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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
59#ifdef GTEST_HAS_ABSL
60#include <type_traits>
61
62#include "absl/strings/internal/has_absl_stringify.h"
63#include "absl/strings/str_cat.h"
64#endif // GTEST_HAS_ABSL
65
66GTEST_DISABLE_MSC_WARNINGS_PUSH_(4251 \
67/* class A needs to have dll-interface to be used by clients of class B */)
68
69// Ensures that there is at least one operator<< in the global namespace.
70// See Message& operator<<(...) below for why.
71void operator<<(const testing::internal::Secret&, int);
72
73namespace testing {
74
75// The Message class works like an ostream repeater.
76//
77// Typical usage:
78//
79// 1. You stream a bunch of values to a Message object.
80// It will remember the text in a stringstream.
81// 2. Then you stream the Message object to an ostream.
82// This causes the text in the Message to be streamed
83// to the ostream.
84//
85// For example;
86//
87// testing::Message foo;
88// foo << 1 << " != " << 2;
89// std::cout << foo;
90//
91// will print "1 != 2".
92//
93// Message is not intended to be inherited from. In particular, its
94// destructor is not virtual.
95//
96// Note that stringstream behaves differently in gcc and in MSVC. You
97// can stream a NULL char pointer to it in the former, but not in the
98// latter (it causes an access violation if you do). The Message
99// class hides this difference by treating a NULL char pointer as
100// "(null)".
101class GTEST_API_ Message {
102 private:
103 // The type of basic IO manipulators (endl, ends, and flush) for
104 // narrow streams.
105 typedef std::ostream& (*BasicNarrowIoManip)(std::ostream&);
106
107 public:
108 // Constructs an empty Message.
109 Message();
110
111 // Copy constructor.
112 Message(const Message& msg) : ss_(new ::std::stringstream) { // NOLINT
113 *ss_ << msg.GetString();
114 }
115
116 // Constructs a Message from a C-string.
117 explicit Message(const char* str) : ss_(new ::std::stringstream) {
118 *ss_ << str;
119 }
120
121 // Streams a non-pointer value to this object. If building a version of
122 // GoogleTest with ABSL, this overload is only enabled if the value does not
123 // have an AbslStringify definition.
124 template <typename T
125#ifdef GTEST_HAS_ABSL
126 ,
127 typename std::enable_if<
128 !absl::strings_internal::HasAbslStringify<T>::value, // NOLINT
129 int>::type = 0
130#endif // GTEST_HAS_ABSL
131 >
132 inline Message& operator<<(const T& val) {
133 // Some libraries overload << for STL containers. These
134 // overloads are defined in the global namespace instead of ::std.
135 //
136 // C++'s symbol lookup rule (i.e. Koenig lookup) says that these
137 // overloads are visible in either the std namespace or the global
138 // namespace, but not other namespaces, including the testing
139 // namespace which Google Test's Message class is in.
140 //
141 // To allow STL containers (and other types that has a << operator
142 // defined in the global namespace) to be used in Google Test
143 // assertions, testing::Message must access the custom << operator
144 // from the global namespace. With this using declaration,
145 // overloads of << defined in the global namespace and those
146 // visible via Koenig lookup are both exposed in this function.
147 using ::operator<<;
148 *ss_ << val;
149 return *this;
150 }
151
152#ifdef GTEST_HAS_ABSL
153 // Streams a non-pointer value with an AbslStringify definition to this
154 // object.
155 template <typename T,
156 typename std::enable_if<
157 absl::strings_internal::HasAbslStringify<T>::value, // NOLINT
158 int>::type = 0>
159 inline Message& operator<<(const T& val) {
160 // ::operator<< is needed here for a similar reason as with the non-Abseil
161 // version above
162 using ::operator<<;
163 *ss_ << absl::StrCat(val);
164 return *this;
165 }
166#endif // GTEST_HAS_ABSL
167
168 // Streams a pointer value to this object.
169 //
170 // This function is an overload of the previous one. When you
171 // stream a pointer to a Message, this definition will be used as it
172 // is more specialized. (The C++ Standard, section
173 // [temp.func.order].) If you stream a non-pointer, then the
174 // previous definition will be used.
175 //
176 // The reason for this overload is that streaming a NULL pointer to
177 // ostream is undefined behavior. Depending on the compiler, you
178 // may get "0", "(nil)", "(null)", or an access violation. To
179 // ensure consistent result across compilers, we always treat NULL
180 // as "(null)".
181 template <typename T>
182 inline Message& operator<<(T* const& pointer) { // NOLINT
183 if (pointer == nullptr) {
184 *ss_ << "(null)";
185 } else {
186 *ss_ << pointer;
187 }
188 return *this;
189 }
190
191 // Since the basic IO manipulators are overloaded for both narrow
192 // and wide streams, we have to provide this specialized definition
193 // of operator <<, even though its body is the same as the
194 // templatized version above. Without this definition, streaming
195 // endl or other basic IO manipulators to Message will confuse the
196 // compiler.
197 Message& operator<<(BasicNarrowIoManip val) {
198 *ss_ << val;
199 return *this;
200 }
201
202 // Instead of 1/0, we want to see true/false for bool values.
203 Message& operator<<(bool b) { return *this << (b ? "true" : "false"); }
204
205 // These two overloads allow streaming a wide C string to a Message
206 // using the UTF-8 encoding.
207 Message& operator<<(const wchar_t* wide_c_str);
208 Message& operator<<(wchar_t* wide_c_str);
209
210#if GTEST_HAS_STD_WSTRING
211 // Converts the given wide string to a narrow string using the UTF-8
212 // encoding, and streams the result to this Message object.
213 Message& operator<<(const ::std::wstring& wstr);
214#endif // GTEST_HAS_STD_WSTRING
215
216 // Gets the text streamed to this object so far as an std::string.
217 // Each '\0' character in the buffer is replaced with "\\0".
218 //
219 // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
220 std::string GetString() const;
221
222 private:
223 // We'll hold the text streamed to this object here.
224 const std::unique_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.
232inline std::ostream& operator<<(std::ostream& os, const Message& sb) {
233 return os << sb.GetString();
234}
235
236namespace 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".
242template <typename T>
243std::string StreamableToString(const T& streamable) {
244 return (Message() << streamable).GetString();
245}
246
247} // namespace internal
248} // namespace testing
249
250GTEST_DISABLE_MSC_WARNINGS_POP_() // 4251
251
252#endif // GOOGLETEST_INCLUDE_GTEST_GTEST_MESSAGE_H_
253