mosesdecoder/moses/FF/StatefulFeatureFunction.h
2015-02-19 12:27:23 +00:00

67 lines
1.8 KiB
C++

#pragma once
#include "FeatureFunction.h"
#include "moses/Syntax/SHyperedge.h"
namespace Moses
{
class FFState;
/** base class for all stateful feature functions.
* eg. LM, distortion penalty
*/
class StatefulFeatureFunction: public FeatureFunction
{
//All statefull FFs
static std::vector<const StatefulFeatureFunction*> m_statefulFFs;
public:
static const std::vector<const StatefulFeatureFunction*>&
GetStatefulFeatureFunctions() {
return m_statefulFFs;
}
StatefulFeatureFunction(const std::string &line);
StatefulFeatureFunction(size_t numScoreComponents, const std::string &line);
/**
* \brief This interface should be implemented.
* Notes: When evaluating the value of this feature function, you should avoid
* calling hypo.GetPrevHypo(). If you need something from the "previous"
* hypothesis, you should store it in an FFState object which will be passed
* in as prev_state. If you don't do this, you will get in trouble.
*/
virtual FFState* EvaluateWhenApplied(
const Hypothesis& cur_hypo,
const FFState* prev_state,
ScoreComponentCollection* accumulator) const = 0;
virtual FFState* EvaluateWhenApplied(
const ChartHypothesis& /* cur_hypo */,
int /* featureID - used to index the state in the previous hypotheses */,
ScoreComponentCollection* accumulator) const = 0;
virtual FFState* EvaluateWhenApplied(
const Syntax::SHyperedge& /* cur_hypo */,
int /* featureID - used to index the state in the previous hypotheses */,
ScoreComponentCollection* accumulator) const {
assert(false);
return 0; /* FIXME */
}
//! return the state associated with the empty hypothesis for a given sentence
virtual const FFState* EmptyHypothesisState(const InputType &input) const = 0;
bool IsStateless() const {
return false;
}
};
}