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PaddleSpeech/third_party/ctc_decoders/path_trie.h

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// Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "COPYING.APACHE2.0");
// 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
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef PATH_TRIE_H
#define PATH_TRIE_H
#include <algorithm>
#include <limits>
#include <memory>
#include <utility>
#include <vector>
#include "fst/fstlib.h"
/* Trie tree for prefix storing and manipulating, with a dictionary in
* finite-state transducer for spelling correction.
*/
class PathTrie {
public:
PathTrie();
~PathTrie();
// get new prefix after appending new char
PathTrie* get_path_trie(int new_char, bool reset = true);
// get the prefix in index from root to current node
PathTrie* get_path_vec(std::vector<int>& output);
// get the prefix in index from some stop node to current nodel
PathTrie* get_path_vec(
std::vector<int>& output,
int stop,
size_t max_steps = std::numeric_limits<size_t>::max());
// update log probs
void iterate_to_vec(std::vector<PathTrie*>& output);
// set dictionary for FST
void set_dictionary(fst::StdVectorFst* dictionary);
void set_matcher(std::shared_ptr<fst::SortedMatcher<fst::StdVectorFst>>);
bool is_empty() { return ROOT_ == character; }
// remove current path from root
void remove();
float log_prob_b_prev;
float log_prob_nb_prev;
float log_prob_b_cur;
float log_prob_nb_cur;
float score;
float approx_ctc;
int character;
PathTrie* parent;
private:
int ROOT_;
bool exists_;
bool has_dictionary_;
std::vector<std::pair<int, PathTrie*>> children_;
// pointer to dictionary of FST
fst::StdVectorFst* dictionary_;
fst::StdVectorFst::StateId dictionary_state_;
// true if finding ars in FST
std::shared_ptr<fst::SortedMatcher<fst::StdVectorFst>> matcher_;
};
#endif // PATH_TRIE_H