1 // expanded-fst.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 // Generic FST augmented with state count - interface class definition.
18
19 #ifndef FST_LIB_EXPANDED_FST_H__
20 #define FST_LIB_EXPANDED_FST_H__
21
22 #include "fst/lib/fst.h"
23
24 namespace fst {
25
26 // A generic FST plus state count.
27 template <class A>
28 class ExpandedFst : public Fst<A> {
29 public:
30 typedef A Arc;
31 typedef typename A::StateId StateId;
32
33 virtual StateId NumStates() const = 0; // State count
34
35 // Get a copy of this ExpandedFst.
36 virtual ExpandedFst<A> *Copy() const = 0;
37 // Read an ExpandedFst from an input stream; return NULL on error.
Read(istream & strm,const FstReadOptions & opts)38 static ExpandedFst<A> *Read(istream &strm, const FstReadOptions &opts) {
39 FstReadOptions ropts(opts);
40 FstHeader hdr;
41 if (ropts.header)
42 hdr = *opts.header;
43 else {
44 if (!hdr.Read(strm, opts.source))
45 return 0;
46 ropts.header = &hdr;
47 }
48 if (!(hdr.Properties() & kExpanded)) {
49 LOG(ERROR) << "ExpandedFst::Read: Not an ExpandedFst: " << ropts.source;
50 return 0;
51 }
52 FstRegister<A> *registr = FstRegister<A>::GetRegister();
53 const typename FstRegister<A>::Reader reader =
54 registr->GetReader(hdr.FstType());
55 if (!reader) {
56 LOG(ERROR) << "ExpandedFst::Read: Unknown FST type \"" << hdr.FstType()
57 << "\" (arc type = \"" << A::Type()
58 << "\"): " << ropts.source;
59 return 0;
60 }
61 Fst<A> *fst = reader(strm, ropts);
62 if (!fst) return 0;
63 return down_cast<ExpandedFst<A> *>(fst);
64 }
65 // Read an ExpandedFst from a file; return NULL on error.
Read(const string & filename)66 static ExpandedFst<A> *Read(const string &filename) {
67 ifstream strm(filename.c_str());
68 if (!strm) {
69 LOG(ERROR) << "ExpandedFst::Read: Can't open file: " << filename;
70 return 0;
71 }
72 return Read(strm, FstReadOptions(filename));
73 }
74 };
75
76 // A useful alias when using StdArc.
77 typedef ExpandedFst<StdArc> StdExpandedFst;
78
79 // Function to return the number of states in an FST, counting them
80 // if necessary.
81 template <class Arc>
CountStates(const Fst<Arc> & fst)82 typename Arc::StateId CountStates(const Fst<Arc> &fst) {
83 if (fst.Properties(kExpanded, false)) {
84 const ExpandedFst<Arc> *efst = down_cast<const ExpandedFst<Arc> *>(&fst);
85 return efst->NumStates();
86 } else {
87 typename Arc::StateId nstates = 0;
88 for (StateIterator< Fst<Arc> > siter(fst); !siter.Done(); siter.Next())
89 ++nstates;
90 return nstates;
91 }
92 }
93
94 } // FST_LIB_FST_H__
95
96 #endif // FST_LIB_EXPANDED_FST_H__
97