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https://github.com/moses-smt/mosesdecoder.git
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118 lines
3.7 KiB
C++
118 lines
3.7 KiB
C++
// $Id$
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// vim:tabstop=2
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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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#include <string>
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#include <iostream>
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#include "EstimatedScores.h"
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using namespace std;
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namespace Moses2
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{
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/**
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* Calculate future score estimate for a given coverage bitmap
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*
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* /param bitmap coverage bitmap
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*/
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float EstimatedScores::CalcEstimatedScore(Bitmap const &bitmap) const
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{
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const size_t notInGap = numeric_limits<size_t>::max();
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size_t startGap = notInGap;
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float estimatedScore = 0.0f;
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for (size_t currPos = 0; currPos < bitmap.GetSize(); currPos++) {
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// start of a new gap?
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if (bitmap.GetValue(currPos) == false && startGap == notInGap) {
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startGap = currPos;
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}
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// end of a gap?
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else if (bitmap.GetValue(currPos) == true && startGap != notInGap) {
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estimatedScore += GetValue(startGap, currPos - 1);
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startGap = notInGap;
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}
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}
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// coverage ending with gap?
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if (startGap != notInGap) {
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estimatedScore += GetValue(startGap, bitmap.GetSize() - 1);
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}
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return estimatedScore;
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}
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/**
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* Calculare future score estimate for a given coverage bitmap
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* and an additional span that is also covered. This function is used
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* to compute future score estimates for hypotheses that we may want
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* build, but first want to check.
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*
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* Note: this function is implemented a bit more complex than
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* the basic one (w/o additional phrase) for speed reasons,
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* which is probably overkill.
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*
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* /param bitmap coverage bitmap
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* /param startPos start of the span that is added to the coverage
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* /param endPos end of the span that is added to the coverage
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*/
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float EstimatedScores::CalcEstimatedScore(Bitmap const &bitmap, size_t startPos,
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size_t endPos) const
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{
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const size_t notInGap = numeric_limits<size_t>::max();
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float estimatedScore = 0.0f;
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size_t startGap = bitmap.GetFirstGapPos();
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if (startGap == NOT_FOUND) return estimatedScore; // everything filled
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// start loop at first gap
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size_t startLoop = startGap + 1;
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if (startPos == startGap) { // unless covered by phrase
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startGap = notInGap;
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startLoop = endPos + 1; // -> postpone start
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}
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size_t lastCovered = bitmap.GetLastPos();
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if (endPos > lastCovered || lastCovered == NOT_FOUND) lastCovered = endPos;
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for (size_t currPos = startLoop; currPos <= lastCovered; currPos++) {
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// start of a new gap?
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if (startGap == notInGap && bitmap.GetValue(currPos) == false
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&& (currPos < startPos || currPos > endPos)) {
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startGap = currPos;
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}
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// end of a gap?
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else if (startGap != notInGap
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&& (bitmap.GetValue(currPos) == true
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|| (startPos <= currPos && currPos <= endPos))) {
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estimatedScore += GetValue(startGap, currPos - 1);
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startGap = notInGap;
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}
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}
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// coverage ending with gap?
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if (lastCovered != bitmap.GetSize() - 1) {
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estimatedScore += GetValue(lastCovered + 1, bitmap.GetSize() - 1);
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}
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return estimatedScore;
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}
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}
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