ::std::stringstream) {
111 *ss_ << str;
112 }
113
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.
119 //
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.
124 //
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.
131 using ::operator<<;
132 *ss_ << val;
133 return *this;
134 }
135
136 // Streams a pointer value to this object.
137 //
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.
143 //
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
148 // as "(null)".
149 template <typename T>
150 inline Message& operator<<(T* const& pointer) { // NOLINT
151 if (pointer == nullptr) {
152 *ss_ << "(null)";
153 } else {
154 *ss_ << pointer;
155 }
156 return *this;
157 }
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) { return *this << (b ? "true" : "false"); }
172
173 // These two overloads allow streaming a wide C string to a Message
174 // using the UTF-8 encoding.
175 Message& operator<<(const wchar_t* wide_c_str);
176 Message& operator<<(wchar_t* wide_c_str);
177
178#if GTEST_HAS_STD_WSTRING
179 // Converts the given wide string to a narrow string using the UTF-8
180 // encoding, and streams the result to this Message object.
181 Message& operator<<(const ::std::wstring& wstr);
182#endif // GTEST_HAS_STD_WSTRING
183
184 // Gets the text streamed to this object so far as an std::string.
185 // Each '\0' character in the buffer is replaced with "\\0".
186 //
187 // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
188 std::string GetString() const;
189
190 private:
191 // We'll hold the text streamed to this object here.
192 const std::unique_ptr< ::std::stringstream> ss_;
193
194 // We declare (but don't implement) this to prevent the compiler
195 // from implementing the assignment operator.
196 void operator=(const Message&);
197};
198
199// Streams a Message to an ostream.
200inline std::ostream& operator<<(std::ostream& os, const Message& sb) {
201 return os << sb.GetString();
202}
203
204namespace internal {
205
206// Converts a streamable value to an std::string. A NULL pointer is
207// converted to "(null)". When the input value is a ::string,
208// ::std::string, ::wstring, or ::std::wstring object, each NUL
209// character in it is replaced with "\\0".
210template <typename T>
211std::string StreamableToString(const T& streamable) {
212 return (Message() << streamable).GetString();
213}
214
215} // namespace internal
216} // namespace testing
217
218GTEST_DISABLE_MSC_WARNINGS_POP_() // 4251
219
220#endif // GOOGLETEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
221