random-weight.h revision 8fc5a7f51e62cb4ae44a27bdf4176d04adc80ede 
1// random-weight.h
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//      http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14//
15//
16// \file
17// Function objects to generate random weights in various semirings
18// for testing purposes.
19
20#ifndef FST_LIB_RANDOM_WEIGHT_H__
21#define FST_LIB_RANDOM_WEIGHT_H__
22
23#include <cstdlib>
24#include <ctime>
25
26#include "fst/lib/float-weight.h"
27#include "fst/lib/product-weight.h"
28#include "fst/lib/string-weight.h"
29
30namespace fst {
31
32// The boolean 'allow_zero' below determines whether Zero() and zero
33// divisors should be returned in the random weight generation.
34
35// This function object returns TropicalWeights that are random integers
36// chosen from [0, kNumRandomWeights).
37class TropicalWeightGenerator {
38 public:
39  typedef TropicalWeight Weight;
40
41  TropicalWeightGenerator(int seed = time(0), bool allow_zero = true)
42      : allow_zero_(allow_zero) {
43    srand(seed);
44  }
45
46  Weight operator() () const {
47    int n = rand() % (kNumRandomWeights + allow_zero_);
48    if (allow_zero_ && n == kNumRandomWeights)
49      return Weight::Zero();
50
51    return Weight(static_cast<float>(n));
52  }
53
54 private:
55  // The number of alternative random weights.
56  static const int kNumRandomWeights = 5;
57
58  bool allow_zero_;  // permit Zero() and zero divisors
59};
60
61
62// This function object returns LogWeights that are random integers
63// chosen from [0, kNumRandomWeights).
64class LogWeightGenerator {
65 public:
66  typedef LogWeight Weight;
67
68  LogWeightGenerator(int seed = time(0), bool allow_zero = true)
69      : allow_zero_(allow_zero) {
70    srand(seed);
71  }
72
73  Weight operator() () const {
74    int n = rand() % (kNumRandomWeights + allow_zero_);
75    if (allow_zero_ && n == kNumRandomWeights)
76      return Weight::Zero();
77
78    return Weight(static_cast<float>(n));
79  }
80
81 private:
82  // Number of alternative random weights.
83  static const int kNumRandomWeights = 5;
84
85  bool allow_zero_;  // permit Zero() and zero divisors
86};
87
88
89// This function object returns StringWeights that are random integer
90// strings chosen from {1,...,kAlphabetSize}^{0,kMaxStringLength} U { Zero }
91template <typename L, StringType S = STRING_LEFT>
92class StringWeightGenerator {
93 public:
94  typedef StringWeight<L, S> Weight;
95
96  StringWeightGenerator(int seed = time(0), bool allow_zero = true)
97      : allow_zero_(allow_zero) {
98     srand(seed);
99  }
100
101  Weight operator() () const {
102    int n = rand() % (kMaxStringLength + allow_zero_);
103    if (allow_zero_ && n == kMaxStringLength)
104      return Weight::Zero();
105
106    vector<L> v;
107    for (int i = 0; i < n; ++i)
108      v.push_back(rand() % kAlphabetSize + 1);
109    return Weight(v.begin(), v.end());
110  }
111
112 private:
113  // Alphabet size for random weights.
114  static const int kAlphabetSize = 5;
115  // Number of alternative random weights.
116  static const int kMaxStringLength = 5;
117
118  bool allow_zero_;  // permit Zero() and zero divisors
119};
120
121
122// This function object returns a weight generator over the product of the
123// weights for the generators G1 and G2.
124template <class G1, class G2>
125class ProductWeightGenerator {
126 public:
127  typedef typename G1::Weight W1;
128  typedef typename G2::Weight W2;
129  typedef ProductWeight<W1, W2> Weight;
130
131  ProductWeightGenerator(int seed = time(0), bool allow_zero = true)
132      : generator1_(seed, allow_zero), generator2_(seed, allow_zero) {}
133
134  Weight operator() () const {
135    W1 w1 = generator1_();
136    W2 w2 = generator2_();
137    return Weight(w1, w2);
138  }
139
140 private:
141  G1 generator1_;
142  G2 generator2_;
143};
144
145// Product generator of a string weight generator and an
146// arbitrary weight generator.
147template <class L, class G, StringType S = STRING_LEFT>
148class GallicWeightGenerator
149    : public ProductWeightGenerator<StringWeightGenerator<L, S>, G> {
150
151 public:
152  typedef ProductWeightGenerator<StringWeightGenerator<L, S>, G> PG;
153  typedef typename G::Weight W;
154  typedef GallicWeight<L, W, S> Weight;
155
156  GallicWeightGenerator(int seed = time(0), bool allow_zero = true)
157      : PG(seed, allow_zero) {}
158
159  GallicWeightGenerator(const PG &pg) : PG(pg) {}
160};
161
162}  // namespace fst;
163
164#endif  // FST_LIB_RANDOM_WEIGHT_H__
165