mosesdecoder/moses/TrellisPath.cpp
2016-01-19 22:34:06 +00:00

253 lines
7.9 KiB
C++

// $Id$
/***********************************************************************
Moses - factored phrase-based language decoder
Copyright (C) 2006 University of Edinburgh
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
***********************************************************************/
#include "TrellisPath.h"
#include "TrellisPathList.h"
#include "TrellisPathCollection.h"
#include "StaticData.h"
#include "Manager.h"
using namespace std;
namespace Moses
{
TrellisPath::TrellisPath(const Hypothesis *hypo)
: m_prevEdgeChanged(NOT_FOUND)
{
m_totalScore = hypo->GetFutureScore();
// enumerate path using prevHypo
while (hypo != NULL) {
m_path.push_back(hypo);
hypo = hypo->GetPrevHypo();
}
}
void TrellisPath::InitTotalScore()
{
m_totalScore = m_path[0]->GetWinningHypo()->GetFutureScore();
//calc score
size_t sizePath = m_path.size();
for (size_t pos = 0 ; pos < sizePath ; pos++) {
const Hypothesis *hypo = m_path[pos];
const Hypothesis *winningHypo = hypo->GetWinningHypo();
if (hypo != winningHypo) {
m_totalScore += hypo->GetFutureScore() - winningHypo->GetFutureScore();
}
}
}
TrellisPath::TrellisPath(const TrellisPath &copy, size_t edgeIndex, const Hypothesis *arc)
:m_prevEdgeChanged(edgeIndex)
{
m_path.reserve(copy.m_path.size());
for (size_t currEdge = 0 ; currEdge < edgeIndex ; currEdge++) {
// copy path from parent
m_path.push_back(copy.m_path[currEdge]);
}
// 1 deviation
m_path.push_back(arc);
// rest of path comes from following best path backwards
const Hypothesis *prevHypo = arc->GetPrevHypo();
while (prevHypo != NULL) {
m_path.push_back(prevHypo);
prevHypo = prevHypo->GetPrevHypo();
}
InitTotalScore();
}
TrellisPath::TrellisPath(const vector<const Hypothesis*> edges)
:m_prevEdgeChanged(NOT_FOUND)
{
m_path.resize(edges.size());
copy(edges.rbegin(),edges.rend(),m_path.begin());
InitTotalScore();
}
void TrellisPath::CreateDeviantPaths(TrellisPathCollection &pathColl) const
{
const size_t sizePath = m_path.size();
if (m_prevEdgeChanged == NOT_FOUND) {
// initial enumration from a pure hypo
for (size_t currEdge = 0 ; currEdge < sizePath ; currEdge++) {
const Hypothesis *hypo = static_cast<const Hypothesis*>(m_path[currEdge]);
const ArcList *pAL = hypo->GetArcList();
if (!pAL) continue;
const ArcList &arcList = *pAL;
// every possible Arc to replace this edge
ArcList::const_iterator iterArc;
for (iterArc = arcList.begin() ; iterArc != arcList.end() ; ++iterArc) {
const Hypothesis *arc = *iterArc;
TrellisPath *deviantPath = new TrellisPath(*this, currEdge, arc);
pathColl.Add(deviantPath);
}
}
} else {
// wiggle 1 of the edges only
for (size_t currEdge = m_prevEdgeChanged + 1 ; currEdge < sizePath ; currEdge++) {
const ArcList *pAL = m_path[currEdge]->GetArcList();
if (!pAL) continue;
const ArcList &arcList = *pAL;
ArcList::const_iterator iterArc;
for (iterArc = arcList.begin() ; iterArc != arcList.end() ; ++iterArc) {
// copy this Path & change 1 edge
const Hypothesis *arcReplace = *iterArc;
TrellisPath *deviantPath = new TrellisPath(*this, currEdge, arcReplace);
pathColl.Add(deviantPath);
} // for (iterArc...
} // for (currEdge = 0 ...
}
}
void TrellisPath::CreateDeviantPaths(TrellisPathList &pathColl) const
{
const size_t sizePath = m_path.size();
if (m_prevEdgeChanged == NOT_FOUND) {
// initial enumration from a pure hypo
for (size_t currEdge = 0 ; currEdge < sizePath ; currEdge++) {
const Hypothesis *hypo = static_cast<const Hypothesis*>(m_path[currEdge]);
const ArcList *pAL = hypo->GetArcList();
if (!pAL) continue;
const ArcList &arcList = *pAL;
// every possible Arc to replace this edge
ArcList::const_iterator iterArc;
for (iterArc = arcList.begin() ; iterArc != arcList.end() ; ++iterArc) {
const Hypothesis *arc = *iterArc;
TrellisPath *deviantPath = new TrellisPath(*this, currEdge, arc);
pathColl.Add(deviantPath);
}
}
} else {
// wiggle 1 of the edges only
for (size_t currEdge = m_prevEdgeChanged + 1 ; currEdge < sizePath ; currEdge++) {
const ArcList *pAL = m_path[currEdge]->GetArcList();
if (!pAL) continue;
const ArcList &arcList = *pAL;
ArcList::const_iterator iterArc;
for (iterArc = arcList.begin() ; iterArc != arcList.end() ; ++iterArc) {
// copy this Path & change 1 edge
const Hypothesis *arcReplace = *iterArc;
TrellisPath *deviantPath = new TrellisPath(*this, currEdge, arcReplace);
pathColl.Add(deviantPath);
} // for (iterArc...
} // for (currEdge = 0 ...
}
}
boost::shared_ptr<ScoreComponentCollection> const
TrellisPath::
GetScoreBreakdown() const
{
if (!m_scoreBreakdown) {
m_scoreBreakdown.reset(new ScoreComponentCollection());
m_scoreBreakdown->PlusEquals(m_path[0]->GetWinningHypo()->GetScoreBreakdown());
// adjust score
// I assume things are done this way on the assumption that most hypothesis edges
// are shared with the winning path, so that score adjustments are cheaper than
// recomputing the score from scratch. UG
size_t sizePath = m_path.size();
for (size_t pos = 0 ; pos < sizePath ; pos++) {
const Hypothesis *hypo = m_path[pos];
const Hypothesis *winningHypo = hypo->GetWinningHypo();
if (hypo != winningHypo) {
m_scoreBreakdown->MinusEquals(winningHypo->GetScoreBreakdown());
m_scoreBreakdown->PlusEquals(hypo->GetScoreBreakdown());
}
}
}
return m_scoreBreakdown;
}
Phrase TrellisPath::GetTargetPhrase() const
{
Phrase targetPhrase(ARRAY_SIZE_INCR);
int numHypo = (int) m_path.size();
for (int node = numHypo - 2 ; node >= 0 ; --node) {
// don't do the empty hypo - waste of time and decode step id is invalid
const Hypothesis &hypo = *m_path[node];
const Phrase &currTargetPhrase = hypo.GetCurrTargetPhrase();
targetPhrase.Append(currTargetPhrase);
}
return targetPhrase;
}
Phrase TrellisPath::GetSurfacePhrase() const
{
std::vector<FactorType> const& oFactor = manager().options()->output.factor_order;
Phrase targetPhrase = GetTargetPhrase();
Phrase ret(targetPhrase.GetSize());
for (size_t pos = 0 ; pos < targetPhrase.GetSize() ; ++pos) {
Word &newWord = ret.AddWord();
for (size_t i = 0 ; i < oFactor.size() ; i++) {
FactorType factorType = oFactor[i];
const Factor *factor = targetPhrase.GetFactor(pos, factorType);
UTIL_THROW_IF2(factor == NULL,
"No factor " << factorType << " at position " << pos);
newWord[factorType] = factor;
}
}
return ret;
}
Range TrellisPath::GetTargetWordsRange(const Hypothesis &hypo) const
{
size_t startPos = 0;
for (int indEdge = (int) m_path.size() - 1 ; indEdge >= 0 ; --indEdge) {
const Hypothesis *currHypo = m_path[indEdge];
size_t endPos = startPos + currHypo->GetCurrTargetLength() - 1;
if (currHypo == &hypo) {
return Range(startPos, endPos);
}
startPos = endPos + 1;
}
// have to give a hypo in the trellis path, but u didn't.
UTIL_THROW(util::Exception, "Hypothesis not found");
return Range(NOT_FOUND, NOT_FOUND);
}
TO_STRING_BODY(TrellisPath);
}