| // 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: riley@google.com (Michael Riley) |
| // |
| // \file |
| // Expand a PDT to an FST. |
| |
| #ifndef FST_EXTENSIONS_PDT_REVERSE_H__ |
| #define FST_EXTENSIONS_PDT_REVERSE_H__ |
| |
| #include <unordered_map> |
| using std::tr1::unordered_map; |
| using std::tr1::unordered_multimap; |
| #include <vector> |
| using std::vector; |
| |
| #include <fst/mutable-fst.h> |
| #include <fst/relabel.h> |
| #include <fst/reverse.h> |
| |
| namespace fst { |
| |
| // Reverses a pushdown transducer (PDT) encoded as an FST. |
| template<class Arc, class RevArc> |
| void Reverse(const Fst<Arc> &ifst, |
| const vector<pair<typename Arc::Label, |
| typename Arc::Label> > &parens, |
| MutableFst<RevArc> *ofst) { |
| typedef typename Arc::Label Label; |
| |
| // Reverses FST |
| Reverse(ifst, ofst); |
| |
| // Exchanges open and close parenthesis pairs |
| vector<pair<Label, Label> > relabel_pairs; |
| for (size_t i = 0; i < parens.size(); ++i) { |
| relabel_pairs.push_back(make_pair(parens[i].first, parens[i].second)); |
| relabel_pairs.push_back(make_pair(parens[i].second, parens[i].first)); |
| } |
| Relabel(ofst, relabel_pairs, relabel_pairs); |
| } |
| |
| } // namespace fst |
| |
| #endif // FST_EXTENSIONS_PDT_REVERSE_H__ |