duckstation

gtest-printers.h (29699B)

---

 // Copyright 2007, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
 // in the documentation and/or other materials provided with the
 // distribution.
 //     * Neither the name of Google Inc. nor the names of its
 // contributors may be used to endorse or promote products derived from
 // this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
 // Google Test - The Google C++ Testing and Mocking Framework
 //
 // This file implements a universal value printer that can print a
 // value of any type T:
 //
 //   void ::testing::internal::UniversalPrinter<T>::Print(value, ostream_ptr);
 //
 // A user can teach this function how to print a class type T by
 // defining either operator<<() or PrintTo() in the namespace that
 // defines T.  More specifically, the FIRST defined function in the
 // following list will be used (assuming T is defined in namespace
 // foo):
 //
 //   1. foo::PrintTo(const T&, ostream*)
 //   2. operator<<(ostream&, const T&) defined in either foo or the
 //      global namespace.
 //
 // However if T is an STL-style container then it is printed element-wise
 // unless foo::PrintTo(const T&, ostream*) is defined. Note that
 // operator<<() is ignored for container types.
 //
 // If none of the above is defined, it will print the debug string of
 // the value if it is a protocol buffer, or print the raw bytes in the
 // value otherwise.
 //
 // To aid debugging: when T is a reference type, the address of the
 // value is also printed; when T is a (const) char pointer, both the
 // pointer value and the NUL-terminated string it points to are
 // printed.
 //
 // We also provide some convenient wrappers:
 //
 //   // Prints a value to a string.  For a (const or not) char
 //   // pointer, the NUL-terminated string (but not the pointer) is
 //   // printed.
 //   std::string ::testing::PrintToString(const T& value);
 //
 //   // Prints a value tersely: for a reference type, the referenced
 //   // value (but not the address) is printed; for a (const or not) char
 //   // pointer, the NUL-terminated string (but not the pointer) is
 //   // printed.
 //   void ::testing::internal::UniversalTersePrint(const T& value, ostream*);
 //
 //   // Prints value using the type inferred by the compiler.  The difference
 //   // from UniversalTersePrint() is that this function prints both the
 //   // pointer and the NUL-terminated string for a (const or not) char pointer.
 //   void ::testing::internal::UniversalPrint(const T& value, ostream*);
 //
 //   // Prints the fields of a tuple tersely to a string vector, one
 //   // element for each field. Tuple support must be enabled in
 //   // gtest-port.h.
 //   std::vector<string> UniversalTersePrintTupleFieldsToStrings(
 //       const Tuple& value);
 //
 // Known limitation:
 //
 // The print primitives print the elements of an STL-style container
 // using the compiler-inferred type of *iter where iter is a
 // const_iterator of the container.  When const_iterator is an input
 // iterator but not a forward iterator, this inferred type may not
 // match value_type, and the print output may be incorrect.  In
 // practice, this is rarely a problem as for most containers
 // const_iterator is a forward iterator.  We'll fix this if there's an
 // actual need for it.  Note that this fix cannot rely on value_type
 // being defined as many user-defined container types don't have
 // value_type.
 
 // GOOGLETEST_CM0001 DO NOT DELETE
 
 #ifndef GTEST_INCLUDE_GTEST_GTEST_PRINTERS_H_
 #define GTEST_INCLUDE_GTEST_GTEST_PRINTERS_H_
 
 #include <functional>
 #include <ostream>  // NOLINT
 #include <sstream>
 #include <string>
 #include <tuple>
 #include <type_traits>
 #include <utility>
 #include <vector>
 #include "gtest/internal/gtest-internal.h"
 #include "gtest/internal/gtest-port.h"
 
 #if GTEST_HAS_ABSL
 #include "absl/strings/string_view.h"
 #include "absl/types/optional.h"
 #include "absl/types/variant.h"
 #endif  // GTEST_HAS_ABSL
 
 namespace testing {
 
 // Definitions in the internal* namespaces are subject to change without notice.
 // DO NOT USE THEM IN USER CODE!
 namespace internal {
 
 template <typename T>
 void UniversalPrint(const T& value, ::std::ostream* os);
 
 // Used to print an STL-style container when the user doesn't define
 // a PrintTo() for it.
 struct ContainerPrinter {
   template <typename T,
             typename = typename std::enable_if<
                 (sizeof(IsContainerTest<T>(0)) == sizeof(IsContainer)) &&
                 !IsRecursiveContainer<T>::value>::type>
   static void PrintValue(const T& container, std::ostream* os) {
     const size_t kMaxCount = 32;  // The maximum number of elements to print.
     *os << '{';
     size_t count = 0;
     for (auto&& elem : container) {
       if (count > 0) {
         *os << ',';
         if (count == kMaxCount) {  // Enough has been printed.
           *os << " ...";
           break;
         }
       }
       *os << ' ';
       // We cannot call PrintTo(elem, os) here as PrintTo() doesn't
       // handle `elem` being a native array.
       internal::UniversalPrint(elem, os);
       ++count;
     }
 
     if (count > 0) {
       *os << ' ';
     }
     *os << '}';
   }
 };
 
 // Used to print a pointer that is neither a char pointer nor a member
 // pointer, when the user doesn't define PrintTo() for it.  (A member
 // variable pointer or member function pointer doesn't really point to
 // a location in the address space.  Their representation is
 // implementation-defined.  Therefore they will be printed as raw
 // bytes.)
 struct FunctionPointerPrinter {
   template <typename T, typename = typename std::enable_if<
                             std::is_function<T>::value>::type>
   static void PrintValue(T* p, ::std::ostream* os) {
     if (p == nullptr) {
       *os << "NULL";
     } else {
       // T is a function type, so '*os << p' doesn't do what we want
       // (it just prints p as bool).  We want to print p as a const
       // void*.
       *os << reinterpret_cast<const void*>(p);
     }
   }
 };
 
 struct PointerPrinter {
   template <typename T>
   static void PrintValue(T* p, ::std::ostream* os) {
     if (p == nullptr) {
       *os << "NULL";
     } else {
       // T is not a function type.  We just call << to print p,
       // relying on ADL to pick up user-defined << for their pointer
       // types, if any.
       *os << p;
     }
   }
 };
 
 namespace internal_stream {
 
 struct Sentinel;
 template <typename Char, typename CharTraits, typename T>
 Sentinel* operator<<(::std::basic_ostream<Char, CharTraits>& os, const T& x);
 
 // Check if the user has a user-defined operator<< for their type.
 //
 // We put this in its own namespace to inject a custom operator<< that allows us
 // to probe the type's operator.
 //
 // Note that this operator<< takes a generic std::basic_ostream<Char,
 // CharTraits> type instead of the more restricted std::ostream.  If
 // we define it to take an std::ostream instead, we'll get an
 // "ambiguous overloads" compiler error when trying to print a type
 // Foo that supports streaming to std::basic_ostream<Char,
 // CharTraits>, as the compiler cannot tell whether
 // operator<<(std::ostream&, const T&) or
 // operator<<(std::basic_stream<Char, CharTraits>, const Foo&) is more
 // specific.
 template <typename T>
 constexpr bool UseStreamOperator() {
   return !std::is_same<decltype(std::declval<std::ostream&>()
                                 << std::declval<const T&>()),
                        Sentinel*>::value;
 }
 
 }  // namespace internal_stream
 
 struct StreamPrinter {
   template <typename T, typename = typename std::enable_if<
                             internal_stream::UseStreamOperator<T>()>::type>
   static void PrintValue(const T& value, ::std::ostream* os) {
     *os << value;
   }
 };
 
 struct ProtobufPrinter {
   // We print a protobuf using its ShortDebugString() when the string
   // doesn't exceed this many characters; otherwise we print it using
   // DebugString() for better readability.
   static const size_t kProtobufOneLinerMaxLength = 50;
 
   template <typename T, typename = typename std::enable_if<
                             internal::IsAProtocolMessage<T>::value>::type>
   static void PrintValue(const T& value, ::std::ostream* os) {
     std::string pretty_str = value.ShortDebugString();
     if (pretty_str.length() > kProtobufOneLinerMaxLength) {
       pretty_str = "\n" + value.DebugString();
     }
     *os << ("<" + pretty_str + ">");
   }
 };
 
 struct ConvertibleToIntegerPrinter {
   // Since T has no << operator or PrintTo() but can be implicitly
   // converted to BiggestInt, we print it as a BiggestInt.
   //
   // Most likely T is an enum type (either named or unnamed), in which
   // case printing it as an integer is the desired behavior.  In case
   // T is not an enum, printing it as an integer is the best we can do
   // given that it has no user-defined printer.
   static void PrintValue(internal::BiggestInt value, ::std::ostream* os) {
     *os << value;
   }
 };
 
 struct ConvertibleToStringViewPrinter {
 #if GTEST_INTERNAL_HAS_STRING_VIEW
   static void PrintValue(internal::StringView value, ::std::ostream* os) {
     internal::UniversalPrint(value, os);
   }
 #endif
 };
 
 
 // Prints the given number of bytes in the given object to the given
 // ostream.
 GTEST_API_ void PrintBytesInObjectTo(const unsigned char* obj_bytes,
                                      size_t count,
                                      ::std::ostream* os);
 struct FallbackPrinter {
   template <typename T>
   static void PrintValue(const T& value, ::std::ostream* os) {
     PrintBytesInObjectTo(
         static_cast<const unsigned char*>(
             reinterpret_cast<const void*>(std::addressof(value))),
         sizeof(value), os);
   }
 };
 
 // Try every printer in order and return the first one that works.
 template <typename T, typename E, typename Printer, typename... Printers>
 struct FindFirstPrinter : FindFirstPrinter<T, E, Printers...> {};
 
 template <typename T, typename Printer, typename... Printers>
 struct FindFirstPrinter<
     T, decltype(Printer::PrintValue(std::declval<const T&>(), nullptr)),
     Printer, Printers...> {
   using type = Printer;
 };
 
 // Select the best printer in the following order:
 //  - Print containers (they have begin/end/etc).
 //  - Print function pointers.
 //  - Print object pointers.
 //  - Use the stream operator, if available.
 //  - Print protocol buffers.
 //  - Print types convertible to BiggestInt.
 //  - Print types convertible to StringView, if available.
 //  - Fallback to printing the raw bytes of the object.
 template <typename T>
 void PrintWithFallback(const T& value, ::std::ostream* os) {
   using Printer = typename FindFirstPrinter<
       T, void, ContainerPrinter, FunctionPointerPrinter, PointerPrinter,
       StreamPrinter, ProtobufPrinter, ConvertibleToIntegerPrinter,
       ConvertibleToStringViewPrinter, FallbackPrinter>::type;
   Printer::PrintValue(value, os);
 }
 
 // FormatForComparison<ToPrint, OtherOperand>::Format(value) formats a
 // value of type ToPrint that is an operand of a comparison assertion
 // (e.g. ASSERT_EQ).  OtherOperand is the type of the other operand in
 // the comparison, and is used to help determine the best way to
 // format the value.  In particular, when the value is a C string
 // (char pointer) and the other operand is an STL string object, we
 // want to format the C string as a string, since we know it is
 // compared by value with the string object.  If the value is a char
 // pointer but the other operand is not an STL string object, we don't
 // know whether the pointer is supposed to point to a NUL-terminated
 // string, and thus want to print it as a pointer to be safe.
 //
 // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
 
 // The default case.
 template <typename ToPrint, typename OtherOperand>
 class FormatForComparison {
  public:
   static ::std::string Format(const ToPrint& value) {
     return ::testing::PrintToString(value);
   }
 };
 
 // Array.
 template <typename ToPrint, size_t N, typename OtherOperand>
 class FormatForComparison<ToPrint[N], OtherOperand> {
  public:
   static ::std::string Format(const ToPrint* value) {
     return FormatForComparison<const ToPrint*, OtherOperand>::Format(value);
   }
 };
 
 // By default, print C string as pointers to be safe, as we don't know
 // whether they actually point to a NUL-terminated string.
 
 #define GTEST_IMPL_FORMAT_C_STRING_AS_POINTER_(CharType)                \
   template <typename OtherOperand>                                      \
   class FormatForComparison<CharType*, OtherOperand> {                  \
    public:                                                              \
     static ::std::string Format(CharType* value) {                      \
       return ::testing::PrintToString(static_cast<const void*>(value)); \
     }                                                                   \
   }
 
 GTEST_IMPL_FORMAT_C_STRING_AS_POINTER_(char);
 GTEST_IMPL_FORMAT_C_STRING_AS_POINTER_(const char);
 GTEST_IMPL_FORMAT_C_STRING_AS_POINTER_(wchar_t);
 GTEST_IMPL_FORMAT_C_STRING_AS_POINTER_(const wchar_t);
 
 #undef GTEST_IMPL_FORMAT_C_STRING_AS_POINTER_
 
 // If a C string is compared with an STL string object, we know it's meant
 // to point to a NUL-terminated string, and thus can print it as a string.
 
 #define GTEST_IMPL_FORMAT_C_STRING_AS_STRING_(CharType, OtherStringType) \
   template <>                                                           \
   class FormatForComparison<CharType*, OtherStringType> {               \
    public:                                                              \
     static ::std::string Format(CharType* value) {                      \
       return ::testing::PrintToString(value);                           \
     }                                                                   \
   }
 
 GTEST_IMPL_FORMAT_C_STRING_AS_STRING_(char, ::std::string);
 GTEST_IMPL_FORMAT_C_STRING_AS_STRING_(const char, ::std::string);
 
 #if GTEST_HAS_STD_WSTRING
 GTEST_IMPL_FORMAT_C_STRING_AS_STRING_(wchar_t, ::std::wstring);
 GTEST_IMPL_FORMAT_C_STRING_AS_STRING_(const wchar_t, ::std::wstring);
 #endif
 
 #undef GTEST_IMPL_FORMAT_C_STRING_AS_STRING_
 
 // Formats a comparison assertion (e.g. ASSERT_EQ, EXPECT_LT, and etc)
 // operand to be used in a failure message.  The type (but not value)
 // of the other operand may affect the format.  This allows us to
 // print a char* as a raw pointer when it is compared against another
 // char* or void*, and print it as a C string when it is compared
 // against an std::string object, for example.
 //
 // INTERNAL IMPLEMENTATION - DO NOT USE IN A USER PROGRAM.
 template <typename T1, typename T2>
 std::string FormatForComparisonFailureMessage(
     const T1& value, const T2& /* other_operand */) {
   return FormatForComparison<T1, T2>::Format(value);
 }
 
 // UniversalPrinter<T>::Print(value, ostream_ptr) prints the given
 // value to the given ostream.  The caller must ensure that
 // 'ostream_ptr' is not NULL, or the behavior is undefined.
 //
 // We define UniversalPrinter as a class template (as opposed to a
 // function template), as we need to partially specialize it for
 // reference types, which cannot be done with function templates.
 template <typename T>
 class UniversalPrinter;
 
 // Prints the given value using the << operator if it has one;
 // otherwise prints the bytes in it.  This is what
 // UniversalPrinter<T>::Print() does when PrintTo() is not specialized
 // or overloaded for type T.
 //
 // A user can override this behavior for a class type Foo by defining
 // an overload of PrintTo() in the namespace where Foo is defined.  We
 // give the user this option as sometimes defining a << operator for
 // Foo is not desirable (e.g. the coding style may prevent doing it,
 // or there is already a << operator but it doesn't do what the user
 // wants).
 template <typename T>
 void PrintTo(const T& value, ::std::ostream* os) {
   internal::PrintWithFallback(value, os);
 }
 
 // The following list of PrintTo() overloads tells
 // UniversalPrinter<T>::Print() how to print standard types (built-in
 // types, strings, plain arrays, and pointers).
 
 // Overloads for various char types.
 GTEST_API_ void PrintTo(unsigned char c, ::std::ostream* os);
 GTEST_API_ void PrintTo(signed char c, ::std::ostream* os);
 inline void PrintTo(char c, ::std::ostream* os) {
   // When printing a plain char, we always treat it as unsigned.  This
   // way, the output won't be affected by whether the compiler thinks
   // char is signed or not.
   PrintTo(static_cast<unsigned char>(c), os);
 }
 
 // Overloads for other simple built-in types.
 inline void PrintTo(bool x, ::std::ostream* os) {
   *os << (x ? "true" : "false");
 }
 
 // Overload for wchar_t type.
 // Prints a wchar_t as a symbol if it is printable or as its internal
 // code otherwise and also as its decimal code (except for L'\0').
 // The L'\0' char is printed as "L'\\0'". The decimal code is printed
 // as signed integer when wchar_t is implemented by the compiler
 // as a signed type and is printed as an unsigned integer when wchar_t
 // is implemented as an unsigned type.
 GTEST_API_ void PrintTo(wchar_t wc, ::std::ostream* os);
 
 // Overloads for C strings.
 GTEST_API_ void PrintTo(const char* s, ::std::ostream* os);
 inline void PrintTo(char* s, ::std::ostream* os) {
   PrintTo(ImplicitCast_<const char*>(s), os);
 }
 
 // signed/unsigned char is often used for representing binary data, so
 // we print pointers to it as void* to be safe.
 inline void PrintTo(const signed char* s, ::std::ostream* os) {
   PrintTo(ImplicitCast_<const void*>(s), os);
 }
 inline void PrintTo(signed char* s, ::std::ostream* os) {
   PrintTo(ImplicitCast_<const void*>(s), os);
 }
 inline void PrintTo(const unsigned char* s, ::std::ostream* os) {
   PrintTo(ImplicitCast_<const void*>(s), os);
 }
 inline void PrintTo(unsigned char* s, ::std::ostream* os) {
   PrintTo(ImplicitCast_<const void*>(s), os);
 }
 
 // MSVC can be configured to define wchar_t as a typedef of unsigned
 // short.  It defines _NATIVE_WCHAR_T_DEFINED when wchar_t is a native
 // type.  When wchar_t is a typedef, defining an overload for const
 // wchar_t* would cause unsigned short* be printed as a wide string,
 // possibly causing invalid memory accesses.
 #if !defined(_MSC_VER) || defined(_NATIVE_WCHAR_T_DEFINED)
 // Overloads for wide C strings
 GTEST_API_ void PrintTo(const wchar_t* s, ::std::ostream* os);
 inline void PrintTo(wchar_t* s, ::std::ostream* os) {
   PrintTo(ImplicitCast_<const wchar_t*>(s), os);
 }
 #endif
 
 // Overload for C arrays.  Multi-dimensional arrays are printed
 // properly.
 
 // Prints the given number of elements in an array, without printing
 // the curly braces.
 template <typename T>
 void PrintRawArrayTo(const T a[], size_t count, ::std::ostream* os) {
   UniversalPrint(a[0], os);
   for (size_t i = 1; i != count; i++) {
     *os << ", ";
     UniversalPrint(a[i], os);
   }
 }
 
 // Overloads for ::std::string.
 GTEST_API_ void PrintStringTo(const ::std::string&s, ::std::ostream* os);
 inline void PrintTo(const ::std::string& s, ::std::ostream* os) {
   PrintStringTo(s, os);
 }
 
 // Overloads for ::std::wstring.
 #if GTEST_HAS_STD_WSTRING
 GTEST_API_ void PrintWideStringTo(const ::std::wstring&s, ::std::ostream* os);
 inline void PrintTo(const ::std::wstring& s, ::std::ostream* os) {
   PrintWideStringTo(s, os);
 }
 #endif  // GTEST_HAS_STD_WSTRING
 
 #if GTEST_INTERNAL_HAS_STRING_VIEW
 // Overload for internal::StringView.
 inline void PrintTo(internal::StringView sp, ::std::ostream* os) {
   PrintTo(::std::string(sp), os);
 }
 #endif  // GTEST_INTERNAL_HAS_STRING_VIEW
 
 inline void PrintTo(std::nullptr_t, ::std::ostream* os) { *os << "(nullptr)"; }
 
 template <typename T>
 void PrintTo(std::reference_wrapper<T> ref, ::std::ostream* os) {
   UniversalPrinter<T&>::Print(ref.get(), os);
 }
 
 // Helper function for printing a tuple.  T must be instantiated with
 // a tuple type.
 template <typename T>
 void PrintTupleTo(const T&, std::integral_constant<size_t, 0>,
                   ::std::ostream*) {}
 
 template <typename T, size_t I>
 void PrintTupleTo(const T& t, std::integral_constant<size_t, I>,
                   ::std::ostream* os) {
   PrintTupleTo(t, std::integral_constant<size_t, I - 1>(), os);
   GTEST_INTENTIONAL_CONST_COND_PUSH_()
   if (I > 1) {
     GTEST_INTENTIONAL_CONST_COND_POP_()
     *os << ", ";
   }
   UniversalPrinter<typename std::tuple_element<I - 1, T>::type>::Print(
       std::get<I - 1>(t), os);
 }
 
 template <typename... Types>
 void PrintTo(const ::std::tuple<Types...>& t, ::std::ostream* os) {
   *os << "(";
   PrintTupleTo(t, std::integral_constant<size_t, sizeof...(Types)>(), os);
   *os << ")";
 }
 
 // Overload for std::pair.
 template <typename T1, typename T2>
 void PrintTo(const ::std::pair<T1, T2>& value, ::std::ostream* os) {
   *os << '(';
   // We cannot use UniversalPrint(value.first, os) here, as T1 may be
   // a reference type.  The same for printing value.second.
   UniversalPrinter<T1>::Print(value.first, os);
   *os << ", ";
   UniversalPrinter<T2>::Print(value.second, os);
   *os << ')';
 }
 
 // Implements printing a non-reference type T by letting the compiler
 // pick the right overload of PrintTo() for T.
 template <typename T>
 class UniversalPrinter {
  public:
   // MSVC warns about adding const to a function type, so we want to
   // disable the warning.
   GTEST_DISABLE_MSC_WARNINGS_PUSH_(4180)
 
   // Note: we deliberately don't call this PrintTo(), as that name
   // conflicts with ::testing::internal::PrintTo in the body of the
   // function.
   static void Print(const T& value, ::std::ostream* os) {
     // By default, ::testing::internal::PrintTo() is used for printing
     // the value.
     //
     // Thanks to Koenig look-up, if T is a class and has its own
     // PrintTo() function defined in its namespace, that function will
     // be visible here.  Since it is more specific than the generic ones
     // in ::testing::internal, it will be picked by the compiler in the
     // following statement - exactly what we want.
     PrintTo(value, os);
   }
 
   GTEST_DISABLE_MSC_WARNINGS_POP_()
 };
 
 #if GTEST_HAS_ABSL
 
 // Printer for absl::optional
 
 template <typename T>
 class UniversalPrinter<::absl::optional<T>> {
  public:
   static void Print(const ::absl::optional<T>& value, ::std::ostream* os) {
     *os << '(';
     if (!value) {
       *os << "nullopt";
     } else {
       UniversalPrint(*value, os);
     }
     *os << ')';
   }
 };
 
 // Printer for absl::variant
 
 template <typename... T>
 class UniversalPrinter<::absl::variant<T...>> {
  public:
   static void Print(const ::absl::variant<T...>& value, ::std::ostream* os) {
     *os << '(';
     absl::visit(Visitor{os}, value);
     *os << ')';
   }
 
  private:
   struct Visitor {
     template <typename U>
     void operator()(const U& u) const {
       *os << "'" << GetTypeName<U>() << "' with value ";
       UniversalPrint(u, os);
     }
     ::std::ostream* os;
   };
 };
 
 #endif  // GTEST_HAS_ABSL
 
 // UniversalPrintArray(begin, len, os) prints an array of 'len'
 // elements, starting at address 'begin'.
 template <typename T>
 void UniversalPrintArray(const T* begin, size_t len, ::std::ostream* os) {
   if (len == 0) {
     *os << "{}";
   } else {
     *os << "{ ";
     const size_t kThreshold = 18;
     const size_t kChunkSize = 8;
     // If the array has more than kThreshold elements, we'll have to
     // omit some details by printing only the first and the last
     // kChunkSize elements.
     if (len <= kThreshold) {
       PrintRawArrayTo(begin, len, os);
     } else {
       PrintRawArrayTo(begin, kChunkSize, os);
       *os << ", ..., ";
       PrintRawArrayTo(begin + len - kChunkSize, kChunkSize, os);
     }
     *os << " }";
   }
 }
 // This overload prints a (const) char array compactly.
 GTEST_API_ void UniversalPrintArray(
     const char* begin, size_t len, ::std::ostream* os);
 
 // This overload prints a (const) wchar_t array compactly.
 GTEST_API_ void UniversalPrintArray(
     const wchar_t* begin, size_t len, ::std::ostream* os);
 
 // Implements printing an array type T[N].
 template <typename T, size_t N>
 class UniversalPrinter<T[N]> {
  public:
   // Prints the given array, omitting some elements when there are too
   // many.
   static void Print(const T (&a)[N], ::std::ostream* os) {
     UniversalPrintArray(a, N, os);
   }
 };
 
 // Implements printing a reference type T&.
 template <typename T>
 class UniversalPrinter<T&> {
  public:
   // MSVC warns about adding const to a function type, so we want to
   // disable the warning.
   GTEST_DISABLE_MSC_WARNINGS_PUSH_(4180)
 
   static void Print(const T& value, ::std::ostream* os) {
     // Prints the address of the value.  We use reinterpret_cast here
     // as static_cast doesn't compile when T is a function type.
     *os << "@" << reinterpret_cast<const void*>(&value) << " ";
 
     // Then prints the value itself.
     UniversalPrint(value, os);
   }
 
   GTEST_DISABLE_MSC_WARNINGS_POP_()
 };
 
 // Prints a value tersely: for a reference type, the referenced value
 // (but not the address) is printed; for a (const) char pointer, the
 // NUL-terminated string (but not the pointer) is printed.
 
 template <typename T>
 class UniversalTersePrinter {
  public:
   static void Print(const T& value, ::std::ostream* os) {
     UniversalPrint(value, os);
   }
 };
 template <typename T>
 class UniversalTersePrinter<T&> {
  public:
   static void Print(const T& value, ::std::ostream* os) {
     UniversalPrint(value, os);
   }
 };
 template <typename T, size_t N>
 class UniversalTersePrinter<T[N]> {
  public:
   static void Print(const T (&value)[N], ::std::ostream* os) {
     UniversalPrinter<T[N]>::Print(value, os);
   }
 };
 template <>
 class UniversalTersePrinter<const char*> {
  public:
   static void Print(const char* str, ::std::ostream* os) {
     if (str == nullptr) {
       *os << "NULL";
     } else {
       UniversalPrint(std::string(str), os);
     }
   }
 };
 template <>
 class UniversalTersePrinter<char*> {
  public:
   static void Print(char* str, ::std::ostream* os) {
     UniversalTersePrinter<const char*>::Print(str, os);
   }
 };
 
 #if GTEST_HAS_STD_WSTRING
 template <>
 class UniversalTersePrinter<const wchar_t*> {
  public:
   static void Print(const wchar_t* str, ::std::ostream* os) {
     if (str == nullptr) {
       *os << "NULL";
     } else {
       UniversalPrint(::std::wstring(str), os);
     }
   }
 };
 #endif
 
 template <>
 class UniversalTersePrinter<wchar_t*> {
  public:
   static void Print(wchar_t* str, ::std::ostream* os) {
     UniversalTersePrinter<const wchar_t*>::Print(str, os);
   }
 };
 
 template <typename T>
 void UniversalTersePrint(const T& value, ::std::ostream* os) {
   UniversalTersePrinter<T>::Print(value, os);
 }
 
 // Prints a value using the type inferred by the compiler.  The
 // difference between this and UniversalTersePrint() is that for a
 // (const) char pointer, this prints both the pointer and the
 // NUL-terminated string.
 template <typename T>
 void UniversalPrint(const T& value, ::std::ostream* os) {
   // A workarond for the bug in VC++ 7.1 that prevents us from instantiating
   // UniversalPrinter with T directly.
   typedef T T1;
   UniversalPrinter<T1>::Print(value, os);
 }
 
 typedef ::std::vector< ::std::string> Strings;
 
   // Tersely prints the first N fields of a tuple to a string vector,
   // one element for each field.
 template <typename Tuple>
 void TersePrintPrefixToStrings(const Tuple&, std::integral_constant<size_t, 0>,
                                Strings*) {}
 template <typename Tuple, size_t I>
 void TersePrintPrefixToStrings(const Tuple& t,
                                std::integral_constant<size_t, I>,
                                Strings* strings) {
   TersePrintPrefixToStrings(t, std::integral_constant<size_t, I - 1>(),
                             strings);
   ::std::stringstream ss;
   UniversalTersePrint(std::get<I - 1>(t), &ss);
   strings->push_back(ss.str());
 }
 
 // Prints the fields of a tuple tersely to a string vector, one
 // element for each field.  See the comment before
 // UniversalTersePrint() for how we define "tersely".
 template <typename Tuple>
 Strings UniversalTersePrintTupleFieldsToStrings(const Tuple& value) {
   Strings result;
   TersePrintPrefixToStrings(
       value, std::integral_constant<size_t, std::tuple_size<Tuple>::value>(),
       &result);
   return result;
 }
 
 }  // namespace internal
 
 template <typename T>
 ::std::string PrintToString(const T& value) {
   ::std::stringstream ss;
   internal::UniversalTersePrinter<T>::Print(value, &ss);
   return ss.str();
 }
 
 }  // namespace testing
 
 // Include any custom printer added by the local installation.
 // We must include this header at the end to make sure it can use the
 // declarations from this file.
 #include "gtest/internal/custom/gtest-printers.h"
 
 #endif  // GTEST_INCLUDE_GTEST_GTEST_PRINTERS_H_