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#ifndef _EXTRACT_H_
#define _EXTRACT_H_
#include <iostream>
#include <utility>
#include <vector>
#include "array2d.h"
#include "wordid.h"
#include "sparse_vector.h"
struct AnnotatedParallelSentence;
// usually represents a consistent phrase, which may
// be annotated with a type (cat)
// inside the rule extractor, this class is also used to represent a word
// in a partial rule.
struct ParallelSpan {
// i1 = i of f side
// i2 = j of f side
// j1 = i of e side
// j2 = j of e side
short i1,i2,j1,j2;
// cat is set by AnnotatePhrasesWithCategoryTypes, otherwise it's 0
WordID cat; // category type of span (also overloaded by RuleItem class
// to be a word ID)
ParallelSpan() : i1(-1), i2(-1), j1(-1), j2(-1), cat() {}
// used by Rule class to represent a terminal symbol:
explicit ParallelSpan(WordID w) : i1(-1), i2(-1), j1(-1), j2(-1), cat(w) {}
ParallelSpan(int pi1, int pi2, int pj1, int pj2) : i1(pi1), i2(pi2), j1(pj1), j2(pj2), cat() {}
ParallelSpan(int pi1, int pi2, int pj1, int pj2, WordID c) : i1(pi1), i2(pi2), j1(pj1), j2(pj2), cat(c) {}
// ParallelSpan is used in the Rule class where it is
// overloaded to also represent terminal symbols
inline bool IsVariable() const { return i1 != -1; }
};
// rule extraction logic lives here. this has no data, it's just got
// static member functions.
struct Extract {
// RuleObserver's CountRule is called for each rule extracted
// implement CountRuleImpl to do things like count the rules,
// write them to a file, etc.
struct RuleObserver {
RuleObserver() : count() {}
virtual void CountRule(WordID lhs,
const std::vector<WordID>& rhs_f,
const std::vector<WordID>& rhs_e,
const std::vector<std::pair<short, short> >& fe_terminal_alignments) {
++count;
CountRuleImpl(lhs, rhs_f, rhs_e, fe_terminal_alignments);
}
virtual ~RuleObserver();
protected:
virtual void CountRuleImpl(WordID lhs,
const std::vector<WordID>& rhs_f,
const std::vector<WordID>& rhs_e,
const std::vector<std::pair<short, short> >& fe_terminal_alignments) = 0;
private:
int count;
};
// given a set of "tight" phrases and the aligned sentence they were
// extracted from, "loosen" them
static void LoosenPhraseBounds(const AnnotatedParallelSentence& sentence,
const int max_base_phrase_size,
std::vector<ParallelSpan>* phrases);
// extract all consistent phrase pairs, up to size max_base_phrase_size
// (on the source side). these phrases will be "tight".
static void ExtractBasePhrases(const int max_base_phrase_size,
const AnnotatedParallelSentence& sentence,
std::vector<ParallelSpan>* phrases);
// this uses the TARGET span (i,j) to annotate phrases, will copy
// phrases if there is more than one annotation.
// TODO: support source annotation
static void AnnotatePhrasesWithCategoryTypes(const WordID default_cat,
const Array2D<std::vector<WordID> >& types,
std::vector<ParallelSpan>* phrases);
// use the Chiang (2007) extraction logic to extract consistent subphrases
// observer->CountRule is called once for each rule extracted
static void ExtractConsistentRules(const AnnotatedParallelSentence& sentence,
const std::vector<ParallelSpan>& phrases,
const int max_vars,
const int max_syms,
const bool permit_adjacent_nonterminals,
const bool require_aligned_terminal,
RuleObserver* observer,
std::vector<WordID>* all_cats);
};
#endif
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