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#ifndef _RULE_EXTRACTOR_H_
#define _RULE_EXTRACTOR_H_
#include <memory>
#include <unordered_map>
#include <vector>
#include "phrase.h"
using namespace std;
namespace extractor {
typedef vector<pair<int, int> > PhraseAlignment;
class Alignment;
class DataArray;
class PhraseBuilder;
class PhraseLocation;
class Rule;
class RuleExtractorHelper;
class Scorer;
class TargetPhraseExtractor;
/**
* Structure containing data about the occurrences of a source-target phrase pair
* in the parallel corpus.
*/
struct Extract {
Extract(const Phrase& source_phrase, const Phrase& target_phrase,
double pairs_count, const PhraseAlignment& alignment) :
source_phrase(source_phrase), target_phrase(target_phrase),
pairs_count(pairs_count), alignment(alignment) {}
Phrase source_phrase;
Phrase target_phrase;
double pairs_count;
PhraseAlignment alignment;
};
/**
* Component for extracting SCFG rules.
*/
class RuleExtractor {
public:
RuleExtractor(shared_ptr<DataArray> source_data_array,
shared_ptr<DataArray> target_data_array,
shared_ptr<Alignment> alingment,
shared_ptr<PhraseBuilder> phrase_builder,
shared_ptr<Scorer> scorer,
shared_ptr<Vocabulary> vocabulary,
int min_gap_size,
int max_rule_span,
int max_nonterminals,
int max_rule_symbols,
bool require_aligned_terminal,
bool require_aligned_chunks,
bool require_tight_phrases);
// For testing only.
RuleExtractor(shared_ptr<DataArray> source_data_array,
shared_ptr<PhraseBuilder> phrase_builder,
shared_ptr<Scorer> scorer,
shared_ptr<TargetPhraseExtractor> target_phrase_extractor,
shared_ptr<RuleExtractorHelper> helper,
int max_rule_span,
int min_gap_size,
int max_nonterminals,
int max_rule_symbols,
bool require_tight_phrases);
virtual ~RuleExtractor();
// Extracts SCFG rules given a source phrase and a set of its occurrences
// in the source data.
virtual vector<Rule> ExtractRules(const Phrase& phrase,
const PhraseLocation& location) const;
protected:
RuleExtractor();
private:
// Finds all target phrases that can be aligned with the source phrase for a
// particular occurrence in the data.
vector<Extract> ExtractAlignments(const Phrase& phrase,
const vector<int>& matching) const;
// Extracts all target phrases for a given occurrence of the source phrase in
// the data. Constructs a vector of Extracts using these target phrases.
void AddExtracts(
vector<Extract>& extracts, const Phrase& source_phrase,
const unordered_map<int, int>& source_indexes,
const vector<pair<int, int> >& target_gaps, const vector<int>& target_low,
int target_phrase_low, int target_phrase_high, int sentence_id) const;
// Adds a leading and/or trailing nonterminal to the source phrase and
// extracts target phrases that can be aligned with the extended source
// phrase.
void AddNonterminalExtremities(
vector<Extract>& extracts, const vector<int>& matching,
const vector<int>& chunklen, const Phrase& source_phrase,
int source_back_low, int source_back_high, const vector<int>& source_low,
const vector<int>& source_high, const vector<int>& target_low,
const vector<int>& target_high, vector<pair<int, int> > target_gaps,
int sentence_id, int starts_with_x, int ends_with_x, int extend_left,
int extend_right) const;
private:
shared_ptr<DataArray> target_data_array;
shared_ptr<DataArray> source_data_array;
shared_ptr<PhraseBuilder> phrase_builder;
shared_ptr<Scorer> scorer;
shared_ptr<TargetPhraseExtractor> target_phrase_extractor;
shared_ptr<RuleExtractorHelper> helper;
int max_rule_span;
int min_gap_size;
int max_nonterminals;
int max_rule_symbols;
bool require_tight_phrases;
};
} // namespace extractor
#endif
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