arcfilter.h revision 4a68b3365c8c50aa93505e99ead2565ab73dcdb0 
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
22namespace fst {
23
24// True for all arcs.
25template <class A>
26class AnyArcFilter {
27public:
28  bool operator()(const A &arc) const { return true; }
29};
30
31
32// True for (input/output) epsilon arcs.
33template <class A>
34class EpsilonArcFilter {
35public:
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