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90 lines
2.8 KiB
90 lines
2.8 KiB
// Copyright 2005-2024 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the 'License');
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an 'AS IS' BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// See www.openfst.org for extensive documentation on this weighted
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// finite-state transducer library.
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//
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// Function to sort states of an FST.
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#ifndef FST_STATESORT_H_
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#define FST_STATESORT_H_
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#include <algorithm>
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#include <utility>
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#include <vector>
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#include <fst/log.h>
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#include <fst/fst.h>
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#include <fst/mutable-fst.h>
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#include <fst/properties.h>
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#include <fst/util.h>
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namespace fst {
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// Sorts the input states of an FST. order[i] gives the state ID after
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// sorting that corresponds to the state ID i before sorting; it must
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// therefore be a permutation of the input FST's states ID sequence.
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template <class Arc>
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void StateSort(MutableFst<Arc> *fst,
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const std::vector<typename Arc::StateId> &order) {
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using StateId = typename Arc::StateId;
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using Weight = typename Arc::Weight;
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if (order.size() != fst->NumStates()) {
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FSTERROR() << "StateSort: Bad order vector size: " << order.size();
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fst->SetProperties(kError, kError);
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return;
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}
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if (fst->Start() == kNoStateId) return;
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const auto props = fst->Properties(kStateSortProperties, false);
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std::vector<bool> done(order.size(), false);
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std::vector<Arc> arcsa;
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std::vector<Arc> arcsb;
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fst->SetStart(order[fst->Start()]);
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for (StateIterator<MutableFst<Arc>> siter(*fst); !siter.Done();
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siter.Next()) {
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auto s1 = siter.Value();
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StateId s2;
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if (done[s1]) continue;
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auto final1 = fst->Final(s1);
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auto final2 = Weight::Zero();
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arcsa.clear();
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for (ArcIterator<MutableFst<Arc>> aiter(*fst, s1); !aiter.Done();
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aiter.Next()) {
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arcsa.push_back(aiter.Value());
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}
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for (; !done[s1]; s1 = s2, final1 = final2, std::swap(arcsa, arcsb)) {
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s2 = order[s1];
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if (!done[s2]) {
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final2 = fst->Final(s2);
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arcsb.clear();
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for (ArcIterator<MutableFst<Arc>> aiter(*fst, s2); !aiter.Done();
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aiter.Next()) {
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arcsb.push_back(aiter.Value());
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}
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}
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fst->SetFinal(s2, final1);
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fst->DeleteArcs(s2);
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for (auto arc : arcsa) { // NOLINT(performance-for-range-copy)
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arc.nextstate = order[arc.nextstate];
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fst->AddArc(s2, arc);
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}
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done[s1] = true;
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}
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}
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fst->SetProperties(props, kFstProperties);
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}
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} // namespace fst
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#endif // FST_STATESORT_H_
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