tesseract-ocr/ccutil/unicharmap.cpp

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// File:        unicharmap.cpp
// Description: Unicode character/ligature to integer id class.
// Author:      Thomas Kielbus
// Created:     Wed Jun 28 17:05:01 PDT 2006
//
// (C) Copyright 2006, Google Inc.
// 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 <assert.h>
#include "unichar.h"
#include "host.h"
#include "unicharmap.h"

UNICHARMAP::UNICHARMAP() :
nodes(0) {
}

UNICHARMAP::~UNICHARMAP() {
  if (nodes != 0)
    delete[] nodes;
}

// Search the given unichar representation in the tree. Each character in the
// string is interpreted as an index in an array of nodes.
UNICHAR_ID UNICHARMAP::unichar_to_id(const char* const unichar_repr) const {
  const char* current_char = unichar_repr;
  UNICHARMAP_NODE* current_nodes = nodes;

  assert(*unichar_repr != '\0');

  do {
    if (*(current_char + 1) == '\0')
      return current_nodes[static_cast<unsigned char>(*current_char)].id;
    current_nodes =
        current_nodes[static_cast<unsigned char>(*current_char)].children;
    ++current_char;
  } while (true);
}

// Search the given unichar representation in the tree, using length characters
// from it maximum. Each character in the string is interpreted as an index in
// an array of nodes.
UNICHAR_ID UNICHARMAP::unichar_to_id(const char* const unichar_repr,
                                     int length) const {
  const char* current_char = unichar_repr;
  UNICHARMAP_NODE* current_nodes = nodes;

  assert(*unichar_repr != '\0');
  assert(length > 0 && length <= UNICHAR_LEN);

  do {
    if (length == 1 || *(current_char + 1) == '\0')
      return current_nodes[static_cast<unsigned char>(*current_char)].id;
    current_nodes =
        current_nodes[static_cast<unsigned char>(*current_char)].children;
    ++current_char;
    --length;
  } while (true);
}

// Search the given unichar representation in the tree, creating the possibly
// missing nodes. Once the right place has been found, insert the given id and
// update the inserted flag to keep track of the insert. Each character in the
// string is interpreted as an index in an array of nodes.
void UNICHARMAP::insert(const char* const unichar_repr, UNICHAR_ID id) {
  const char* current_char = unichar_repr;
  UNICHARMAP_NODE** current_nodes_pointer = &nodes;

  assert(*unichar_repr != '\0');
  assert(id >= 0);

  do {
    if (*current_nodes_pointer == 0)
      *current_nodes_pointer = new UNICHARMAP_NODE[256];
    if (*(current_char + 1) == '\0') {
      (*current_nodes_pointer)
          [static_cast<unsigned char>(*current_char)].id = id;
      return;
    }
    current_nodes_pointer =
        &((*current_nodes_pointer)
          [static_cast<unsigned char>(*current_char)].children);
    ++current_char;
  } while (true);
}

// Search the given unichar representation in the tree. Each character in the
// string is interpreted as an index in an array of nodes. Stop once the tree
// does not have anymore nodes or once we found the right unichar_repr.
bool UNICHARMAP::contains(const char* const unichar_repr) const {
  const char* current_char = unichar_repr;
  UNICHARMAP_NODE* current_nodes = nodes;

  assert(*unichar_repr != '\0');

  while (current_nodes != 0 && *(current_char + 1) != '\0') {
    current_nodes =
        current_nodes[static_cast<unsigned char>(*current_char)].children;
    ++current_char;
  }
  return current_nodes != 0 && *(current_char + 1) == '\0' &&
      current_nodes[static_cast<unsigned char>(*current_char)].id >= 0;
}

// Search the given unichar representation in the tree, using length characters
// from it maximum. Each character in the string is interpreted as an index in
// an array of nodes. Stop once the tree does not have anymore nodes or once we
// found the right unichar_repr.
bool UNICHARMAP::contains(const char* const unichar_repr,
                          int length) const {
  const char* current_char = unichar_repr;
  UNICHARMAP_NODE* current_nodes = nodes;

  assert(*unichar_repr != '\0');
  assert(length > 0 && length <= UNICHAR_LEN);

  while (current_nodes != 0 && (length > 1 && *(current_char + 1) != '\0')) {
    current_nodes =
        current_nodes[static_cast<unsigned char>(*current_char)].children;
    --length;
    ++current_char;
  }
  return current_nodes != 0 && (length == 1 || *(current_char + 1) == '\0') &&
      current_nodes[static_cast<unsigned char>(*current_char)].id >= 0;
}

// Return the minimum number of characters that must be used from this string
// to obtain a match in the UNICHARMAP.
int UNICHARMAP::minmatch(const char* const unichar_repr) const {
  const char* current_char = unichar_repr;
  UNICHARMAP_NODE* current_nodes = nodes;

  while (current_nodes != NULL && *current_char != '\0') {
    if (current_nodes[static_cast<unsigned char>(*current_char)].id >= 0)
      return current_char + 1 - unichar_repr;
    current_nodes =
        current_nodes[static_cast<unsigned char>(*current_char)].children;
    ++current_char;
  }
  return 0;
}

void UNICHARMAP::clear() {
  if (nodes != 0)
  {
    delete[] nodes;
    nodes = 0;
  }
}

UNICHARMAP::UNICHARMAP_NODE::UNICHARMAP_NODE() :
children(0),
id(-1) {
}

// Recursively delete the children
UNICHARMAP::UNICHARMAP_NODE::~UNICHARMAP_NODE() {
  if (children != 0) {
    delete[] children;
  }
}