mirror of
https://github.com/moses-smt/mosesdecoder.git
synced 2024-12-26 13:23:25 +03:00
324 lines
11 KiB
C++
324 lines
11 KiB
C++
#include "Manager.h"
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#include "Util.h"
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#include "SearchCubePruning.h"
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#include "StaticData.h"
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#include "InputType.h"
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#include "TranslationOptionCollection.h"
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using namespace std;
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namespace Moses
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{
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class BitmapContainerOrderer
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{
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public:
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bool operator()(const BitmapContainer* A, const BitmapContainer* B) const {
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if (B->Empty()) {
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if (A->Empty()) {
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return A < B;
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}
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return false;
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}
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if (A->Empty()) {
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return true;
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}
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// Compare the top hypothesis of each bitmap container using the TotalScore, which includes future cost
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const float scoreA = A->Top()->GetHypothesis()->GetTotalScore();
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const float scoreB = B->Top()->GetHypothesis()->GetTotalScore();
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if (scoreA < scoreB) {
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return true;
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} else if (scoreA > scoreB) {
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return false;
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} else {
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return A < B;
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}
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}
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};
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SearchCubePruning::SearchCubePruning(Manager& manager, const InputType &source, const TranslationOptionCollection &transOptColl)
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:Search(manager)
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,m_source(source)
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,m_hypoStackColl(source.GetSize() + 1)
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,m_start(clock())
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,m_transOptColl(transOptColl)
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{
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const StaticData &staticData = StaticData::Instance();
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std::vector < HypothesisStackCubePruning >::iterator iterStack;
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for (size_t ind = 0 ; ind < m_hypoStackColl.size() ; ++ind) {
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HypothesisStackCubePruning *sourceHypoColl = new HypothesisStackCubePruning(m_manager);
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sourceHypoColl->SetMaxHypoStackSize(staticData.GetMaxHypoStackSize());
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sourceHypoColl->SetBeamWidth(staticData.GetBeamWidth());
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m_hypoStackColl[ind] = sourceHypoColl;
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}
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}
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SearchCubePruning::~SearchCubePruning()
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{
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RemoveAllInColl(m_hypoStackColl);
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}
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/**
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* Main decoder loop that translates a sentence by expanding
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* hypotheses stack by stack, until the end of the sentence.
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*/
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void SearchCubePruning::ProcessSentence()
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{
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const StaticData &staticData = StaticData::Instance();
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// initial seed hypothesis: nothing translated, no words produced
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Hypothesis *hypo = Hypothesis::Create(m_manager,m_source, m_initialTransOpt);
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HypothesisStackCubePruning &firstStack = *static_cast<HypothesisStackCubePruning*>(m_hypoStackColl.front());
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firstStack.AddInitial(hypo);
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// Call this here because the loop below starts at the second stack.
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firstStack.CleanupArcList();
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CreateForwardTodos(firstStack);
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const size_t PopLimit = StaticData::Instance().GetCubePruningPopLimit();
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VERBOSE(3,"Cube Pruning pop limit is " << PopLimit << std::endl)
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const size_t Diversity = StaticData::Instance().GetCubePruningDiversity();
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VERBOSE(3,"Cube Pruning diversity is " << Diversity << std::endl)
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// go through each stack
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size_t stackNo = 1;
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std::vector < HypothesisStack* >::iterator iterStack;
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for (iterStack = ++m_hypoStackColl.begin() ; iterStack != m_hypoStackColl.end() ; ++iterStack) {
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// check if decoding ran out of time
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double _elapsed_time = GetUserTime();
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if (_elapsed_time > staticData.GetTimeoutThreshold()) {
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VERBOSE(1,"Decoding is out of time (" << _elapsed_time << "," << staticData.GetTimeoutThreshold() << ")" << std::endl);
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return;
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}
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HypothesisStackCubePruning &sourceHypoColl = *static_cast<HypothesisStackCubePruning*>(*iterStack);
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// priority queue which has a single entry for each bitmap container, sorted by score of top hyp
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std::priority_queue< BitmapContainer*, std::vector< BitmapContainer* >, BitmapContainerOrderer> BCQueue;
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_BMType::const_iterator bmIter;
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const _BMType &accessor = sourceHypoColl.GetBitmapAccessor();
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for(bmIter = accessor.begin(); bmIter != accessor.end(); ++bmIter) {
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bmIter->second->InitializeEdges();
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BCQueue.push(bmIter->second);
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// old algorithm
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// bmIter->second->EnsureMinStackHyps(PopLimit);
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}
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// main search loop, pop k best hyps
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for (size_t numpops = 1; numpops <= PopLimit && !BCQueue.empty(); numpops++) {
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BitmapContainer *bc = BCQueue.top();
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BCQueue.pop();
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bc->ProcessBestHypothesis();
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if (!bc->Empty())
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BCQueue.push(bc);
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}
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// ensure diversity, a minimum number of inserted hyps for each bitmap container;
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// NOTE: diversity doesn't ensure they aren't pruned at some later point
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if (Diversity > 0) {
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for(bmIter = accessor.begin(); bmIter != accessor.end(); ++bmIter) {
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bmIter->second->EnsureMinStackHyps(Diversity);
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}
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}
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// the stack is pruned before processing (lazy pruning):
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VERBOSE(3,"processing hypothesis from next stack");
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// VERBOSE("processing next stack at ");
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sourceHypoColl.PruneToSize(staticData.GetMaxHypoStackSize());
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VERBOSE(3,std::endl);
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sourceHypoColl.CleanupArcList();
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CreateForwardTodos(sourceHypoColl);
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stackNo++;
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}
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//PrintBitmapContainerGraph();
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// some more logging
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IFVERBOSE(2) {
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m_manager.GetSentenceStats().SetTimeTotal( clock()-m_start );
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}
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VERBOSE(2, m_manager.GetSentenceStats());
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}
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void SearchCubePruning::CreateForwardTodos(HypothesisStackCubePruning &stack)
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{
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const _BMType &bitmapAccessor = stack.GetBitmapAccessor();
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_BMType::const_iterator iterAccessor;
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size_t size = m_source.GetSize();
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stack.AddHypothesesToBitmapContainers();
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for (iterAccessor = bitmapAccessor.begin() ; iterAccessor != bitmapAccessor.end() ; ++iterAccessor) {
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const WordsBitmap &bitmap = iterAccessor->first;
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BitmapContainer &bitmapContainer = *iterAccessor->second;
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if (bitmapContainer.GetHypothesesSize() == 0) {
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// no hypothese to expand. don't bother doing it
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continue;
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}
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// Sort the hypotheses inside the Bitmap Container as they are being used by now.
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bitmapContainer.SortHypotheses();
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// check bitamp and range doesn't overlap
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size_t startPos, endPos;
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for (startPos = 0 ; startPos < size ; startPos++) {
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if (bitmap.GetValue(startPos))
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continue;
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// not yet covered
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WordsRange applyRange(startPos, startPos);
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if (CheckDistortion(bitmap, applyRange)) {
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// apply range
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CreateForwardTodos(bitmap, applyRange, bitmapContainer);
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}
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size_t maxSize = size - startPos;
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size_t maxSizePhrase = StaticData::Instance().GetMaxPhraseLength();
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maxSize = std::min(maxSize, maxSizePhrase);
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for (endPos = startPos+1; endPos < startPos + maxSize; endPos++) {
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if (bitmap.GetValue(endPos))
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break;
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WordsRange applyRange(startPos, endPos);
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if (CheckDistortion(bitmap, applyRange)) {
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// apply range
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CreateForwardTodos(bitmap, applyRange, bitmapContainer);
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}
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}
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}
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}
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}
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void SearchCubePruning::CreateForwardTodos(const WordsBitmap &bitmap, const WordsRange &range, BitmapContainer &bitmapContainer)
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{
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WordsBitmap newBitmap = bitmap;
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newBitmap.SetValue(range.GetStartPos(), range.GetEndPos(), true);
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size_t numCovered = newBitmap.GetNumWordsCovered();
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const TranslationOptionList &transOptList = m_transOptColl.GetTranslationOptionList(range);
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const SquareMatrix &futureScore = m_transOptColl.GetFutureScore();
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if (transOptList.size() > 0) {
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HypothesisStackCubePruning &newStack = *static_cast<HypothesisStackCubePruning*>(m_hypoStackColl[numCovered]);
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newStack.SetBitmapAccessor(newBitmap, newStack, range, bitmapContainer, futureScore, transOptList);
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}
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}
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bool SearchCubePruning::CheckDistortion(const WordsBitmap &hypoBitmap, const WordsRange &range) const
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{
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// since we check for reordering limits, its good to have that limit handy
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int maxDistortion = StaticData::Instance().GetMaxDistortion();
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// if there are reordering limits, make sure it is not violated
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// the coverage bitmap is handy here (and the position of the first gap)
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const size_t hypoFirstGapPos = hypoBitmap.GetFirstGapPos()
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, startPos = range.GetStartPos()
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, endPos = range.GetEndPos();
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// if reordering constraints are used (--monotone-at-punctuation or xml), check if passes all
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if (! m_source.GetReorderingConstraint().Check( hypoBitmap, startPos, endPos ) ) {
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return false;
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}
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// no limit of reordering: no problem
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if (maxDistortion < 0) {
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return true;
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}
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bool leftMostEdge = (hypoFirstGapPos == startPos);
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// any length extension is okay if starting at left-most edge
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if (leftMostEdge) {
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return true;
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}
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// starting somewhere other than left-most edge, use caution
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// the basic idea is this: we would like to translate a phrase starting
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// from a position further right than the left-most open gap. The
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// distortion penalty for the following phrase will be computed relative
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// to the ending position of the current extension, so we ask now what
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// its maximum value will be (which will always be the value of the
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// hypothesis starting at the left-most edge). If this vlaue is than
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// the distortion limit, we don't allow this extension to be made.
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WordsRange bestNextExtension(hypoFirstGapPos, hypoFirstGapPos);
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int required_distortion =
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m_source.ComputeDistortionDistance(range, bestNextExtension);
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if (required_distortion > maxDistortion) {
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return false;
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}
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return true;
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}
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/**
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* Find best hypothesis on the last stack.
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* This is the end point of the best translation, which can be traced back from here
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*/
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const Hypothesis *SearchCubePruning::GetBestHypothesis() const
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{
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// const HypothesisStackCubePruning &hypoColl = m_hypoStackColl.back();
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const HypothesisStack &hypoColl = *m_hypoStackColl.back();
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return hypoColl.GetBestHypothesis();
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}
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/**
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* Logging of hypothesis stack sizes
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*/
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void SearchCubePruning::OutputHypoStackSize()
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{
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std::vector < HypothesisStack* >::const_iterator iterStack = m_hypoStackColl.begin();
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TRACE_ERR( "Stack sizes: " << (int)(*iterStack)->size());
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for (++iterStack; iterStack != m_hypoStackColl.end() ; ++iterStack) {
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TRACE_ERR( ", " << (int)(*iterStack)->size());
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}
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TRACE_ERR( endl);
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}
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void SearchCubePruning::PrintBitmapContainerGraph()
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{
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HypothesisStackCubePruning &lastStack = *static_cast<HypothesisStackCubePruning*>(m_hypoStackColl.back());
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const _BMType &bitmapAccessor = lastStack.GetBitmapAccessor();
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_BMType::const_iterator iterAccessor;
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for (iterAccessor = bitmapAccessor.begin(); iterAccessor != bitmapAccessor.end(); ++iterAccessor) {
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cerr << iterAccessor->first << endl;
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//BitmapContainer &container = *iterAccessor->second;
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}
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}
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/**
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* Logging of hypothesis stack contents
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* \param stack number of stack to be reported, report all stacks if 0
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*/
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void SearchCubePruning::OutputHypoStack(int stack)
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{
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if (stack >= 0) {
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TRACE_ERR( "Stack " << stack << ": " << endl << m_hypoStackColl[stack] << endl);
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} else {
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// all stacks
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int i = 0;
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vector < HypothesisStack* >::iterator iterStack;
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for (iterStack = m_hypoStackColl.begin() ; iterStack != m_hypoStackColl.end() ; ++iterStack) {
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HypothesisStackCubePruning &hypoColl = *static_cast<HypothesisStackCubePruning*>(*iterStack);
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TRACE_ERR( "Stack " << i++ << ": " << endl << hypoColl << endl);
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}
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}
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}
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const std::vector < HypothesisStack* >& SearchCubePruning::GetHypothesisStacks() const
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{
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return m_hypoStackColl;
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}
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}
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