1 // intersect.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 // Copyright 2005-2010 Google, Inc. 16 // Author: riley (at) google.com (Michael Riley) 17 // 18 // \file 19 // Class to compute the intersection of two FSAs 20 21 #ifndef FST_LIB_INTERSECT_H__ 22 #define FST_LIB_INTERSECT_H__ 23 24 #include <algorithm> 25 #include <vector> 26 using std::vector; 27 28 #include <fst/cache.h> 29 #include <fst/compose.h> 30 31 32 namespace fst { 33 34 template <class A, 35 class M = Matcher<Fst<A> >, 36 class F = SequenceComposeFilter<M>, 37 class T = GenericComposeStateTable<A, typename F::FilterState> > 38 struct IntersectFstOptions : public ComposeFstOptions<A, M, F, T> { 39 explicit IntersectFstOptions(const CacheOptions &opts, 40 M *mat1 = 0, M *mat2 = 0, 41 F *filt = 0, T *sttable= 0) 42 : ComposeFstOptions<A, M, F, T>(opts, mat1, mat2, filt, sttable) { } 43 44 IntersectFstOptions() {} 45 }; 46 47 // Computes the intersection (Hadamard product) of two FSAs. This 48 // version is a delayed Fst. Only strings that are in both automata 49 // are retained in the result. 50 // 51 // The two arguments must be acceptors. One of the arguments must be 52 // label-sorted. 53 // 54 // Complexity: same as ComposeFst. 55 // 56 // Caveats: same as ComposeFst. 57 template <class A> 58 class IntersectFst : public ComposeFst<A> { 59 public: 60 using ComposeFst<A>::CreateBase; 61 using ComposeFst<A>::CreateBase1; 62 using ComposeFst<A>::Properties; 63 using ImplToFst< ComposeFstImplBase<A> >::GetImpl; 64 using ImplToFst< ComposeFstImplBase<A> >::SetImpl; 65 66 typedef A Arc; 67 typedef typename A::Weight Weight; 68 typedef typename A::StateId StateId; 69 70 IntersectFst(const Fst<A> &fst1, const Fst<A> &fst2, 71 const CacheOptions opts = CacheOptions()) { 72 bool acceptors = fst1.Properties(kAcceptor, true) && 73 fst2.Properties(kAcceptor, true); 74 SetImpl(CreateBase(fst1, fst2, opts)); 75 if (!acceptors) { 76 FSTERROR() << "IntersectFst: input FSTs are not acceptors"; 77 GetImpl()->SetProperties(kError); 78 } 79 } 80 81 template <class M, class F, class T> 82 IntersectFst(const Fst<A> &fst1, const Fst<A> &fst2, 83 const IntersectFstOptions<A, M, F, T> &opts) { 84 bool acceptors = fst1.Properties(kAcceptor, true) && 85 fst2.Properties(kAcceptor, true); 86 SetImpl(CreateBase1(fst1, fst2, opts)); 87 if (!acceptors) { 88 FSTERROR() << "IntersectFst: input FSTs are not acceptors"; 89 GetImpl()->SetProperties(kError); 90 } 91 } 92 93 // See Fst<>::Copy() for doc. 94 IntersectFst(const IntersectFst<A> &fst, bool safe = false) : 95 ComposeFst<A>(fst, safe) {} 96 97 // Get a copy of this IntersectFst. See Fst<>::Copy() for further doc. 98 virtual IntersectFst<A> *Copy(bool safe = false) const { 99 return new IntersectFst<A>(*this, safe); 100 } 101 }; 102 103 104 // Specialization for IntersectFst. 105 template <class A> 106 class StateIterator< IntersectFst<A> > 107 : public StateIterator< ComposeFst<A> > { 108 public: 109 explicit StateIterator(const IntersectFst<A> &fst) 110 : StateIterator< ComposeFst<A> >(fst) {} 111 }; 112 113 114 // Specialization for IntersectFst. 115 template <class A> 116 class ArcIterator< IntersectFst<A> > 117 : public ArcIterator< ComposeFst<A> > { 118 public: 119 typedef typename A::StateId StateId; 120 121 ArcIterator(const IntersectFst<A> &fst, StateId s) 122 : ArcIterator< ComposeFst<A> >(fst, s) {} 123 }; 124 125 // Useful alias when using StdArc. 126 typedef IntersectFst<StdArc> StdIntersectFst; 127 128 129 typedef ComposeOptions IntersectOptions; 130 131 132 // Computes the intersection (Hadamard product) of two FSAs. This 133 // version writes the intersection to an output MurableFst. Only 134 // strings that are in both automata are retained in the result. 135 // 136 // The two arguments must be acceptors. One of the arguments must be 137 // label-sorted. 138 // 139 // Complexity: same as Compose. 140 // 141 // Caveats: same as Compose. 142 template<class Arc> 143 void Intersect(const Fst<Arc> &ifst1, const Fst<Arc> &ifst2, 144 MutableFst<Arc> *ofst, 145 const IntersectOptions &opts = IntersectOptions()) { 146 typedef Matcher< Fst<Arc> > M; 147 148 if (opts.filter_type == AUTO_FILTER) { 149 CacheOptions nopts; 150 nopts.gc_limit = 0; // Cache only the last state for fastest copy. 151 *ofst = IntersectFst<Arc>(ifst1, ifst2, nopts); 152 } else if (opts.filter_type == SEQUENCE_FILTER) { 153 IntersectFstOptions<Arc> iopts; 154 iopts.gc_limit = 0; // Cache only the last state for fastest copy. 155 *ofst = IntersectFst<Arc>(ifst1, ifst2, iopts); 156 } else if (opts.filter_type == ALT_SEQUENCE_FILTER) { 157 IntersectFstOptions<Arc, M, AltSequenceComposeFilter<M> > iopts; 158 iopts.gc_limit = 0; // Cache only the last state for fastest copy. 159 *ofst = IntersectFst<Arc>(ifst1, ifst2, iopts); 160 } else if (opts.filter_type == MATCH_FILTER) { 161 IntersectFstOptions<Arc, M, MatchComposeFilter<M> > iopts; 162 iopts.gc_limit = 0; // Cache only the last state for fastest copy. 163 *ofst = IntersectFst<Arc>(ifst1, ifst2, iopts); 164 } 165 166 if (opts.connect) 167 Connect(ofst); 168 } 169 170 } // namespace fst 171 172 #endif // FST_LIB_INTERSECT_H__ 173
