diff options
author | Determinant <[email protected]> | 2015-08-14 11:51:42 +0800 |
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committer | Determinant <[email protected]> | 2015-08-14 11:51:42 +0800 |
commit | 96a32415ab43377cf1575bd3f4f2980f58028209 (patch) | |
tree | 30a2d92d73e8f40ac87b79f6f56e227bfc4eea6e /kaldi_io/src/tools/openfst/include/fst/reverse.h | |
parent | c177a7549bd90670af4b29fa813ddea32cfe0f78 (diff) |
add implementation for kaldi io (by ymz)
Diffstat (limited to 'kaldi_io/src/tools/openfst/include/fst/reverse.h')
-rw-r--r-- | kaldi_io/src/tools/openfst/include/fst/reverse.h | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/kaldi_io/src/tools/openfst/include/fst/reverse.h b/kaldi_io/src/tools/openfst/include/fst/reverse.h new file mode 100644 index 0000000..4d4c75c --- /dev/null +++ b/kaldi_io/src/tools/openfst/include/fst/reverse.h @@ -0,0 +1,91 @@ +// reverse.h + +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +// Copyright 2005-2010 Google, Inc. +// Author: [email protected] (Michael Riley) +// +// \file +// Functions and classes to sort arcs in an FST. + +#ifndef FST_LIB_REVERSE_H__ +#define FST_LIB_REVERSE_H__ + +#include <algorithm> +#include <vector> +using std::vector; + +#include <fst/cache.h> + + +namespace fst { + +// Reverses an FST. The reversed result is written to an output +// MutableFst. If A transduces string x to y with weight a, then the +// reverse of A transduces the reverse of x to the reverse of y with +// weight a.Reverse(). +// +// Typically, a = a.Reverse() and Arc = RevArc (e.g. for +// TropicalWeight or LogWeight). In general, e.g. when the weights +// only form a left or right semiring, the output arc type must match +// the input arc type except having the reversed Weight type. +template<class Arc, class RevArc> +void Reverse(const Fst<Arc> &ifst, MutableFst<RevArc> *ofst) { + typedef typename Arc::StateId StateId; + typedef typename Arc::Weight Weight; + typedef typename RevArc::Weight RevWeight; + + ofst->DeleteStates(); + ofst->SetInputSymbols(ifst.InputSymbols()); + ofst->SetOutputSymbols(ifst.OutputSymbols()); + if (ifst.Properties(kExpanded, false)) + ofst->ReserveStates(CountStates(ifst) + 1); + StateId istart = ifst.Start(); + StateId ostart = ofst->AddState(); + ofst->SetStart(ostart); + + for (StateIterator< Fst<Arc> > siter(ifst); + !siter.Done(); + siter.Next()) { + StateId is = siter.Value(); + StateId os = is + 1; + while (ofst->NumStates() <= os) + ofst->AddState(); + if (is == istart) + ofst->SetFinal(os, RevWeight::One()); + + Weight final = ifst.Final(is); + if (final != Weight::Zero()) { + RevArc oarc(0, 0, final.Reverse(), os); + ofst->AddArc(0, oarc); + } + + for (ArcIterator< Fst<Arc> > aiter(ifst, is); + !aiter.Done(); + aiter.Next()) { + const Arc &iarc = aiter.Value(); + RevArc oarc(iarc.ilabel, iarc.olabel, iarc.weight.Reverse(), os); + StateId nos = iarc.nextstate + 1; + while (ofst->NumStates() <= nos) + ofst->AddState(); + ofst->AddArc(nos, oarc); + } + } + uint64 iprops = ifst.Properties(kCopyProperties, false); + uint64 oprops = ofst->Properties(kFstProperties, false); + ofst->SetProperties(ReverseProperties(iprops) | oprops, kFstProperties); +} + +} // namespace fst + +#endif // FST_LIB_REVERSE_H__ |