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99 lines
3.9 KiB
99 lines
3.9 KiB
3 years ago
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// fstext/pre-determinize.h
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// Copyright 2009-2011 Microsoft Corporation
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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_PRE_DETERMINIZE_H_
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#define KALDI_FSTEXT_PRE_DETERMINIZE_H_
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#include <fst/fst-decl.h>
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#include <fst/fstlib.h>
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#include <algorithm>
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#include <map>
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#include <set>
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#include <string>
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#include <vector>
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#include "base/kaldi-common.h"
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namespace fst {
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/* PreDeterminize inserts extra symbols on the input side of an FST as necessary
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to ensure that, after epsilon removal, it will be compactly determinizable by
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the determinize* algorithm. By compactly determinizable we mean that no
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original FST state is represented in more than one determinized state).
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Caution: this code is now only used in testing.
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The new symbols start from the value "first_new_symbol", which should be
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higher than the largest-numbered symbol currently in the FST. The new
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symbols added are put in the array syms_out, which should be empty at start.
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*/
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template <class Arc, class Int>
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void PreDeterminize(MutableFst<Arc> *fst, typename Arc::Label first_new_symbol,
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std::vector<Int> *syms_out);
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/* CreateNewSymbols is a helper function used inside PreDeterminize, and is also
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useful when you need to add a number of extra symbols to a different
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vocabulary from the one modified by PreDeterminize. */
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template <class Label>
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void CreateNewSymbols(SymbolTable *inputSymTable, int nSym, std::string prefix,
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std::vector<Label> *syms_out);
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/** AddSelfLoops is a function you will probably want to use alongside
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PreDeterminize, to add self-loops to any FSTs that you compose on the left
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hand side of the one modified by PreDeterminize.
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This function inserts loops with "special symbols" [e.g. \#0, \#1] into an
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FST. This is done at each final state and each state with non-epsilon output
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symbols on at least one arc out of it. This is to ensure that these symbols,
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when inserted into the input side of an FST we will compose with on the
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right, can "pass through" this FST.
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At input, isyms and osyms must be vectors of the same size n, corresponding
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to symbols that currently do not exist in 'fst'. For each state in n that
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has non-epsilon symbols on the output side of arcs leaving it, or which is a
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final state, this function inserts n self-loops with unit weight and one of
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the n pairs of symbols on its input and output.
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*/
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template <class Arc>
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void AddSelfLoops(MutableFst<Arc> *fst,
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const std::vector<typename Arc::Label> &isyms,
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const std::vector<typename Arc::Label> &osyms);
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/* DeleteSymbols replaces any instances of symbols in the vector symsIn,
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appearing on the input side, with epsilon. */
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/* It returns the number of instances of symbols deleted. */
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template <class Arc>
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int64 DeleteISymbols(MutableFst<Arc> *fst,
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std::vector<typename Arc::Label> symsIn);
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/* CreateSuperFinal takes an FST, and creates an equivalent FST with a single
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final state with no transitions out and unit final weight, by inserting
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epsilon transitions as necessary. */
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template <class Arc>
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typename Arc::StateId CreateSuperFinal(MutableFst<Arc> *fst);
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} // end namespace fst
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#include "fstext/pre-determinize-inl.h"
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#endif // KALDI_FSTEXT_PRE_DETERMINIZE_H_
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