push-lattice.h
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// lat/push-lattice.h
// Copyright 2013 Johns Hopkins University (Author: Daniel Povey)
// 2014 Guoguo Chen
// See ../../COPYING for clarification regarding multiple authors
//
// 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
//
// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
// MERCHANTABLITY OR NON-INFRINGEMENT.
// See the Apache 2 License for the specific language governing permissions and
// limitations under the License.
#ifndef KALDI_LAT_PUSH_LATTICE_H_
#define KALDI_LAT_PUSH_LATTICE_H_
#include <vector>
#include <map>
#include "base/kaldi-common.h"
#include "util/common-utils.h"
#include "fstext/fstext-lib.h"
#include "lat/kaldi-lattice.h"
namespace fst {
/// This function pushes the transition-ids as far towards the start as they
/// will go. It can be useful prior to lattice-align-words (for non-linear
/// lattices). We can't use the generic OpenFst "push" function because
/// it uses the sum as the divisor, which is not appropriate in this case
/// (a+b generally won't divide a or b in this semiring).
/// It returns true on success, false if it failed due to TopSort failing,
/// which should never happen, but we handle it gracefully by just leaving the
/// lattice the same.
/// This function used to be called just PushCompactLattice.
template<class Weight, class IntType>
bool PushCompactLatticeStrings(
MutableFst<ArcTpl<CompactLatticeWeightTpl<Weight, IntType> > > *clat);
/// This function pushes the weights in the CompactLattice so that all states
/// except possibly the start state, have Weight components (of type
/// LatticeWeight) that "sum to one" in the LatticeWeight (i.e. interpreting the
/// weights as negated log-probs). It returns true on success, false if it
/// failed due to TopSort failing, which should never happen, but we handle it
/// gracefully by just leaving the lattice the same.
template<class Weight, class IntType>
bool PushCompactLatticeWeights(
MutableFst<ArcTpl<CompactLatticeWeightTpl<Weight, IntType> > > *clat);
} // namespace fst
#endif // KALDI_LAT_PUSH_LATTICE_H_