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namespace Gecode { namespace Int { namespace NValues {
forceinline Graph::Graph(void) : n_matched(0) {}
forceinline int Graph::size(void) const { return n_matched; }
forceinline void Graph::init(Space& home, const ValSet& vs, const ViewArray<IntView>& x) { using namespace ViewValGraph; n_view = x.size() + vs.size(); view = home.alloc<ViewNode<IntView>*>(n_view);
// Create nodes corresponding to the value set vs { int i = x.size(); ValSet::Ranges vsr(vs); ValNode<IntView>** v = &val; for (Iter::Ranges::ToValues<ValSet::Ranges> n(vsr); n(); ++n) { // Create view node view[i] = new (home) ViewNode<IntView>(); // Create and link value node ValNode<IntView>* nv = new (home) ValNode<IntView>(n.val()); *v = nv; v = nv->next_val_ref(); // Create and link single edge Edge<IntView>** e = view[i]->val_edges_ref(); *e = new (home) Edge<IntView>(nv,view[i],nullptr); // Match edge (*e)->revert(view[i]); nv->matching(*e); i++; } *v = nullptr; n_val = vs.size(); n_matched = vs.size(); assert(i - x.size() == vs.size()); }
// Initialize real view nodes for (int i=0; i<x.size(); i++) { view[i] = new (home) ViewNode<IntView>(x[i]); ViewValGraph::Graph<IntView>::init(home,view[i]); }
// Match the real view nodes, if possible Region r; ViewNodeStack m(r,n_view); for (int i=0; i<x.size(); i++) if (match(m,view[i])) n_matched++; }
forceinline void Graph::sync(void) { using namespace ViewValGraph; Region r;
// Whether to rematch bool rematch = false;
// Synchronize nodes for (int i=0; i<n_view; i++) { ViewNode<IntView>* x = view[i]; // Skip faked view nodes, they correspond to values in the value set if (!x->fake()) { if (x->changed()) { ViewRanges<IntView> rx(x->view()); Edge<IntView>* m = x->matched() ? x->edge_fst() : nullptr; Edge<IntView>** p = x->val_edges_ref(); Edge<IntView>* e = *p; GECODE_ASSUME(e != nullptr); do { while (e->val(x)->val() < rx.min()) { // Skip edge e->unlink(); e->mark(); e = e->next_edge(); } *p = e; assert(rx.min() == e->val(x)->val()); // This edges must be kept for (unsigned int j=rx.width(); j--; ) { e->free(); p = e->next_edge_ref(); e = e->next_edge(); } ++rx; } while (rx()); *p = nullptr; while (e != nullptr) { e->unlink(); e->mark(); e = e->next_edge(); } if ((m != nullptr) && m->marked()) { // Matching has been deleted! m->val(x)->matching(nullptr); rematch = true; n_matched--; } } else { // Just free edges for (Edge<IntView>* e=x->val_edges(); e != nullptr; e = e->next_edge()) e->free(); } } }
if (rematch) { ViewNodeStack m(r,n_view); for (int i=0; i<n_view; i++) if (!view[i]->matched() && match(m,view[i])) n_matched++; } }
forceinline bool Graph::mark(void) { using namespace ViewValGraph; Region r;
int n_view_visited = 0; { // Marks all edges as used that are on simple paths in the graph // that start from a free value node by depth-first-search Support::StaticStack<ValNode<IntView>*,Region> visit(r,n_val);
// Insert all free value nodes count++; { ValNode<IntView>** v = &val; while (*v != nullptr) // Is the node free? if (!(*v)->matching()) { // Eliminate empty value nodes if ((*v)->empty()) { *v = (*v)->next_val(); n_val--; } else { (*v)->min = count; visit.push(*v); v = (*v)->next_val_ref(); } } else { v = (*v)->next_val_ref(); } }
// Invariant: only value nodes are on the stack! while (!visit.empty()) { ValNode<IntView>* n = visit.pop(); for (Edge<IntView>* e = n->edge_fst(); e != n->edge_lst(); e = e->next()) { // Is the view node is matched: the path must be alternating! ViewNode<IntView>* x = e->view(n); if (x->matched()) { // Mark the edge as used e->use(); if (x->min < count) { n_view_visited++; x->min = count; assert(x->edge_fst()->next() == x->edge_lst()); ValNode<IntView>* m = x->edge_fst()->val(x); x->edge_fst()->use(); if (m->min < count) { m->min = count; visit.push(m); } } } } }
}
if (n_view_visited < n_view) { // Mark all edges as used starting from a free view node on // an alternating path by depth-first search. Support::StaticStack<ViewNode<IntView>*,Region> visit(r,n_view);
// Insert all free view nodes count++; for (int i=0; i<n_view; i++) if (!view[i]->matched()) { view[i]->min = count; visit.push(view[i]); }
// Invariant: only view nodes are on the stack! while (!visit.empty()) { n_view_visited++; ViewNode<IntView>* x = visit.pop(); for (Edge<IntView>* e = x->val_edges(); e != nullptr; e = e->next_edge()) // Consider only free edges if (e != x->edge_fst()) { ValNode<IntView>* n = e->val(x); // Is there a matched edge from the value node to a view node? if (n->matching() != nullptr) { e->use(); n->matching()->use(); ViewNode<IntView>* y = n->matching()->view(n); if (y->min < count) { y->min = count; visit.push(y); } } } }
}
if (n_view_visited < n_view) { scc(); return true; } else { return false; } }
forceinline ExecStatus Graph::prune(Space& home) { using namespace ViewValGraph; // Tell constraints and also eliminate nodes and edges for (int i = n_view; i--; ) { ViewNode<IntView>* x = view[i]; if (!x->fake()) { if (x->matched() && !x->edge_fst()->used(x)) { GECODE_ME_CHECK(x->view().eq(home,x->edge_fst()->val(x)->val())); x->edge_fst()->val(x)->matching(nullptr); for (Edge<IntView>* e = x->val_edges(); e != nullptr; e=e->next_edge()) e->unlink(); view[i] = view[--n_view]; } else { IterPruneVal<IntView> pv(x); GECODE_ME_CHECK(x->view().minus_v(home,pv,false)); } } }
return ES_OK; }
}}}
// STATISTICS: int-prop