text: /* -*- Mode: C; indent-tabs-mode: nil; c-basic-offset: 8-*- */
  
  /*
   * This file is part of The Croco Library
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 3 of the GNU General Public
   * License as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
   * USA
   *
   * Author: Dodji Seketeli
   * See COPYRIGHTS file for copyright information.
   */
  
  #include <config.h>
  #include "stdio.h"
  #include <string.h>
  #include "cr-input.h"
  #include "cr-enc-handler.h"
  
  /**
   *@CRInput:
   *
   *The definition of the #CRInput class.
   */
  
  /*******************
   *Private type defs
   *******************/
  
  /**
   *The private attributes of
   *the #CRInputPriv class.
   */
  struct _CRInputPriv {
          /*
           *The input buffer
           */
          guchar *in_buf;
          gulong in_buf_size;
  
          gulong nb_bytes;
  
          /*
           *The index of the next byte
           *to be read.
           */
          gulong next_byte_index;
  
          /*
           *The current line number
           */
          gulong line;
  
          /*
           *The current col number
           */
          gulong col;
  
          gboolean end_of_line;
          gboolean end_of_input;
  
          /*
           *the reference count of this
           *instance.
           */
          guint ref_count;
          gboolean free_in_buf;
  };
  
  #define PRIVATE(object) (object)->priv
  
  /***************************
   *private constants
   **************************/
  #define CR_INPUT_MEM_CHUNK_SIZE 1024 * 4
  
  static CRInput *cr_input_new_real (void);
  
  static CRInput *
  cr_input_new_real (void)
  {
          CRInput *result = NULL;
  
          result = g_try_malloc (sizeof (CRInput));
          if (!result) {
                  cr_utils_trace_info ("Out of memory");
                  return NULL;
          }
          memset (result, 0, sizeof (CRInput));
  
          PRIVATE (result) = g_try_malloc (sizeof (CRInputPriv));
          if (!PRIVATE (result)) {
                  cr_utils_trace_info ("Out of memory");
                  g_free (result);
                  return NULL;
          }
          memset (PRIVATE (result), 0, sizeof (CRInputPriv));
          PRIVATE (result)->free_in_buf = TRUE;
          return result;
  }
  
  /****************
   *Public methods
   ***************/
  
  /**
   * cr_input_new_from_buf:
   *@a_buf: the memory buffer to create the input stream from.
   *The #CRInput keeps this pointer so user should not free it !.
   *@a_len: the size of the input buffer.
   *@a_enc: the buffer's encoding.
   *@a_free_buf: if set to TRUE, this a_buf will be freed
   *at the destruction of this instance. If set to false, it is up
   *to the caller to free it.
   *
   *Creates a new input stream from a memory buffer.
   *Returns the newly built instance of #CRInput.
   */
  CRInput *
  cr_input_new_from_buf (guchar * a_buf,
                         gulong a_len,
                         enum CREncoding a_enc,
                         gboolean a_free_buf)
  {
          CRInput *result = NULL;
          enum CRStatus status = CR_OK;
          CREncHandler *enc_handler = NULL;
          gulong len = a_len;
  
          g_return_val_if_fail (a_buf, NULL);
  
          result = cr_input_new_real ();
          g_return_val_if_fail (result, NULL);
  
          /*transform the encoding in utf8 */
          if (a_enc != CR_UTF_8) {
                  enc_handler = cr_enc_handler_get_instance (a_enc);
                  if (!enc_handler) {
                          goto error;
                  }
  
                  status = cr_enc_handler_convert_input
                          (enc_handler, a_buf, &len,
                           &PRIVATE (result)->in_buf,
                           &PRIVATE (result)->in_buf_size);
                  if (status != CR_OK)
                          goto error;
                  PRIVATE (result)->free_in_buf = TRUE;
                  if (a_free_buf == TRUE && a_buf) {
                          g_free (a_buf) ;
                          a_buf = NULL ;
                  }                
                  PRIVATE (result)->nb_bytes = PRIVATE (result)->in_buf_size;
          } else {
                  PRIVATE (result)->in_buf = (guchar *) a_buf;
                  PRIVATE (result)->in_buf_size = a_len;
                  PRIVATE (result)->nb_bytes = a_len;
                  PRIVATE (result)->free_in_buf = a_free_buf;
          }
          PRIVATE (result)->line = 1;
          PRIVATE (result)->col =  0;
          return result;
  
   error:
          if (result) {
                  cr_input_destroy (result);
                  result = NULL;
          }
  
          return NULL;
  }
  
  /**
   * cr_input_new_from_uri:
   *@a_file_uri: the file to create *the input stream from.
   *@a_enc: the encoding of the file *to create the input from.
   *
   *Creates a new input stream from
   *a file.
   *
   *Returns the newly created input stream if
   *this method could read the file and create it,
   *NULL otherwise.
   */
  
  CRInput *
  cr_input_new_from_uri (const gchar * a_file_uri, enum CREncoding a_enc)
  {
          CRInput *result = NULL;
          enum CRStatus status = CR_OK;
          FILE *file_ptr = NULL;
          guchar tmp_buf[CR_INPUT_MEM_CHUNK_SIZE] = { 0 };
          gulong nb_read = 0,
                  len = 0,
                  buf_size = 0;
          gboolean loop = TRUE;
          guchar *buf = NULL;
  
          g_return_val_if_fail (a_file_uri, NULL);
  
          file_ptr = fopen (a_file_uri, "r");
  
          if (file_ptr == NULL) {
  
  #ifdef CR_DEBUG
                  cr_utils_trace_debug ("could not open file");
  #endif
                  g_warning ("Could not open file %s\n", a_file_uri);
  
                  return NULL;
          }
  
          /*load the file */
          while (loop) {
                  nb_read = fread (tmp_buf, 1 /*read bytes */ ,
                                   CR_INPUT_MEM_CHUNK_SIZE /*nb of bytes */ ,
                                   file_ptr);
  
                  if (nb_read != CR_INPUT_MEM_CHUNK_SIZE) {
                          /*we read less chars than we wanted */
                          if (feof (file_ptr)) {
                                  /*we reached eof */
                                  loop = FALSE;
                          } else {
                                  /*a pb occured !! */
                                  cr_utils_trace_debug ("an io error occured");
                                  status = CR_ERROR;
                                  goto cleanup;
                          }
                  }
  
                  if (status == CR_OK) {
                          /*read went well */
                          buf = g_realloc (buf, len + CR_INPUT_MEM_CHUNK_SIZE);
                          memcpy (buf + len, tmp_buf, nb_read);
                          len += nb_read;
                          buf_size += CR_INPUT_MEM_CHUNK_SIZE;
                  }
          }
  
          if (status == CR_OK) {
                  result = cr_input_new_from_buf (buf, len, a_enc, TRUE);
                  if (!result) {
                          goto cleanup;
                  }
                  /*
                   *we should  free buf here because it's own by CRInput.
                   *(see the last parameter of cr_input_new_from_buf().
                   */
                  buf = NULL ;
          }
  
   cleanup:
          if (file_ptr) {
                  fclose (file_ptr);
                  file_ptr = NULL;
          }
  
          if (buf) {
                  g_free (buf);
                  buf = NULL;
          }
  
          return result;
  }
  
  /**
   * cr_input_destroy:
   *@a_this: the current instance of #CRInput.
   *
   *The destructor of the #CRInput class.
   */
  void
  cr_input_destroy (CRInput * a_this)
  {
          if (a_this == NULL)
                  return;
  
          if (PRIVATE (a_this)) {
                  if (PRIVATE (a_this)->in_buf && PRIVATE (a_this)->free_in_buf) {
                          g_free (PRIVATE (a_this)->in_buf);
                          PRIVATE (a_this)->in_buf = NULL;
                  }
  
                  g_free (PRIVATE (a_this));
                  PRIVATE (a_this) = NULL;
          }
  
          g_free (a_this);
  }
  
  /**
   * cr_input_ref:
   *@a_this: the current instance of #CRInput.
   *
   *Increments the reference count of the current
   *instance of #CRInput.
   */
  void
  cr_input_ref (CRInput * a_this)
  {
          g_return_if_fail (a_this && PRIVATE (a_this));
  
          PRIVATE (a_this)->ref_count++;
  }
  
  /**
   * cr_input_unref:
   *@a_this: the current instance of #CRInput.
   *
   *Decrements the reference count of this instance
   *of #CRInput. If the reference count goes down to
   *zero, this instance is destroyed.
   *
   * Returns TRUE if the instance of #CRInput got destroyed, false otherwise.
   */
  gboolean
  cr_input_unref (CRInput * a_this)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), FALSE);
  
          if (PRIVATE (a_this)->ref_count) {
                  PRIVATE (a_this)->ref_count--;
          }
  
          if (PRIVATE (a_this)->ref_count == 0) {
                  cr_input_destroy (a_this);
                  return TRUE;
          }
          return FALSE;
  }
  
  /**
   * cr_input_end_of_input:
   *@a_this: the current instance of #CRInput.
   *@a_end_of_input: out parameter. Is set to TRUE if
   *the current instance has reached the end of its input buffer,
   *FALSE otherwise.
   *
   *Tests wether the current instance of
   *#CRInput has reached its input buffer.
   *
   * Returns CR_OK upon successful completion, an error code otherwise.
   * Note that all the out parameters of this method are valid if
   * and only if this method returns CR_OK.
   */
  enum CRStatus
  cr_input_end_of_input (CRInput * a_this, gboolean * a_end_of_input)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this)
                                && a_end_of_input, CR_BAD_PARAM_ERROR);
  
          *a_end_of_input = (PRIVATE (a_this)->next_byte_index
                             >= PRIVATE (a_this)->in_buf_size) ? TRUE : FALSE;
  
          return CR_OK;
  }
  
  /**
   * cr_input_get_nb_bytes_left:
   *@a_this: the current instance of #CRInput.
   *
   *Returns the number of bytes left in the input stream
   *before the end, -1 in case of error.
   */
  glong
  cr_input_get_nb_bytes_left (CRInput * a_this)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), -1);
          g_return_val_if_fail (PRIVATE (a_this)->nb_bytes
                                <= PRIVATE (a_this)->in_buf_size, -1);
          g_return_val_if_fail (PRIVATE (a_this)->next_byte_index
                                <= PRIVATE (a_this)->nb_bytes, -1);
  
          if (PRIVATE (a_this)->end_of_input)
                  return 0;
  
          return PRIVATE (a_this)->nb_bytes - PRIVATE (a_this)->next_byte_index;
  }
  
  /**
   * cr_input_read_byte:
   *@a_this: the current instance of #CRInput.
   *@a_byte: out parameter the returned byte.
   *
   *Gets the next byte of the input.
   *Updates the state of the input so that
   *the next invocation of this method  returns
   *the next coming byte.
   *
   *Returns CR_OK upon successful completion, an error code
   *otherwise. All the out parameters of this method are valid if
   *and only if this method returns CR_OK.
   */
  enum CRStatus
  cr_input_read_byte (CRInput * a_this, guchar * a_byte)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this)
                                && a_byte, CR_BAD_PARAM_ERROR);
  
          g_return_val_if_fail (PRIVATE (a_this)->next_byte_index <=
                                PRIVATE (a_this)->nb_bytes, CR_BAD_PARAM_ERROR);
  
          if (PRIVATE (a_this)->end_of_input == TRUE)
                  return CR_END_OF_INPUT_ERROR;
  
          *a_byte = PRIVATE (a_this)->in_buf[PRIVATE (a_this)->next_byte_index];
  
          if (PRIVATE (a_this)->nb_bytes -
              PRIVATE (a_this)->next_byte_index < 2) {
                  PRIVATE (a_this)->end_of_input = TRUE;
          } else {
                  PRIVATE (a_this)->next_byte_index++;
          }
  
          return CR_OK;
  }
  
  /**
   * cr_input_read_char:
   *@a_this: the current instance of CRInput.
   *@a_char: out parameter. The read character.
   *
   *Reads an unicode character from the current instance of
   *#CRInput.
   *
   *Returns CR_OK upon successful completion, an error code
   *otherwise.
   */
  enum CRStatus
  cr_input_read_char (CRInput * a_this, guint32 * a_char)
  {
          enum CRStatus status = CR_OK;
          gulong consumed = 0,
                  nb_bytes_left = 0;
  
          g_return_val_if_fail (a_this && PRIVATE (a_this) && a_char,
                                CR_BAD_PARAM_ERROR);
  
          if (PRIVATE (a_this)->end_of_input == TRUE)
                  return CR_END_OF_INPUT_ERROR;
  
          nb_bytes_left = cr_input_get_nb_bytes_left (a_this);
  
          if (nb_bytes_left < 1) {
                  return CR_END_OF_INPUT_ERROR;
          }
  
          status = cr_utils_read_char_from_utf8_buf
                  (PRIVATE (a_this)->in_buf
                   +
                   PRIVATE (a_this)->next_byte_index,
                   nb_bytes_left, a_char, &consumed);
  
          if (status == CR_OK) {
                  /*update next byte index */
                  PRIVATE (a_this)->next_byte_index += consumed;
  
                  /*update line and column number */
                  if (PRIVATE (a_this)->end_of_line == TRUE) {
                          PRIVATE (a_this)->col = 1;
                          PRIVATE (a_this)->line++;
                          PRIVATE (a_this)->end_of_line = FALSE;
                  } else if (*a_char != '\n') {
                          PRIVATE (a_this)->col++;
                  }
  
                  if (*a_char == '\n') {
                          PRIVATE (a_this)->end_of_line = TRUE;
                  }
  
          }
  
          return status;
  }
  
  /**
   * cr_input_set_line_num:
   *@a_this: the "this pointer" of the current instance of #CRInput.
   *@a_line_num: the new line number.
   *
   *Setter of the current line number.
   *
   *Return CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_set_line_num (CRInput * a_this, glong a_line_num)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          PRIVATE (a_this)->line = a_line_num;
  
          return CR_OK;
  }
  
  /**
   * cr_input_get_line_num:
   *@a_this: the "this pointer" of the current instance of #CRInput.
   *@a_line_num: the returned line number.
   *
   *Getter of the current line number.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_get_line_num (CRInput * a_this, glong * a_line_num)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this)
                                && a_line_num, CR_BAD_PARAM_ERROR);
  
          *a_line_num = PRIVATE (a_this)->line;
  
          return CR_OK;
  }
  
  /**
   * cr_input_set_column_num:
   *@a_this: the "this pointer" of the current instance of #CRInput.
   *@a_col: the new column number.
   *
   *Setter of the current column number.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_set_column_num (CRInput * a_this, glong a_col)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          PRIVATE (a_this)->col = a_col;
  
          return CR_OK;
  }
  
  /**
   * cr_input_get_column_num:
   *@a_this: the "this pointer" of the current instance of #CRInput.
   *@a_col: out parameter
   *
   *Getter of the current column number.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_get_column_num (CRInput * a_this, glong * a_col)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this) && a_col,
                                CR_BAD_PARAM_ERROR);
  
          *a_col = PRIVATE (a_this)->col;
  
          return CR_OK;
  }
  
  /**
   * cr_input_increment_line_num:
   *@a_this: the "this pointer" of the current instance of #CRInput.
   *@a_increment: the increment to add to the line number.
   *
   *Increments the current line number.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_increment_line_num (CRInput * a_this, glong a_increment)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          PRIVATE (a_this)->line += a_increment;
  
          return CR_OK;
  }
  
  /**
   * cr_input_increment_col_num:
   *@a_this: the "this pointer" of the current instance of #CRInput.
   *@a_increment: the increment to add to the column number.
   *
   *Increments the current column number.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_increment_col_num (CRInput * a_this, glong a_increment)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          PRIVATE (a_this)->col += a_increment;
  
          return CR_OK;
  }
  
  /**
   * cr_input_consume_char:
   *@a_this: the this pointer.
   *@a_char: the character to consume. If set to zero,
   *consumes any character.
   *
   *Consumes the next character of the input stream if
   *and only if that character equals a_char.
   *
   *Returns CR_OK upon successful completion, CR_PARSING_ERROR if
   *next char is different from a_char, an other error code otherwise
   */
  enum CRStatus
  cr_input_consume_char (CRInput * a_this, guint32 a_char)
  {
          guint32 c;
          enum CRStatus status;
  
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          if ((status = cr_input_peek_char (a_this, &c)) != CR_OK) {
                  return status;
          }
  
          if (c == a_char || a_char == 0) {
                  status = cr_input_read_char (a_this, &c);
          } else {
                  return CR_PARSING_ERROR;
          }
  
          return status;
  }
  
  /**
   * cr_input_consume_chars:
   *@a_this: the this pointer of the current instance of #CRInput.
   *@a_char: the character to consume.
   *@a_nb_char: in/out parameter. The number of characters to consume.
   *If set to a negative value, the function will consume all the occurences
   *of a_char found.
   *After return, if the return value equals CR_OK, this variable contains 
   *the number of characters actually consumed.
   *
   *Consumes up to a_nb_char occurences of the next contiguous characters 
   *which equal a_char. Note that the next character of the input stream
   **MUST* equal a_char to trigger the consumption, or else, the error
   *code CR_PARSING_ERROR is returned.
   *If the number of contiguous characters that equals a_char is less than
   *a_nb_char, then this function consumes all the characters it can consume.
   * 
   *Returns CR_OK if at least one character has been consumed, an error code
   *otherwise.
   */
  enum CRStatus
  cr_input_consume_chars (CRInput * a_this, guint32 a_char, gulong * a_nb_char)
  {
          enum CRStatus status = CR_OK;
          gulong nb_consumed = 0;
  
          g_return_val_if_fail (a_this && PRIVATE (a_this) && a_nb_char,
                                CR_BAD_PARAM_ERROR);
  
          g_return_val_if_fail (a_char != 0 || a_nb_char != NULL,
                                CR_BAD_PARAM_ERROR);
  
          for (nb_consumed = 0; ((status == CR_OK)
                                 && (*a_nb_char > 0
                                     && nb_consumed < *a_nb_char));
               nb_consumed++) {
                  status = cr_input_consume_char (a_this, a_char);
          }
  
          *a_nb_char = nb_consumed;
  
          if ((nb_consumed > 0)
              && ((status == CR_PARSING_ERROR)
                  || (status == CR_END_OF_INPUT_ERROR))) {
                  status = CR_OK;
          }
  
          return status;
  }
  
  /**
   * cr_input_consume_white_spaces:
   *@a_this: the "this pointer" of the current instance of #CRInput.
   *@a_nb_chars: in/out parameter. The number of white spaces to
   *consume. After return, holds the number of white spaces actually consumed.
   *
   *Same as cr_input_consume_chars() but this one consumes white
   *spaces.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_consume_white_spaces (CRInput * a_this, gulong * a_nb_chars)
  {
          enum CRStatus status = CR_OK;
          guint32 cur_char = 0,
                  nb_consumed = 0;
  
          g_return_val_if_fail (a_this && PRIVATE (a_this) && a_nb_chars,
                                CR_BAD_PARAM_ERROR);
  
          for (nb_consumed = 0;
               ((*a_nb_chars > 0) && (nb_consumed < *a_nb_chars));
               nb_consumed++) {
                  status = cr_input_peek_char (a_this, &cur_char);
                  if (status != CR_OK)
                          break;
  
                  /*if the next char is a white space, consume it ! */
                  if (cr_utils_is_white_space (cur_char) == TRUE) {
                          status = cr_input_read_char (a_this, &cur_char);
                          if (status != CR_OK)
                                  break;
                          continue;
                  }
  
                  break;
  
          }
  
          if (nb_consumed && status == CR_END_OF_INPUT_ERROR) {
                  status = CR_OK;
          }
  
          return status;
  }
  
  /**
   * cr_input_peek_char:
   *@a_this: the current instance of #CRInput.
   *@a_char: out parameter. The returned character.
   *
   *Same as cr_input_read_char() but does not update the
   *internal state of the input stream. The next call
   *to cr_input_peek_char() or cr_input_read_char() will thus
   *return the same character as the current one.
   *
   *Returns CR_OK upon successful completion, an error code
   *otherwise.
   */
  enum CRStatus
  cr_input_peek_char (CRInput * a_this, guint32 * a_char)
  {
          enum CRStatus status = CR_OK;
          glong consumed = 0,
                  nb_bytes_left = 0;
  
          g_return_val_if_fail (a_this && PRIVATE (a_this)
                                && a_char, CR_BAD_PARAM_ERROR);
  
          if (PRIVATE (a_this)->next_byte_index >=
              PRIVATE (a_this)->in_buf_size) {
                  return CR_END_OF_INPUT_ERROR;
          }
  
          nb_bytes_left = cr_input_get_nb_bytes_left (a_this);
  
          if (nb_bytes_left < 1) {
                  return CR_END_OF_INPUT_ERROR;
          }
  
          status = cr_utils_read_char_from_utf8_buf
                  (PRIVATE (a_this)->in_buf +
                   PRIVATE (a_this)->next_byte_index,
                   nb_bytes_left, a_char, &consumed);
  
          return status;
  }
  
  /**
   * cr_input_peek_byte:
   *@a_this: the current instance of #CRInput.
   *@a_origin: the origin to consider in the calculation
   *of the position of the byte to peek.
   *@a_offset: the offset of the byte to peek, starting from
   *the origin specified by a_origin.
   *@a_byte: out parameter the peeked byte.
   *
   *Gets a byte from the input stream,
   *starting from the current position in the input stream.
   *Unlike cr_input_peek_next_byte() this method
   *does not update the state of the current input stream.
   *Subsequent calls to cr_input_peek_byte with the same arguments
   *will return the same byte.
   *
   *Returns CR_OK upon successful completion or,
   *CR_BAD_PARAM_ERROR if at least one of the parameters is invalid;
   *CR_OUT_OF_BOUNDS_ERROR if the indexed byte is out of bounds.
   */
  enum CRStatus
  cr_input_peek_byte (CRInput * a_this, enum CRSeekPos a_origin,
                      gulong a_offset, guchar * a_byte)
  {
          gulong abs_offset = 0;
  
          g_return_val_if_fail (a_this && PRIVATE (a_this)
                                && a_byte, CR_BAD_PARAM_ERROR);
  
          switch (a_origin) {
  
          case CR_SEEK_CUR:
                  abs_offset = PRIVATE (a_this)->next_byte_index - 1 + a_offset;
                  break;
  
          case CR_SEEK_BEGIN:
                  abs_offset = a_offset;
                  break;
  
          case CR_SEEK_END:
                  abs_offset = PRIVATE (a_this)->in_buf_size - 1 - a_offset;
                  break;
  
          default:
                  return CR_BAD_PARAM_ERROR;
          }
  
          if (abs_offset < PRIVATE (a_this)->in_buf_size) {
  
                  *a_byte = PRIVATE (a_this)->in_buf[abs_offset];
  
                  return CR_OK;
  
          } else {
                  return CR_END_OF_INPUT_ERROR;
          }
  }
  
  /**
   * cr_input_peek_byte2:
   *@a_this: the current byte input stream.
   *@a_offset: the offset of the byte to peek, starting
   *from the current input position pointer.
   *@a_eof: out parameter. Is set to true is we reach end of
   *stream. If set to NULL by the caller, this parameter is not taken
   *in account.
   *
   *Same as cr_input_peek_byte() but with a simplified
   *interface.
   *
   *Returns the read byte or 0 if something bad happened.
   */
  guchar
  cr_input_peek_byte2 (CRInput * a_this, gulong a_offset, gboolean * a_eof)
  {
          guchar result = 0;
          enum CRStatus status = CR_ERROR;
  
          g_return_val_if_fail (a_this && PRIVATE (a_this), 0);
  
          if (a_eof)
                  *a_eof = FALSE;
  
          status = cr_input_peek_byte (a_this, CR_SEEK_CUR, a_offset, &result);
  
          if ((status == CR_END_OF_INPUT_ERROR)
              && a_eof)
                  *a_eof = TRUE;
  
          return result;
  }
  
  /**
   * cr_input_get_byte_addr:
   *@a_this: the current instance of #CRInput.
   *@a_offset: the offset of the byte in the input stream starting
   *from the beginning of the stream.
   *
   *Gets the memory address of the byte located at a given offset
   *in the input stream.
   *
   *Returns the address, otherwise NULL if an error occured.
   */
  guchar *
  cr_input_get_byte_addr (CRInput * a_this, gulong a_offset)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), NULL);
  
          if (a_offset >= PRIVATE (a_this)->nb_bytes) {
                  return NULL;
          }
  
          return &PRIVATE (a_this)->in_buf[a_offset];
  }
  
  /**
   * cr_input_get_cur_byte_addr:
   *@a_this: the current input stream
   *@a_offset: out parameter. The returned address.
   *
   *Gets the address of the current character pointer.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_get_cur_byte_addr (CRInput * a_this, guchar ** a_offset)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this) && a_offset,
                                CR_BAD_PARAM_ERROR);
  
          if (!PRIVATE (a_this)->next_byte_index) {
                  return CR_START_OF_INPUT_ERROR;
          }
  
          *a_offset = cr_input_get_byte_addr
                  (a_this, PRIVATE (a_this)->next_byte_index - 1);
  
          return CR_OK;
  }
  
  /**
   * cr_input_seek_index:
   *@a_this: the current instance of #CRInput.
   *@a_origin: the origin to consider during the calculation
   *of the absolute position of the new "current byte index".
   *@a_pos: the relative offset of the new "current byte index."
   *This offset is relative to the origin a_origin.
   *
   *Sets the "current byte index" of the current instance
   *of #CRInput. Next call to cr_input_get_byte() will return
   *the byte next after the new "current byte index".
   *
   *Returns CR_OK upon successful completion otherwise returns
   *CR_BAD_PARAM_ERROR if at least one of the parameters is not valid
   *or CR_OUT_BOUNDS_ERROR in case of error.
   */
  enum CRStatus
  cr_input_seek_index (CRInput * a_this, enum CRSeekPos a_origin, gint a_pos)
  {
  
          glong abs_offset = 0;
  
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          switch (a_origin) {
  
          case CR_SEEK_CUR:
                  abs_offset = PRIVATE (a_this)->next_byte_index - 1 + a_pos;
                  break;
  
          case CR_SEEK_BEGIN:
                  abs_offset = a_pos;
                  break;
  
          case CR_SEEK_END:
                  abs_offset = PRIVATE (a_this)->in_buf_size - 1 - a_pos;
                  break;
  
          default:
                  return CR_BAD_PARAM_ERROR;
          }
  
          if ((abs_offset > 0)
              && (gulong) abs_offset < PRIVATE (a_this)->nb_bytes) {
  
                  /*update the input stream's internal state */
                  PRIVATE (a_this)->next_byte_index = abs_offset + 1;
  
                  return CR_OK;
          }
  
          return CR_OUT_OF_BOUNDS_ERROR;
  }
  
  /**
   * cr_input_get_cur_pos:
   *@a_this: the current instance of #CRInput.
   *@a_pos: out parameter. The returned position.
   *
   *Gets the position of the "current byte index" which
   *is basically the position of the last returned byte in the
   *input stream.
   *
   *Returns CR_OK upon successful completion. Otherwise,
   *CR_BAD_PARAMETER_ERROR if at least one of the arguments is invalid.
   *CR_START_OF_INPUT if no call to either cr_input_read_byte()
   *or cr_input_seek_index() have been issued before calling 
   *cr_input_get_cur_pos()
   *Note that the out parameters of this function are valid if and only if this
   *function returns CR_OK.
   */
  enum CRStatus
  cr_input_get_cur_pos (CRInput * a_this, CRInputPos * a_pos)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this) && a_pos,
                                CR_BAD_PARAM_ERROR);
  
          a_pos->next_byte_index = PRIVATE (a_this)->next_byte_index;
          a_pos->line = PRIVATE (a_this)->line;
          a_pos->col = PRIVATE (a_this)->col;
          a_pos->end_of_line = PRIVATE (a_this)->end_of_line;
          a_pos->end_of_file = PRIVATE (a_this)->end_of_input;
  
          return CR_OK;
  }
  
  /**
   * cr_input_get_parsing_location:
   *@a_this: the current instance of #CRInput
   *@a_loc: the set parsing location.
   *
   *Gets the current parsing location.
   *The Parsing location is a public datastructure that
   *represents the current line/column/byte offset/ in the input
   *stream.
   *
   *Returns CR_OK upon successful completion, an error
   *code otherwise.
   */
  enum CRStatus
  cr_input_get_parsing_location (CRInput *a_this,
                                 CRParsingLocation *a_loc)
  {
          g_return_val_if_fail (a_this 
                                && PRIVATE (a_this)
                                && a_loc, 
                                CR_BAD_PARAM_ERROR) ;
  
          a_loc->line = PRIVATE (a_this)->line ;
          a_loc->column = PRIVATE (a_this)->col ;
          if (PRIVATE (a_this)->next_byte_index) {
                  a_loc->byte_offset = PRIVATE (a_this)->next_byte_index - 1 ;
          } else {
                  a_loc->byte_offset = PRIVATE (a_this)->next_byte_index  ;
          }
          return CR_OK ;
  }
  
  /**
   * cr_input_get_cur_index:
   *@a_this: the "this pointer" of the current instance of
   *#CRInput
   *@a_index: out parameter. The returned index.
   *
   *Getter of the next byte index. 
   *It actually returns the index of the
   *next byte to be read.
   *
   *Returns CR_OK upon successful completion, an error code
   *otherwise.
   */
  enum CRStatus
  cr_input_get_cur_index (CRInput * a_this, glong * a_index)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this)
                                && a_index, CR_BAD_PARAM_ERROR);
  
          *a_index = PRIVATE (a_this)->next_byte_index;
  
          return CR_OK;
  }
  
  /**
   * cr_input_set_cur_index:
   *@a_this: the "this pointer" of the current instance
   *of #CRInput .
   *@a_index: the new index to set.
   *
   *Setter of the next byte index.
   *It sets the index of the next byte to be read.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_set_cur_index (CRInput * a_this, glong a_index)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          PRIVATE (a_this)->next_byte_index = a_index;
  
          return CR_OK;
  }
  
  /**
   * cr_input_set_end_of_file:
   *@a_this: the current instance of #CRInput.
   *@a_eof: the new end of file flag.
   *
   *Sets the end of file flag.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_set_end_of_file (CRInput * a_this, gboolean a_eof)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          PRIVATE (a_this)->end_of_input = a_eof;
  
          return CR_OK;
  }
  
  /**
   * cr_input_get_end_of_file:
   *@a_this: the current instance of #CRInput.
   *@a_eof: out parameter the place to put the end of
   *file flag.
   *
   *Gets the end of file flag.
   *
   *Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_get_end_of_file (CRInput * a_this, gboolean * a_eof)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this)
                                && a_eof, CR_BAD_PARAM_ERROR);
  
          *a_eof = PRIVATE (a_this)->end_of_input;
  
          return CR_OK;
  }
  
  /**
   * cr_input_set_end_of_line:
   *@a_this: the current instance of #CRInput.
   *@a_eol: the new end of line flag.
   *
   *Sets the end of line flag.
   *
   *Returns CR_OK upon successful completion, an error code
   *otherwise.
   */
  enum CRStatus
  cr_input_set_end_of_line (CRInput * a_this, gboolean a_eol)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this), CR_BAD_PARAM_ERROR);
  
          PRIVATE (a_this)->end_of_line = a_eol;
  
          return CR_OK;
  }
  
  /**
   * cr_input_get_end_of_line:
   *@a_this: the current instance of #CRInput
   *@a_eol: out parameter. The place to put
   *the returned flag
   *
   *Gets the end of line flag of the current input.
   *
   *Returns CR_OK upon successful completion, an error code
   *otherwise.
   */
  enum CRStatus
  cr_input_get_end_of_line (CRInput * a_this, gboolean * a_eol)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this)
                                && a_eol, CR_BAD_PARAM_ERROR);
  
          *a_eol = PRIVATE (a_this)->end_of_line;
  
          return CR_OK;
  }
  
  /**
   * cr_input_set_cur_pos:
   *@a_this: the "this pointer" of the current instance of
   *#CRInput.
   *@a_pos: the new position.
   *
   *Sets the current position in the input stream.
   *
   * Returns CR_OK upon successful completion, an error code otherwise.
   */
  enum CRStatus
  cr_input_set_cur_pos (CRInput * a_this, CRInputPos * a_pos)
  {
          g_return_val_if_fail (a_this && PRIVATE (a_this) && a_pos,
                                CR_BAD_PARAM_ERROR);
  
          cr_input_set_column_num (a_this, a_pos->col);
          cr_input_set_line_num (a_this, a_pos->line);
          cr_input_set_cur_index (a_this, a_pos->next_byte_index);
          cr_input_set_end_of_line (a_this, a_pos->end_of_line);
          cr_input_set_end_of_file (a_this, a_pos->end_of_file);
  
          return CR_OK;
  }
  