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154 lines
5.3 KiB
C++
154 lines
5.3 KiB
C++
// $Id$
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/***********************************************************************
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Moses - factored phrase-based language decoder
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Copyright (C) 2006 University of Edinburgh
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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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#ifndef moses_HypothesisStackCubePruning_h
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#define moses_HypothesisStackCubePruning_h
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#include <limits>
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#include <set>
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#include <boost/unordered_map.hpp>
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#include "Hypothesis.h"
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#include "BitmapContainer.h"
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#include "HypothesisStack.h"
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#include "Util.h"
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namespace Moses
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{
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class BitmapContainer;
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class TranslationOptionList;
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class Manager;
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//typedef boost::unordered_map<Bitmap, BitmapContainer*, UnorderedComparer<Bitmap>, UnorderedComparer<Bitmap> > _BMType;
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typedef boost::unordered_map<const Bitmap*, BitmapContainer*> _BMType;
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// can compare Bitmap* 'cos all bitmaps are created from bitmaps factory class. MUST ensure this is the case
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/** A stack for phrase-based decoding with cube-pruning. */
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class HypothesisStackCubePruning : public HypothesisStack
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{
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public:
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friend std::ostream& operator<<(std::ostream&, const HypothesisStackCubePruning&);
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protected:
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_BMType m_bitmapAccessor;
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float m_bestScore; /**< score of the best hypothesis in collection */
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float m_worstScore; /**< score of the worse hypthesis in collection */
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float m_beamWidth; /**< minimum score due to threashold pruning */
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size_t m_maxHypoStackSize; /**< maximum number of hypothesis allowed in this stack */
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bool m_nBestIsEnabled; /**< flag to determine whether to keep track of old arcs */
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bool m_deterministic; /**< flag to determine whether to sort hypotheses deterministically */
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/** add hypothesis to stack. Prune if necessary.
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* Returns false if equiv hypo exists in collection, otherwise returns true
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*/
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std::pair<HypothesisStackCubePruning::iterator, bool> Add(Hypothesis *hypothesis);
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/** destroy all instances of Hypothesis in this collection */
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void RemoveAll();
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BitmapContainer *AddBitmapContainer(const Bitmap &bitmap, HypothesisStackCubePruning &stack);
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public:
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HypothesisStackCubePruning(Manager& manager);
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~HypothesisStackCubePruning() {
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RemoveAll();
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m_bitmapAccessor.clear();
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}
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/** adds the hypo, but only if within thresholds (beamThr, stackSize).
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* This function will recombine hypotheses silently! There is no record
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* (could affect n-best list generation...TODO)
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* Call stack for adding hypothesis is
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AddPrune()
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Add()
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AddNoPrune()
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*/
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bool AddPrune(Hypothesis *hypothesis);
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void AddInitial(Hypothesis *hypo);
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/** set maximum number of hypotheses in the collection
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* \param maxHypoStackSize maximum number (typical number: 100)
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*/
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inline void SetMaxHypoStackSize(size_t maxHypoStackSize) {
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m_maxHypoStackSize = maxHypoStackSize;
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}
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inline size_t GetMaxHypoStackSize() const {
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return m_maxHypoStackSize;
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}
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/** set beam threshold, hypotheses in the stack must not be worse than
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* this factor times the best score to be allowed in the stack
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* \param beamThreshold minimum factor (typical number: 0.03)
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*/
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inline void SetBeamWidth(float beamWidth) {
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m_beamWidth = beamWidth;
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}
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/** return score of the best hypothesis in the stack */
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inline float GetBestScore() const {
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return m_bestScore;
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}
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/** return worst score allowed for the stack */
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inline float GetWorstScore() const {
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return m_worstScore;
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}
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void AddHypothesesToBitmapContainers();
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const _BMType& GetBitmapAccessor() const {
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return m_bitmapAccessor;
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}
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void SetBitmapAccessor(const Bitmap &newBitmap
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, HypothesisStackCubePruning &stack
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, const Range &range
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, BitmapContainer &bitmapContainer
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, const SquareMatrix &estimatedScores
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, const TranslationOptionList &transOptList);
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/** pruning, if too large.
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* Pruning algorithm: find a threshold and delete all hypothesis below it.
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* The threshold is chosen so that exactly newSize top items remain on the
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* stack in fact, in situations where some of the hypothesis fell below
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* m_beamWidth, the stack will contain less items.
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* \param newSize maximum size */
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void PruneToSize(size_t newSize);
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//! return the hypothesis with best score. Used to get the translated at end of decoding
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const Hypothesis *GetBestHypothesis() const;
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//! return all hypothesis, sorted by descending score. Used in creation of N best list
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std::vector<const Hypothesis*> GetSortedList() const;
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/** make all arcs in point to the equiv hypothesis that contains them.
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* Ie update doubly linked list be hypo & arcs
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*/
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void CleanupArcList();
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TO_STRING();
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};
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}
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#endif
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