1 // arcfilter.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 restrict which arcs are traversed in an FST. 18 19 #ifndef FST_LIB_ARCFILTER_H__ 20 #define FST_LIB_ARCFILTER_H__ 21 22 namespace fst { 23 24 // True for all arcs. 25 template <class A> 26 class AnyArcFilter { 27 public: operator()28 bool operator()(const A &arc) const { return true; } 29 }; 30 31 32 // True for (input/output) epsilon arcs. 33 template <class A> 34 class EpsilonArcFilter { 35 public: operator()36 bool operator()(const A &arc) const { 37 return arc.ilabel == 0 && arc.olabel == 0; 38 } 39 }; 40 41 } // namespace fst 42 43 #endif // FST_LIB_ARCFILTER_H__ 44