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
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
#include "lextrans.h"
#include <iostream>
#include <cstdlib>
#include "filelib.h"
#include "hg.h"
#include "tdict.h"
#include "grammar.h"
#include "sentence_metadata.h"
using namespace std;
struct LexicalTransImpl {
LexicalTransImpl(const boost::program_options::variables_map& conf) :
use_null(conf.count("lextrans_use_null") > 0),
align_only_(conf.count("lextrans_align_only") > 0),
psg_file_(),
kXCAT(TD::Convert("X")*-1),
kNULL(TD::Convert("<eps>")),
kBINARY(new TRule("[X] ||| [X,1] [X,2] ||| [1] [2]")),
kGOAL_RULE(new TRule("[Goal] ||| [X,1] ||| [1]")) {
if (conf.count("per_sentence_grammar_file")) {
psg_file_ = new ifstream(conf["per_sentence_grammar_file"].as<string>().c_str());
}
vector<string> gfiles = conf["grammar"].as<vector<string> >();
assert(gfiles.size() == 1);
ReadFile rf(gfiles.front());
TextGrammar *tg = new TextGrammar;
grammar.reset(tg);
istream* in = rf.stream();
int lc = 0;
bool flag = false;
string line;
while(*in) {
getline(*in, line);
if (!*in) continue;
++lc;
TRulePtr r(TRule::CreateRulePhrasetable(line));
tg->AddRule(r);
if (lc % 50000 == 0) { cerr << '.'; flag = true; }
if (lc % 2000000 == 0) { cerr << " [" << lc << "]\n"; flag = false; }
}
if (flag) cerr << endl;
cerr << "Loaded " << lc << " rules\n";
}
void LoadSentenceGrammar(const string& s_offset) {
const unsigned long long int offset = strtoull(s_offset.c_str(), NULL, 10);
psg_file_->seekg(offset, ios::beg);
TextGrammar *tg = new TextGrammar;
sup_grammar.reset(tg);
const string kEND_MARKER = "###EOS###";
string line;
while(true) {
assert(*psg_file_);
getline(*psg_file_, line);
if (line == kEND_MARKER) break;
TRulePtr r(TRule::CreateRulePhrasetable(line));
tg->AddRule(r);
}
}
bool BuildTrellis(const Lattice& lattice, const SentenceMetadata& smeta, Hypergraph* forest) {
if (psg_file_) {
const string offset = smeta.GetSGMLValue("psg");
if (offset.size() < 2 || offset[0] != '@') {
cerr << "per_sentence_grammar_file given but sentence id=" << smeta.GetSentenceID() << " doesn't have grammar info!\n";
abort();
}
LoadSentenceGrammar(offset.substr(1));
}
const int e_len = smeta.GetTargetLength();
assert(e_len > 0);
const int f_len = lattice.size();
// hack to tell the feature function system how big the sentence pair is
const int f_start = (use_null ? -1 : 0);
int prev_node_id = -1;
set<WordID> target_vocab; // only set for alignment_only mode
if (align_only_) {
const Lattice& ref = smeta.GetReference();
for (int i = 0; i < ref.size(); ++i) {
target_vocab.insert(ref[i][0].label);
}
}
for (int i = 0; i < e_len; ++i) { // for each word in the *target*
Hypergraph::Node* node = forest->AddNode(kXCAT);
const int new_node_id = node->id_;
for (int j = f_start; j < f_len; ++j) { // for each word in the source
const WordID src_sym = (j < 0 ? kNULL : lattice[j][0].label);
const GrammarIter* gi = grammar->GetRoot()->Extend(src_sym);
if (!gi) {
if (psg_file_)
gi = sup_grammar->GetRoot()->Extend(src_sym);
if (!gi) {
cerr << "No translations found for: " << TD::Convert(src_sym) << "\n";
return false;
}
}
const RuleBin* rb = gi->GetRules();
assert(rb);
for (int k = 0; k < rb->GetNumRules(); ++k) {
TRulePtr rule = rb->GetIthRule(k);
if (align_only_) {
if (target_vocab.count(rule->e_[0]) == 0)
continue;
}
Hypergraph::Edge* edge = forest->AddEdge(rule, Hypergraph::TailNodeVector());
edge->i_ = j;
edge->j_ = j+1;
edge->prev_i_ = i;
edge->prev_j_ = i+1;
edge->feature_values_ += edge->rule_->GetFeatureValues();
forest->ConnectEdgeToHeadNode(edge->id_, new_node_id);
}
}
if (prev_node_id >= 0) {
const int comb_node_id = forest->AddNode(kXCAT)->id_;
Hypergraph::TailNodeVector tail(2, prev_node_id);
tail[1] = new_node_id;
Hypergraph::Edge* edge = forest->AddEdge(kBINARY, tail);
forest->ConnectEdgeToHeadNode(edge->id_, comb_node_id);
prev_node_id = comb_node_id;
} else {
prev_node_id = new_node_id;
}
}
Hypergraph::TailNodeVector tail(1, forest->nodes_.size() - 1);
Hypergraph::Node* goal = forest->AddNode(TD::Convert("Goal")*-1);
Hypergraph::Edge* hg_edge = forest->AddEdge(kGOAL_RULE, tail);
forest->ConnectEdgeToHeadNode(hg_edge, goal);
return true;
}
private:
const bool use_null;
const bool align_only_;
ifstream* psg_file_;
const WordID kXCAT;
const WordID kNULL;
const TRulePtr kBINARY;
const TRulePtr kGOAL_RULE;
GrammarPtr grammar;
GrammarPtr sup_grammar;
};
LexicalTrans::LexicalTrans(const boost::program_options::variables_map& conf) :
pimpl_(new LexicalTransImpl(conf)) {}
bool LexicalTrans::TranslateImpl(const string& input,
SentenceMetadata* smeta,
const vector<double>& weights,
Hypergraph* forest) {
Lattice& lattice = smeta->src_lattice_;
LatticeTools::ConvertTextOrPLF(input, &lattice);
if (!lattice.IsSentence()) {
// lexical models make independence assumptions
// that don't work with lattices or conf nets
cerr << "LexicalTrans: cannot deal with lattice source input!\n";
abort();
}
smeta->SetSourceLength(lattice.size());
if (!pimpl_->BuildTrellis(lattice, *smeta, forest)) return false;
forest->is_linear_chain_ = true;
forest->Reweight(weights);
return true;
}
|
