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85 lines
2.7 KiB
C
85 lines
2.7 KiB
C
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/**********************************************************************
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* File: search_column.h
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* Description: Declaration of the Beam Search Column Class
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* Author: Ahmad Abdulkader
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* Created: 2008
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*
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* (C) Copyright 2008, Google Inc.
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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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** http://www.apache.org/licenses/LICENSE-2.0
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** Unless required by applicable law or agreed to in writing, software
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** distributed under the License is distributed on an "AS IS" BASIS,
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** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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** See the License for the specific language governing permissions and
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** limitations under the License.
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*
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**********************************************************************/
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// The SearchColumn class abstracts a column in the lattice that is created
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// by the BeamSearch during the recognition process
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// The class holds the lattice nodes. New nodes are added by calls to AddNode
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// made from the BeamSearch
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// The class maintains a hash table of the nodes to be able to lookup nodes
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// quickly using their lang_mod_edge. This is needed to merge similar paths
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// in the lattice
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#ifndef SEARCH_COLUMN_H
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#define SEARCH_COLUMN_H
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#include "search_node.h"
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#include "lang_mod_edge.h"
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#include "cube_reco_context.h"
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namespace tesseract {
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class SearchColumn {
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public:
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SearchColumn(int col_idx, int max_node_cnt);
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~SearchColumn();
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// Accessor functions
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inline int ColIdx() const { return col_idx_; }
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inline int NodeCount() const { return node_cnt_; }
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inline SearchNode **Nodes() const { return node_array_; }
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// Prune the nodes if necessary. Pruning is done such that a max
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// number of nodes is kept, i.e., the beam width
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void Prune();
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SearchNode *AddNode(LangModEdge *edge, int score,
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SearchNode *parent, CubeRecoContext *cntxt);
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// Returns the node with the least cost
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SearchNode *BestNode();
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// Sort the lattice nodes. Needed for visualization
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void Sort();
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// Free up the Hash Table. Added to be called by the Beam Search after
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// a column is pruned to reduce memory foot print
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void FreeHashTable() {
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if (node_hash_table_ != NULL) {
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delete node_hash_table_;
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node_hash_table_ = NULL;
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}
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}
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private:
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static const int kNodeAllocChunk = 1024;
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static const int kScoreBins = 1024;
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bool init_;
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int min_cost_;
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int max_cost_;
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int max_node_cnt_;
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int node_cnt_;
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int col_idx_;
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int score_bins_[kScoreBins];
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SearchNode **node_array_;
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SearchNodeHashTable *node_hash_table_;
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// Free node array and hash table
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void Cleanup();
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// Create hash table
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bool Init();
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};
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}
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#endif // SEARCH_COLUMN_H
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