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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
38 #include <string.h>
39 #include <iostream>
40 #include <sstream>
41 #include <string>
42
43 namespace testing {
44 namespace internal {
45
46 // Returns the description for a matcher defined using the MATCHER*()
47 // macro where the user-supplied description string is "", if
48 // 'negation' is false; otherwise returns the description of the
49 // negation of the matcher. 'param_values' contains a list of strings
50 // that are the print-out of the matcher's parameters.
FormatMatcherDescription(bool negation,const char * matcher_name,const Strings & param_values)51 GTEST_API_ std::string FormatMatcherDescription(bool negation,
52 const char* matcher_name,
53 const Strings& param_values) {
54 std::string result = ConvertIdentifierNameToWords(matcher_name);
55 if (param_values.size() >= 1) result += " " + JoinAsTuple(param_values);
56 return negation ? "not (" + result + ")" : result;
57 }
58
59 // FindMaxBipartiteMatching and its helper class.
60 //
61 // Uses the well-known Ford-Fulkerson max flow method to find a maximum
62 // bipartite matching. Flow is considered to be from left to right.
63 // There is an implicit source node that is connected to all of the left
64 // nodes, and an implicit sink node that is connected to all of the
65 // right nodes. All edges have unit capacity.
66 //
67 // Neither the flow graph nor the residual flow graph are represented
68 // explicitly. Instead, they are implied by the information in 'graph' and
69 // a vector<int> called 'left_' whose elements are initialized to the
70 // value kUnused. This represents the initial state of the algorithm,
71 // where the flow graph is empty, and the residual flow graph has the
72 // following edges:
73 // - An edge from source to each left_ node
74 // - An edge from each right_ node to sink
75 // - An edge from each left_ node to each right_ node, if the
76 // corresponding edge exists in 'graph'.
77 //
78 // When the TryAugment() method adds a flow, it sets left_[l] = r for some
79 // nodes l and r. This induces the following changes:
80 // - The edges (source, l), (l, r), and (r, sink) are added to the
81 // flow graph.
82 // - The same three edges are removed from the residual flow graph.
83 // - The reverse edges (l, source), (r, l), and (sink, r) are added
84 // to the residual flow graph, which is a directional graph
85 // representing unused flow capacity.
86 //
87 // When the method augments a flow (moving left_[l] from some r1 to some
88 // other r2), this can be thought of as "undoing" the above steps with
89 // respect to r1 and "redoing" them with respect to r2.
90 //
91 // It bears repeating that the flow graph and residual flow graph are
92 // never represented explicitly, but can be derived by looking at the
93 // information in 'graph' and in left_.
94 //
95 // As an optimization, there is a second vector<int> called right_ which
96 // does not provide any new information. Instead, it enables more
97 // efficient queries about edges entering or leaving the right-side nodes
98 // of the flow or residual flow graphs. The following invariants are
99 // maintained:
100 //
101 // left[l] == kUnused or right[left[l]] == l
102 // right[r] == kUnused or left[right[r]] == r
103 //
104 // . [ source ] .
105 // . ||| .
106 // . ||| .
107 // . ||\--> left[0]=1 ---\ right[0]=-1 ----\ .
108 // . || | | .
109 // . |\---> left[1]=-1 \--> right[1]=0 ---\| .
110 // . | || .
111 // . \----> left[2]=2 ------> right[2]=2 --\|| .
112 // . ||| .
113 // . elements matchers vvv .
114 // . [ sink ] .
115 //
116 // See Also:
117 // [1] Cormen, et al (2001). "Section 26.2: The Ford-Fulkerson method".
118 // "Introduction to Algorithms (Second ed.)", pp. 651-664.
119 // [2] "Ford-Fulkerson algorithm", Wikipedia,
120 // 'http://en.wikipedia.org/wiki/Ford%E2%80%93Fulkerson_algorithm'
121 class MaxBipartiteMatchState {
122 public:
MaxBipartiteMatchState(const MatchMatrix & graph)123 explicit MaxBipartiteMatchState(const MatchMatrix& graph)
124 : graph_(&graph),
125 left_(graph_->LhsSize(), kUnused),
126 right_(graph_->RhsSize(), kUnused) {}
127
128 // Returns the edges of a maximal match, each in the form {left, right}.
Compute()129 ElementMatcherPairs Compute() {
130 // 'seen' is used for path finding { 0: unseen, 1: seen }.
131 ::std::vector<char> seen;
132 // Searches the residual flow graph for a path from each left node to
133 // the sink in the residual flow graph, and if one is found, add flow
134 // to the graph. It's okay to search through the left nodes once. The
135 // edge from the implicit source node to each previously-visited left
136 // node will have flow if that left node has any path to the sink
137 // whatsoever. Subsequent augmentations can only add flow to the
138 // network, and cannot take away that previous flow unit from the source.
139 // Since the source-to-left edge can only carry one flow unit (or,
140 // each element can be matched to only one matcher), there is no need
141 // to visit the left nodes more than once looking for augmented paths.
142 // The flow is known to be possible or impossible by looking at the
143 // node once.
144 for (size_t ilhs = 0; ilhs < graph_->LhsSize(); ++ilhs) {
145 // Reset the path-marking vector and try to find a path from
146 // source to sink starting at the left_[ilhs] node.
147 GTEST_CHECK_(left_[ilhs] == kUnused)
148 << "ilhs: " << ilhs << ", left_[ilhs]: " << left_[ilhs];
149 // 'seen' initialized to 'graph_->RhsSize()' copies of 0.
150 seen.assign(graph_->RhsSize(), 0);
151 TryAugment(ilhs, &seen);
152 }
153 ElementMatcherPairs result;
154 for (size_t ilhs = 0; ilhs < left_.size(); ++ilhs) {
155 size_t irhs = left_[ilhs];
156 if (irhs == kUnused) continue;
157 result.push_back(ElementMatcherPair(ilhs, irhs));
158 }
159 return result;
160 }
161
162 private:
163 static const size_t kUnused = static_cast<size_t>(-1);
164
165 // Perform a depth-first search from left node ilhs to the sink. If a
166 // path is found, flow is added to the network by linking the left and
167 // right vector elements corresponding each segment of the path.
168 // Returns true if a path to sink was found, which means that a unit of
169 // flow was added to the network. The 'seen' vector elements correspond
170 // to right nodes and are marked to eliminate cycles from the search.
171 //
172 // Left nodes will only be explored at most once because they
173 // are accessible from at most one right node in the residual flow
174 // graph.
175 //
176 // Note that left_[ilhs] is the only element of left_ that TryAugment will
177 // potentially transition from kUnused to another value. Any other
178 // left_ element holding kUnused before TryAugment will be holding it
179 // when TryAugment returns.
180 //
TryAugment(size_t ilhs,::std::vector<char> * seen)181 bool TryAugment(size_t ilhs, ::std::vector<char>* seen) {
182 for (size_t irhs = 0; irhs < graph_->RhsSize(); ++irhs) {
183 if ((*seen)[irhs]) continue;
184 if (!graph_->HasEdge(ilhs, irhs)) continue;
185 // There's an available edge from ilhs to irhs.
186 (*seen)[irhs] = 1;
187 // Next a search is performed to determine whether
188 // this edge is a dead end or leads to the sink.
189 //
190 // right_[irhs] == kUnused means that there is residual flow from
191 // right node irhs to the sink, so we can use that to finish this
192 // flow path and return success.
193 //
194 // Otherwise there is residual flow to some ilhs. We push flow
195 // along that path and call ourselves recursively to see if this
196 // ultimately leads to sink.
197 if (right_[irhs] == kUnused || TryAugment(right_[irhs], seen)) {
198 // Add flow from left_[ilhs] to right_[irhs].
199 left_[ilhs] = irhs;
200 right_[irhs] = ilhs;
201 return true;
202 }
203 }
204 return false;
205 }
206
207 const MatchMatrix* graph_; // not owned
208 // Each element of the left_ vector represents a left hand side node
209 // (i.e. an element) and each element of right_ is a right hand side
210 // node (i.e. a matcher). The values in the left_ vector indicate
211 // outflow from that node to a node on the right_ side. The values
212 // in the right_ indicate inflow, and specify which left_ node is
213 // feeding that right_ node, if any. For example, left_[3] == 1 means
214 // there's a flow from element #3 to matcher #1. Such a flow would also
215 // be redundantly represented in the right_ vector as right_[1] == 3.
216 // Elements of left_ and right_ are either kUnused or mutually
217 // referent. Mutually referent means that left_[right_[i]] = i and
218 // right_[left_[i]] = i.
219 ::std::vector<size_t> left_;
220 ::std::vector<size_t> right_;
221
222 GTEST_DISALLOW_ASSIGN_(MaxBipartiteMatchState);
223 };
224
225 const size_t MaxBipartiteMatchState::kUnused;
226
FindMaxBipartiteMatching(const MatchMatrix & g)227 GTEST_API_ ElementMatcherPairs FindMaxBipartiteMatching(const MatchMatrix& g) {
228 return MaxBipartiteMatchState(g).Compute();
229 }
230
LogElementMatcherPairVec(const ElementMatcherPairs & pairs,::std::ostream * stream)231 static void LogElementMatcherPairVec(const ElementMatcherPairs& pairs,
232 ::std::ostream* stream) {
233 typedef ElementMatcherPairs::const_iterator Iter;
234 ::std::ostream& os = *stream;
235 os << "{";
236 const char* sep = "";
237 for (Iter it = pairs.begin(); it != pairs.end(); ++it) {
238 os << sep << "\n ("
239 << "element #" << it->first << ", "
240 << "matcher #" << it->second << ")";
241 sep = ",";
242 }
243 os << "\n}";
244 }
245
NextGraph()246 bool MatchMatrix::NextGraph() {
247 for (size_t ilhs = 0; ilhs < LhsSize(); ++ilhs) {
248 for (size_t irhs = 0; irhs < RhsSize(); ++irhs) {
249 char& b = matched_[SpaceIndex(ilhs, irhs)];
250 if (!b) {
251 b = 1;
252 return true;
253 }
254 b = 0;
255 }
256 }
257 return false;
258 }
259
Randomize()260 void MatchMatrix::Randomize() {
261 for (size_t ilhs = 0; ilhs < LhsSize(); ++ilhs) {
262 for (size_t irhs = 0; irhs < RhsSize(); ++irhs) {
263 char& b = matched_[SpaceIndex(ilhs, irhs)];
264 b = static_cast<char>(rand() & 1); // NOLINT
265 }
266 }
267 }
268
DebugString() const269 std::string MatchMatrix::DebugString() const {
270 ::std::stringstream ss;
271 const char* sep = "";
272 for (size_t i = 0; i < LhsSize(); ++i) {
273 ss << sep;
274 for (size_t j = 0; j < RhsSize(); ++j) {
275 ss << HasEdge(i, j);
276 }
277 sep = ";";
278 }
279 return ss.str();
280 }
281
DescribeToImpl(::std::ostream * os) const282 void UnorderedElementsAreMatcherImplBase::DescribeToImpl(
283 ::std::ostream* os) const {
284 switch (match_flags()) {
285 case UnorderedMatcherRequire::ExactMatch:
286 if (matcher_describers_.empty()) {
287 *os << "is empty";
288 return;
289 }
290 if (matcher_describers_.size() == 1) {
291 *os << "has " << Elements(1) << " and that element ";
292 matcher_describers_[0]->DescribeTo(os);
293 return;
294 }
295 *os << "has " << Elements(matcher_describers_.size())
296 << " and there exists some permutation of elements such that:\n";
297 break;
298 case UnorderedMatcherRequire::Superset:
299 *os << "a surjection from elements to requirements exists such that:\n";
300 break;
301 case UnorderedMatcherRequire::Subset:
302 *os << "an injection from elements to requirements exists such that:\n";
303 break;
304 }
305
306 const char* sep = "";
307 for (size_t i = 0; i != matcher_describers_.size(); ++i) {
308 *os << sep;
309 if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
310 *os << " - element #" << i << " ";
311 } else {
312 *os << " - an element ";
313 }
314 matcher_describers_[i]->DescribeTo(os);
315 if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
316 sep = ", and\n";
317 } else {
318 sep = "\n";
319 }
320 }
321 }
322
DescribeNegationToImpl(::std::ostream * os) const323 void UnorderedElementsAreMatcherImplBase::DescribeNegationToImpl(
324 ::std::ostream* os) const {
325 switch (match_flags()) {
326 case UnorderedMatcherRequire::ExactMatch:
327 if (matcher_describers_.empty()) {
328 *os << "isn't empty";
329 return;
330 }
331 if (matcher_describers_.size() == 1) {
332 *os << "doesn't have " << Elements(1) << ", or has " << Elements(1)
333 << " that ";
334 matcher_describers_[0]->DescribeNegationTo(os);
335 return;
336 }
337 *os << "doesn't have " << Elements(matcher_describers_.size())
338 << ", or there exists no permutation of elements such that:\n";
339 break;
340 case UnorderedMatcherRequire::Superset:
341 *os << "no surjection from elements to requirements exists such that:\n";
342 break;
343 case UnorderedMatcherRequire::Subset:
344 *os << "no injection from elements to requirements exists such that:\n";
345 break;
346 }
347 const char* sep = "";
348 for (size_t i = 0; i != matcher_describers_.size(); ++i) {
349 *os << sep;
350 if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
351 *os << " - element #" << i << " ";
352 } else {
353 *os << " - an element ";
354 }
355 matcher_describers_[i]->DescribeTo(os);
356 if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
357 sep = ", and\n";
358 } else {
359 sep = "\n";
360 }
361 }
362 }
363
364 // Checks that all matchers match at least one element, and that all
365 // elements match at least one matcher. This enables faster matching
366 // and better error reporting.
367 // Returns false, writing an explanation to 'listener', if and only
368 // if the success criteria are not met.
VerifyMatchMatrix(const::std::vector<std::string> & element_printouts,const MatchMatrix & matrix,MatchResultListener * listener) const369 bool UnorderedElementsAreMatcherImplBase::VerifyMatchMatrix(
370 const ::std::vector<std::string>& element_printouts,
371 const MatchMatrix& matrix, MatchResultListener* listener) const {
372 bool result = true;
373 ::std::vector<char> element_matched(matrix.LhsSize(), 0);
374 ::std::vector<char> matcher_matched(matrix.RhsSize(), 0);
375
376 for (size_t ilhs = 0; ilhs < matrix.LhsSize(); ilhs++) {
377 for (size_t irhs = 0; irhs < matrix.RhsSize(); irhs++) {
378 char matched = matrix.HasEdge(ilhs, irhs);
379 element_matched[ilhs] |= matched;
380 matcher_matched[irhs] |= matched;
381 }
382 }
383
384 if (match_flags() & UnorderedMatcherRequire::Superset) {
385 const char* sep =
386 "where the following matchers don't match any elements:\n";
387 for (size_t mi = 0; mi < matcher_matched.size(); ++mi) {
388 if (matcher_matched[mi]) continue;
389 result = false;
390 if (listener->IsInterested()) {
391 *listener << sep << "matcher #" << mi << ": ";
392 matcher_describers_[mi]->DescribeTo(listener->stream());
393 sep = ",\n";
394 }
395 }
396 }
397
398 if (match_flags() & UnorderedMatcherRequire::Subset) {
399 const char* sep =
400 "where the following elements don't match any matchers:\n";
401 const char* outer_sep = "";
402 if (!result) {
403 outer_sep = "\nand ";
404 }
405 for (size_t ei = 0; ei < element_matched.size(); ++ei) {
406 if (element_matched[ei]) continue;
407 result = false;
408 if (listener->IsInterested()) {
409 *listener << outer_sep << sep << "element #" << ei << ": "
410 << element_printouts[ei];
411 sep = ",\n";
412 outer_sep = "";
413 }
414 }
415 }
416 return result;
417 }
418
FindPairing(const MatchMatrix & matrix,MatchResultListener * listener) const419 bool UnorderedElementsAreMatcherImplBase::FindPairing(
420 const MatchMatrix& matrix, MatchResultListener* listener) const {
421 ElementMatcherPairs matches = FindMaxBipartiteMatching(matrix);
422
423 size_t max_flow = matches.size();
424 if ((match_flags() & UnorderedMatcherRequire::Superset) &&
425 max_flow < matrix.RhsSize()) {
426 if (listener->IsInterested()) {
427 *listener << "where no permutation of the elements can satisfy all "
428 "matchers, and the closest match is "
429 << max_flow << " of " << matrix.RhsSize()
430 << " matchers with the pairings:\n";
431 LogElementMatcherPairVec(matches, listener->stream());
432 }
433 return false;
434 }
435 if ((match_flags() & UnorderedMatcherRequire::Subset) &&
436 max_flow < matrix.LhsSize()) {
437 if (listener->IsInterested()) {
438 *listener
439 << "where not all elements can be matched, and the closest match is "
440 << max_flow << " of " << matrix.RhsSize()
441 << " matchers with the pairings:\n";
442 LogElementMatcherPairVec(matches, listener->stream());
443 }
444 return false;
445 }
446
447 if (matches.size() > 1) {
448 if (listener->IsInterested()) {
449 const char* sep = "where:\n";
450 for (size_t mi = 0; mi < matches.size(); ++mi) {
451 *listener << sep << " - element #" << matches[mi].first
452 << " is matched by matcher #" << matches[mi].second;
453 sep = ",\n";
454 }
455 }
456 }
457 return true;
458 }
459
460 } // namespace internal
461 } // namespace testing
462