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