mosesdecoder/moses/FF/RuleAmbiguity.cpp

#include "RuleAmbiguity.h"
#include "moses/StaticData.h"
#include "moses/Word.h"

namespace Moses
{
RuleAmbiguity::RuleAmbiguity(const std::string &line)
:StatelessFeatureFunction(1, line)
,m_sourceSyntax(true)
{
}

bool IsAmbiguous(const Word &word, bool sourceSyntax)
{
  const Word &inputDefaultNonTerminal = StaticData::Instance().GetInputDefaultNonTerminal();
  return word.IsNonTerminal() && (!sourceSyntax || word == inputDefaultNonTerminal);
}

void RuleAmbiguity::Evaluate(const Phrase &source
						, const TargetPhrase &targetPhrase
						, ScoreComponentCollection &scoreBreakdown
						, ScoreComponentCollection &estimatedFutureScore) const
{
  // source can't be empty, right?
  float score = 0;

  int count = 0;
  for (size_t i = 0; i < source.GetSize() - 0; ++i) {
	const Word &word = source.GetWord(i);
	bool ambiguous = IsAmbiguous(word, m_sourceSyntax);
	if (ambiguous) {
		++count;
	}
	else {
		if (count > 0) {
			score += count;
		}
		count = -1;
	}
  }

  // 1st & last always adjacent to ambiguity
  ++count;
  if (count > 0) {
	score += count;
  }

  scoreBreakdown.PlusEquals(this, score);
}

void RuleAmbiguity::SetParameter(const std::string& key, const std::string& value)
{
  if (key == "source-syntax") {
	  m_sourceSyntax = Scan<bool>(value);
  } else {
    StatelessFeatureFunction::SetParameter(key, value);
  }
}

}