// lat/push-lattice.h
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// Copyright 2013 Johns Hopkins University (Author: Daniel Povey)
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// 2014 Guoguo Chen
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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_LAT_PUSH_LATTICE_H_
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#define KALDI_LAT_PUSH_LATTICE_H_
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#include <vector>
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#include <map>
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#include "base/kaldi-common.h"
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#include "util/common-utils.h"
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#include "fstext/fstext-lib.h"
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#include "lat/kaldi-lattice.h"
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namespace fst {
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/// This function pushes the transition-ids as far towards the start as they
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/// will go. It can be useful prior to lattice-align-words (for non-linear
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/// lattices). We can't use the generic OpenFst "push" function because
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/// it uses the sum as the divisor, which is not appropriate in this case
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/// (a+b generally won't divide a or b in this semiring).
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/// It returns true on success, false if it failed due to TopSort failing,
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/// which should never happen, but we handle it gracefully by just leaving the
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/// lattice the same.
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/// This function used to be called just PushCompactLattice.
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template<class Weight, class IntType>
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bool PushCompactLatticeStrings(
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MutableFst<ArcTpl<CompactLatticeWeightTpl<Weight, IntType> > > *clat);
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/// This function pushes the weights in the CompactLattice so that all states
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/// except possibly the start state, have Weight components (of type
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/// LatticeWeight) that "sum to one" in the LatticeWeight (i.e. interpreting the
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/// weights as negated log-probs). It returns true on success, false if it
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/// failed due to TopSort failing, which should never happen, but we handle it
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/// gracefully by just leaving the lattice the same.
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template<class Weight, class IntType>
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bool PushCompactLatticeWeights(
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MutableFst<ArcTpl<CompactLatticeWeightTpl<Weight, IntType> > > *clat);
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} // namespace fst
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#endif // KALDI_LAT_PUSH_LATTICE_H_
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