1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
#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 source_sent_start, 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
|
