// Copyright 2007, Google Inc.
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//
// * Redistributions of source code must retain the above copyright
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// contributors may be used to endorse or promote products derived from
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//
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// Google Mock - a framework for writing C++ mock classes.
//
// This file implements Matcher<const string&>, Matcher<string>, and
// utilities for defining matchers.
#include "gmock/gmock-matchers.h"
#include "gmock/gmock-generated-matchers.h"
#include <string.h>
#include <iostream>
#include <sstream>
#include <string>
namespace testing {
namespace internal {
// Returns the description for a matcher defined using the MATCHER*()
// macro where the user-supplied description string is "", if
// 'negation' is false; otherwise returns the description of the
// negation of the matcher. 'param_values' contains a list of strings
// that are the print-out of the matcher's parameters.
GTEST_API_ std::string FormatMatcherDescription(bool negation,
const char* matcher_name,
const Strings& param_values) {
std::string result = ConvertIdentifierNameToWords(matcher_name);
if (param_values.size() >= 1) result += " " + JoinAsTuple(param_values);
return negation ? "not (" + result + ")" : result;
}
// FindMaxBipartiteMatching and its helper class.
//
// Uses the well-known Ford-Fulkerson max flow method to find a maximum
// bipartite matching. Flow is considered to be from left to right.
// There is an implicit source node that is connected to all of the left
// nodes, and an implicit sink node that is connected to all of the
// right nodes. All edges have unit capacity.
//
// Neither the flow graph nor the residual flow graph are represented
// explicitly. Instead, they are implied by the information in 'graph' and
// a vector<int> called 'left_' whose elements are initialized to the
// value kUnused. This represents the initial state of the algorithm,
// where the flow graph is empty, and the residual flow graph has the
// following edges:
// - An edge from source to each left_ node
// - An edge from each right_ node to sink
// - An edge from each left_ node to each right_ node, if the
// corresponding edge exists in 'graph'.
//
// When the TryAugment() method adds a flow, it sets left_[l] = r for some
// nodes l and r. This induces the following changes:
// - The edges (source, l), (l, r), and (r, sink) are added to the
// flow graph.
// - The same three edges are removed from the residual flow graph.
// - The reverse edges (l, source), (r, l), and (sink, r) are added
// to the residual flow graph, which is a directional graph
// representing unused flow capacity.
//
// When the method augments a flow (moving left_[l] from some r1 to some
// other r2), this can be thought of as "undoing" the above steps with
// respect to r1 and "redoing" them with respect to r2.
//
// It bears repeating that the flow graph and residual flow graph are
// never represented explicitly, but can be derived by looking at the
// information in 'graph' and in left_.
//
// As an optimization, there is a second vector<int> called right_ which
// does not provide any new information. Instead, it enables more
// efficient queries about edges entering or leaving the right-side nodes
// of the flow or residual flow graphs. The following invariants are
// maintained:
//
// left[l] == kUnused or right[left[l]] == l
// right[r] == kUnused or left[right[r]] == r
//
// . [ source ] .
// . ||| .
// . ||| .
// . ||\--> left[0]=1 ---\ right[0]=-1 ----\ .
// . || | | .
// . |\---> left[1]=-1 \--> right[1]=0 ---\| .
// . | || .
// . \----> left[2]=2 ------> right[2]=2 --\|| .
// . ||| .
// . elements matchers vvv .
// . [ sink ] .
//
// See Also:
// [1] Cormen, et al (2001). "Section 26.2: The Ford-Fulkerson method".
// "Introduction to Algorithms (Second ed.)", pp. 651-664.
// [2] "Ford-Fulkerson algorithm", Wikipedia,
// 'http://en.wikipedia.org/wiki/Ford%E2%80%93Fulkerson_algorithm'
class MaxBipartiteMatchState {
public:
explicit MaxBipartiteMatchState(const MatchMatrix& graph)
: graph_(&graph),
left_(graph_->LhsSize(), kUnused),
right_(graph_->RhsSize(), kUnused) {}
// Returns the edges of a maximal match, each in the form {left, right}.
ElementMatcherPairs Compute() {
// 'seen' is used for path finding { 0: unseen, 1: seen }.
::std::vector<char> seen;
// Searches the residual flow graph for a path from each left node to
// the sink in the residual flow graph, and if one is found, add flow
// to the graph. It's okay to search through the left nodes once. The
// edge from the implicit source node to each previously-visited left
// node will have flow if that left node has any path to the sink
// whatsoever. Subsequent augmentations can only add flow to the
// network, and cannot take away that previous flow unit from the source.
// Since the source-to-left edge can only carry one flow unit (or,
// each element can be matched to only one matcher), there is no need
// to visit the left nodes more than once looking for augmented paths.
// The flow is known to be possible or impossible by looking at the
// node once.
for (size_t ilhs = 0; ilhs < graph_->LhsSize(); ++ilhs) {
// Reset the path-marking vector and try to find a path from
// source to sink starting at the left_[ilhs] node.
GTEST_CHECK_(left_[ilhs] == kUnused)
<< "ilhs: " << ilhs << ", left_[ilhs]: " << left_[ilhs];
// 'seen' initialized to 'graph_->RhsSize()' copies of 0.
seen.assign(graph_->RhsSize(), 0);
TryAugment(ilhs, &seen);
}
ElementMatcherPairs result;
for (size_t ilhs = 0; ilhs < left_.size(); ++ilhs) {
size_t irhs = left_[ilhs];
if (irhs == kUnused) continue;
result.push_back(ElementMatcherPair(ilhs, irhs));
}
return result;
}
private:
static const size_t kUnused = static_cast<size_t>(-1);
// Perform a depth-first search from left node ilhs to the sink. If a
// path is found, flow is added to the network by linking the left and
// right vector elements corresponding each segment of the path.
// Returns true if a path to sink was found, which means that a unit of
// flow was added to the network. The 'seen' vector elements correspond
// to right nodes and are marked to eliminate cycles from the search.
//
// Left nodes will only be explored at most once because they
// are accessible from at most one right node in the residual flow
// graph.
//
// Note that left_[ilhs] is the only element of left_ that TryAugment will
// potentially transition from kUnused to another value. Any other
// left_ element holding kUnused before TryAugment will be holding it
// when TryAugment returns.
//
bool TryAugment(size_t ilhs, ::std::vector<char>* seen) {
for (size_t irhs = 0; irhs < graph_->RhsSize(); ++irhs) {
if ((*seen)[irhs]) continue;
if (!graph_->HasEdge(ilhs, irhs)) continue;
// There's an available edge from ilhs to irhs.
(*seen)[irhs] = 1;
// Next a search is performed to determine whether
// this edge is a dead end or leads to the sink.
//
// right_[irhs] == kUnused means that there is residual flow from
// right node irhs to the sink, so we can use that to finish this
// flow path and return success.
//
// Otherwise there is residual flow to some ilhs. We push flow
// along that path and call ourselves recursively to see if this
// ultimately leads to sink.
if (right_[irhs] == kUnused || TryAugment(right_[irhs], seen)) {
// Add flow from left_[ilhs] to right_[irhs].
left_[ilhs] = irhs;
right_[irhs] = ilhs;
return true;
}
}
return false;
}
const MatchMatrix* graph_; // not owned
// Each element of the left_ vector represents a left hand side node
// (i.e. an element) and each element of right_ is a right hand side
// node (i.e. a matcher). The values in the left_ vector indicate
// outflow from that node to a node on the right_ side. The values
// in the right_ indicate inflow, and specify which left_ node is
// feeding that right_ node, if any. For example, left_[3] == 1 means
// there's a flow from element #3 to matcher #1. Such a flow would also
// be redundantly represented in the right_ vector as right_[1] == 3.
// Elements of left_ and right_ are either kUnused or mutually
// referent. Mutually referent means that left_[right_[i]] = i and
// right_[left_[i]] = i.
::std::vector<size_t> left_;
::std::vector<size_t> right_;
GTEST_DISALLOW_ASSIGN_(MaxBipartiteMatchState);
};
const size_t MaxBipartiteMatchState::kUnused;
GTEST_API_ ElementMatcherPairs FindMaxBipartiteMatching(const MatchMatrix& g) {
return MaxBipartiteMatchState(g).Compute();
}
static void LogElementMatcherPairVec(const ElementMatcherPairs& pairs,
::std::ostream* stream) {
typedef ElementMatcherPairs::const_iterator Iter;
::std::ostream& os = *stream;
os << "{";
const char* sep = "";
for (Iter it = pairs.begin(); it != pairs.end(); ++it) {
os << sep << "\n ("
<< "element #" << it->first << ", "
<< "matcher #" << it->second << ")";
sep = ",";
}
os << "\n}";
}
bool MatchMatrix::NextGraph() {
for (size_t ilhs = 0; ilhs < LhsSize(); ++ilhs) {
for (size_t irhs = 0; irhs < RhsSize(); ++irhs) {
char& b = matched_[SpaceIndex(ilhs, irhs)];
if (!b) {
b = 1;
return true;
}
b = 0;
}
}
return false;
}
void MatchMatrix::Randomize() {
for (size_t ilhs = 0; ilhs < LhsSize(); ++ilhs) {
for (size_t irhs = 0; irhs < RhsSize(); ++irhs) {
char& b = matched_[SpaceIndex(ilhs, irhs)];
b = static_cast<char>(rand() & 1); // NOLINT
}
}
}
std::string MatchMatrix::DebugString() const {
::std::stringstream ss;
const char* sep = "";
for (size_t i = 0; i < LhsSize(); ++i) {
ss << sep;
for (size_t j = 0; j < RhsSize(); ++j) {
ss << HasEdge(i, j);
}
sep = ";";
}
return ss.str();
}
void UnorderedElementsAreMatcherImplBase::DescribeToImpl(
::std::ostream* os) const {
switch (match_flags()) {
case UnorderedMatcherRequire::ExactMatch:
if (matcher_describers_.empty()) {
*os << "is empty";
return;
}
if (matcher_describers_.size() == 1) {
*os << "has " << Elements(1) << " and that element ";
matcher_describers_[0]->DescribeTo(os);
return;
}
*os << "has " << Elements(matcher_describers_.size())
<< " and there exists some permutation of elements such that:\n";
break;
case UnorderedMatcherRequire::Superset:
*os << "a surjection from elements to requirements exists such that:\n";
break;
case UnorderedMatcherRequire::Subset:
*os << "an injection from elements to requirements exists such that:\n";
break;
}
const char* sep = "";
for (size_t i = 0; i != matcher_describers_.size(); ++i) {
*os << sep;
if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
*os << " - element #" << i << " ";
} else {
*os << " - an element ";
}
matcher_describers_[i]->DescribeTo(os);
if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
sep = ", and\n";
} else {
sep = "\n";
}
}
}
void UnorderedElementsAreMatcherImplBase::DescribeNegationToImpl(
::std::ostream* os) const {
switch (match_flags()) {
case UnorderedMatcherRequire::ExactMatch:
if (matcher_describers_.empty()) {
*os << "isn't empty";
return;
}
if (matcher_describers_.size() == 1) {
*os << "doesn't have " << Elements(1) << ", or has " << Elements(1)
<< " that ";
matcher_describers_[0]->DescribeNegationTo(os);
return;
}
*os << "doesn't have " << Elements(matcher_describers_.size())
<< ", or there exists no permutation of elements such that:\n";
break;
case UnorderedMatcherRequire::Superset:
*os << "no surjection from elements to requirements exists such that:\n";
break;
case UnorderedMatcherRequire::Subset:
*os << "no injection from elements to requirements exists such that:\n";
break;
}
const char* sep = "";
for (size_t i = 0; i != matcher_describers_.size(); ++i) {
*os << sep;
if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
*os << " - element #" << i << " ";
} else {
*os << " - an element ";
}
matcher_describers_[i]->DescribeTo(os);
if (match_flags() == UnorderedMatcherRequire::ExactMatch) {
sep = ", and\n";
} else {
sep = "\n";
}
}
}
// Checks that all matchers match at least one element, and that all
// elements match at least one matcher. This enables faster matching
// and better error reporting.
// Returns false, writing an explanation to 'listener', if and only
// if the success criteria are not met.
bool UnorderedElementsAreMatcherImplBase::VerifyMatchMatrix(
const ::std::vector<std::string>& element_printouts,
const MatchMatrix& matrix, MatchResultListener* listener) const {
bool result = true;
::std::vector<char> element_matched(matrix.LhsSize(), 0);
::std::vector<char> matcher_matched(matrix.RhsSize(), 0);
for (size_t ilhs = 0; ilhs < matrix.LhsSize(); ilhs++) {
for (size_t irhs = 0; irhs < matrix.RhsSize(); irhs++) {
char matched = matrix.HasEdge(ilhs, irhs);
element_matched[ilhs] |= matched;
matcher_matched[irhs] |= matched;
}
}
if (match_flags() & UnorderedMatcherRequire::Superset) {
const char* sep =
"where the following matchers don't match any elements:\n";
for (size_t mi = 0; mi < matcher_matched.size(); ++mi) {
if (matcher_matched[mi]) continue;
result = false;
if (listener->IsInterested()) {
*listener << sep << "matcher #" << mi << ": ";
matcher_describers_[mi]->DescribeTo(listener->stream());
sep = ",\n";
}
}
}
if (match_flags() & UnorderedMatcherRequire::Subset) {
const char* sep =
"where the following elements don't match any matchers:\n";
const char* outer_sep = "";
if (!result) {
outer_sep = "\nand ";
}
for (size_t ei = 0; ei < element_matched.size(); ++ei) {
if (element_matched[ei]) continue;
result = false;
if (listener->IsInterested()) {
*listener << outer_sep << sep << "element #" << ei << ": "
<< element_printouts[ei];
sep = ",\n";
outer_sep = "";
}
}
}
return result;
}
bool UnorderedElementsAreMatcherImplBase::FindPairing(
const MatchMatrix& matrix, MatchResultListener* listener) const {
ElementMatcherPairs matches = FindMaxBipartiteMatching(matrix);
size_t max_flow = matches.size();
if ((match_flags() & UnorderedMatcherRequire::Superset) &&
max_flow < matrix.RhsSize()) {
if (listener->IsInterested()) {
*listener << "where no permutation of the elements can satisfy all "
"matchers, and the closest match is "
<< max_flow << " of " << matrix.RhsSize()
<< " matchers with the pairings:\n";
LogElementMatcherPairVec(matches, listener->stream());
}
return false;
}
if ((match_flags() & UnorderedMatcherRequire::Subset) &&
max_flow < matrix.LhsSize()) {
if (listener->IsInterested()) {
*listener
<< "where not all elements can be matched, and the closest match is "
<< max_flow << " of " << matrix.RhsSize()
<< " matchers with the pairings:\n";
LogElementMatcherPairVec(matches, listener->stream());
}
return false;
}
if (matches.size() > 1) {
if (listener->IsInterested()) {
const char* sep = "where:\n";
for (size_t mi = 0; mi < matches.size(); ++mi) {
*listener << sep << " - element #" << matches[mi].first
<< " is matched by matcher #" << matches[mi].second;
sep = ",\n";
}
}
}
return true;
}
} // namespace internal
} // namespace testing