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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
|
#include "transliterations.h"
#include <iostream>
#include <vector>
#include <tr1/unordered_map>
#include "grammar.h"
#include "bottom_up_parser.h"
#include "hg.h"
#include "hg_intersect.h"
#include "filelib.h"
#include "ccrp.h"
#include "m.h"
#include "lattice.h"
#include "verbose.h"
using namespace std;
using namespace std::tr1;
static WordID kX;
static int kMAX_SRC_SIZE = 0;
static vector<vector<WordID> > cur_trg_chunks;
vector<GrammarIter*> tlttofreelist;
static void InitTargetChunks(int max_size, const vector<WordID>& trg) {
cur_trg_chunks.clear();
vector<WordID> tmp;
unordered_set<vector<WordID>, boost::hash<vector<WordID> > > u;
for (int len = 1; len <= max_size; ++len) {
int end = trg.size() + 1;
end -= len;
for (int i = 0; i < end; ++i) {
tmp.clear();
for (int j = 0; j < len; ++j)
tmp.push_back(trg[i + j]);
if (u.insert(tmp).second) cur_trg_chunks.push_back(tmp);
}
}
}
struct TransliterationGrammarIter : public GrammarIter, public RuleBin {
TransliterationGrammarIter() { tlttofreelist.push_back(this); }
TransliterationGrammarIter(const TRulePtr& inr, int symbol) {
if (inr) {
r.reset(new TRule(*inr));
} else {
r.reset(new TRule);
}
TRule& rr = *r;
rr.lhs_ = kX;
rr.f_.push_back(symbol);
tlttofreelist.push_back(this);
}
virtual int GetNumRules() const {
if (!r) return 0;
return cur_trg_chunks.size();
}
virtual TRulePtr GetIthRule(int i) const {
TRulePtr nr(new TRule(*r));
nr->e_ = cur_trg_chunks[i];
//cerr << nr->AsString() << endl;
return nr;
}
virtual int Arity() const {
return 0;
}
virtual const RuleBin* GetRules() const {
if (!r) return NULL; else return this;
}
virtual const GrammarIter* Extend(int symbol) const {
if (symbol <= 0) return NULL;
if (!r || !kMAX_SRC_SIZE || r->f_.size() < kMAX_SRC_SIZE)
return new TransliterationGrammarIter(r, symbol);
else
return NULL;
}
TRulePtr r;
};
struct TransliterationGrammar : public Grammar {
virtual const GrammarIter* GetRoot() const {
return new TransliterationGrammarIter;
}
virtual bool HasRuleForSpan(int, int, int distance) const {
return (distance < kMAX_SRC_SIZE);
}
};
struct TInfo {
TInfo() : initialized(false) {}
bool initialized;
Hypergraph lattice; // may be empty if transliteration is not possible
prob_t est_prob; // will be zero if not possible
};
struct TransliterationsImpl {
TransliterationsImpl() {
kX = TD::Convert("X")*-1;
kMAX_SRC_SIZE = 4;
grammars.push_back(GrammarPtr(new TransliterationGrammar));
grammars.push_back(GrammarPtr(new GlueGrammar("S", "X")));
SetSilent(true);
}
void Initialize(WordID src, const vector<WordID>& src_lets, WordID trg, const vector<WordID>& trg_lets) {
if (src >= graphs.size()) graphs.resize(src + 1);
if (graphs[src][trg].initialized) return;
int kMAX_TRG_SIZE = 4;
InitTargetChunks(kMAX_TRG_SIZE, trg_lets);
ExhaustiveBottomUpParser parser("S", grammars);
Lattice lat(src_lets.size()), tlat(trg_lets.size());
for (unsigned i = 0; i < src_lets.size(); ++i)
lat[i].push_back(LatticeArc(src_lets[i], 0.0, 1));
for (unsigned i = 0; i < trg_lets.size(); ++i)
tlat[i].push_back(LatticeArc(trg_lets[i], 0.0, 1));
//cerr << "Creating lattice for: " << TD::Convert(src) << " --> " << TD::Convert(trg) << endl;
//cerr << "'" << TD::GetString(src_lets) << "' --> " << TD::GetString(trg_lets) << endl;
if (!parser.Parse(lat, &graphs[src][trg].lattice)) {
//cerr << "Failed to parse " << TD::GetString(src_lets) << endl;
abort();
}
if (HG::Intersect(tlat, &graphs[src][trg].lattice)) {
graphs[src][trg].est_prob = prob_t(1e-4);
} else {
graphs[src][trg].lattice.clear();
//cerr << "Failed to intersect " << TD::GetString(src_lets) << " ||| " << TD::GetString(trg_lets) << endl;
graphs[src][trg].est_prob = prob_t::Zero();
}
for (unsigned i = 0; i < tlttofreelist.size(); ++i)
delete tlttofreelist[i];
tlttofreelist.clear();
//cerr << "Number of paths: " << graphs[src][trg].lattice.NumberOfPaths() << endl;
graphs[src][trg].initialized = true;
}
const prob_t& EstimateProbability(WordID src, WordID trg) const {
assert(src < graphs.size());
const unordered_map<WordID, TInfo>& um = graphs[src];
const unordered_map<WordID, TInfo>::const_iterator it = um.find(trg);
assert(it != um.end());
assert(it->second.initialized);
return it->second.est_prob;
}
void Forbid(WordID src, WordID trg) {
if (src >= graphs.size()) graphs.resize(src + 1);
graphs[src][trg].est_prob = prob_t::Zero();
graphs[src][trg].initialized = true;
}
void GraphSummary() const {
double tlp = 0;
int tt = 0;
for (int i = 0; i < graphs.size(); ++i) {
const unordered_map<WordID, TInfo>& um = graphs[i];
unordered_map<WordID, TInfo>::const_iterator it;
for (it = um.begin(); it != um.end(); ++it) {
if (it->second.lattice.empty()) continue;
//cerr << TD::Convert(i) << " --> " << TD::Convert(it->first) << ": " << it->second.lattice.NumberOfPaths() << endl;
tlp += log(it->second.lattice.NumberOfPaths());
tt++;
}
}
tlp /= tt;
cerr << "E[log paths] = " << tlp << endl;
cerr << "exp(E[log paths]) = " << exp(tlp) << endl;
}
vector<unordered_map<WordID, TInfo> > graphs;
vector<GrammarPtr> grammars;
};
Transliterations::Transliterations() : pimpl_(new TransliterationsImpl) {}
Transliterations::~Transliterations() { delete pimpl_; }
void Transliterations::Initialize(WordID src, const vector<WordID>& src_lets, WordID trg, const vector<WordID>& trg_lets) {
pimpl_->Initialize(src, src_lets, trg, trg_lets);
}
prob_t Transliterations::EstimateProbability(WordID src, WordID trg) const {
return pimpl_->EstimateProbability(src,trg);
}
void Transliterations::Forbid(WordID src, WordID trg) {
pimpl_->Forbid(src, trg);
}
void Transliterations::GraphSummary() const {
pimpl_->GraphSummary();
}
|
