1 // statesort.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 to sort states of an Fst.
18
19 #ifndef FST_LIB_STATESORT_H__
20 #define FST_LIB_STATESORT_H__
21
22 #include <algorithm>
23
24 #include "fst/lib/mutable-fst.h"
25
26 namespace fst {
27
28 // Sorts the input states of an FST, modifying it. ORDER[i] gives the
29 // the state Id after sorting that corresponds to state Id i before
30 // sorting. ORDER must be a permutation of FST's states ID sequence:
31 // (1, 2, ..., fst->NumStates() - 1).
32 template <class Arc>
StateSort(MutableFst<Arc> * fst,const vector<typename Arc::StateId> & order)33 void StateSort(MutableFst<Arc> *fst,
34 const vector<typename Arc::StateId> &order) {
35 typedef typename Arc::StateId StateId;
36 typedef typename Arc::Weight Weight;
37
38 CHECK_EQ(order.size(), fst->NumStates());
39
40 if (fst->Start() == kNoStateId)
41 return;
42
43 uint64 props = fst->Properties(kStateSortProperties, false);
44
45 vector<bool> done(order.size(), false);
46 vector<Arc> arcsa, arcsb;
47 vector<Arc> *arcs1 = &arcsa, *arcs2 = &arcsb;
48
49 fst->SetStart(order[fst->Start()]);
50
51 for (StateIterator< MutableFst<Arc> > siter(*fst);
52 !siter.Done();
53 siter.Next()) {
54 StateId s1 = siter.Value(), s2;
55 if (done[s1])
56 continue;
57 Weight final1 = fst->Final(s1), final2 = Weight::Zero();
58 arcs1->clear();
59 for (ArcIterator< MutableFst<Arc> > aiter(*fst, s1);
60 !aiter.Done();
61 aiter.Next())
62 arcs1->push_back(aiter.Value());
63 for (; !done[s1]; s1 = s2, final1 = final2, swap(arcs1, arcs2)) {
64 s2 = order[s1];
65 if (!done[s2]) {
66 final2 = fst->Final(s2);
67 arcs2->clear();
68 for (ArcIterator< MutableFst<Arc> > aiter(*fst, s2);
69 !aiter.Done();
70 aiter.Next())
71 arcs2->push_back(aiter.Value());
72 }
73 fst->SetFinal(s2, final1);
74 fst->DeleteArcs(s2);
75 for (size_t i = 0; i < arcs1->size(); ++i) {
76 Arc arc = (*arcs1)[i];
77 arc.nextstate = order[arc.nextstate];
78 fst->AddArc(s2, arc);
79 }
80 done[s1] = true;
81 }
82 }
83 fst->SetProperties(props, kFstProperties);
84 }
85
86 } // namespace fst
87
88 #endif // FST_LIB_STATESORT_H__
89