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
|
#ifndef _RULE_FACTORY_H_
#define _RULE_FACTORY_H_
#include <memory>
#include <vector>
#include <unordered_set>
#include "matchings_trie.h"
using namespace std;
namespace extractor {
class Alignment;
class DataArray;
class FastIntersector;
class Grammar;
class MatchingsFinder;
class PhraseBuilder;
class Precomputation;
class Rule;
class RuleExtractor;
class Sampler;
class Scorer;
class State;
class SuffixArray;
class Vocabulary;
/**
* Component containing most of the logic for extracting SCFG rules for a given
* sentence.
*
* Given a sentence (as a vector of word ids), this class constructs all the
* possible source phrases starting from this sentence. For each source phrase,
* it finds all its occurrences in the source data and samples some of these
* occurrences to extract aligned source-target phrase pairs. A trie cache is
* used to avoid unnecessary computations if a source phrase can be constructed
* more than once (e.g. some words occur more than once in the sentence).
*/
class HieroCachingRuleFactory {
public:
HieroCachingRuleFactory(
shared_ptr<SuffixArray> source_suffix_array,
shared_ptr<DataArray> target_data_array,
shared_ptr<Alignment> alignment,
const shared_ptr<Vocabulary>& vocabulary,
shared_ptr<Precomputation> precomputation,
shared_ptr<Scorer> scorer,
int min_gap_size,
int max_rule_span,
int max_nonterminals,
int max_rule_symbols,
int max_samples,
bool require_tight_phrases);
// For testing only.
HieroCachingRuleFactory(
shared_ptr<MatchingsFinder> finder,
shared_ptr<FastIntersector> fast_intersector,
shared_ptr<PhraseBuilder> phrase_builder,
shared_ptr<RuleExtractor> rule_extractor,
shared_ptr<Vocabulary> vocabulary,
shared_ptr<Sampler> sampler,
shared_ptr<Scorer> scorer,
int min_gap_size,
int max_rule_span,
int max_nonterminals,
int max_chunks,
int max_rule_symbols);
virtual ~HieroCachingRuleFactory();
// Constructs SCFG rules for a given sentence.
// (See class description for more details.)
virtual Grammar GetGrammar(
const vector<int>& word_ids,
const unordered_set<int>& blacklisted_sentence_ids);
protected:
HieroCachingRuleFactory();
private:
// Checks if the phrase (if previously encountered) or its prefix have any
// occurrences in the source data.
bool CannotHaveMatchings(shared_ptr<TrieNode> node, int word_id);
// Checks if the phrase has previously been analyzed.
bool RequiresLookup(shared_ptr<TrieNode> node, int word_id);
// Creates a new state in the trie that corresponds to adding a trailing
// nonterminal to the current phrase.
void AddTrailingNonterminal(vector<int> symbols,
const Phrase& prefix,
const shared_ptr<TrieNode>& prefix_node,
bool starts_with_x);
// Extends the current state by possibly adding a nonterminal followed by a
// terminal.
vector<State> ExtendState(const vector<int>& word_ids,
const State& state,
vector<int> symbols,
const Phrase& phrase,
const shared_ptr<TrieNode>& node);
shared_ptr<MatchingsFinder> matchings_finder;
shared_ptr<FastIntersector> fast_intersector;
shared_ptr<PhraseBuilder> phrase_builder;
shared_ptr<RuleExtractor> rule_extractor;
shared_ptr<Vocabulary> vocabulary;
shared_ptr<Sampler> sampler;
shared_ptr<Scorer> scorer;
int min_gap_size;
int max_rule_span;
int max_nonterminals;
int max_chunks;
int max_rule_symbols;
};
} // namespace extractor
#endif
|
