tesseract/ccutil/tessdatamanager.h

///////////////////////////////////////////////////////////////////////
// File:        tessdatamanager.h
// Description: Functions to handle loading/combining tesseract data files.
// Author:      Daria Antonova
// Created:     Wed Jun 03 11:26:43 PST 2009
//
// (C) Copyright 2009, 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.
//
///////////////////////////////////////////////////////////////////////

#ifndef TESSERACT_CCUTIL_TESSDATAMANAGER_H_
#define TESSERACT_CCUTIL_TESSDATAMANAGER_H_

#include <stdio.h>
#include "host.h"
#include "tprintf.h"
#include "varable.h"

extern BOOL_VAR_H(global_load_punc_dawg, true,
                  "Load dawg with punctuation patterns.");
extern BOOL_VAR_H(global_load_system_dawg, true, "Load system word dawg.");
extern BOOL_VAR_H(global_load_number_dawg, true,
                  "Load dawg with number patterns.");
extern BOOL_VAR_H(global_load_freq_dawg, true, "Load frequent word dawg.");

extern INT_VAR_H(global_tessdata_manager_debug_level, 0,
                 "Debug level for TessdataManager functions.");

static const char kTrainedDataSuffix[] = "traineddata";

static const char kLangConfigFileSuffix[] = "config";
static const char kUnicharsetFileSuffix[] = "unicharset";
static const char kAmbigsFileSuffix[] = "unicharambigs";
static const char kBuiltInTemplatesFileSuffix[] = "inttemp";
static const char kBuiltInCutoffsFileSuffix[] = "pffmtable";
static const char kNormProtoFileSuffix[] = "normproto";
static const char kPuncDawgFileSuffix[] = "punc-dawg";
static const char kSystemDawgFileSuffix[] = "word-dawg";
static const char kNumberDawgFileSuffix[] = "number-dawg";
static const char kFreqDawgFileSuffix[] = "freq-dawg";

namespace tesseract {

enum TessdataType {
  TESSDATA_LANG_CONFIG,  // 0
  TESSDATA_UNICHARSET,   // 1
  TESSDATA_AMBIGS,       // 2
  TESSDATA_INTTEMP,      // 3
  TESSDATA_PFFMTABLE,    // 4
  TESSDATA_NORMPROTO,    // 5
  TESSDATA_PUNC_DAWG,    // 6
  TESSDATA_SYSTEM_DAWG,  // 7
  TESSDATA_NUMBER_DAWG,  // 8
  TESSDATA_FREQ_DAWG,    // 9

  TESSDATA_NUM_ENTRIES
};

// TessdataType could be updated to contain more entries, however
// we do not expect that number to be astronomically high.
// In order to automatically detect endianness TessdataManager will
// flip the bits if actual_tessdata_num_entries_ is larger than
// kMaxNumTessdataEntries.
static const int kMaxNumTessdataEntries = 1000;


class TessdataManager {
 public:
  TessdataManager() {
    data_file_ = NULL;
    actual_tessdata_num_entries_ = 0;
    for (int i = 0; i < TESSDATA_NUM_ENTRIES; ++i) {
      offset_table_[i] = -1;
    }
  }
  ~TessdataManager() {}

  // Opens the given data file and reads the offset table.
  void Init(const char *data_file_name);

  // Returns data file pointer.
  inline FILE *GetDataFilePtr() const { return data_file_; }

  // Returns false if there is no data of the given type.
  // Otherwise does a seek on the data_file_ to position the pointer
  // at the start of the data of the given type.
  inline bool SeekToStart(TessdataType tessdata_type) {
    if (global_tessdata_manager_debug_level) {
      tprintf("TessdataManager: seek to offset %lld (start of tessdata"
              "type %d)\n", offset_table_[tessdata_type], tessdata_type);
    }
    if (offset_table_[tessdata_type] < 0) {
      return false;
    } else {
      ASSERT_HOST(fseek(data_file_,
                        offset_table_[tessdata_type], SEEK_SET) == 0);
      return true;
    }
  }
  // Returns the end offset for the given tesseract data file type.
  inline inT64 GetEndOffset(TessdataType tessdata_type) const {
    int index = tessdata_type + 1;
    while (index < actual_tessdata_num_entries_ && offset_table_[index] == -1) {
      ++index;  // skip tessdata types not present in the combined file
    }
    if (global_tessdata_manager_debug_level) {
      tprintf("TessdataManager: end offset for type %d is %lld\n",
              tessdata_type,
              (index == actual_tessdata_num_entries_) ? -1
              : offset_table_[index]);
    }
    return (index == actual_tessdata_num_entries_) ? -1 : offset_table_[index] - 1;
  }
  // Closes data_file_ (if it was opened by Init()).
  inline void End() {
    if (data_file_ != NULL) {
      fclose(data_file_);
      data_file_ = NULL;
    }
  }

  // Reads all the standard tesseract config and data files for a language
  // at the given path and bundles them up into one binary data file.
  static void CombineDataFiles(const char *language_data_path_prefix,
                               const char *output_filename);

 private:

  // Opens the file whose name is a concatentation of language_data_path_prefix
  // and file_suffix. Terminates the program if required_file is set to true,
  // but the file could not be found or opened for reading.
  // Returns a file pointer to the opened file.
  static FILE *GetFilePtr(const char *language_data_path_prefix,
                          const char *file_suffix, bool required_file,
                          bool text_file);

  // Copies all the bytes in the given input file to the output_file provided.
  static void CopyFile(FILE *input_file, FILE *output_file, bool newline_end);

  // Each offset_table_[i] contains a file offset in the combined data file
  // where the data of TessdataFileType i is stored.
  inT64 offset_table_[TESSDATA_NUM_ENTRIES];
  // Actual number of entries in the tessdata table. This value can only be
  // same or smaller than TESSDATA_NUM_ENTRIES, but can never be larger,
  // since then it would be impossible to interpret the type of tessdata at
  // indices same and higher than TESSDATA_NUM_ENTRIES.
  // This parameter is used to allow for backward compatiblity
  // when new tessdata types are introduced.
  inT32 actual_tessdata_num_entries_;
  FILE *data_file_;  // pointer to the data file.
};


}  // namespace tesseract

#endif  // TESSERACT_CCUTIL_TESSDATAMANAGER_H_