graph.hpp
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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
* Main authors:
* Christian Schulte <schulte@gecode.org>
*
* Copyright:
* Christian Schulte, 2003
*
* This file is part of Gecode, the generic constraint
* development environment:
* http://www.gecode.org
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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#include <climits>
namespace Gecode { namespace Int { namespace Distinct {
template<class View>
forceinline
Graph<View>::Graph(void) {}
template<class View>
forceinline ExecStatus
Graph<View>::init(Space& home, ViewArray<View>& x) {
using namespace ViewValGraph;
n_view = x.size();
view = home.alloc<ViewNode<View>*>(n_view);
// Find value information for construction of view value graph
int min = x[0].min();
int max = x[0].max();
for (int i=1; i<n_view; i++) {
min = std::min(min,x[i].min());
max = std::max(max,x[i].max());
}
unsigned int width = static_cast<unsigned int>(max-min+1);
// Definitly not enough values
if (width < static_cast<unsigned int>(n_view))
return ES_FAILED;
// Initialize view nodes
for (int i=0; i<n_view; i++)
view[i] = new (home) ViewNode<View>(x[i]);
Region r;
if (static_cast<unsigned int>(n_view)*4 >= width) {
// Values are dense: use a mapping
ValNode<View>** val2node = r.alloc<ValNode<View>* >(width);
for (unsigned int i=0U; i<width; i++)
val2node[i]=NULL;
for (int i=0; i<n_view; i++) {
Edge<View>** edge_p = view[i]->val_edges_ref();
for (ViewValues<View> xi(x[i]); xi(); ++xi) {
if (val2node[xi.val()-min] == NULL)
val2node[xi.val()-min] = new (home) ValNode<View>(xi.val());
*edge_p = new (home) Edge<View>(val2node[xi.val()-min],view[i]);
edge_p = (*edge_p)->next_edge_ref();
}
*edge_p = NULL;
}
for (unsigned int i=width; i--; )
if (val2node[i] != NULL) {
val2node[i]->next_val(val);
val = val2node[i];
n_val++;
}
} else {
// Values are sparse
for (int i=0; i<n_view; i++)
ViewValGraph::Graph<View>::init(home,view[i]);
}
if (n_val < n_view)
return ES_FAILED;
typename ViewValGraph::Graph<View>::ViewNodeStack m(r,n_view);
for (int i=0; i<n_view; i++)
if (!match(m,view[i]))
return ES_FAILED;
return ES_OK;
}
template<class View>
forceinline bool
Graph<View>::sync(void) {
using namespace ViewValGraph;
Region r;
// Stack for view nodes to be rematched
typename ViewValGraph::Graph<View>::ViewNodeStack re(r,n_view);
// Synchronize nodes
for (int i = n_view; i--; ) {
ViewNode<View>* x = view[i];
GECODE_ASSUME(x != NULL);
if (x->view().assigned()) {
x->edge_fst()->val(x)->matching(NULL);
for (Edge<View>* e = x->val_edges(); e != NULL; e = e->next_edge())
e->unlink();
view[i] = view[--n_view];
} else if (x->changed()) {
ViewRanges<View> rx(x->view());
Edge<View>* m = x->edge_fst(); // Matching edge
Edge<View>** p = x->val_edges_ref();
Edge<View>* e = *p;
GECODE_ASSUME(e != NULL);
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 = NULL;
while (e != NULL) {
e->unlink(); e->mark();
e = e->next_edge();
}
if (m->marked()) {
// Matching has been deleted!
m->val(x)->matching(NULL);
re.push(x);
}
x->update();
} else {
// Just free edges
for (Edge<View>* e = x->val_edges(); e != NULL; e = e->next_edge())
e->free();
}
}
typename ViewValGraph::Graph<View>::ViewNodeStack m(r,n_view);
while (!re.empty())
if (!match(m,re.pop()))
return false;
return true;
}
template<class View>
forceinline bool
Graph<View>::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 (unmatched node) by depth-first-search
Support::StaticStack<ValNode<View>*,Region> visit(r,n_val);
// Insert all free nodes: they can be only value nodes as we
// have a maximum matching covering all view nodes
count++;
{
ValNode<View>** v = &val;
while (*v != NULL)
if (!(*v)->matching()) {
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<View>* n = visit.pop();
for (Edge<View>* e = n->edge_fst(); e != n->edge_lst(); e=e->next()) {
// Get the value node
e->use();
ViewNode<View>* x = e->view(n);
if (x->min < count) {
n_view_visited++;
x->min = count;
assert(x->edge_fst()->next() == x->edge_lst());
ValNode<View>* m = x->edge_fst()->val(x);
x->edge_fst()->use();
if (m->min < count) {
m->min = count;
visit.push(m);
}
}
}
}
}
// If all view nodes have been visited, also all edges are used!
if (n_view_visited < n_view) {
scc();
return true;
} else {
return false;
}
}
template<class View>
forceinline ExecStatus
Graph<View>::prune(Space& home, bool& assigned) {
using namespace ViewValGraph;
assigned = false;
// Tell constraints and also eliminate nodes and edges
for (int i = n_view; i--; ) {
ViewNode<View>* x = view[i];
if (!x->edge_fst()->used(x)) {
GECODE_ME_CHECK(x->view().eq(home,x->edge_fst()->val(x)->val()));
x->edge_fst()->val(x)->matching(NULL);
for (Edge<View>* e = x->val_edges(); e != NULL; e = e->next_edge())
e->unlink();
view[i] = view[--n_view];
assigned = true;
} else {
IterPruneVal<View> pv(view[i]);
GECODE_ME_CHECK(view[i]->view().minus_v(home,pv,false));
}
}
return ES_OK;
}
}}}
// STATISTICS: int-prop
Gecode::Int::Distinct::Graph::Graph
Graph(void)
Construct graph as not yet initialized.
Definition graph.hpp:40
Gecode::Int::Distinct::Graph::mark
bool mark(void)
Mark edges in graph, return true if pruning is at all possible.
Definition graph.hpp:176
Gecode::Int::Distinct::Graph::sync
bool sync(void)
Synchronize graph with new view domains.
Definition graph.hpp:112
Gecode::Int::Distinct::Graph::init
ExecStatus init(Space &home, ViewArray< View > &x)
Initialize graph.
Definition graph.hpp:44
Gecode::Int::Distinct::Graph::prune
ExecStatus prune(Space &home, bool &assigned)
Prune unmarked edges, assigned is true if a view got assigned.
Definition graph.hpp:240
Gecode::Int::ViewRanges
Range iterator for integer views.
Definition view.hpp:54
Gecode::Int::ViewRanges::min
int min(void) const
Return smallest value of range.
Gecode::Int::ViewRanges::width
unsigned int width(void) const
Return width of range (distance between minimum and maximum).
Gecode::Int::ViewValGraph::Graph::ViewNodeStack
Support::StaticStack< ViewNode< View > *, Region > ViewNodeStack
Stack used during matching.
Definition view-val-graph.hh:307
Gecode::Int::ViewValGraph::Graph::init
void init(Space &home, ViewNode< View > *x)
Initialize the edges for the view node x.
Definition graph.hpp:51
Gecode::Int::ViewValGraph::Graph::count
unsigned int count
Marking counter.
Definition view-val-graph.hh:305
Gecode::Int::ViewValGraph::Graph::view
ViewNode< View > ** view
Array of view nodes.
Definition view-val-graph.hh:297
Gecode::Int::ViewValGraph::Graph::match
bool match(ViewNodeStack &m, ViewNode< View > *x)
Find a matching for node x.
Definition graph.hpp:87
Gecode::Int::ViewValGraph::Graph::n_view
int n_view
Number of view nodes.
Definition view-val-graph.hh:301
Gecode::Int::ViewValGraph::Graph::n_val
int n_val
Number of value nodes.
Definition view-val-graph.hh:303
Gecode::Int::ViewValGraph::Graph::scc
void scc(void)
Compute the strongly connected components.
Definition graph.hpp:142
Gecode::Int::ViewValGraph::Graph::val
ValNode< View > * val
Array of value nodes.
Definition view-val-graph.hh:299
Gecode::Int::ViewValues
Value iterator for integer views.
Definition view.hpp:94
Gecode::Region
Handle to region.
Definition region.hpp:55
Gecode::Space
Computation spaces.
Definition core.hpp:1742
Gecode::Space::alloc
T * alloc(long unsigned int n)
Allocate block of n objects of type T from space heap.
Definition core.hpp:2837
Gecode::Support::StaticStack
Stack with fixed number of elements.
Definition static-stack.hpp:42
Gecode::Support::StaticStack::push
void push(const T &x)
Push element x on top of stack.
Definition static-stack.hpp:137
Gecode::Support::StaticStack::pop
T pop(void)
Pop topmost element from stack and return it.
Definition static-stack.hpp:116
Gecode::Support::StaticStack::empty
bool empty(void) const
Test whether stack is empty.
Definition static-stack.hpp:98
Gecode::ViewArray
View arrays.
Definition array.hpp:253
Gecode::ViewArray::size
int size(void) const
Return size of array (number of elements).
Definition array.hpp:1156
GECODE_ME_CHECK
#define GECODE_ME_CHECK(me)
Check whether modification event me is failed, and forward failure.
Definition macros.hpp:52
Gecode::Int::Distinct
Distinct propagators
Gecode::Int::ViewValGraph
Support classes for propagators using a view-value graph.
Gecode::Int
Finite domain integers.
Gecode
Gecode toplevel namespace
Gecode::min
void min(Home home, FloatVar x0, FloatVar x1, FloatVar x2)
Post propagator for .
Definition arithmetic.cpp:67
Gecode::ExecStatus
ExecStatus
Definition core.hpp:472
Gecode::ES_OK
@ ES_OK
Execution is okay.
Definition core.hpp:476
Gecode::ES_FAILED
@ ES_FAILED
Execution has resulted in failure.
Definition core.hpp:474
Gecode::max
void max(Home home, FloatVar x0, FloatVar x1, FloatVar x2)
Post propagator for .
Definition arithmetic.cpp:49
forceinline
#define forceinline
Definition config.hpp:187
GECODE_ASSUME
#define GECODE_ASSUME(p)
Assert certain property.
Definition macros.hpp:114