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31 // Google Mock - a framework for writing C++ mock classes.
33 // This file implements Matcher<const string&>, Matcher<string>, and
34 // utilities for defining matchers.
36 #include "gmock/gmock-matchers.h"
37 #include "gmock/gmock-generated-matchers.h"
47 // Returns the description for a matcher defined using the MATCHER*()
48 // macro where the user-supplied description string is "", if
49 // 'negation' is false; otherwise returns the description of the
50 // negation of the matcher. 'param_values' contains a list of strings
51 // that are the print-out of the matcher's parameters.
52 GTEST_API_
std::string
FormatMatcherDescription(bool negation
,
53 const char* matcher_name
,
54 const Strings
& param_values
) {
55 std::string result
= ConvertIdentifierNameToWords(matcher_name
);
56 if (param_values
.size() >= 1) result
+= " " + JoinAsTuple(param_values
);
57 return negation
? "not (" + result
+ ")" : result
;
60 // FindMaxBipartiteMatching and its helper class.
62 // Uses the well-known Ford-Fulkerson max flow method to find a maximum
63 // bipartite matching. Flow is considered to be from left to right.
64 // There is an implicit source node that is connected to all of the left
65 // nodes, and an implicit sink node that is connected to all of the
66 // right nodes. All edges have unit capacity.
68 // Neither the flow graph nor the residual flow graph are represented
69 // explicitly. Instead, they are implied by the information in 'graph' and
70 // a vector<int> called 'left_' whose elements are initialized to the
71 // value kUnused. This represents the initial state of the algorithm,
72 // where the flow graph is empty, and the residual flow graph has the
74 // - An edge from source to each left_ node
75 // - An edge from each right_ node to sink
76 // - An edge from each left_ node to each right_ node, if the
77 // corresponding edge exists in 'graph'.
79 // When the TryAugment() method adds a flow, it sets left_[l] = r for some
80 // nodes l and r. This induces the following changes:
81 // - The edges (source, l), (l, r), and (r, sink) are added to the
83 // - The same three edges are removed from the residual flow graph.
84 // - The reverse edges (l, source), (r, l), and (sink, r) are added
85 // to the residual flow graph, which is a directional graph
86 // representing unused flow capacity.
88 // When the method augments a flow (moving left_[l] from some r1 to some
89 // other r2), this can be thought of as "undoing" the above steps with
90 // respect to r1 and "redoing" them with respect to r2.
92 // It bears repeating that the flow graph and residual flow graph are
93 // never represented explicitly, but can be derived by looking at the
94 // information in 'graph' and in left_.
96 // As an optimization, there is a second vector<int> called right_ which
97 // does not provide any new information. Instead, it enables more
98 // efficient queries about edges entering or leaving the right-side nodes
99 // of the flow or residual flow graphs. The following invariants are
102 // left[l] == kUnused or right[left[l]] == l
103 // right[r] == kUnused or left[right[r]] == r
108 // . ||\--> left[0]=1 ---\ right[0]=-1 ----\ .
110 // . |\---> left[1]=-1 \--> right[1]=0 ---\| .
112 // . \----> left[2]=2 ------> right[2]=2 --\|| .
114 // . elements matchers vvv .
118 // [1] Cormen, et al (2001). "Section 26.2: The Ford-Fulkerson method".
119 // "Introduction to Algorithms (Second ed.)", pp. 651-664.
120 // [2] "Ford-Fulkerson algorithm", Wikipedia,
121 // 'http://en.wikipedia.org/wiki/Ford%E2%80%93Fulkerson_algorithm'
122 class MaxBipartiteMatchState
{
124 explicit MaxBipartiteMatchState(const MatchMatrix
& graph
)
126 left_(graph_
->LhsSize(), kUnused
),
127 right_(graph_
->RhsSize(), kUnused
) {}
129 // Returns the edges of a maximal match, each in the form {left, right}.
130 ElementMatcherPairs
Compute() {
131 // 'seen' is used for path finding { 0: unseen, 1: seen }.
132 ::std::vector
<char> seen
;
133 // Searches the residual flow graph for a path from each left node to
134 // the sink in the residual flow graph, and if one is found, add flow
135 // to the graph. It's okay to search through the left nodes once. The
136 // edge from the implicit source node to each previously-visited left
137 // node will have flow if that left node has any path to the sink
138 // whatsoever. Subsequent augmentations can only add flow to the
139 // network, and cannot take away that previous flow unit from the source.
140 // Since the source-to-left edge can only carry one flow unit (or,
141 // each element can be matched to only one matcher), there is no need
142 // to visit the left nodes more than once looking for augmented paths.
143 // The flow is known to be possible or impossible by looking at the
145 for (size_t ilhs
= 0; ilhs
< graph_
->LhsSize(); ++ilhs
) {
146 // Reset the path-marking vector and try to find a path from
147 // source to sink starting at the left_[ilhs] node.
148 GTEST_CHECK_(left_
[ilhs
] == kUnused
)
149 << "ilhs: " << ilhs
<< ", left_[ilhs]: " << left_
[ilhs
];
150 // 'seen' initialized to 'graph_->RhsSize()' copies of 0.
151 seen
.assign(graph_
->RhsSize(), 0);
152 TryAugment(ilhs
, &seen
);
154 ElementMatcherPairs result
;
155 for (size_t ilhs
= 0; ilhs
< left_
.size(); ++ilhs
) {
156 size_t irhs
= left_
[ilhs
];
157 if (irhs
== kUnused
) continue;
158 result
.push_back(ElementMatcherPair(ilhs
, irhs
));
164 static const size_t kUnused
= static_cast<size_t>(-1);
166 // Perform a depth-first search from left node ilhs to the sink. If a
167 // path is found, flow is added to the network by linking the left and
168 // right vector elements corresponding each segment of the path.
169 // Returns true if a path to sink was found, which means that a unit of
170 // flow was added to the network. The 'seen' vector elements correspond
171 // to right nodes and are marked to eliminate cycles from the search.
173 // Left nodes will only be explored at most once because they
174 // are accessible from at most one right node in the residual flow
177 // Note that left_[ilhs] is the only element of left_ that TryAugment will
178 // potentially transition from kUnused to another value. Any other
179 // left_ element holding kUnused before TryAugment will be holding it
180 // when TryAugment returns.
182 bool TryAugment(size_t ilhs
, ::std::vector
<char>* seen
) {
183 for (size_t irhs
= 0; irhs
< graph_
->RhsSize(); ++irhs
) {
184 if ((*seen
)[irhs
]) continue;
185 if (!graph_
->HasEdge(ilhs
, irhs
)) continue;
186 // There's an available edge from ilhs to irhs.
188 // Next a search is performed to determine whether
189 // this edge is a dead end or leads to the sink.
191 // right_[irhs] == kUnused means that there is residual flow from
192 // right node irhs to the sink, so we can use that to finish this
193 // flow path and return success.
195 // Otherwise there is residual flow to some ilhs. We push flow
196 // along that path and call ourselves recursively to see if this
197 // ultimately leads to sink.
198 if (right_
[irhs
] == kUnused
|| TryAugment(right_
[irhs
], seen
)) {
199 // Add flow from left_[ilhs] to right_[irhs].
208 const MatchMatrix
* graph_
; // not owned
209 // Each element of the left_ vector represents a left hand side node
210 // (i.e. an element) and each element of right_ is a right hand side
211 // node (i.e. a matcher). The values in the left_ vector indicate
212 // outflow from that node to a node on the right_ side. The values
213 // in the right_ indicate inflow, and specify which left_ node is
214 // feeding that right_ node, if any. For example, left_[3] == 1 means
215 // there's a flow from element #3 to matcher #1. Such a flow would also
216 // be redundantly represented in the right_ vector as right_[1] == 3.
217 // Elements of left_ and right_ are either kUnused or mutually
218 // referent. Mutually referent means that left_[right_[i]] = i and
219 // right_[left_[i]] = i.
220 ::std::vector
<size_t> left_
;
221 ::std::vector
<size_t> right_
;
223 GTEST_DISALLOW_ASSIGN_(MaxBipartiteMatchState
);
226 const size_t MaxBipartiteMatchState::kUnused
;
228 GTEST_API_ ElementMatcherPairs
FindMaxBipartiteMatching(const MatchMatrix
& g
) {
229 return MaxBipartiteMatchState(g
).Compute();
232 static void LogElementMatcherPairVec(const ElementMatcherPairs
& pairs
,
233 ::std::ostream
* stream
) {
234 typedef ElementMatcherPairs::const_iterator Iter
;
235 ::std::ostream
& os
= *stream
;
237 const char* sep
= "";
238 for (Iter it
= pairs
.begin(); it
!= pairs
.end(); ++it
) {
240 << "element #" << it
->first
<< ", "
241 << "matcher #" << it
->second
<< ")";
247 bool MatchMatrix::NextGraph() {
248 for (size_t ilhs
= 0; ilhs
< LhsSize(); ++ilhs
) {
249 for (size_t irhs
= 0; irhs
< RhsSize(); ++irhs
) {
250 char& b
= matched_
[SpaceIndex(ilhs
, irhs
)];
261 void MatchMatrix::Randomize() {
262 for (size_t ilhs
= 0; ilhs
< LhsSize(); ++ilhs
) {
263 for (size_t irhs
= 0; irhs
< RhsSize(); ++irhs
) {
264 char& b
= matched_
[SpaceIndex(ilhs
, irhs
)];
265 b
= static_cast<char>(rand() & 1); // NOLINT
270 std::string
MatchMatrix::DebugString() const {
271 ::std::stringstream ss
;
272 const char* sep
= "";
273 for (size_t i
= 0; i
< LhsSize(); ++i
) {
275 for (size_t j
= 0; j
< RhsSize(); ++j
) {
283 void UnorderedElementsAreMatcherImplBase::DescribeToImpl(
284 ::std::ostream
* os
) const {
285 switch (match_flags()) {
286 case UnorderedMatcherRequire::ExactMatch
:
287 if (matcher_describers_
.empty()) {
291 if (matcher_describers_
.size() == 1) {
292 *os
<< "has " << Elements(1) << " and that element ";
293 matcher_describers_
[0]->DescribeTo(os
);
296 *os
<< "has " << Elements(matcher_describers_
.size())
297 << " and there exists some permutation of elements such that:\n";
299 case UnorderedMatcherRequire::Superset
:
300 *os
<< "a surjection from elements to requirements exists such that:\n";
302 case UnorderedMatcherRequire::Subset
:
303 *os
<< "an injection from elements to requirements exists such that:\n";
307 const char* sep
= "";
308 for (size_t i
= 0; i
!= matcher_describers_
.size(); ++i
) {
310 if (match_flags() == UnorderedMatcherRequire::ExactMatch
) {
311 *os
<< " - element #" << i
<< " ";
313 *os
<< " - an element ";
315 matcher_describers_
[i
]->DescribeTo(os
);
316 if (match_flags() == UnorderedMatcherRequire::ExactMatch
) {
324 void UnorderedElementsAreMatcherImplBase::DescribeNegationToImpl(
325 ::std::ostream
* os
) const {
326 switch (match_flags()) {
327 case UnorderedMatcherRequire::ExactMatch
:
328 if (matcher_describers_
.empty()) {
329 *os
<< "isn't empty";
332 if (matcher_describers_
.size() == 1) {
333 *os
<< "doesn't have " << Elements(1) << ", or has " << Elements(1)
335 matcher_describers_
[0]->DescribeNegationTo(os
);
338 *os
<< "doesn't have " << Elements(matcher_describers_
.size())
339 << ", or there exists no permutation of elements such that:\n";
341 case UnorderedMatcherRequire::Superset
:
342 *os
<< "no surjection from elements to requirements exists such that:\n";
344 case UnorderedMatcherRequire::Subset
:
345 *os
<< "no injection from elements to requirements exists such that:\n";
348 const char* sep
= "";
349 for (size_t i
= 0; i
!= matcher_describers_
.size(); ++i
) {
351 if (match_flags() == UnorderedMatcherRequire::ExactMatch
) {
352 *os
<< " - element #" << i
<< " ";
354 *os
<< " - an element ";
356 matcher_describers_
[i
]->DescribeTo(os
);
357 if (match_flags() == UnorderedMatcherRequire::ExactMatch
) {
365 // Checks that all matchers match at least one element, and that all
366 // elements match at least one matcher. This enables faster matching
367 // and better error reporting.
368 // Returns false, writing an explanation to 'listener', if and only
369 // if the success criteria are not met.
370 bool UnorderedElementsAreMatcherImplBase::VerifyMatchMatrix(
371 const ::std::vector
<std::string
>& element_printouts
,
372 const MatchMatrix
& matrix
, MatchResultListener
* listener
) const {
374 ::std::vector
<char> element_matched(matrix
.LhsSize(), 0);
375 ::std::vector
<char> matcher_matched(matrix
.RhsSize(), 0);
377 for (size_t ilhs
= 0; ilhs
< matrix
.LhsSize(); ilhs
++) {
378 for (size_t irhs
= 0; irhs
< matrix
.RhsSize(); irhs
++) {
379 char matched
= matrix
.HasEdge(ilhs
, irhs
);
380 element_matched
[ilhs
] |= matched
;
381 matcher_matched
[irhs
] |= matched
;
385 if (match_flags() & UnorderedMatcherRequire::Superset
) {
387 "where the following matchers don't match any elements:\n";
388 for (size_t mi
= 0; mi
< matcher_matched
.size(); ++mi
) {
389 if (matcher_matched
[mi
]) continue;
391 if (listener
->IsInterested()) {
392 *listener
<< sep
<< "matcher #" << mi
<< ": ";
393 matcher_describers_
[mi
]->DescribeTo(listener
->stream());
399 if (match_flags() & UnorderedMatcherRequire::Subset
) {
401 "where the following elements don't match any matchers:\n";
402 const char* outer_sep
= "";
404 outer_sep
= "\nand ";
406 for (size_t ei
= 0; ei
< element_matched
.size(); ++ei
) {
407 if (element_matched
[ei
]) continue;
409 if (listener
->IsInterested()) {
410 *listener
<< outer_sep
<< sep
<< "element #" << ei
<< ": "
411 << element_printouts
[ei
];
420 bool UnorderedElementsAreMatcherImplBase::FindPairing(
421 const MatchMatrix
& matrix
, MatchResultListener
* listener
) const {
422 ElementMatcherPairs matches
= FindMaxBipartiteMatching(matrix
);
424 size_t max_flow
= matches
.size();
425 if ((match_flags() & UnorderedMatcherRequire::Superset
) &&
426 max_flow
< matrix
.RhsSize()) {
427 if (listener
->IsInterested()) {
428 *listener
<< "where no permutation of the elements can satisfy all "
429 "matchers, and the closest match is "
430 << max_flow
<< " of " << matrix
.RhsSize()
431 << " matchers with the pairings:\n";
432 LogElementMatcherPairVec(matches
, listener
->stream());
436 if ((match_flags() & UnorderedMatcherRequire::Subset
) &&
437 max_flow
< matrix
.LhsSize()) {
438 if (listener
->IsInterested()) {
440 << "where not all elements can be matched, and the closest match is "
441 << max_flow
<< " of " << matrix
.RhsSize()
442 << " matchers with the pairings:\n";
443 LogElementMatcherPairVec(matches
, listener
->stream());
448 if (matches
.size() > 1) {
449 if (listener
->IsInterested()) {
450 const char* sep
= "where:\n";
451 for (size_t mi
= 0; mi
< matches
.size(); ++mi
) {
452 *listener
<< sep
<< " - element #" << matches
[mi
].first
453 << " is matched by matcher #" << matches
[mi
].second
;
461 } // namespace internal
462 } // namespace testing