summaryrefslogtreecommitdiffstats
path: root/googletest/include/gtest/gtest-matchers.h
blob: eae210e99ddae4d0a3c81fbfeda48bac397fd2a5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
// 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.

// The Google C++ Testing and Mocking Framework (Google Test)
//
// This file implements just enough of the matcher interface to allow
// EXPECT_DEATH and friends to accept a matcher argument.

// IWYU pragma: private, include "gtest/gtest.h"
// IWYU pragma: friend gtest/.*
// IWYU pragma: friend gmock/.*

#ifndef GOOGLETEST_INCLUDE_GTEST_GTEST_MATCHERS_H_
#define GOOGLETEST_INCLUDE_GTEST_GTEST_MATCHERS_H_

#include <atomic>
#include <functional>
#include <memory>
#include <ostream>
#include <string>
#include <type_traits>

#include "gtest/gtest-printers.h"
#include "gtest/internal/gtest-internal.h"
#include "gtest/internal/gtest-port.h"

// MSVC warning C5046 is new as of VS2017 version 15.8.
#if defined(_MSC_VER) && _MSC_VER >= 1915
#define GTEST_MAYBE_5046_ 5046
#else
#define GTEST_MAYBE_5046_
#endif

GTEST_DISABLE_MSC_WARNINGS_PUSH_(
    4251 GTEST_MAYBE_5046_ /* class A needs to have dll-interface to be used by
                              clients of class B */
    /* Symbol involving type with internal linkage not defined */)

namespace testing {

// To implement a matcher Foo for type T, define:
//   1. a class FooMatcherMatcher that implements the matcher interface:
//     using is_gtest_matcher = void;
//     bool MatchAndExplain(const T&, std::ostream*);
//       (MatchResultListener* can also be used instead of std::ostream*)
//     void DescribeTo(std::ostream*);
//     void DescribeNegationTo(std::ostream*);
//
//   2. a factory function that creates a Matcher<T> object from a
//      FooMatcherMatcher.

class MatchResultListener {
 public:
  // Creates a listener object with the given underlying ostream.  The
  // listener does not own the ostream, and does not dereference it
  // in the constructor or destructor.
  explicit MatchResultListener(::std::ostream* os) : stream_(os) {}
  virtual ~MatchResultListener() = 0;  // Makes this class abstract.

  // Streams x to the underlying ostream; does nothing if the ostream
  // is NULL.
  template <typename T>
  MatchResultListener& operator<<(const T& x) {
    if (stream_ != nullptr) *stream_ << x;
    return *this;
  }

  // Returns the underlying ostream.
  ::std::ostream* stream() { return stream_; }

  // Returns true if and only if the listener is interested in an explanation
  // of the match result.  A matcher's MatchAndExplain() method can use
  // this information to avoid generating the explanation when no one
  // intends to hear it.
  bool IsInterested() const { return stream_ != nullptr; }

 private:
  ::std::ostream* const stream_;

  MatchResultListener(const MatchResultListener&) = delete;
  MatchResultListener& operator=(const MatchResultListener&) = delete;
};

inline MatchResultListener::~MatchResultListener() = default;

// An instance of a subclass of this knows how to describe itself as a
// matcher.
class GTEST_API_ MatcherDescriberInterface {
 public:
  virtual ~MatcherDescriberInterface() = default;

  // Describes this matcher to an ostream.  The function should print
  // a verb phrase that describes the property a value matching this
  // matcher should have.  The subject of the verb phrase is the value
  // being matched.  For example, the DescribeTo() method of the Gt(7)
  // matcher prints "is greater than 7".
  virtual void DescribeTo(::std::ostream* os) const = 0;

  // Describes the negation of this matcher to an ostream.  For
  // example, if the description of this matcher is "is greater than
  // 7", the negated description could be "is not greater than 7".
  // You are not required to override this when implementing
  // MatcherInterface, but it is highly advised so that your matcher
  // can produce good error messages.
  virtual void DescribeNegationTo(::std::ostream* os) const {
    *os << "not (";
    DescribeTo(os);
    *os << ")";
  }
};

// The implementation of a matcher.
template <typename T>
class MatcherInterface : public MatcherDescriberInterface {
 public:
  // Returns true if and only if the matcher matches x; also explains the
  // match result to 'listener' if necessary (see the next paragraph), in
  // the form of a non-restrictive relative clause ("which ...",
  // "whose ...", etc) that describes x.  For example, the
  // MatchAndExplain() method of the Pointee(...) matcher should
  // generate an explanation like "which points to ...".
  //
  // Implementations of MatchAndExplain() should add an explanation of
  // the match result *if and only if* they can provide additional
  // information that's not already present (or not obvious) in the
  // print-out of x and the matcher's description.  Whether the match
  // succeeds is not a factor in deciding whether an explanation is
  // needed, as sometimes the caller needs to print a failure message
  // when the match succeeds (e.g. when the matcher is used inside
  // Not()).
  //
  // For example, a "has at least 10 elements" matcher should explain
  // what the actual element count is, regardless of the match result,
  // as it is useful information to the reader; on the other hand, an
  // "is empty" matcher probably only needs to explain what the actual
  // size is when the match fails, as it's redundant to say that the
  // size is 0 when the value is already known to be empty.
  //
  // You should override this method when defining a new matcher.
  //
  // It's the responsibility of the caller (Google Test) to guarantee
  // that 'listener' is not NULL.  This helps to simplify a matcher's
  // implementation when it doesn't care about the performance, as it
  // can talk to 'listener' without checking its validity first.
  // However, in order to implement dummy listeners efficiently,
  // listener->stream() may be NULL.
  virtual bool MatchAndExplain(T x, MatchResultListener* listener) const = 0;

  // Inherits these methods from MatcherDescriberInterface:
  //   virtual void DescribeTo(::std::ostream* os) const = 0;
  //   virtual void DescribeNegationTo(::std::ostream* os) const;
};

namespace internal {

// A match result listener that ignores the explanation.
class DummyMatchResultListener : public MatchResultListener {
 public:
  DummyMatchResultListener() : MatchResultListener(nullptr) {}

 private:
  DummyMatchResultListener(const DummyMatchResultListener&) = delete;
  DummyMatchResultListener& operator=(const DummyMatchResultListener&) = delete;
};

// A match result listener that forwards the explanation to a given
// ostream.  The difference between this and MatchResultListener is
// that the former is concrete.
class StreamMatchResultListener : public MatchResultListener {
 public:
  explicit StreamMatchResultListener(::std::ostream* os)
      : MatchResultListener(os) {}

 private:
  StreamMatchResultListener(const StreamMatchResultListener&) = delete;
  StreamMatchResultListener& operator=(const StreamMatchResultListener&) =
      delete;
};

struct SharedPayloadBase {
  std::atomic<int> ref{1};
  void Ref() { ref.fetch_add(1, std::memory_order_relaxed); }
  bool Unref() { return ref.fetch_sub(1, std::memory_order_acq_rel) == 1; }
};

template <typename T>
struct SharedPayload : SharedPayloadBase {
  explicit SharedPayload(const T& v) : value(v) {}
  explicit SharedPayload(T&& v) : value(std::move(v)) {}

  static void Destroy(SharedPayloadBase* shared) {
    delete static_cast<SharedPayload*>(shared);
  }

  T value;
};

// An internal class for implementing Matcher<T>, which will derive
// from it.  We put functionalities common to all Matcher<T>
// specializations here to avoid code duplication.
template <typename T>
class MatcherBase : private MatcherDescriberInterface {
 public:
  // Returns true if and only if the matcher matches x; also explains the
  // match result to 'listener'.
  bool MatchAndExplain(const T& x, MatchResultListener* listener) const {
    GTEST_CHECK_(vtable_ != nullptr);
    return vtable_->match_and_explain(*this, x, listener);
  }

  // Returns true if and only if this matcher matches x.
  bool Matches(const T& x) const {
    DummyMatchResultListener dummy;
    return MatchAndExplain(x, &dummy);
  }

  // Describes this matcher to an ostream.
  void DescribeTo(::std::ostream* os) const final {
    GTEST_CHECK_(vtable_ != nullptr);
    vtable_->describe(*this, os, false);
  }

  // Describes the negation of this matcher to an ostream.
  void DescribeNegationTo(::std::ostream* os) const final {
    GTEST_CHECK_(vtable_ != nullptr);
    vtable_->describe(*this, os, true);
  }

  // Explains why x matches, or doesn't match, the matcher.
  void ExplainMatchResultTo(const T& x, ::std::ostream* os) const {
    StreamMatchResultListener listener(os);
    MatchAndExplain(x, &listener);
  }

  // Returns the describer for this matcher object; retains ownership
  // of the describer, which is only guaranteed to be alive when
  // this matcher object is alive.
  const MatcherDescriberInterface* GetDescriber() const {
    if (vtable_ == nullptr) return nullptr;
    return vtable_->get_describer(*this);
  }

 protected:
  MatcherBase() : vtable_(nullptr), buffer_() {}

  // Constructs a matcher from its implementation.
  template <typename U>
  explicit MatcherBase(const MatcherInterface<U>* impl)
      : vtable_(nullptr), buffer_() {
    Init(impl);
  }

  template <typename M, typename = typename std::remove_reference<
                            M>::type::is_gtest_matcher>
  MatcherBase(M&& m) : vtable_(nullptr), buffer_() {  // NOLINT
    Init(std::forward<M>(m));
  }

  MatcherBase(const MatcherBase& other)
      : vtable_(other.vtable_), buffer_(other.buffer_) {
    if (IsShared()) buffer_.shared->Ref();
  }

  MatcherBase& operator=(const MatcherBase& other) {
    if (this == &other) return *this;
    Destroy();
    vtable_ = other.vtable_;
    buffer_ = other.buffer_;
    if (IsShared()) buffer_.shared->Ref();
    return *this;
  }

  MatcherBase(MatcherBase&& other)
      : vtable_(other.vtable_), buffer_(other.buffer_) {
    other.vtable_ = nullptr;
  }

  MatcherBase& operator=(MatcherBase&& other) {
    if (this == &other) return *this;
    Destroy();
    vtable_ = other.vtable_;
    buffer_ = other.buffer_;
    other.vtable_ = nullptr;
    return *this;
  }

  ~MatcherBase() override { Destroy(); }

 private:
  struct VTable {
    bool (*match_and_explain)(const MatcherBase&, const T&,
                              MatchResultListener*);
    void (*describe)(const MatcherBase&, std::ostream*, bool negation);
    // Returns the captured object if it implements the interface, otherwise
    // returns the MatcherBase itself.
    const MatcherDescriberInterface* (*get_describer)(const MatcherBase&);
    // Called on shared instances when the reference count reaches 0.
    void (*shared_destroy)(SharedPayloadBase*);
  };

  bool IsShared() const {
    return vtable_ != nullptr && vtable_->shared_destroy != nullptr;
  }

  // If the implementation uses a listener, call that.
  template <typename P>
  static auto MatchAndExplainImpl(const MatcherBase& m, const T& value,
                                  MatchResultListener* listener)
      -> decltype(P::Get(m).MatchAndExplain(value, listener->stream())) {
    return P::Get(m).MatchAndExplain(value, listener->stream());
  }

  template <typename P>
  static auto MatchAndExplainImpl(const MatcherBase& m, const T& value,
                                  MatchResultListener* listener)
      -> decltype(P::Get(m).MatchAndExplain(value, listener)) {
    return P::Get(m).MatchAndExplain(value, listener);
  }

  template <typename P>
  static void DescribeImpl(const MatcherBase& m, std::ostream* os,
                           bool negation) {
    if (negation) {
      P::Get(m).DescribeNegationTo(os);
    } else {
      P::Get(m).DescribeTo(os);
    }
  }

  template <typename P>
  static const MatcherDescriberInterface* GetDescriberImpl(
      const MatcherBase& m) {
    // If the impl is a MatcherDescriberInterface, then return it.
    // Otherwise use MatcherBase itself.
    // This allows us to implement the GetDescriber() function without support
    // from the impl, but some users really want to get their impl back when
    // they call GetDescriber().
    // We use std::get on a tuple as a workaround of not having `if constexpr`.
    return std::get<(
        std::is_convertible<decltype(&P::Get(m)),
                            const MatcherDescriberInterface*>::value
            ? 1
            : 0)>(std::make_tuple(&m, &P::Get(m)));
  }

  template <typename P>
  const VTable* GetVTable() {
    static constexpr VTable kVTable = {&MatchAndExplainImpl<P>,
                                       &DescribeImpl<P>, &GetDescriberImpl<P>,
                                       P::shared_destroy};
    return &kVTable;
  }

  union Buffer {
    // Add some types to give Buffer some common alignment/size use cases.
    void* ptr;
    double d;
    int64_t i;
    // And add one for the out-of-line cases.
    SharedPayloadBase* shared;
  };

  void Destroy() {
    if (IsShared() && buffer_.shared->Unref()) {
      vtable_->shared_destroy(buffer_.shared);
    }
  }

  template <typename M>
  static constexpr bool IsInlined() {
    return sizeof(M) <= sizeof(Buffer) && alignof(M) <= alignof(Buffer) &&
           std::is_trivially_copy_constructible<M>::value &&
           std::is_trivially_destructible<M>::value;
  }

  template <typename M, bool = MatcherBase::IsInlined<M>()>
  struct ValuePolicy {
    static const M& Get(const MatcherBase& m) {
      // When inlined along with Init, need to be explicit to avoid violating
      // strict aliasing rules.
      const M* ptr =
          static_cast<const M*>(static_cast<const void*>(&m.buffer_));
      return *ptr;
    }
    static void Init(MatcherBase& m, M impl) {
      ::new (static_cast<void*>(&m.buffer_)) M(impl);
    }
    static constexpr auto shared_destroy = nullptr;
  };

  template <typename M>
  struct ValuePolicy<M, false> {
    using Shared = SharedPayload<M>;
    static const M& Get(const MatcherBase& m) {
      return static_cast<Shared*>(m.buffer_.shared)->value;
    }
    template <typename Arg>
    static void Init(MatcherBase& m, Arg&& arg) {
      m.buffer_.shared = new Shared(std::forward<Arg>(arg));
    }
    static constexpr auto shared_destroy = &Shared::Destroy;
  };

  template <typename U, bool B>
  struct ValuePolicy<const MatcherInterface<U>*, B> {
    using M = const MatcherInterface<U>;
    using Shared = SharedPayload<std::unique_ptr<M>>;
    static const M& Get(const MatcherBase& m) {
      return *static_cast<Shared*>(m.buffer_.shared)->value;
    }
    static void Init(MatcherBase& m, M* impl) {
      m.buffer_.shared = new Shared(std::unique_ptr<M>(impl));
    }

    static constexpr auto shared_destroy = &Shared::Destroy;
  };

  template <typename M>
  void Init(M&& m) {
    using MM = typename std::decay<M>::type;
    using Policy = ValuePolicy<MM>;
    vtable_ = GetVTable<Policy>();
    Policy::Init(*this, std::forward<M>(m));
  }

  const VTable* vtable_;
  Buffer buffer_;
};

}  // namespace internal

// A Matcher<T> is a copyable and IMMUTABLE (except by assignment)
// object that can check whether a value of type T matches.  The
// implementation of Matcher<T> is just a std::shared_ptr to const
// MatcherInterface<T>.  Don't inherit from Matcher!
template <typename T>
class Matcher : public internal::MatcherBase<T> {
 public:
  // Constructs a null matcher.  Needed for storing Matcher objects in STL
  // containers.  A default-constructed matcher is not yet initialized.  You
  // cannot use it until a valid value has been assigned to it.
  explicit Matcher() {}  // NOLINT

  // Constructs a matcher from its implementation.
  explicit Matcher(const MatcherInterface<const T&>* impl)
      : internal::MatcherBase<T>(impl) {}

  template <typename U>
  explicit Matcher(
      const MatcherInterface<U>* impl,
      typename std::enable_if<!std::is_same<U, const U&>::value>::type* =
          nullptr)
      : internal::MatcherBase<T>(impl) {}

  template <typename M, typename = typename std::remove_reference<
                            M>::type::is_gtest_matcher>
  Matcher(M&& m) : internal::MatcherBase<T>(std::forward<M>(m)) {}  // NOLINT

  // Implicit constructor here allows people to write
  // EXPECT_CALL(foo, Bar(5)) instead of EXPECT_CALL(foo, Bar(Eq(5))) sometimes
  Matcher(T value);  // NOLINT
};

// The following two specializations allow the user to write str
// instead of Eq(str) and "foo" instead of Eq("foo") when a std::string
// matcher is expected.
template <>
class GTEST_API_ Matcher<const std::string&>
    : public internal::MatcherBase<const std::string&> {
 public:
  Matcher() = default;

  explicit Matcher(const MatcherInterface<const std::string&>* impl)
      : internal::MatcherBase<const std::string&>(impl) {}

  template <typename M, typename = typename std::remove_reference<
                            M>::type::is_gtest_matcher>
  Matcher(M&& m)  // NOLINT
      : internal::MatcherBase<const std::string&>(std::forward<M>(m)) {}

  // Allows the user to write str instead of Eq(str) sometimes, where
  // str is a std::string object.
  Matcher(const std::string& s);  // NOLINT

  // Allows the user to write "foo" instead of Eq("foo") sometimes.
  Matcher(const char* s);  // NOLINT
};

template <>
class GTEST_API_ Matcher<std::string>
    : public internal::MatcherBase<std::string> {
 public:
  Matcher() = default;

  explicit Matcher(const MatcherInterface<const std::string&>* impl)
      : internal::MatcherBase<std::string>(impl) {}
  explicit Matcher(const MatcherInterface<std::string>* impl)
      : internal::MatcherBase<std::string>(impl) {}

  template <typename M, typename = typename std::remove_reference<
                            M>::type::is_gtest_matcher>
  Matcher(M&& m)  // NOLINT
      : internal::MatcherBase<std::string>(std::forward<M>(m)) {}

  // Allows the user to write str instead of Eq(str) sometimes, where
  // str is a string object.
  Matcher(const std::string& s);  // NOLINT

  // Allows the user to write "foo" instead of Eq("foo") sometimes.
  Matcher(const char* s);  // NOLINT
};

#if GTEST_INTERNAL_HAS_STRING_VIEW
// The following two specializations allow the user to write str
// instead of Eq(str) and "foo" instead of Eq("foo") when a absl::string_view
// matcher is expected.
template <>
class GTEST_API_ Matcher<const internal::StringView&>
    : public internal::MatcherBase<const internal::StringView&> {
 public:
  Matcher() = default;

  explicit Matcher(const MatcherInterface<const internal::StringView&>* impl)
      : internal::MatcherBase<const internal::StringView&>(impl) {}

  template <typename M, typename = typename std::remove_reference<
                            M>::type::is_gtest_matcher>
  Matcher(M&& m)  // NOLINT
      : internal::MatcherBase<const internal::StringView&>(std::forward<M>(m)) {
  }

  // Allows the user to write str instead of Eq(str) sometimes, where
  // str is a std::string object.
  Matcher(const std::string& s);  // NOLINT

  // Allows the user to write "foo" instead of Eq("foo") sometimes.
  Matcher(const char* s);  // NOLINT

  // Allows the user to pass absl::string_views or std::string_views directly.
  Matcher(internal::StringView s);  // NOLINT
};

template <>
class GTEST_API_ Matcher<internal::StringView>
    : public internal::MatcherBase<internal::StringView> {
 public:
  Matcher() = default;

  explicit Matcher(const MatcherInterface<const internal::StringView&>* impl)
      : internal::MatcherBase<internal::StringView>(impl) {}
  explicit Matcher(const MatcherInterface<internal::StringView>* impl)
      : internal::MatcherBase<internal::StringView>(impl) {}

  template <typename M, typename = typename std::remove_reference<
                            M>::type::is_gtest_matcher>
  Matcher(M&& m)  // NOLINT
      : internal::MatcherBase<internal::StringView>(std::forward<M>(m)) {}

  // Allows the user to write str instead of Eq(str) sometimes, where
  // str is a std::string object.
  Matcher(const std::string& s);  // NOLINT

  // Allows the user to write "foo" instead of Eq("foo") sometimes.
  Matcher(const char* s);  // NOLINT

  // Allows the user to pass absl::string_views or std::string_views directly.
  Matcher(internal::StringView s);  // NOLINT
};
#endif  // GTEST_INTERNAL_HAS_STRING_VIEW

// Prints a matcher in a human-readable format.
template <typename T>
std::ostream& operator<<(std::ostream& os, const Matcher<T>& matcher) {
  matcher.DescribeTo(&os);
  return os;
}

// The PolymorphicMatcher class template makes it easy to implement a
// polymorphic matcher (i.e. a matcher that can match values of more
// than one type, e.g. Eq(n) and NotNull()).
//
// To define a polymorphic matcher, a user should provide an Impl
// class that has a DescribeTo() method and a DescribeNegationTo()
// method, and define a member function (or member function template)
//
//   bool MatchAndExplain(const Value& value,
//                        MatchResultListener* listener) const;
//
// See the definition of NotNull() for a complete example.
template <class Impl>
class PolymorphicMatcher {
 public:
  explicit PolymorphicMatcher(const Impl& an_impl) : impl_(an_impl) {}

  // Returns a mutable reference to the underlying matcher
  // implementation object.
  Impl& mutable_impl() { return impl_; }

  // Returns an immutable reference to the underlying matcher
  // implementation object.
  const Impl& impl() const { return impl_; }

  template <typename T>
  operator Matcher<T>() const {
    return Matcher<T>(new MonomorphicImpl<const T&>(impl_));
  }

 private:
  template <typename T>
  class MonomorphicImpl : public MatcherInterface<T> {
   public:
    explicit MonomorphicImpl(const Impl& impl) : impl_(impl) {}

    void DescribeTo(::std::ostream* os) const override { impl_.DescribeTo(os); }

    void DescribeNegationTo(::std::ostream* os) const override {
      impl_.DescribeNegationTo(os);
    }

    bool MatchAndExplain(T x, MatchResultListener* listener) const override {
      return impl_.MatchAndExplain(x, listener);
    }

   private:
    const Impl impl_;
  };

  Impl impl_;
};

// Creates a matcher from its implementation.
// DEPRECATED: Especially in the generic code, prefer:
//   Matcher<T>(new MyMatcherImpl<const T&>(...));
//
// MakeMatcher may create a Matcher that accepts its argument by value, which
// leads to unnecessary copies & lack of support for non-copyable types.
template <typename T>
inline Matcher<T> MakeMatcher(const MatcherInterface<T>* impl) {
  return Matcher<T>(impl);
}

// Creates a polymorphic matcher from its implementation.  This is
// easier to use than the PolymorphicMatcher<Impl> constructor as it
// doesn't require you to explicitly write the template argument, e.g.
//
//   MakePolymorphicMatcher(foo);
// vs
//   PolymorphicMatcher<TypeOfFoo>(foo);
template <class Impl>
inline PolymorphicMatcher<Impl> MakePolymorphicMatcher(const Impl& impl) {
  return PolymorphicMatcher<Impl>(impl);
}

namespace internal {
// Implements a matcher that compares a given value with a
// pre-supplied value using one of the ==, <=, <, etc, operators.  The
// two values being compared don't have to have the same type.
//
// The matcher defined here is polymorphic (for example, Eq(5) can be
// used to match an int, a short, a double, etc).  Therefore we use
// a template type conversion operator in the implementation.
//
// The following template definition assumes that the Rhs parameter is
// a "bare" type (i.e. neither 'const T' nor 'T&').
template <typename D, typename Rhs, typename Op>
class ComparisonBase {
 public:
  explicit ComparisonBase(const Rhs& rhs) : rhs_(rhs) {}

  using is_gtest_matcher = void;

  template <typename Lhs>
  bool MatchAndExplain(const Lhs& lhs, std::ostream*) const {
    return Op()(lhs, Unwrap(rhs_));
  }
  void DescribeTo(std::ostream* os) const {
    *os << D::Desc() << " ";
    UniversalPrint(Unwrap(rhs_), os);
  }
  void DescribeNegationTo(std::ostream* os) const {
    *os << D::NegatedDesc() << " ";
    UniversalPrint(Unwrap(rhs_), os);
  }

 private:
  template <typename T>
  static const T& Unwrap(const T& v) {
    return v;
  }
  template <typename T>
  static const T& Unwrap(std::reference_wrapper<T> v) {
    return v;
  }

  Rhs rhs_;
};

template <typename Rhs>
class EqMatcher : public ComparisonBase<EqMatcher<Rhs>, Rhs, std::equal_to<>> {
 public:
  explicit EqMatcher(const Rhs& rhs)
      : ComparisonBase<EqMatcher<Rhs>, Rhs, std::equal_to<>>(rhs) {}
  static const char* Desc() { return "is equal to"; }
  static const char* NegatedDesc() { return "isn't equal to"; }
};
template <typename Rhs>
class NeMatcher
    : public ComparisonBase<NeMatcher<Rhs>, Rhs, std::not_equal_to<>> {
 public:
  explicit NeMatcher(const Rhs& rhs)
      : ComparisonBase<NeMatcher<Rhs>, Rhs, std::not_equal_to<>>(rhs) {}
  static const char* Desc() { return "isn't equal to"; }
  static const char* NegatedDesc() { return "is equal to"; }
};
template <typename Rhs>
class LtMatcher : public ComparisonBase<LtMatcher<Rhs>, Rhs, std::less<>> {
 public:
  explicit LtMatcher(const Rhs& rhs)
      : ComparisonBase<LtMatcher<Rhs>, Rhs, std::less<>>(rhs) {}
  static const char* Desc() { return "is <"; }
  static const char* NegatedDesc() { return "isn't <"; }
};
template <typename Rhs>
class GtMatcher : public ComparisonBase<GtMatcher<Rhs>, Rhs, std::greater<>> {
 public:
  explicit GtMatcher(const Rhs& rhs)
      : ComparisonBase<GtMatcher<Rhs>, Rhs, std::greater<>>(rhs) {}
  static const char* Desc() { return "is >"; }
  static const char* NegatedDesc() { return "isn't >"; }
};
template <typename Rhs>
class LeMatcher
    : public ComparisonBase<LeMatcher<Rhs>, Rhs, std::less_equal<>> {
 public:
  explicit LeMatcher(const Rhs& rhs)
      : ComparisonBase<LeMatcher<Rhs>, Rhs, std::less_equal<>>(rhs) {}
  static const char* Desc() { return "is <="; }
  static const char* NegatedDesc() { return "isn't <="; }
};
template <typename Rhs>
class GeMatcher
    : public ComparisonBase<GeMatcher<Rhs>, Rhs, std::greater_equal<>> {
 public:
  explicit GeMatcher(const Rhs& rhs)
      : ComparisonBase<GeMatcher<Rhs>, Rhs, std::greater_equal<>>(rhs) {}
  static const char* Desc() { return "is >="; }
  static const char* NegatedDesc() { return "isn't >="; }
};

template <typename T, typename = typename std::enable_if<
                          std::is_constructible<std::string, T>::value>::type>
using StringLike = T;

// Implements polymorphic matchers MatchesRegex(regex) and
// ContainsRegex(regex), which can be used as a Matcher<T> as long as
// T can be converted to a string.
class MatchesRegexMatcher {
 public:
  MatchesRegexMatcher(const RE* regex, bool full_match)
      : regex_(regex), full_match_(full_match) {}

#if GTEST_INTERNAL_HAS_STRING_VIEW
  bool MatchAndExplain(const internal::StringView& s,
                       MatchResultListener* listener) const {
    return MatchAndExplain(std::string(s), listener);
  }
#endif  // GTEST_INTERNAL_HAS_STRING_VIEW

  // Accepts pointer types, particularly:
  //   const char*
  //   char*
  //   const wchar_t*
  //   wchar_t*
  template <typename CharType>
  bool MatchAndExplain(CharType* s, MatchResultListener* listener) const {
    return s != nullptr && MatchAndExplain(std::string(s), listener);
  }

  // Matches anything that can convert to std::string.
  //
  // This is a template, not just a plain function with const std::string&,
  // because absl::string_view has some interfering non-explicit constructors.
  template <class MatcheeStringType>
  bool MatchAndExplain(const MatcheeStringType& s,
                       MatchResultListener* /* listener */) const {
    const std::string s2(s);
    return full_match_ ? RE::FullMatch(s2, *regex_)
                       : RE::PartialMatch(s2, *regex_);
  }

  void DescribeTo(::std::ostream* os) const {
    *os << (full_match_ ? "matches" : "contains") << " regular expression ";
    UniversalPrinter<std::string>::Print(regex_->pattern(), os);
  }

  void DescribeNegationTo(::std::ostream* os) const {
    *os << "doesn't " << (full_match_ ? "match" : "contain")
        << " regular expression ";
    UniversalPrinter<std::string>::Print(regex_->pattern(), os);
  }

 private:
  const std::shared_ptr<const RE> regex_;
  const bool full_match_;
};
}  // namespace internal

// Matches a string that fully matches regular expression 'regex'.
// The matcher takes ownership of 'regex'.
inline PolymorphicMatcher<internal::MatchesRegexMatcher> MatchesRegex(
    const internal::RE* regex) {
  return MakePolymorphicMatcher(internal::MatchesRegexMatcher(regex, true));
}
template <typename T = std::string>
PolymorphicMatcher<internal::MatchesRegexMatcher> MatchesRegex(
    const internal::StringLike<T>& regex) {
  return MatchesRegex(new internal::RE(std::string(regex)));
}

// Matches a string that contains regular expression 'regex'.
// The matcher takes ownership of 'regex'.
inline PolymorphicMatcher<internal::MatchesRegexMatcher> ContainsRegex(
    const internal::RE* regex) {
  return MakePolymorphicMatcher(internal::MatchesRegexMatcher(regex, false));
}
template <typename T = std::string>
PolymorphicMatcher<internal::MatchesRegexMatcher> ContainsRegex(
    const internal::StringLike<T>& regex) {
  return ContainsRegex(new internal::RE(std::string(regex)));
}

// Creates a polymorphic matcher that matches anything equal to x.
// Note: if the parameter of Eq() were declared as const T&, Eq("foo")
// wouldn't compile.
template <typename T>
inline internal::EqMatcher<T> Eq(T x) {
  return internal::EqMatcher<T>(x);
}

// Constructs a Matcher<T> from a 'value' of type T.  The constructed
// matcher matches any value that's equal to 'value'.
template <typename T>
Matcher<T>::Matcher(T value) {
  *this = Eq(value);
}

// Creates a monomorphic matcher that matches anything with type Lhs
// and equal to rhs.  A user may need to use this instead of Eq(...)
// in order to resolve an overloading ambiguity.
//
// TypedEq<T>(x) is just a convenient short-hand for Matcher<T>(Eq(x))
// or Matcher<T>(x), but more readable than the latter.
//
// We could define similar monomorphic matchers for other comparison
// operations (e.g. TypedLt, TypedGe, and etc), but decided not to do
// it yet as those are used much less than Eq() in practice.  A user
// can always write Matcher<T>(Lt(5)) to be explicit about the type,
// for example.
template <typename Lhs, typename Rhs>
inline Matcher<Lhs> TypedEq(const Rhs& rhs) {
  return Eq(rhs);
}

// Creates a polymorphic matcher that matches anything >= x.
template <typename Rhs>
inline internal::GeMatcher<Rhs> Ge(Rhs x) {
  return internal::GeMatcher<Rhs>(x);
}

// Creates a polymorphic matcher that matches anything > x.
template <typename Rhs>
inline internal::GtMatcher<Rhs> Gt(Rhs x) {
  return internal::GtMatcher<Rhs>(x);
}

// Creates a polymorphic matcher that matches anything <= x.
template <typename Rhs>
inline internal::LeMatcher<Rhs> Le(Rhs x) {
  return internal::LeMatcher<Rhs>(x);
}

// Creates a polymorphic matcher that matches anything < x.
template <typename Rhs>
inline internal::LtMatcher<Rhs> Lt(Rhs x) {
  return internal::LtMatcher<Rhs>(x);
}

// Creates a polymorphic matcher that matches anything != x.
template <typename Rhs>
inline internal::NeMatcher<Rhs> Ne(Rhs x) {
  return internal::NeMatcher<Rhs>(x);
}
}  // namespace testing

GTEST_DISABLE_MSC_WARNINGS_POP_()  //  4251 5046

#endif  // GOOGLETEST_INCLUDE_GTEST_GTEST_MATCHERS_H_