mosesdecoder/moses/ChartTranslationOptionList.cpp
2014-08-08 18:11:30 +01:00

216 lines
7.0 KiB
C++

/***********************************************************************
Moses - factored phrase-based language decoder
Copyright (C) 2010 Hieu Hoang
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 <algorithm>
#include <iostream>
#include <vector>
#include "StaticData.h"
#include "ChartTranslationOptionList.h"
#include "ChartTranslationOptions.h"
#include "ChartCellCollection.h"
#include "WordsRange.h"
#include "InputType.h"
#include "InputPath.h"
using namespace std;
namespace Moses
{
ChartTranslationOptionList::ChartTranslationOptionList(size_t ruleLimit, const InputType &input)
: m_size(0)
, m_ruleLimit(ruleLimit)
{
m_scoreThreshold = std::numeric_limits<float>::infinity();
}
ChartTranslationOptionList::~ChartTranslationOptionList()
{
RemoveAllInColl(m_collection);
}
void ChartTranslationOptionList::Clear()
{
m_size = 0;
m_scoreThreshold = std::numeric_limits<float>::infinity();
}
class ChartTranslationOptionOrderer
{
public:
bool operator()(const ChartTranslationOptions* itemA, const ChartTranslationOptions* itemB) const {
return itemA->GetEstimateOfBestScore() > itemB->GetEstimateOfBestScore();
}
};
void ChartTranslationOptionList::Add(const TargetPhraseCollection &tpc,
const StackVec &stackVec,
const WordsRange &range)
{
if (tpc.IsEmpty()) {
return;
}
for (size_t i = 0; i < stackVec.size(); ++i) {
const ChartCellLabel &chartCellLabel = *stackVec[i];
size_t numHypos = chartCellLabel.GetStack().cube->size();
if (numHypos == 0) {
return; // empty stack. These rules can't be used
}
}
const TargetPhrase &targetPhrase = **(tpc.begin());
float score = targetPhrase.GetFutureScore();
for (StackVec::const_iterator p = stackVec.begin(); p != stackVec.end(); ++p) {
score += (*p)->GetBestScore(this);
}
// If the rule limit has already been reached then don't add the option
// unless it is better than at least one existing option.
if (m_ruleLimit && m_size > m_ruleLimit && score < m_scoreThreshold) {
return;
}
// Add the option to the list.
if (m_size == m_collection.size()) {
// m_collection has reached capacity: create a new object.
m_collection.push_back(new ChartTranslationOptions(tpc, stackVec,
range, score));
} else {
// Overwrite an unused object.
*(m_collection[m_size]) = ChartTranslationOptions(tpc, stackVec,
range, score);
}
++m_size;
// If the rule limit hasn't been exceeded then update the threshold.
if (!m_ruleLimit || m_size <= m_ruleLimit) {
m_scoreThreshold = (score < m_scoreThreshold) ? score : m_scoreThreshold;
}
// Prune if bursting
if (m_ruleLimit && m_size == m_ruleLimit * 2) {
NTH_ELEMENT4(m_collection.begin(),
m_collection.begin() + m_ruleLimit - 1,
m_collection.begin() + m_size,
ChartTranslationOptionOrderer());
m_scoreThreshold = m_collection[m_ruleLimit-1]->GetEstimateOfBestScore();
m_size = m_ruleLimit;
}
}
void ChartTranslationOptionList::AddPhraseOOV(TargetPhrase &phrase, std::list<TargetPhraseCollection*> &waste_memory, const WordsRange &range)
{
TargetPhraseCollection *tpc = new TargetPhraseCollection();
tpc->Add(&phrase);
waste_memory.push_back(tpc);
StackVec empty;
Add(*tpc, empty, range);
}
void ChartTranslationOptionList::ApplyThreshold()
{
if (m_ruleLimit && m_size > m_ruleLimit) {
// Something's gone wrong if the list has grown to m_ruleLimit * 2
// without being pruned.
assert(m_size < m_ruleLimit * 2);
// Reduce the list to the best m_ruleLimit options. The remaining
// options can be overwritten on subsequent calls to Add().
NTH_ELEMENT4(m_collection.begin(),
m_collection.begin()+m_ruleLimit,
m_collection.begin()+m_size,
ChartTranslationOptionOrderer());
m_size = m_ruleLimit;
}
// keep only those over best + threshold
float scoreThreshold = -std::numeric_limits<float>::infinity();
CollType::const_iterator iter;
for (iter = m_collection.begin(); iter != m_collection.begin()+m_size; ++iter) {
const ChartTranslationOptions *transOpt = *iter;
float score = transOpt->GetEstimateOfBestScore();
scoreThreshold = (score > scoreThreshold) ? score : scoreThreshold;
}
scoreThreshold += StaticData::Instance().GetTranslationOptionThreshold();
CollType::iterator bound = std::partition(m_collection.begin(),
m_collection.begin()+m_size,
ScoreThresholdPred(scoreThreshold));
m_size = std::distance(m_collection.begin(), bound);
}
float ChartTranslationOptionList::GetBestScore(const ChartCellLabel *chartCell) const
{
const HypoList *stack = chartCell->GetStack().cube;
assert(stack);
assert(!stack->empty());
const ChartHypothesis &bestHypo = **(stack->begin());
return bestHypo.GetTotalScore();
}
void ChartTranslationOptionList::EvaluateWithSourceContext(const InputType &input, const InputPath &inputPath)
{
// NEVER iterate over ALL of the collection. Just over the first m_size
CollType::iterator iter;
for (iter = m_collection.begin(); iter != m_collection.begin() + m_size; ++iter) {
ChartTranslationOptions &transOpts = **iter;
transOpts.EvaluateWithSourceContext(input, inputPath);
}
// get rid of empty trans opts
size_t numDiscard = 0;
for (size_t i = 0; i < m_size; ++i) {
ChartTranslationOptions *transOpts = m_collection[i];
if (transOpts->GetSize() == 0) {
//delete transOpts;
++numDiscard;
}
else if (numDiscard) {
SwapTranslationOptions(i - numDiscard, i);
//m_collection[] = transOpts;
}
}
size_t newSize = m_size - numDiscard;
m_size = newSize;
}
void ChartTranslationOptionList::SwapTranslationOptions(size_t a, size_t b)
{
ChartTranslationOptions *transOptsA = m_collection[a];
ChartTranslationOptions *transOptsB = m_collection[b];
m_collection[a] = transOptsB;
m_collection[b] = transOptsA;
}
std::ostream& operator<<(std::ostream &out, const ChartTranslationOptionList &obj)
{
for (size_t i = 0; i < obj.m_collection.size(); ++i) {
const ChartTranslationOptions &transOpts = *obj.m_collection[i];
out << transOpts << endl;
}
return out;
}
}