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495 lines
18 KiB
C++
495 lines
18 KiB
C++
//=======================================================================
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// Copyright (C) 2005-2009 Jongsoo Park <jongsoo.park -at- gmail.com>
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//=======================================================================
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#ifndef BOOST_GRAPH_DOMINATOR_HPP
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#define BOOST_GRAPH_DOMINATOR_HPP
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#include <boost/config.hpp>
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#include <deque>
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#include <set>
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#include <boost/graph/depth_first_search.hpp>
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#include <boost/concept/assert.hpp>
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// Dominator tree computation
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namespace boost {
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namespace detail {
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/**
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* An extended time_stamper which also records vertices for each dfs number
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*/
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template<class TimeMap, class VertexVector, class TimeT, class Tag>
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class time_stamper_with_vertex_vector
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: public base_visitor<
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time_stamper_with_vertex_vector<TimeMap, VertexVector, TimeT, Tag> >
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{
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public :
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typedef Tag event_filter;
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time_stamper_with_vertex_vector(TimeMap timeMap, VertexVector& v,
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TimeT& t)
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: timeStamper_(timeMap, t), v_(v) { }
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template<class Graph>
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void
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operator()(const typename property_traits<TimeMap>::key_type& v,
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const Graph& g)
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{
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timeStamper_(v, g);
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v_[timeStamper_.m_time] = v;
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}
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private :
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time_stamper<TimeMap, TimeT, Tag> timeStamper_;
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VertexVector& v_;
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};
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/**
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* A convenient way to create a time_stamper_with_vertex_vector
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*/
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template<class TimeMap, class VertexVector, class TimeT, class Tag>
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time_stamper_with_vertex_vector<TimeMap, VertexVector, TimeT, Tag>
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stamp_times_with_vertex_vector(TimeMap timeMap, VertexVector& v, TimeT& t,
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Tag)
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{
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return time_stamper_with_vertex_vector<TimeMap, VertexVector, TimeT,
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Tag>(timeMap, v, t);
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}
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template<class Graph, class IndexMap, class TimeMap, class PredMap,
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class DomTreePredMap>
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class dominator_visitor
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{
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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typedef typename graph_traits<Graph>::vertices_size_type VerticesSizeType;
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public :
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/**
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* @param g [in] the target graph of the dominator tree
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* @param entry [in] the entry node of g
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* @param indexMap [in] the vertex index map for g
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* @param domTreePredMap [out] the immediate dominator map
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* (parent map in dominator tree)
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*/
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dominator_visitor(const Graph& g, const Vertex& entry,
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const IndexMap& indexMap,
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DomTreePredMap domTreePredMap)
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: semi_(num_vertices(g)),
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ancestor_(num_vertices(g), graph_traits<Graph>::null_vertex()),
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samedom_(ancestor_),
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best_(semi_),
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semiMap_(make_iterator_property_map(semi_.begin(),
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indexMap)),
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ancestorMap_(make_iterator_property_map(ancestor_.begin(),
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indexMap)),
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bestMap_(make_iterator_property_map(best_.begin(),
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indexMap)),
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buckets_(num_vertices(g)),
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bucketMap_(make_iterator_property_map(buckets_.begin(),
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indexMap)),
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entry_(entry),
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domTreePredMap_(domTreePredMap),
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numOfVertices_(num_vertices(g)),
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samedomMap(make_iterator_property_map(samedom_.begin(),
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indexMap))
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{
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}
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void
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operator()(const Vertex& n, const TimeMap& dfnumMap,
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const PredMap& parentMap, const Graph& g)
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{
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if (n == entry_) return;
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const Vertex p(get(parentMap, n));
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Vertex s(p);
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// 1. Calculate the semidominator of n,
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// based on the semidominator thm.
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// * Semidominator thm. : To find the semidominator of a node n,
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// consider all predecessors v of n in the CFG (Control Flow Graph).
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// - If v is a proper ancestor of n in the spanning tree
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// (so dfnum(v) < dfnum(n)), then v is a candidate for semi(n)
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// - If v is a non-ancestor of n (so dfnum(v) > dfnum(n))
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// then for each u that is an ancestor of v (or u = v),
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// Let semi(u) be a candidate for semi(n)
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// of all these candidates, the one with lowest dfnum is
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// the semidominator of n.
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// For each predecessor of n
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typename graph_traits<Graph>::in_edge_iterator inItr, inEnd;
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for (boost::tie(inItr, inEnd) = in_edges(n, g); inItr != inEnd; ++inItr)
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{
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const Vertex v = source(*inItr, g);
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// To deal with unreachable nodes
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if (get(dfnumMap, v) < 0 || get(dfnumMap, v) >= numOfVertices_)
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continue;
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Vertex s2;
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if (get(dfnumMap, v) <= get(dfnumMap, n))
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s2 = v;
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else
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s2 = get(semiMap_, ancestor_with_lowest_semi_(v, dfnumMap));
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if (get(dfnumMap, s2) < get(dfnumMap, s))
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s = s2;
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}
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put(semiMap_, n, s);
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// 2. Calculation of n's dominator is deferred until
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// the path from s to n has been linked into the forest
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get(bucketMap_, s).push_back(n);
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get(ancestorMap_, n) = p;
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get(bestMap_, n) = n;
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// 3. Now that the path from p to v has been linked into
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// the spanning forest, these lines calculate the dominator of v,
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// based on the dominator thm., or else defer the calculation
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// until y's dominator is known
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// * Dominator thm. : On the spanning-tree path below semi(n) and
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// above or including n, let y be the node
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// with the smallest-numbered semidominator. Then,
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//
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// idom(n) = semi(n) if semi(y)=semi(n) or
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// idom(y) if semi(y) != semi(n)
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typename std::deque<Vertex>::iterator buckItr;
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for (buckItr = get(bucketMap_, p).begin();
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buckItr != get(bucketMap_, p).end();
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++buckItr)
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{
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const Vertex v(*buckItr);
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const Vertex y(ancestor_with_lowest_semi_(v, dfnumMap));
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if (get(semiMap_, y) == get(semiMap_, v))
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put(domTreePredMap_, v, p);
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else
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put(samedomMap, v, y);
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}
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get(bucketMap_, p).clear();
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}
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protected :
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/**
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* Evaluate function in Tarjan's path compression
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*/
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const Vertex
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ancestor_with_lowest_semi_(const Vertex& v, const TimeMap& dfnumMap)
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{
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const Vertex a(get(ancestorMap_, v));
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if (get(ancestorMap_, a) != graph_traits<Graph>::null_vertex())
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{
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const Vertex b(ancestor_with_lowest_semi_(a, dfnumMap));
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put(ancestorMap_, v, get(ancestorMap_, a));
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if (get(dfnumMap, get(semiMap_, b)) <
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get(dfnumMap, get(semiMap_, get(bestMap_, v))))
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put(bestMap_, v, b);
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}
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return get(bestMap_, v);
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}
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std::vector<Vertex> semi_, ancestor_, samedom_, best_;
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PredMap semiMap_, ancestorMap_, bestMap_;
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std::vector< std::deque<Vertex> > buckets_;
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iterator_property_map<typename std::vector<std::deque<Vertex> >::iterator,
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IndexMap> bucketMap_;
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const Vertex& entry_;
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DomTreePredMap domTreePredMap_;
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const VerticesSizeType numOfVertices_;
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public :
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PredMap samedomMap;
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};
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} // namespace detail
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/**
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* @brief Build dominator tree using Lengauer-Tarjan algorithm.
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* It takes O((V+E)log(V+E)) time.
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*
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* @pre dfnumMap, parentMap and verticesByDFNum have dfs results corresponding
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* indexMap.
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* If dfs has already run before,
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* this function would be good for saving computations.
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* @pre Unreachable nodes must be masked as
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* graph_traits<Graph>::null_vertex in parentMap.
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* @pre Unreachable nodes must be masked as
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* (std::numeric_limits<VerticesSizeType>::max)() in dfnumMap.
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*
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* @param domTreePredMap [out] : immediate dominator map (parent map
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* in dom. tree)
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*
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* @note reference Appel. p. 452~453. algorithm 19.9, 19.10.
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*
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* @todo : Optimization in Finding Dominators in Practice, Loukas Georgiadis
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*/
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template<class Graph, class IndexMap, class TimeMap, class PredMap,
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class VertexVector, class DomTreePredMap>
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void
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lengauer_tarjan_dominator_tree_without_dfs
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(const Graph& g,
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const typename graph_traits<Graph>::vertex_descriptor& entry,
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const IndexMap& indexMap,
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TimeMap dfnumMap, PredMap parentMap, VertexVector& verticesByDFNum,
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DomTreePredMap domTreePredMap)
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{
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// Typedefs and concept check
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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typedef typename graph_traits<Graph>::vertices_size_type VerticesSizeType;
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BOOST_CONCEPT_ASSERT(( BidirectionalGraphConcept<Graph> ));
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const VerticesSizeType numOfVertices = num_vertices(g);
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if (numOfVertices == 0) return;
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// 1. Visit each vertex in reverse post order and calculate sdom.
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detail::dominator_visitor<Graph, IndexMap, TimeMap, PredMap, DomTreePredMap>
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visitor(g, entry, indexMap, domTreePredMap);
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VerticesSizeType i;
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for (i = 0; i < numOfVertices; ++i)
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{
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const Vertex u(verticesByDFNum[numOfVertices - 1 - i]);
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if (u != graph_traits<Graph>::null_vertex())
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visitor(u, dfnumMap, parentMap, g);
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}
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// 2. Now all the deferred dominator calculations,
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// based on the second clause of the dominator thm., are performed
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for (i = 0; i < numOfVertices; ++i)
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{
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const Vertex n(verticesByDFNum[i]);
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if (n == entry || n == graph_traits<Graph>::null_vertex())
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continue;
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Vertex u = get(visitor.samedomMap, n);
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if (u != graph_traits<Graph>::null_vertex())
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{
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put(domTreePredMap, n, get(domTreePredMap, u));
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}
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}
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}
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/**
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* Unlike lengauer_tarjan_dominator_tree_without_dfs,
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* dfs is run in this function and
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* the result is written to dfnumMap, parentMap, vertices.
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*
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* If the result of dfs required after this algorithm,
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* this function can eliminate the need of rerunning dfs.
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*/
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template<class Graph, class IndexMap, class TimeMap, class PredMap,
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class VertexVector, class DomTreePredMap>
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void
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lengauer_tarjan_dominator_tree
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(const Graph& g,
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const typename graph_traits<Graph>::vertex_descriptor& entry,
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const IndexMap& indexMap,
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TimeMap dfnumMap, PredMap parentMap, VertexVector& verticesByDFNum,
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DomTreePredMap domTreePredMap)
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{
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// Typedefs and concept check
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typedef typename graph_traits<Graph>::vertices_size_type VerticesSizeType;
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BOOST_CONCEPT_ASSERT(( BidirectionalGraphConcept<Graph> ));
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// 1. Depth first visit
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const VerticesSizeType numOfVertices = num_vertices(g);
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if (numOfVertices == 0) return;
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VerticesSizeType time =
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(std::numeric_limits<VerticesSizeType>::max)();
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std::vector<default_color_type>
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colors(numOfVertices, color_traits<default_color_type>::white());
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depth_first_visit
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(g, entry,
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make_dfs_visitor
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(make_pair(record_predecessors(parentMap, on_tree_edge()),
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detail::stamp_times_with_vertex_vector
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(dfnumMap, verticesByDFNum, time, on_discover_vertex()))),
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make_iterator_property_map(colors.begin(), indexMap));
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// 2. Run main algorithm.
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lengauer_tarjan_dominator_tree_without_dfs(g, entry, indexMap, dfnumMap,
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parentMap, verticesByDFNum,
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domTreePredMap);
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}
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/**
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* Use vertex_index as IndexMap and make dfnumMap, parentMap, verticesByDFNum
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* internally.
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* If we don't need the result of dfs (dfnumMap, parentMap, verticesByDFNum),
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* this function would be more convenient one.
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*/
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template<class Graph, class DomTreePredMap>
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void
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lengauer_tarjan_dominator_tree
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(const Graph& g,
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const typename graph_traits<Graph>::vertex_descriptor& entry,
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DomTreePredMap domTreePredMap)
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{
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// typedefs
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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typedef typename graph_traits<Graph>::vertices_size_type VerticesSizeType;
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typedef typename property_map<Graph, vertex_index_t>::const_type IndexMap;
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typedef
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iterator_property_map<typename std::vector<VerticesSizeType>::iterator,
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IndexMap> TimeMap;
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typedef
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iterator_property_map<typename std::vector<Vertex>::iterator, IndexMap>
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PredMap;
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// Make property maps
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const VerticesSizeType numOfVertices = num_vertices(g);
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if (numOfVertices == 0) return;
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const IndexMap indexMap = get(vertex_index, g);
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std::vector<VerticesSizeType> dfnum(numOfVertices, 0);
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TimeMap dfnumMap(make_iterator_property_map(dfnum.begin(), indexMap));
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std::vector<Vertex> parent(numOfVertices,
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graph_traits<Graph>::null_vertex());
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PredMap parentMap(make_iterator_property_map(parent.begin(), indexMap));
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std::vector<Vertex> verticesByDFNum(parent);
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// Run main algorithm
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lengauer_tarjan_dominator_tree(g, entry,
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indexMap, dfnumMap, parentMap,
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verticesByDFNum, domTreePredMap);
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}
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/**
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* Muchnick. p. 182, 184
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*
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* using iterative bit vector analysis
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*/
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template<class Graph, class IndexMap, class DomTreePredMap>
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void
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iterative_bit_vector_dominator_tree
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(const Graph& g,
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const typename graph_traits<Graph>::vertex_descriptor& entry,
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const IndexMap& indexMap,
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DomTreePredMap domTreePredMap)
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{
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typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
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typedef typename graph_traits<Graph>::vertex_iterator vertexItr;
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typedef typename graph_traits<Graph>::vertices_size_type VerticesSizeType;
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typedef
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iterator_property_map<typename std::vector< std::set<Vertex> >::iterator,
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IndexMap> vertexSetMap;
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BOOST_CONCEPT_ASSERT(( BidirectionalGraphConcept<Graph> ));
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// 1. Finding dominator
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// 1.1. Initialize
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const VerticesSizeType numOfVertices = num_vertices(g);
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if (numOfVertices == 0) return;
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vertexItr vi, viend;
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boost::tie(vi, viend) = vertices(g);
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const std::set<Vertex> N(vi, viend);
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bool change = true;
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std::vector< std::set<Vertex> > dom(numOfVertices, N);
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vertexSetMap domMap(make_iterator_property_map(dom.begin(), indexMap));
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get(domMap, entry).clear();
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get(domMap, entry).insert(entry);
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while (change)
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{
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change = false;
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for (boost::tie(vi, viend) = vertices(g); vi != viend; ++vi)
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{
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if (*vi == entry) continue;
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std::set<Vertex> T(N);
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typename graph_traits<Graph>::in_edge_iterator inItr, inEnd;
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for (boost::tie(inItr, inEnd) = in_edges(*vi, g); inItr != inEnd; ++inItr)
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{
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const Vertex p = source(*inItr, g);
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std::set<Vertex> tempSet;
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std::set_intersection(T.begin(), T.end(),
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get(domMap, p).begin(),
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get(domMap, p).end(),
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std::inserter(tempSet, tempSet.begin()));
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T.swap(tempSet);
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}
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T.insert(*vi);
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if (T != get(domMap, *vi))
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{
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change = true;
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get(domMap, *vi).swap(T);
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}
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} // end of for (boost::tie(vi, viend) = vertices(g)
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} // end of while(change)
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// 2. Build dominator tree
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for (boost::tie(vi, viend) = vertices(g); vi != viend; ++vi)
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get(domMap, *vi).erase(*vi);
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Graph domTree(numOfVertices);
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for (boost::tie(vi, viend) = vertices(g); vi != viend; ++vi)
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{
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if (*vi == entry) continue;
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// We have to iterate through copied dominator set
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const std::set<Vertex> tempSet(get(domMap, *vi));
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typename std::set<Vertex>::const_iterator s;
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for (s = tempSet.begin(); s != tempSet.end(); ++s)
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{
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typename std::set<Vertex>::iterator t;
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for (t = get(domMap, *vi).begin(); t != get(domMap, *vi).end(); )
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{
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typename std::set<Vertex>::iterator old_t = t;
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++t; // Done early because t may become invalid
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if (*old_t == *s) continue;
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if (get(domMap, *s).find(*old_t) != get(domMap, *s).end())
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get(domMap, *vi).erase(old_t);
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}
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}
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}
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for (boost::tie(vi, viend) = vertices(g); vi != viend; ++vi)
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{
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if (*vi != entry && get(domMap, *vi).size() == 1)
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{
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Vertex temp = *get(domMap, *vi).begin();
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put(domTreePredMap, *vi, temp);
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}
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}
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}
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template<class Graph, class DomTreePredMap>
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void
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iterative_bit_vector_dominator_tree
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(const Graph& g,
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const typename graph_traits<Graph>::vertex_descriptor& entry,
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DomTreePredMap domTreePredMap)
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{
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typename property_map<Graph, vertex_index_t>::const_type
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indexMap = get(vertex_index, g);
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iterative_bit_vector_dominator_tree(g, entry, indexMap, domTreePredMap);
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}
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} // namespace boost
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#endif // BOOST_GRAPH_DOMINATOR_HPP
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