mosesdecoder/moses2/HypothesisColl.cpp
2017-02-01 00:27:14 +00:00

281 lines
7.3 KiB
C++

/*
* HypothesisColl.cpp
*
* Created on: 26 Feb 2016
* Author: hieu
*/
#include <iostream>
#include <sstream>
#include <algorithm>
#include <boost/foreach.hpp>
#include "HypothesisColl.h"
#include "ManagerBase.h"
#include "System.h"
#include "MemPoolAllocator.h"
using namespace std;
namespace Moses2
{
HypothesisColl::HypothesisColl(const ManagerBase &mgr)
:m_coll(MemPoolAllocator<const HypothesisBase*>(mgr.GetPool()))
,m_sortedHypos(NULL)
{
m_bestScore = -std::numeric_limits<float>::infinity();
m_worstScore = std::numeric_limits<float>::infinity();
}
const HypothesisBase *HypothesisColl::GetBestHypo() const
{
if (GetSize() == 0) {
return NULL;
}
if (m_sortedHypos) {
return (*m_sortedHypos)[0];
}
SCORE bestScore = -std::numeric_limits<SCORE>::infinity();
const HypothesisBase *bestHypo;
BOOST_FOREACH(const HypothesisBase *hypo, m_coll) {
if (hypo->GetFutureScore() > bestScore) {
bestScore = hypo->GetFutureScore();
bestHypo = hypo;
}
}
return bestHypo;
}
void HypothesisColl::Add(
const ManagerBase &mgr,
HypothesisBase *hypo,
Recycler<HypothesisBase*> &hypoRecycle,
ArcLists &arcLists)
{
size_t maxStackSize = mgr.system.options.search.stack_size;
if (GetSize() > maxStackSize * 2) {
//cerr << "maxStackSize=" << maxStackSize << " " << GetSize() << endl;
PruneHypos(mgr, mgr.arcLists);
}
SCORE futureScore = hypo->GetFutureScore();
/*
cerr << "scores:"
<< futureScore << " "
<< m_bestScore << " "
<< GetSize() << " "
<< endl;
*/
if (GetSize() >= maxStackSize && futureScore < m_worstScore) {
// beam threshold or really bad hypo that won't make the pruning cut
// as more hypos are added, the m_worstScore stat gets out of date and isn't the optimum cut-off point
//cerr << "Discard, really bad score:" << hypo->Debug(mgr.system) << endl;
hypoRecycle.Recycle(hypo);
return;
}
StackAdd added = Add(hypo);
size_t nbestSize = mgr.system.options.nbest.nbest_size;
if (nbestSize) {
arcLists.AddArc(added.added, hypo, added.other);
} else {
if (added.added) {
if (added.other) {
hypoRecycle.Recycle(added.other);
}
} else {
hypoRecycle.Recycle(hypo);
}
}
// update beam variables
if (added.added) {
if (futureScore > m_bestScore) {
m_bestScore = futureScore;
float beamWidth = mgr.system.options.search.beam_width;
if ( m_bestScore + beamWidth > m_worstScore ) {
m_worstScore = m_bestScore + beamWidth;
}
} else if (GetSize() <= maxStackSize && futureScore < m_worstScore) {
m_worstScore = futureScore;
}
}
}
StackAdd HypothesisColl::Add(const HypothesisBase *hypo)
{
std::pair<_HCType::iterator, bool> addRet = m_coll.insert(hypo);
//cerr << endl << "new=" << hypo->Debug(hypo->GetManager().system) << endl;
// CHECK RECOMBINATION
if (addRet.second) {
// equiv hypo doesn't exists
//cerr << "Added " << hypo << endl;
return StackAdd(true, NULL);
} else {
HypothesisBase *hypoExisting = const_cast<HypothesisBase*>(*addRet.first);
//cerr << "hypoExisting=" << hypoExisting->Debug(hypo->GetManager().system) << endl;
if (hypo->GetFutureScore() > hypoExisting->GetFutureScore()) {
// incoming hypo is better than the one we have
const HypothesisBase * const &hypoExisting1 = *addRet.first;
const HypothesisBase *&hypoExisting2 =
const_cast<const HypothesisBase *&>(hypoExisting1);
hypoExisting2 = hypo;
//cerr << "Added " << hypo << " dicard existing " << hypoExisting2 << endl;
return StackAdd(true, hypoExisting);
} else {
// already storing the best hypo. discard incoming hypo
//cerr << "Keep existing " << hypoExisting << " dicard new " << hypo << endl;
return StackAdd(false, hypoExisting);
}
}
//assert(false);
}
const Hypotheses &HypothesisColl::GetSortedAndPrunedHypos(
const ManagerBase &mgr,
ArcLists &arcLists) const
{
if (m_sortedHypos == NULL) {
// create sortedHypos first
MemPool &pool = mgr.GetPool();
m_sortedHypos = new (pool.Allocate<Hypotheses>()) Hypotheses(pool,
m_coll.size());
SortHypos(mgr, m_sortedHypos->GetArray());
// prune
Recycler<HypothesisBase*> &recycler = mgr.GetHypoRecycle();
size_t maxStackSize = mgr.system.options.search.stack_size;
if (maxStackSize && m_sortedHypos->size() > maxStackSize) {
for (size_t i = maxStackSize; i < m_sortedHypos->size(); ++i) {
HypothesisBase *hypo = const_cast<HypothesisBase*>((*m_sortedHypos)[i]);
recycler.Recycle(hypo);
// delete from arclist
if (mgr.system.options.nbest.nbest_size) {
arcLists.Delete(hypo);
}
}
m_sortedHypos->resize(maxStackSize);
}
}
return *m_sortedHypos;
}
void HypothesisColl::PruneHypos(const ManagerBase &mgr, ArcLists &arcLists)
{
size_t maxStackSize = mgr.system.options.search.stack_size;
Recycler<HypothesisBase*> &recycler = mgr.GetHypoRecycle();
const HypothesisBase *sortedHypos[GetSize()];
SortHypos(mgr, sortedHypos);
// update worse score
m_worstScore = sortedHypos[maxStackSize - 1]->GetFutureScore();
// prune
for (size_t i = maxStackSize; i < GetSize(); ++i) {
HypothesisBase *hypo = const_cast<HypothesisBase*>(sortedHypos[i]);
// delete from arclist
if (mgr.system.options.nbest.nbest_size) {
arcLists.Delete(hypo);
}
// delete from collection
Delete(hypo);
recycler.Recycle(hypo);
}
}
void HypothesisColl::SortHypos(const ManagerBase &mgr, const HypothesisBase **sortedHypos) const
{
size_t maxStackSize = mgr.system.options.search.stack_size;
//assert(maxStackSize); // can't do stack=0 - unlimited stack size. No-one ever uses that
//assert(GetSize() > maxStackSize);
//assert(sortedHypos.size() == GetSize());
/*
cerr << "UNSORTED hypos: ";
BOOST_FOREACH(const HypothesisBase *hypo, m_coll) {
cerr << hypo << "(" << hypo->GetFutureScore() << ")" << " ";
}
cerr << endl;
*/
size_t ind = 0;
BOOST_FOREACH(const HypothesisBase *hypo, m_coll) {
sortedHypos[ind] = hypo;
++ind;
}
size_t indMiddle;
if (maxStackSize == 0) {
indMiddle = GetSize();
} else if (GetSize() > maxStackSize) {
indMiddle = maxStackSize;
} else {
// GetSize() <= maxStackSize
indMiddle = GetSize();
}
const HypothesisBase **iterMiddle = sortedHypos + indMiddle;
std::partial_sort(
sortedHypos,
iterMiddle,
sortedHypos + GetSize(),
HypothesisFutureScoreOrderer());
/*
cerr << "sorted hypos: ";
for (size_t i = 0; i < sortedHypos.size(); ++i) {
const HypothesisBase *hypo = sortedHypos[i];
cerr << hypo << " ";
}
cerr << endl;
*/
}
void HypothesisColl::Delete(const HypothesisBase *hypo)
{
//cerr << "hypo=" << hypo << " " << m_coll.size() << endl;
size_t erased = m_coll.erase(hypo);
UTIL_THROW_IF2(erased != 1, "couldn't erase hypo " << hypo);
}
void HypothesisColl::Clear()
{
m_sortedHypos = NULL;
m_coll.clear();
m_bestScore = -std::numeric_limits<float>::infinity();
m_worstScore = std::numeric_limits<float>::infinity();
}
std::string HypothesisColl::Debug(const System &system) const
{
stringstream out;
BOOST_FOREACH (const HypothesisBase *hypo, m_coll) {
out << hypo->Debug(system);
out << std::endl << std::endl;
}
return out.str();
}
} /* namespace Moses2 */