prune-special.h
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// fstext/prune-special.h
// Copyright 2014 Johns Hopkins University (author: Daniel Povey)
// 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_FSTEXT_PRUNE_SPECIAL_H_
#define KALDI_FSTEXT_PRUNE_SPECIAL_H_
#include "fst/fstlib.h"
#include "fstext/lattice-weight.h"
#include "fstext/factor.h"
namespace fst {
/**
The function PruneSpecial is like the standard OpenFst function "prune",
except it does not expand the entire "ifst"- this is useful for cases where
ifst is an on-demand FST such as a ComposeFst and we don't want to visit
it all. It supports pruning either to a specified beam (if beam is
not One()), or to a specified max_states (if max_states is > 0). One of the
two must be specified.
Requirements:
- Costs must be non-negative (equivalently, weights must not be greater than One()).
- There must be a Compare(a, b) function that compares two weights and returns (-1,0,1)
if (a<b, a=b, a>b). We define this in Kaldi, for TropicalWeight, LogWeight (I think),
and LatticeWeight... also CompactLatticeWeight, but we doubt that will be used here;
better to use PruneCompactLattice().
*/
template<class Arc>
void PruneSpecial(const Fst<Arc> &ifst,
VectorFst<Arc> *ofst,
typename Arc::Weight beam,
size_t max_states = 0);
} // end namespace fst
#include "fstext/prune-special-inl.h"
#endif // KALDI_FSTEXT_PRUNE_SPECIAL_H_