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