tesseract/dict/context.cpp

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/* -*-C-*-
********************************************************************************
*
* File: context.c (Formerly context.c)
* Description: Context checking functions
* Author: Mark Seaman, OCR Technology
* Created: Thu Feb 15 11:18:24 1990
* Modified: Tue Jul 9 17:38:16 1991 (Mark Seaman) marks@hpgrlt
* Language: C
* Package: N/A
* Status: Experimental (Do Not Distribute)
*
* (c) Copyright 1990, Hewlett-Packard Company.
** 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
** 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.
*
*********************************************************************************/
#include "dict.h"
#include "tprintf.h"
#include "unicharset.h"
namespace tesseract {
static const int kMinAbsoluteGarbageWordLength = 10;
static const float kMinAbsoluteGarbageAlphanumFrac = 0.5f;
2016-11-08 02:46:33 +08:00
const int case_state_table[6][4] = {
{/* 0. Beginning of word */
/* P U L D */
/* -1. Error on case */
0, 1, 5, 4},
{/* 1. After initial capital */
0, 3, 2, 4},
{/* 2. After lower case */
0, -1, 2, -1},
{/* 3. After upper case */
0, 3, -1, 4},
{/* 4. After a digit */
0, -1, -1, 4},
{/* 5. After initial lower case */
5, -1, 2, -1},
};
int Dict::case_ok(const WERD_CHOICE &word, const UNICHARSET &unicharset) {
int state = 0;
int x;
for (x = 0; x < word.length(); ++x) {
UNICHAR_ID ch_id = word.unichar_id(x);
if (unicharset.get_isupper(ch_id))
state = case_state_table[state][1];
else if (unicharset.get_islower(ch_id))
state = case_state_table[state][2];
else if (unicharset.get_isdigit(ch_id))
state = case_state_table[state][3];
else
state = case_state_table[state][0];
if (state == -1) return false;
}
return state != 5; // single lower is bad
}
bool Dict::absolute_garbage(const WERD_CHOICE &word,
const UNICHARSET &unicharset) {
if (word.length() < kMinAbsoluteGarbageWordLength) return false;
int num_alphanum = 0;
for (int x = 0; x < word.length(); ++x) {
num_alphanum += (unicharset.get_isalpha(word.unichar_id(x)) ||
unicharset.get_isdigit(word.unichar_id(x)));
}
return (static_cast<float>(num_alphanum) /
static_cast<float>(word.length()) < kMinAbsoluteGarbageAlphanumFrac);
}
} // namespace tesseract