// fstext/epsilon-property.h
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// Copyright 2014 Johns Hopkins University (Author: Daniel Povey)
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// See ../../COPYING for clarification regarding multiple authors
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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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// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
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// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
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// MERCHANTABLITY OR NON-INFRINGEMENT.
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// See the Apache 2 License for the specific language governing permissions and
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// limitations under the License.
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#ifndef KALDI_FSTEXT_EPSILON_PROPERTY_H_
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#define KALDI_FSTEXT_EPSILON_PROPERTY_H_
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#include <fst/fstlib.h>
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#include <fst/fst-decl.h>
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namespace fst {
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enum {
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kStateHasEpsilonArcsEntering = 0x1,
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kStateHasNonEpsilonArcsEntering = 0x2,
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kStateHasEpsilonArcsLeaving = 0x4,
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kStateHasNonEpsilonArcsLeaving = 0x8
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}; // use 'char' for this enum.
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/// This function will set epsilon_info to have size equal to the
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/// NumStates() of the FST, containing a logical-or of the enum
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/// values kStateHasEpsilonArcsEntering, kStateHasNonEpsilonArcsEntering,
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/// kStateHasEpsilonArcsLeaving, and kStateHasNonEpsilonArcsLeaving.
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/// The meaning should be obvious. Note: an epsilon arc is defined
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/// as an arc where ilabel == olabel == 0.
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template<class Arc>
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void ComputeStateInfo(const VectorFst<Arc> &fst,
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std::vector<char> *epsilon_info);
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/// This function modifies the fst (while maintaining equivalence) in such a way
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/// that, after the modification, all states of the FST which have epsilon-arcs
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/// entering them, have no non-epsilon arcs entering them, and all states which
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/// have epsilon-arcs leaving them, have no non-epsilon arcs leaving them. It does
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/// this by creating extra states and adding extra epsilon transitions. An epsilon
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/// arc is defined as an arc where both the ilabel and the olabel are epsilons.
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/// This function may fail with KALDI_ASSERT for certain cyclic FSTs, but is safe
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/// in the acyclic case.
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template<class Arc>
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void EnsureEpsilonProperty(VectorFst<Arc> *fst);
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} // end namespace fst
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#include "fstext/epsilon-property-inl.h"
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#endif
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