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  1. // Copyright 2007, Google Inc.
  2. // All rights reserved.
  3. //
  4. // Redistribution and use in source and binary forms, with or without
  5. // modification, are permitted provided that the following conditions are
  6. // met:
  7. //
  8. //     * Redistributions of source code must retain the above copyright
  9. // notice, this list of conditions and the following disclaimer.
  10. //     * Redistributions in binary form must reproduce the above
  11. // copyright notice, this list of conditions and the following disclaimer
  12. // in the documentation and/or other materials provided with the
  13. // distribution.
  14. //     * Neither the name of Google Inc. nor the names of its
  15. // contributors may be used to endorse or promote products derived from
  16. // this software without specific prior written permission.
  17. //
  18. // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19. // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20. // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21. // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22. // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23. // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24. // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25. // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26. // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27. // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28. // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29.  
  30.  
  31. // Google Mock - a framework for writing C++ mock classes.
  32. //
  33. // This file implements Matcher<const string&>, Matcher<string>, and
  34. // utilities for defining matchers.
  35.  
  36. #include "gmock/gmock-matchers.h"
  37. #include "gmock/gmock-generated-matchers.h"
  38.  
  39. #include <string.h>
  40. #include <iostream>
  41. #include <sstream>
  42. #include <string>
  43.  
  44. namespace testing {
  45.  
  46. // Constructs a matcher that matches a const std::string& whose value is
  47. // equal to s.
  48. Matcher<const std::string&>::Matcher(const std::string& s) { *this = Eq(s); }
  49.  
  50. #if GTEST_HAS_GLOBAL_STRING
  51. // Constructs a matcher that matches a const std::string& whose value is
  52. // equal to s.
  53. Matcher<const std::string&>::Matcher(const ::string& s) {
  54.   *this = Eq(static_cast<std::string>(s));
  55. }
  56. #endif  // GTEST_HAS_GLOBAL_STRING
  57.  
  58. // Constructs a matcher that matches a const std::string& whose value is
  59. // equal to s.
  60. Matcher<const std::string&>::Matcher(const char* s) {
  61.   *this = Eq(std::string(s));
  62. }
  63.  
  64. // Constructs a matcher that matches a std::string whose value is equal to
  65. // s.
  66. Matcher<std::string>::Matcher(const std::string& s) { *this = Eq(s); }
  67.  
  68. #if GTEST_HAS_GLOBAL_STRING
  69. // Constructs a matcher that matches a std::string whose value is equal to
  70. // s.
  71. Matcher<std::string>::Matcher(const ::string& s) {
  72.   *this = Eq(static_cast<std::string>(s));
  73. }
  74. #endif  // GTEST_HAS_GLOBAL_STRING
  75.  
  76. // Constructs a matcher that matches a std::string whose value is equal to
  77. // s.
  78. Matcher<std::string>::Matcher(const char* s) { *this = Eq(std::string(s)); }
  79.  
  80. #if GTEST_HAS_GLOBAL_STRING
  81. // Constructs a matcher that matches a const ::string& whose value is
  82. // equal to s.
  83. Matcher<const ::string&>::Matcher(const std::string& s) {
  84.   *this = Eq(static_cast<::string>(s));
  85. }
  86.  
  87. // Constructs a matcher that matches a const ::string& whose value is
  88. // equal to s.
  89. Matcher<const ::string&>::Matcher(const ::string& s) { *this = Eq(s); }
  90.  
  91. // Constructs a matcher that matches a const ::string& whose value is
  92. // equal to s.
  93. Matcher<const ::string&>::Matcher(const char* s) { *this = Eq(::string(s)); }
  94.  
  95. // Constructs a matcher that matches a ::string whose value is equal to s.
  96. Matcher<::string>::Matcher(const std::string& s) {
  97.   *this = Eq(static_cast<::string>(s));
  98. }
  99.  
  100. // Constructs a matcher that matches a ::string whose value is equal to s.
  101. Matcher<::string>::Matcher(const ::string& s) { *this = Eq(s); }
  102.  
  103. // Constructs a matcher that matches a string whose value is equal to s.
  104. Matcher<::string>::Matcher(const char* s) { *this = Eq(::string(s)); }
  105. #endif  // GTEST_HAS_GLOBAL_STRING
  106.  
  107. #if GTEST_HAS_ABSL
  108. // Constructs a matcher that matches a const absl::string_view& whose value is
  109. // equal to s.
  110. Matcher<const absl::string_view&>::Matcher(const std::string& s) {
  111.   *this = Eq(s);
  112. }
  113.  
  114. #if GTEST_HAS_GLOBAL_STRING
  115. // Constructs a matcher that matches a const absl::string_view& whose value is
  116. // equal to s.
  117. Matcher<const absl::string_view&>::Matcher(const ::string& s) { *this = Eq(s); }
  118. #endif  // GTEST_HAS_GLOBAL_STRING
  119.  
  120. // Constructs a matcher that matches a const absl::string_view& whose value is
  121. // equal to s.
  122. Matcher<const absl::string_view&>::Matcher(const char* s) {
  123.   *this = Eq(std::string(s));
  124. }
  125.  
  126. // Constructs a matcher that matches a const absl::string_view& whose value is
  127. // equal to s.
  128. Matcher<const absl::string_view&>::Matcher(absl::string_view s) {
  129.   *this = Eq(std::string(s));
  130. }
  131.  
  132. // Constructs a matcher that matches a absl::string_view whose value is equal to
  133. // s.
  134. Matcher<absl::string_view>::Matcher(const std::string& s) { *this = Eq(s); }
  135.  
  136. #if GTEST_HAS_GLOBAL_STRING
  137. // Constructs a matcher that matches a absl::string_view whose value is equal to
  138. // s.
  139. Matcher<absl::string_view>::Matcher(const ::string& s) { *this = Eq(s); }
  140. #endif  // GTEST_HAS_GLOBAL_STRING
  141.  
  142. // Constructs a matcher that matches a absl::string_view whose value is equal to
  143. // s.
  144. Matcher<absl::string_view>::Matcher(const char* s) {
  145.   *this = Eq(std::string(s));
  146. }
  147.  
  148. // Constructs a matcher that matches a absl::string_view whose value is equal to
  149. // s.
  150. Matcher<absl::string_view>::Matcher(absl::string_view s) {
  151.   *this = Eq(std::string(s));
  152. }
  153. #endif  // GTEST_HAS_ABSL
  154.  
  155. namespace internal {
  156.  
  157. // Returns the description for a matcher defined using the MATCHER*()
  158. // macro where the user-supplied description string is "", if
  159. // 'negation' is false; otherwise returns the description of the
  160. // negation of the matcher.  'param_values' contains a list of strings
  161. // that are the print-out of the matcher's parameters.
  162. GTEST_API_ std::string FormatMatcherDescription(bool negation,
  163.                                                 const char* matcher_name,
  164.                                                 const Strings& param_values) {
  165.   std::string result = ConvertIdentifierNameToWords(matcher_name);
  166.   if (param_values.size() >= 1) result += " " + JoinAsTuple(param_values);
  167.   return negation ? "not (" + result + ")" : result;
  168. }
  169.  
  170. // FindMaxBipartiteMatching and its helper class.
  171. //
  172. // Uses the well-known Ford-Fulkerson max flow method to find a maximum
  173. // bipartite matching. Flow is considered to be from left to right.
  174. // There is an implicit source node that is connected to all of the left
  175. // nodes, and an implicit sink node that is connected to all of the
  176. // right nodes. All edges have unit capacity.
  177. //
  178. // Neither the flow graph nor the residual flow graph are represented
  179. // explicitly. Instead, they are implied by the information in 'graph' and
  180. // a vector<int> called 'left_' whose elements are initialized to the
  181. // value kUnused. This represents the initial state of the algorithm,
  182. // where the flow graph is empty, and the residual flow graph has the
  183. // following edges:
  184. //   - An edge from source to each left_ node
  185. //   - An edge from each right_ node to sink
  186. //   - An edge from each left_ node to each right_ node, if the
  187. //     corresponding edge exists in 'graph'.
  188. //
  189. // When the TryAugment() method adds a flow, it sets left_[l] = r for some
  190. // nodes l and r. This induces the following changes:
  191. //   - The edges (source, l), (l, r), and (r, sink) are added to the
  192. //     flow graph.
  193. //   - The same three edges are removed from the residual flow graph.
  194. //   - The reverse edges (l, source), (r, l), and (sink, r) are added
  195. //     to the residual flow graph, which is a directional graph
  196. //     representing unused flow capacity.
  197. //
  198. // When the method augments a flow (moving left_[l] from some r1 to some
  199. // other r2), this can be thought of as "undoing" the above steps with
  200. // respect to r1 and "redoing" them with respect to r2.
  201. //
  202. // It bears repeating that the flow graph and residual flow graph are
  203. // never represented explicitly, but can be derived by looking at the
  204. // information in 'graph' and in left_.
  205. //
  206. // As an optimization, there is a second vector<int> called right_ which
  207. // does not provide any new information. Instead, it enables more
  208. // efficient queries about edges entering or leaving the right-side nodes
  209. // of the flow or residual flow graphs. The following invariants are
  210. // maintained:
  211. //
  212. // left[l] == kUnused or right[left[l]] == l
  213. // right[r] == kUnused or left[right[r]] == r
  214. //
  215. // . [ source ]                                        .
  216. // .   |||                                             .
  217. // .   |||                                             .
  218. // .   ||\--> left[0]=1  ---\    right[0]=-1 ----\     .
  219. // .   ||                   |                    |     .
  220. // .   |\---> left[1]=-1    \--> right[1]=0  ---\|     .
  221. // .   |                                        ||     .
  222. // .   \----> left[2]=2  ------> right[2]=2  --\||     .
  223. // .                                           |||     .
  224. // .         elements           matchers       vvv     .
  225. // .                                         [ sink ]  .
  226. //
  227. // See Also:
  228. //   [1] Cormen, et al (2001). "Section 26.2: The Ford-Fulkerson method".
  229. //       "Introduction to Algorithms (Second ed.)", pp. 651-664.
  230. //   [2] "Ford-Fulkerson algorithm", Wikipedia,
  231. //       'http://en.wikipedia.org/wiki/Ford%E2%80%93Fulkerson_algorithm'
  232. class MaxBipartiteMatchState {
  233.  public:
  234.   explicit MaxBipartiteMatchState(const MatchMatrix& graph)
  235.       : graph_(&graph),
  236.         left_(graph_->LhsSize(), kUnused),
  237.         right_(graph_->RhsSize(), kUnused) {}
  238.  
  239.   // Returns the edges of a maximal match, each in the form {left, right}.
  240.   ElementMatcherPairs Compute() {
  241.     // 'seen' is used for path finding { 0: unseen, 1: seen }.
  242.     ::std::vector<char> seen;
  243.     // Searches the residual flow graph for a path from each left node to
  244.     // the sink in the residual flow graph, and if one is found, add flow
  245.     // to the graph. It's okay to search through the left nodes once. The
  246.     // edge from the implicit source node to each previously-visited left
  247.     // node will have flow if that left node has any path to the sink
  248.     // whatsoever. Subsequent augmentations can only add flow to the
  249.     // network, and cannot take away that previous flow unit from the source.
  250.     // Since the source-to-left edge can only carry one flow unit (or,
  251.     // each element can be matched to only one matcher), there is no need
  252.     // to visit the left nodes more than once looking for augmented paths.
  253.     // The flow is known to be possible or impossible by looking at the
  254.     // node once.
  255.     for (size_t ilhs = 0; ilhs < graph_->LhsSize(); ++ilhs) {
  256.       // Reset the path-marking vector and try to find a path from
  257.       // source to sink starting at the left_[ilhs] node.
  258.       GTEST_CHECK_(left_[ilhs] == kUnused)
  259.           << "ilhs: " << ilhs << ", left_[ilhs]: " << left_[ilhs];
  260.       // 'seen' initialized to 'graph_->RhsSize()' copies of 0.
  261.       seen.assign(graph_->RhsSize(), 0);
  262.       TryAugment(ilhs, &seen);
  263.     }
  264.     ElementMatcherPairs result;
  265.     for (size_t ilhs = 0; ilhs < left_.size(); ++ilhs) {
  266.       size_t irhs = left_[ilhs];
  267.       if (irhs == kUnused) continue;
  268.       result.push_back(ElementMatcherPair(ilhs, irhs));
  269.     }
  270.     return result;
  271.   }
  272.  
  273.  private:
  274.   static const size_t kUnused = static_cast<size_t>(-1);
  275.  
  276.   // Perform a depth-first search from left node ilhs to the sink.  If a
  277.   // path is found, flow is added to the network by linking the left and
  278.   // right vector elements corresponding each segment of the path.
  279.   // Returns true if a path to sink was found, which means that a unit of
  280.   // flow was added to the network. The 'seen' vector elements correspond
  281.   // to right nodes and are marked to eliminate cycles from the search.
  282.   //
  283.   // Left nodes will only be explored at most once because they
  284.   // are accessible from at most one right node in the residual flow
  285.   // graph.
  286.   //
  287.   // Note that left_[ilhs] is the only element of left_ that TryAugment will
  288.   // potentially transition from kUnused to another value. Any other
  289.   // left_ element holding kUnused before TryAugment will be holding it
  290.   // when TryAugment returns.
  291.   //
  292.   bool TryAugment(size_t ilhs, ::std::vector<char>* seen) {
  293.     for (size_t irhs = 0; irhs < graph_->RhsSize(); ++irhs) {
  294.       if ((*seen)[irhs]) continue;
  295.       if (!graph_->HasEdge(ilhs, irhs)) continue;
  296.       // There's an available edge from ilhs to irhs.
  297.       (*seen)[irhs] = 1;
  298.       // Next a search is performed to determine whether
  299.       // this edge is a dead end or leads to the sink.
  300.       //
  301.       // right_[irhs] == kUnused means that there is residual flow from
  302.       // right node irhs to the sink, so we can use that to finish this
  303.       // flow path and return success.
  304.       //
  305.       // Otherwise there is residual flow to some ilhs. We push flow
  306.       // along that path and call ourselves recursively to see if this
  307.       // ultimately leads to sink.
  308.       if (right_[irhs] == kUnused || TryAugment(right_[irhs], seen)) {
  309.         // Add flow from left_[ilhs] to right_[irhs].
  310.         left_[ilhs] = irhs;
  311.         right_[irhs] = ilhs;
  312.         return true;
  313.       }
  314.     }
  315.     return false;
  316.   }
  317.  
  318.   const MatchMatrix* graph_;  // not owned
  319.   // Each element of the left_ vector represents a left hand side node
  320.   // (i.e. an element) and each element of right_ is a right hand side
  321.   // node (i.e. a matcher). The values in the left_ vector indicate
  322.   // outflow from that node to a node on the right_ side. The values
  323.   // in the right_ indicate inflow, and specify which left_ node is
  324.   // feeding that right_ node, if any. For example, left_[3] == 1 means
  325.   // there's a flow from element #3 to matcher #1. Such a flow would also
  326.   // be redundantly represented in the right_ vector as right_[1] == 3.
  327.   // Elements of left_ and right_ are either kUnused or mutually
  328.   // referent. Mutually referent means that left_[right_[i]] = i and
  329.   // right_[left_[i]] = i.
  330.   ::std::vector<size_t> left_;
  331.   ::std::vector<size_t> right_;
  332.  
  333.   GTEST_DISALLOW_ASSIGN_(MaxBipartiteMatchState);
  334. };
  335.  
  336. const size_t MaxBipartiteMatchState::kUnused;
  337.  
  338. GTEST_API_ ElementMatcherPairs FindMaxBipartiteMatching(const MatchMatrix& g) {
  339.   return MaxBipartiteMatchState(g).Compute();
  340. }
  341.  
  342. static void LogElementMatcherPairVec(const ElementMatcherPairs& pairs,
  343.                                      ::std::ostream* stream) {
  344.   typedef ElementMatcherPairs::const_iterator Iter;
  345.   ::std::ostream& os = *stream;
  346.   os << "{";
  347.   const char* sep = "";
  348.   for (Iter it = pairs.begin(); it != pairs.end(); ++it) {
  349.     os << sep << "\n  ("
  350.        << "element #" << it->first << ", "
  351.        << "matcher #" << it->second << ")";
  352.     sep = ",";
  353.   }
  354.   os << "\n}";
  355. }
  356.  
  357. bool MatchMatrix::NextGraph() {
  358.   for (size_t ilhs = 0; ilhs < LhsSize(); ++ilhs) {
  359.     for (size_t irhs = 0; irhs < RhsSize(); ++irhs) {
  360.       char& b = matched_[SpaceIndex(ilhs, irhs)];
  361.       if (!b) {
  362.         b = 1;
  363.         return true;
  364.       }
  365.       b = 0;
  366.     }
  367.   }
  368.   return false;
  369. }
  370.  
  371. void MatchMatrix::Randomize() {
  372.   for (size_t ilhs = 0; ilhs < LhsSize(); ++ilhs) {
  373.     for (size_t irhs = 0; irhs < RhsSize(); ++irhs) {
  374.       char& b = matched_[SpaceIndex(ilhs, irhs)];
  375.       b = static_cast<char>(rand() & 1);  // NOLINT
  376.     }
  377.   }
  378. }
  379.  
  380. std::string MatchMatrix::DebugString() const {
  381.   ::std::stringstream ss;
  382.   const char* sep = "";
  383.   for (size_t i = 0; i < LhsSize(); ++i) {
  384.     ss << sep;
  385.     for (size_t j = 0; j < RhsSize(); ++j) {
  386.       ss << HasEdge(i, j);
  387.     }
  388.     sep = ";";
  389.   }
  390.   return ss.str();
  391. }
  392.  
  393. void UnorderedElementsAreMatcherImplBase::DescribeToImpl(
  394.     ::std::ostream* os) const {
  395.   switch (match_flags()) {
  396.     case UnorderedMatcherRequire::ExactMatch:
  397.       if (matcher_describers_.empty()) {
  398.         *os << "is empty";
  399.         return;
  400.       }
  401.       if (matcher_describers_.size() == 1) {
  402.         *os << "has " << Elements(1) << " and that element ";
  403.         matcher_describers_[0]->DescribeTo(os);
  404.         return;
  405.       }
  406.       *os << "has " << Elements(matcher_describers_.size())
  407.           << " and there exists some permutation of elements such that:\n";
  408.       break;
  409.     case UnorderedMatcherRequire::Superset:
  410.       *os << "a surjection from elements to requirements exists such that:\n";
  411.       break;
  412.     case UnorderedMatcherRequire::Subset:
  413.       *os << "an injection from elements to requirements exists such that:\n";
  414.       break;
  415.   }
  416.  
  417.   const char* sep = "";
  418.   for (size_t i = 0; i != matcher_describers_.size(); ++i) {
  419.     *os << sep;
  420.     if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
  421.       *os << " - element #" << i << " ";
  422.     } else {
  423.       *os << " - an element ";
  424.     }
  425.     matcher_describers_[i]->DescribeTo(os);
  426.     if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
  427.       sep = ", and\n";
  428.     } else {
  429.       sep = "\n";
  430.     }
  431.   }
  432. }
  433.  
  434. void UnorderedElementsAreMatcherImplBase::DescribeNegationToImpl(
  435.     ::std::ostream* os) const {
  436.   switch (match_flags()) {
  437.     case UnorderedMatcherRequire::ExactMatch:
  438.       if (matcher_describers_.empty()) {
  439.         *os << "isn't empty";
  440.         return;
  441.       }
  442.       if (matcher_describers_.size() == 1) {
  443.         *os << "doesn't have " << Elements(1) << ", or has " << Elements(1)
  444.             << " that ";
  445.         matcher_describers_[0]->DescribeNegationTo(os);
  446.         return;
  447.       }
  448.       *os << "doesn't have " << Elements(matcher_describers_.size())
  449.           << ", or there exists no permutation of elements such that:\n";
  450.       break;
  451.     case UnorderedMatcherRequire::Superset:
  452.       *os << "no surjection from elements to requirements exists such that:\n";
  453.       break;
  454.     case UnorderedMatcherRequire::Subset:
  455.       *os << "no injection from elements to requirements exists such that:\n";
  456.       break;
  457.   }
  458.   const char* sep = "";
  459.   for (size_t i = 0; i != matcher_describers_.size(); ++i) {
  460.     *os << sep;
  461.     if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
  462.       *os << " - element #" << i << " ";
  463.     } else {
  464.       *os << " - an element ";
  465.     }
  466.     matcher_describers_[i]->DescribeTo(os);
  467.     if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
  468.       sep = ", and\n";
  469.     } else {
  470.       sep = "\n";
  471.     }
  472.   }
  473. }
  474.  
  475. // Checks that all matchers match at least one element, and that all
  476. // elements match at least one matcher. This enables faster matching
  477. // and better error reporting.
  478. // Returns false, writing an explanation to 'listener', if and only
  479. // if the success criteria are not met.
  480. bool UnorderedElementsAreMatcherImplBase::VerifyMatchMatrix(
  481.     const ::std::vector<std::string>& element_printouts,
  482.     const MatchMatrix& matrix, MatchResultListener* listener) const {
  483.   bool result = true;
  484.   ::std::vector<char> element_matched(matrix.LhsSize(), 0);
  485.   ::std::vector<char> matcher_matched(matrix.RhsSize(), 0);
  486.  
  487.   for (size_t ilhs = 0; ilhs < matrix.LhsSize(); ilhs++) {
  488.     for (size_t irhs = 0; irhs < matrix.RhsSize(); irhs++) {
  489.       char matched = matrix.HasEdge(ilhs, irhs);
  490.       element_matched[ilhs] |= matched;
  491.       matcher_matched[irhs] |= matched;
  492.     }
  493.   }
  494.  
  495.   if (match_flags() & UnorderedMatcherRequire::Superset) {
  496.     const char* sep =
  497.         "where the following matchers don't match any elements:\n";
  498.     for (size_t mi = 0; mi < matcher_matched.size(); ++mi) {
  499.       if (matcher_matched[mi]) continue;
  500.       result = false;
  501.       if (listener->IsInterested()) {
  502.         *listener << sep << "matcher #" << mi << ": ";
  503.         matcher_describers_[mi]->DescribeTo(listener->stream());
  504.         sep = ",\n";
  505.       }
  506.     }
  507.   }
  508.  
  509.   if (match_flags() & UnorderedMatcherRequire::Subset) {
  510.     const char* sep =
  511.         "where the following elements don't match any matchers:\n";
  512.     const char* outer_sep = "";
  513.     if (!result) {
  514.       outer_sep = "\nand ";
  515.     }
  516.     for (size_t ei = 0; ei < element_matched.size(); ++ei) {
  517.       if (element_matched[ei]) continue;
  518.       result = false;
  519.       if (listener->IsInterested()) {
  520.         *listener << outer_sep << sep << "element #" << ei << ": "
  521.                   << element_printouts[ei];
  522.         sep = ",\n";
  523.         outer_sep = "";
  524.       }
  525.     }
  526.   }
  527.   return result;
  528. }
  529.  
  530. bool UnorderedElementsAreMatcherImplBase::FindPairing(
  531.     const MatchMatrix& matrix, MatchResultListener* listener) const {
  532.   ElementMatcherPairs matches = FindMaxBipartiteMatching(matrix);
  533.  
  534.   size_t max_flow = matches.size();
  535.   if ((match_flags() & UnorderedMatcherRequire::Superset) &&
  536.       max_flow < matrix.RhsSize()) {
  537.     if (listener->IsInterested()) {
  538.       *listener << "where no permutation of the elements can satisfy all "
  539.                    "matchers, and the closest match is "
  540.                 << max_flow << " of " << matrix.RhsSize()
  541.                 << " matchers with the pairings:\n";
  542.       LogElementMatcherPairVec(matches, listener->stream());
  543.     }
  544.     return false;
  545.   }
  546.   if ((match_flags() & UnorderedMatcherRequire::Subset) &&
  547.       max_flow < matrix.LhsSize()) {
  548.     if (listener->IsInterested()) {
  549.       *listener
  550.           << "where not all elements can be matched, and the closest match is "
  551.           << max_flow << " of " << matrix.RhsSize()
  552.           << " matchers with the pairings:\n";
  553.       LogElementMatcherPairVec(matches, listener->stream());
  554.     }
  555.     return false;
  556.   }
  557.  
  558.   if (matches.size() > 1) {
  559.     if (listener->IsInterested()) {
  560.       const char* sep = "where:\n";
  561.       for (size_t mi = 0; mi < matches.size(); ++mi) {
  562.         *listener << sep << " - element #" << matches[mi].first
  563.                   << " is matched by matcher #" << matches[mi].second;
  564.         sep = ",\n";
  565.       }
  566.     }
  567.   }
  568.   return true;
  569. }
  570.  
  571. }  // namespace internal
  572. }  // namespace testing
  573.