mirror of
https://github.com/moses-smt/mosesdecoder.git
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220 lines
7.0 KiB
C++
220 lines
7.0 KiB
C++
/***********************************************************************
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Moses - factored phrase-based language decoder
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Copyright (C) 2010 Hieu Hoang
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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***********************************************************************/
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#include <algorithm>
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#include <iostream>
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#include <vector>
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#include "StaticData.h"
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#include "ChartTranslationOptionList.h"
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#include "ChartTranslationOptions.h"
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#include "ChartCellCollection.h"
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#include "Range.h"
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#include "InputType.h"
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#include "InputPath.h"
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using namespace std;
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namespace Moses
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{
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ChartTranslationOptionList::
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ChartTranslationOptionList(size_t ruleLimit, const InputType &input)
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: m_size(0)
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, m_ruleLimit(ruleLimit)
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{
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m_scoreThreshold = std::numeric_limits<float>::infinity();
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}
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ChartTranslationOptionList::~ChartTranslationOptionList()
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{
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RemoveAllInColl(m_collection);
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}
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void ChartTranslationOptionList::Clear()
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{
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m_size = 0;
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m_scoreThreshold = std::numeric_limits<float>::infinity();
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}
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class ChartTranslationOptionOrderer
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{
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public:
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bool operator()(const ChartTranslationOptions* itemA, const ChartTranslationOptions* itemB) const {
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return itemA->GetEstimateOfBestScore() > itemB->GetEstimateOfBestScore();
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}
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};
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void ChartTranslationOptionList::Add(const TargetPhraseCollection &tpc,
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const StackVec &stackVec,
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const Range &range)
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{
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if (tpc.IsEmpty()) {
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return;
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}
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for (size_t i = 0; i < stackVec.size(); ++i) {
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const ChartCellLabel &chartCellLabel = *stackVec[i];
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size_t numHypos = chartCellLabel.GetStack().cube->size();
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if (numHypos == 0) {
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return; // empty stack. These rules can't be used
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}
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}
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const TargetPhrase &targetPhrase = **(tpc.begin());
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float score = targetPhrase.GetFutureScore();
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for (StackVec::const_iterator p = stackVec.begin(); p != stackVec.end(); ++p) {
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score += (*p)->GetBestScore(this);
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}
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// If the rule limit has already been reached then don't add the option
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// unless it is better than at least one existing option.
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if (m_ruleLimit && m_size > m_ruleLimit && score < m_scoreThreshold) {
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return;
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}
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// Add the option to the list.
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if (m_size == m_collection.size()) {
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// m_collection has reached capacity: create a new object.
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m_collection.push_back(new ChartTranslationOptions(tpc, stackVec,
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range, score));
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} else {
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// Overwrite an unused object.
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*(m_collection[m_size]) = ChartTranslationOptions(tpc, stackVec,
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range, score);
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}
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++m_size;
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// If the rule limit hasn't been exceeded then update the threshold.
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if (!m_ruleLimit || m_size <= m_ruleLimit) {
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m_scoreThreshold = (score < m_scoreThreshold) ? score : m_scoreThreshold;
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}
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// Prune if bursting
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if (m_ruleLimit && m_size == m_ruleLimit * 2) {
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NTH_ELEMENT4(m_collection.begin(),
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m_collection.begin() + m_ruleLimit - 1,
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m_collection.begin() + m_size,
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ChartTranslationOptionOrderer());
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m_scoreThreshold = m_collection[m_ruleLimit-1]->GetEstimateOfBestScore();
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m_size = m_ruleLimit;
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}
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}
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void
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ChartTranslationOptionList::
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AddPhraseOOV(TargetPhrase &phrase,
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std::list<TargetPhraseCollection::shared_ptr > &waste_memory,
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const Range &range)
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{
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TargetPhraseCollection::shared_ptr tpc(new TargetPhraseCollection);
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tpc->Add(&phrase);
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waste_memory.push_back(tpc);
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StackVec empty;
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Add(*tpc, empty, range);
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}
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void ChartTranslationOptionList::ApplyThreshold(float const threshold)
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{
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if (m_ruleLimit && m_size > m_ruleLimit) {
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// Something's gone wrong if the list has grown to m_ruleLimit * 2
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// without being pruned.
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assert(m_size < m_ruleLimit * 2);
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// Reduce the list to the best m_ruleLimit options. The remaining
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// options can be overwritten on subsequent calls to Add().
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NTH_ELEMENT4(m_collection.begin(),
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m_collection.begin()+m_ruleLimit,
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m_collection.begin()+m_size,
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ChartTranslationOptionOrderer());
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m_size = m_ruleLimit;
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}
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// keep only those over best + threshold
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float scoreThreshold = -std::numeric_limits<float>::infinity();
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CollType::const_iterator iter;
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for (iter = m_collection.begin(); iter != m_collection.begin()+m_size; ++iter) {
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const ChartTranslationOptions *transOpt = *iter;
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float score = transOpt->GetEstimateOfBestScore();
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scoreThreshold = (score > scoreThreshold) ? score : scoreThreshold;
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}
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scoreThreshold += threshold; // StaticData::Instance().GetTranslationOptionThreshold();
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CollType::iterator bound = std::partition(m_collection.begin(),
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m_collection.begin()+m_size,
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ScoreThresholdPred(scoreThreshold));
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m_size = std::distance(m_collection.begin(), bound);
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}
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float ChartTranslationOptionList::GetBestScore(const ChartCellLabel *chartCell) const
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{
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const HypoList *stack = chartCell->GetStack().cube;
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assert(stack);
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assert(!stack->empty());
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const ChartHypothesis &bestHypo = **(stack->begin());
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return bestHypo.GetFutureScore();
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}
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void ChartTranslationOptionList::EvaluateWithSourceContext(const InputType &input, const InputPath &inputPath)
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{
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// NEVER iterate over ALL of the collection. Just over the first m_size
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CollType::iterator iter;
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for (iter = m_collection.begin(); iter != m_collection.begin() + m_size; ++iter) {
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ChartTranslationOptions &transOpts = **iter;
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transOpts.EvaluateWithSourceContext(input, inputPath);
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}
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// get rid of empty trans opts
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size_t numDiscard = 0;
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for (size_t i = 0; i < m_size; ++i) {
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ChartTranslationOptions *transOpts = m_collection[i];
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if (transOpts->GetSize() == 0) {
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//delete transOpts;
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++numDiscard;
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} else if (numDiscard) {
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SwapTranslationOptions(i - numDiscard, i);
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//m_collection[] = transOpts;
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}
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}
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size_t newSize = m_size - numDiscard;
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m_size = newSize;
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}
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void ChartTranslationOptionList::SwapTranslationOptions(size_t a, size_t b)
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{
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ChartTranslationOptions *transOptsA = m_collection[a];
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ChartTranslationOptions *transOptsB = m_collection[b];
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m_collection[a] = transOptsB;
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m_collection[b] = transOptsA;
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}
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std::ostream& operator<<(std::ostream &out, const ChartTranslationOptionList &obj)
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{
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for (size_t i = 0; i < obj.m_collection.size(); ++i) {
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const ChartTranslationOptions &transOpts = *obj.m_collection[i];
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out << transOpts << endl;
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}
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return out;
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}
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}
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