/******************************************************************************

 *

 * File:         context.cpp  (Formerly context.c)

 * Description:  Context checking functions

 * Author:       Mark Seaman, OCR Technology

 *

 * (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 "unicharset.h"

namespace tesseract {

static const int kMinAbsoluteGarbageWordLength = 10;

static const float kMinAbsoluteGarbageAlphanumFrac = 0.5f;

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 {

  int state = 0;

  const UNICHARSET *unicharset = word.unicharset();

  for (unsigned 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 (unsigned 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