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
|
#include "lextrans.h"
#include <iostream>
#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),
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]")) {
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;
while(*in) {
string line;
getline(*in, line);
if (line.empty()) 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 BuildTrellis(const Lattice& lattice, const SentenceMetadata& smeta, Hypergraph* forest) {
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;
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) {
cerr << "No translations found for: " << TD::Convert(src_sym) << "\n";
abort();
}
const RuleBin* rb = gi->GetRules();
assert(rb);
for (int k = 0; k < rb->GetNumRules(); ++k) {
TRulePtr rule = rb->GetIthRule(k);
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);
}
private:
const bool use_null;
const WordID kXCAT;
const WordID kNULL;
const TRulePtr kBINARY;
const TRulePtr kGOAL_RULE;
GrammarPtr 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());
pimpl_->BuildTrellis(lattice, *smeta, forest);
forest->is_linear_chain_ = true;
forest->Reweight(weights);
return true;
}
|
