1
2 // Licensed under the Apache License, Version 2.0 (the "License");
3 // you may not use this file except in compliance with the License.
4 // You may obtain a copy of the License at
5 //
6 // http://www.apache.org/licenses/LICENSE-2.0
7 //
8 // Unless required by applicable law or agreed to in writing, software
9 // distributed under the License is distributed on an "AS IS" BASIS,
10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 // See the License for the specific language governing permissions and
12 // limitations under the License.
13 //
14 // Copyright 2005-2010 Google, Inc.
15 // Author: krr@google.com (Kasturi Rangan Raghavan)
16 // \file
17 // LogWeight along with sign information that represents the value X in the
18 // linear domain as <sign(X), -ln(|X|)>
19 // The sign is a TropicalWeight:
20 // positive, TropicalWeight.Value() > 0.0, recommended value 1.0
21 // negative, TropicalWeight.Value() <= 0.0, recommended value -1.0
22
23 #ifndef FST_LIB_SIGNED_LOG_WEIGHT_H_
24 #define FST_LIB_SIGNED_LOG_WEIGHT_H_
25
26 #include <fst/float-weight.h>
27 #include <fst/pair-weight.h>
28
29
30 namespace fst {
31 template <class T>
32 class SignedLogWeightTpl
33 : public PairWeight<TropicalWeight, LogWeightTpl<T> > {
34 public:
35 typedef TropicalWeight X1;
36 typedef LogWeightTpl<T> X2;
37 using PairWeight<X1, X2>::Value1;
38 using PairWeight<X1, X2>::Value2;
39
40 using PairWeight<X1, X2>::Reverse;
41 using PairWeight<X1, X2>::Quantize;
42 using PairWeight<X1, X2>::Member;
43
44 typedef SignedLogWeightTpl<T> ReverseWeight;
45
SignedLogWeightTpl()46 SignedLogWeightTpl() : PairWeight<X1, X2>() {}
47
SignedLogWeightTpl(const SignedLogWeightTpl<T> & w)48 SignedLogWeightTpl(const SignedLogWeightTpl<T>& w)
49 : PairWeight<X1, X2> (w) { }
50
SignedLogWeightTpl(const PairWeight<X1,X2> & w)51 SignedLogWeightTpl(const PairWeight<X1, X2>& w)
52 : PairWeight<X1, X2> (w) { }
53
SignedLogWeightTpl(const X1 & x1,const X2 & x2)54 SignedLogWeightTpl(const X1& x1, const X2& x2)
55 : PairWeight<X1, X2>(x1, x2) { }
56
Zero()57 static const SignedLogWeightTpl<T> &Zero() {
58 static const SignedLogWeightTpl<T> zero(X1(1.0), X2::Zero());
59 return zero;
60 }
61
One()62 static const SignedLogWeightTpl<T> &One() {
63 static const SignedLogWeightTpl<T> one(X1(1.0), X2::One());
64 return one;
65 }
66
NoWeight()67 static const SignedLogWeightTpl<T> &NoWeight() {
68 static const SignedLogWeightTpl<T> no_weight(X1(1.0), X2::NoWeight());
69 return no_weight;
70 }
71
Type()72 static const string &Type() {
73 static const string type = "signed_log_" + X1::Type() + "_" + X2::Type();
74 return type;
75 }
76
77 ProductWeight<X1, X2> Quantize(float delta = kDelta) const {
78 return PairWeight<X1, X2>::Quantize();
79 }
80
Reverse()81 ReverseWeight Reverse() const {
82 return PairWeight<X1, X2>::Reverse();
83 }
84
Member()85 bool Member() const {
86 return PairWeight<X1, X2>::Member();
87 }
88
Properties()89 static uint64 Properties() {
90 // not idempotent nor path
91 return kLeftSemiring | kRightSemiring | kCommutative;
92 }
93
Hash()94 size_t Hash() const {
95 size_t h1;
96 if (Value2() == X2::Zero() || Value1().Value() > 0.0)
97 h1 = TropicalWeight(1.0).Hash();
98 else
99 h1 = TropicalWeight(-1.0).Hash();
100 size_t h2 = Value2().Hash();
101 const int lshift = 5;
102 const int rshift = CHAR_BIT * sizeof(size_t) - 5;
103 return h1 << lshift ^ h1 >> rshift ^ h2;
104 }
105 };
106
107 template <class T>
Plus(const SignedLogWeightTpl<T> & w1,const SignedLogWeightTpl<T> & w2)108 inline SignedLogWeightTpl<T> Plus(const SignedLogWeightTpl<T> &w1,
109 const SignedLogWeightTpl<T> &w2) {
110 if (!w1.Member() || !w2.Member())
111 return SignedLogWeightTpl<T>::NoWeight();
112 bool s1 = w1.Value1().Value() > 0.0;
113 bool s2 = w2.Value1().Value() > 0.0;
114 T f1 = w1.Value2().Value();
115 T f2 = w2.Value2().Value();
116 if (f1 == FloatLimits<T>::PosInfinity())
117 return w2;
118 else if (f2 == FloatLimits<T>::PosInfinity())
119 return w1;
120 else if (f1 == f2) {
121 if (s1 == s2)
122 return SignedLogWeightTpl<T>(w1.Value1(), (f2 - log(2.0F)));
123 else
124 return SignedLogWeightTpl<T>::Zero();
125 } else if (f1 > f2) {
126 if (s1 == s2) {
127 return SignedLogWeightTpl<T>(
128 w1.Value1(), (f2 - log(1.0F + exp(f2 - f1))));
129 } else {
130 return SignedLogWeightTpl<T>(
131 w2.Value1(), (f2 - log(1.0F - exp(f2 - f1))));
132 }
133 } else {
134 if (s2 == s1) {
135 return SignedLogWeightTpl<T>(
136 w2.Value1(), (f1 - log(1.0F + exp(f1 - f2))));
137 } else {
138 return SignedLogWeightTpl<T>(
139 w1.Value1(), (f1 - log(1.0F - exp(f1 - f2))));
140 }
141 }
142 }
143
144 template <class T>
Minus(const SignedLogWeightTpl<T> & w1,const SignedLogWeightTpl<T> & w2)145 inline SignedLogWeightTpl<T> Minus(const SignedLogWeightTpl<T> &w1,
146 const SignedLogWeightTpl<T> &w2) {
147 SignedLogWeightTpl<T> minus_w2(-w2.Value1().Value(), w2.Value2());
148 return Plus(w1, minus_w2);
149 }
150
151 template <class T>
Times(const SignedLogWeightTpl<T> & w1,const SignedLogWeightTpl<T> & w2)152 inline SignedLogWeightTpl<T> Times(const SignedLogWeightTpl<T> &w1,
153 const SignedLogWeightTpl<T> &w2) {
154 if (!w1.Member() || !w2.Member())
155 return SignedLogWeightTpl<T>::NoWeight();
156 bool s1 = w1.Value1().Value() > 0.0;
157 bool s2 = w2.Value1().Value() > 0.0;
158 T f1 = w1.Value2().Value();
159 T f2 = w2.Value2().Value();
160 if (s1 == s2)
161 return SignedLogWeightTpl<T>(TropicalWeight(1.0), (f1 + f2));
162 else
163 return SignedLogWeightTpl<T>(TropicalWeight(-1.0), (f1 + f2));
164 }
165
166 template <class T>
167 inline SignedLogWeightTpl<T> Divide(const SignedLogWeightTpl<T> &w1,
168 const SignedLogWeightTpl<T> &w2,
169 DivideType typ = DIVIDE_ANY) {
170 if (!w1.Member() || !w2.Member())
171 return SignedLogWeightTpl<T>::NoWeight();
172 bool s1 = w1.Value1().Value() > 0.0;
173 bool s2 = w2.Value1().Value() > 0.0;
174 T f1 = w1.Value2().Value();
175 T f2 = w2.Value2().Value();
176 if (f2 == FloatLimits<T>::PosInfinity())
177 return SignedLogWeightTpl<T>(TropicalWeight(1.0),
178 FloatLimits<T>::NumberBad());
179 else if (f1 == FloatLimits<T>::PosInfinity())
180 return SignedLogWeightTpl<T>(TropicalWeight(1.0),
181 FloatLimits<T>::PosInfinity());
182 else if (s1 == s2)
183 return SignedLogWeightTpl<T>(TropicalWeight(1.0), (f1 - f2));
184 else
185 return SignedLogWeightTpl<T>(TropicalWeight(-1.0), (f1 - f2));
186 }
187
188 template <class T>
189 inline bool ApproxEqual(const SignedLogWeightTpl<T> &w1,
190 const SignedLogWeightTpl<T> &w2,
191 float delta = kDelta) {
192 bool s1 = w1.Value1().Value() > 0.0;
193 bool s2 = w2.Value1().Value() > 0.0;
194 if (s1 == s2) {
195 return ApproxEqual(w1.Value2(), w2.Value2(), delta);
196 } else {
197 return w1.Value2() == LogWeightTpl<T>::Zero()
198 && w2.Value2() == LogWeightTpl<T>::Zero();
199 }
200 }
201
202 template <class T>
203 inline bool operator==(const SignedLogWeightTpl<T> &w1,
204 const SignedLogWeightTpl<T> &w2) {
205 bool s1 = w1.Value1().Value() > 0.0;
206 bool s2 = w2.Value1().Value() > 0.0;
207 if (s1 == s2)
208 return w1.Value2() == w2.Value2();
209 else
210 return (w1.Value2() == LogWeightTpl<T>::Zero()) &&
211 (w2.Value2() == LogWeightTpl<T>::Zero());
212 }
213
214
215 // Single-precision signed-log weight
216 typedef SignedLogWeightTpl<float> SignedLogWeight;
217 // Double-precision signed-log weight
218 typedef SignedLogWeightTpl<double> SignedLog64Weight;
219
220 //
221 // WEIGHT CONVERTER SPECIALIZATIONS.
222 //
223
224 template <class W1, class W2>
SignedLogConvertCheck(W1 w)225 bool SignedLogConvertCheck(W1 w) {
226 if (w.Value1().Value() < 0.0) {
227 FSTERROR() << "WeightConvert: can't convert weight from \""
228 << W1::Type() << "\" to \"" << W2::Type();
229 return false;
230 }
231 return true;
232 }
233
234 // Convert to tropical
235 template <>
236 struct WeightConvert<SignedLogWeight, TropicalWeight> {
237 TropicalWeight operator()(SignedLogWeight w) const {
238 if (!SignedLogConvertCheck<SignedLogWeight, TropicalWeight>(w))
239 return TropicalWeight::NoWeight();
240 return w.Value2().Value();
241 }
242 };
243
244 template <>
245 struct WeightConvert<SignedLog64Weight, TropicalWeight> {
246 TropicalWeight operator()(SignedLog64Weight w) const {
247 if (!SignedLogConvertCheck<SignedLog64Weight, TropicalWeight>(w))
248 return TropicalWeight::NoWeight();
249 return w.Value2().Value();
250 }
251 };
252
253 // Convert to log
254 template <>
255 struct WeightConvert<SignedLogWeight, LogWeight> {
256 LogWeight operator()(SignedLogWeight w) const {
257 if (!SignedLogConvertCheck<SignedLogWeight, LogWeight>(w))
258 return LogWeight::NoWeight();
259 return w.Value2().Value();
260 }
261 };
262
263 template <>
264 struct WeightConvert<SignedLog64Weight, LogWeight> {
265 LogWeight operator()(SignedLog64Weight w) const {
266 if (!SignedLogConvertCheck<SignedLog64Weight, LogWeight>(w))
267 return LogWeight::NoWeight();
268 return w.Value2().Value();
269 }
270 };
271
272 // Convert to log64
273 template <>
274 struct WeightConvert<SignedLogWeight, Log64Weight> {
275 Log64Weight operator()(SignedLogWeight w) const {
276 if (!SignedLogConvertCheck<SignedLogWeight, Log64Weight>(w))
277 return Log64Weight::NoWeight();
278 return w.Value2().Value();
279 }
280 };
281
282 template <>
283 struct WeightConvert<SignedLog64Weight, Log64Weight> {
284 Log64Weight operator()(SignedLog64Weight w) const {
285 if (!SignedLogConvertCheck<SignedLog64Weight, Log64Weight>(w))
286 return Log64Weight::NoWeight();
287 return w.Value2().Value();
288 }
289 };
290
291 // Convert to signed log
292 template <>
293 struct WeightConvert<TropicalWeight, SignedLogWeight> {
294 SignedLogWeight operator()(TropicalWeight w) const {
295 TropicalWeight x1 = 1.0;
296 LogWeight x2 = w.Value();
297 return SignedLogWeight(x1, x2);
298 }
299 };
300
301 template <>
302 struct WeightConvert<LogWeight, SignedLogWeight> {
303 SignedLogWeight operator()(LogWeight w) const {
304 TropicalWeight x1 = 1.0;
305 LogWeight x2 = w.Value();
306 return SignedLogWeight(x1, x2);
307 }
308 };
309
310 template <>
311 struct WeightConvert<Log64Weight, SignedLogWeight> {
312 SignedLogWeight operator()(Log64Weight w) const {
313 TropicalWeight x1 = 1.0;
314 LogWeight x2 = w.Value();
315 return SignedLogWeight(x1, x2);
316 }
317 };
318
319 template <>
320 struct WeightConvert<SignedLog64Weight, SignedLogWeight> {
321 SignedLogWeight operator()(SignedLog64Weight w) const {
322 TropicalWeight x1 = w.Value1();
323 LogWeight x2 = w.Value2().Value();
324 return SignedLogWeight(x1, x2);
325 }
326 };
327
328 // Convert to signed log64
329 template <>
330 struct WeightConvert<TropicalWeight, SignedLog64Weight> {
331 SignedLog64Weight operator()(TropicalWeight w) const {
332 TropicalWeight x1 = 1.0;
333 Log64Weight x2 = w.Value();
334 return SignedLog64Weight(x1, x2);
335 }
336 };
337
338 template <>
339 struct WeightConvert<LogWeight, SignedLog64Weight> {
340 SignedLog64Weight operator()(LogWeight w) const {
341 TropicalWeight x1 = 1.0;
342 Log64Weight x2 = w.Value();
343 return SignedLog64Weight(x1, x2);
344 }
345 };
346
347 template <>
348 struct WeightConvert<Log64Weight, SignedLog64Weight> {
349 SignedLog64Weight operator()(Log64Weight w) const {
350 TropicalWeight x1 = 1.0;
351 Log64Weight x2 = w.Value();
352 return SignedLog64Weight(x1, x2);
353 }
354 };
355
356 template <>
357 struct WeightConvert<SignedLogWeight, SignedLog64Weight> {
358 SignedLog64Weight operator()(SignedLogWeight w) const {
359 TropicalWeight x1 = w.Value1();
360 Log64Weight x2 = w.Value2().Value();
361 return SignedLog64Weight(x1, x2);
362 }
363 };
364
365 } // namespace fst
366
367 #endif // FST_LIB_SIGNED_LOG_WEIGHT_H_
368