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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
* Main authors:
* Christian Schulte <schulte@gecode.org>
*
* Copyright:
* Christian Schulte, 2009
*
* 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
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
namespace Gecode { namespace Search { namespace Seq {
template<class Tracer>
forceinline
DFS<Tracer>::DFS(Space* s, const Options& o)
: tracer(o.tracer), opt(o), path(opt.nogoods_limit), d(0) {
if (tracer) {
tracer.engine(SearchTracer::EngineType::DFS, 1U);
tracer.worker();
}
if ((s == nullptr) || (s->status(*this) == SS_FAILED)) {
fail++;
cur = nullptr;
if (!opt.clone)
delete s;
} else {
cur = snapshot(s,opt);
}
}
template<class Tracer>
forceinline void
DFS<Tracer>::reset(Space* s) {
tracer.round();
delete cur;
path.reset();
d = 0;
if ((s == nullptr) || (s->status(*this) == SS_FAILED)) {
delete s;
cur = nullptr;
} else {
cur = s;
}
Worker::reset();
}
template<class Tracer>
forceinline NoGoods&
DFS<Tracer>::nogoods(void) {
return path;
}
template<class Tracer>
forceinline Space*
DFS<Tracer>::next(void) {
/*
* The engine maintains the following invariant:
* - If the current space (cur) is not nullptr, the path always points
* to exactly that space.
* - If the current space (cur) is nullptr, the path always points
* to the next space (if there is any).
*
* This invariant is needed so that no-goods can be extracted properly
* when the engine is stopped or has found a solution.
*
*/
start();
while (true) {
if (stop(opt))
return nullptr;
while (cur == nullptr) {
if (path.empty())
return nullptr;
cur = path.recompute(d,opt.a_d,*this,tracer);
if (cur != nullptr)
break;
path.next();
}
node++;
SearchTracer::EdgeInfo ei;
if (tracer && (path.entries() > 0)) {
typename Path<Tracer>::Edge& top = path.top();
ei.init(tracer.wid(), top.nid(), top.truealt(), *cur, *top.choice());
}
unsigned int nid = tracer.nid();
switch (cur->status(*this)) {
case SS_FAILED:
if (tracer) {
SearchTracer::NodeInfo ni(SearchTracer::NodeType::FAILED,
tracer.wid(), nid, *cur);
tracer.node(ei,ni);
}
fail++;
delete cur;
cur = nullptr;
path.next();
break;
case SS_SOLVED:
{
if (tracer) {
SearchTracer::NodeInfo ni(SearchTracer::NodeType::SOLVED,
tracer.wid(), nid, *cur);
tracer.node(ei,ni);
}
// Deletes all pending branchers
(void) cur->choice();
Space* s = cur;
cur = nullptr;
path.next();
return s;
}
case SS_BRANCH:
{
Space* c;
if ((d == 0) || (d >= opt.c_d)) {
c = cur->clone();
d = 1;
} else {
c = nullptr;
d++;
}
const Choice* ch = path.push(*this,cur,c,nid);
if (tracer) {
SearchTracer::NodeInfo ni(SearchTracer::NodeType::BRANCH,
tracer.wid(), nid, *cur, ch);
tracer.node(ei,ni);
}
cur->commit(*ch,0);
break;
}
default:
GECODE_NEVER;
}
}
GECODE_NEVER;
return nullptr;
}
template<class Tracer>
forceinline Statistics
DFS<Tracer>::statistics(void) const {
return *this;
}
template<class Tracer>
forceinline void
DFS<Tracer>::constrain(const Space& b) {
(void) b;
assert(false);
}
template<class Tracer>
forceinline
DFS<Tracer>::~DFS(void) {
delete cur;
tracer.done();
path.reset();
}
}}}
// STATISTICS: search-seq
|
