496 lines
12 KiB
C++
Executable File
496 lines
12 KiB
C++
Executable File
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/* INCLUDING HEADER FILES */
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#include "csv_parser.hpp"
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/* BEGIN DEFINITION FOR PUBLIC METHODS */
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bool csv_parser::init(FILE * input_file_pointer)
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{
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input_fp = input_file_pointer;
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if (input_fp == NULL)
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{
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//dprintf("Fatal error : unable to open input file from file pointer\n");
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return false;
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}
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/* Resetting the internal pointer to the beginning of the stream */
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rewind(input_fp);
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more_rows = true;
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_skip_lines();
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return true;
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}
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bool csv_parser::init(const char * input_file)
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{
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const size_t filename_length = strlen(input_file);
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if (!filename_length)
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{
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fprintf(stderr, "Fatal error : invalid input file %s\n", input_file);
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return false;
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}
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input_filename = (char *) malloc(filename_length + 1);
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if (input_filename == NULL)
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{
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//dprintf("Fatal error : unable to allocate memory for file name buffer %s\n", input_file);
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return false;
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}
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memset(input_filename, 0, filename_length + 1);
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strcpy(input_filename, input_file);
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input_fp = fopen(input_file, "r");
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if (input_fp == NULL)
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{
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//dprintf("Fatal error : unable to open input file %s\n", input_file);
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CSV_PARSER_FREE_BUFFER_PTR(input_filename);
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return false;
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}
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more_rows = true;
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_skip_lines();
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return true;
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}
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void csv_parser::set_enclosed_char(char fields_enclosed_by, enclosure_type_t enclosure_mode)
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{
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if (fields_enclosed_by != 0)
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{
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enclosed_char = fields_enclosed_by;
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enclosed_length = 1U;
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enclosure_type = enclosure_mode;
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}
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}
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void csv_parser::set_field_term_char(char fields_terminated_by)
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{
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if (fields_terminated_by != 0)
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{
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field_term_char = fields_terminated_by;
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field_term_length = 1U;
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}
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}
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void csv_parser::set_line_term_char(char lines_terminated_by)
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{
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if (lines_terminated_by != 0)
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{
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line_term_char = lines_terminated_by;
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line_term_length = 1U;
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}
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}
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csv_row csv_parser::get_row(void)
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{
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csv_row current_row;
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/* This will store the length of the buffer */
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unsigned int line_length = 0U;
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/* Character array buffer for the current record */
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char * line = NULL;
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/* Grab one record */
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_read_single_line(&line, &line_length);
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/* Select the most suitable field extractor based on the enclosure length */
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switch(enclosure_type)
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{
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case ENCLOSURE_NONE : /* The fields are not enclosed by any character */
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_get_fields_without_enclosure(¤t_row, line, &line_length);
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break;
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case ENCLOSURE_REQUIRED : /* The fields are enclosed by a character */
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_get_fields_with_enclosure(¤t_row, line, &line_length);
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break;
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case ENCLOSURE_OPTIONAL : /* The fields may or may not be enclosed */
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_get_fields_with_optional_enclosure(¤t_row, line, &line_length);
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break;
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default :
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_get_fields_with_optional_enclosure(¤t_row, line, &line_length);
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break;
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}
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/* Deallocate the current buffer */
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CSV_PARSER_FREE_BUFFER_PTR(line);
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/* Keeps track of how many times this has method has been called */
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record_count++;
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return current_row;
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}
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/* BEGIN DEFINITION FOR PROTECTED METHODS */
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/* BEGIN DEFINITION FOR PRIVATE METHODS */
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void csv_parser::_skip_lines(void)
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{
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/* Just in case the user accidentally sets ignore_num_lines to a negative number */
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unsigned int number_of_lines_to_ignore = abs((int) ignore_num_lines);
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while(has_more_rows() && number_of_lines_to_ignore)
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{
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const csv_row row = get_row();
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number_of_lines_to_ignore--;
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}
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record_count = 0U;
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}
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void csv_parser::_get_fields_without_enclosure(csv_row_ptr row, const char * line, const unsigned int * line_length)
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{
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char * field = NULL;
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if (*line_length > 0)
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{
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field = (char *) malloc(*line_length);
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memset(field, 0, *line_length);
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register unsigned int field_start = 0U;
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register unsigned int field_end = 0U;
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register unsigned int char_pos = 0U;
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while(char_pos < *line_length)
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{
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char curr_char = line[char_pos];
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if (curr_char == field_term_char)
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{
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field_end = char_pos;
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const char * field_starts_at = line + field_start;
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/* Field width must exclude field delimiter characters */
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const unsigned int field_width = field_end - field_start;
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/* Copy exactly field_width bytes from field_starts_at to field */
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memcpy(field, field_starts_at, field_width);
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/* This must be a null-terminated character array */
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field[field_width] = 0x00;
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string field_string_obj = field;
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row->push_back(field_string_obj);
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/* This is the starting point of the next field */
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field_start = char_pos + 1;
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} else if (curr_char == line_term_char)
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{
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field_end = char_pos;
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const char * field_starts_at = line + field_start;
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/* Field width must exclude line terminating characters */
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const unsigned int field_width = field_end - field_start;
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/* Copy exactly field_width bytes from field_starts_at to field */
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memcpy(field, field_starts_at, field_width);
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/* This must be a null-terminated character array */
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field[field_width] = 0x00;
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string field_string_obj = field;
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row->push_back(field_string_obj);
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}
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/* Move to the next character in the current line */
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char_pos++;
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}
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/* Deallocate memory for field buffer */
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CSV_PARSER_FREE_BUFFER_PTR(field);
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}
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}
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void csv_parser::_get_fields_with_enclosure(csv_row_ptr row, const char * line, const unsigned int * line_length)
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{
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char * field = NULL;
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if (*line_length > 0)
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{
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field = (char *) malloc(*line_length);
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memset(field, 0, *line_length);
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register unsigned int current_state = 0U;
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register unsigned int field_start = 0U;
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register unsigned int field_end = 0U;
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register unsigned int char_pos = 0U;
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while(char_pos < *line_length)
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{
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char curr_char = line[char_pos];
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if (curr_char == enclosed_char)
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{
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current_state++;
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/* Lets find out if the enclosure character encountered is
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* a 'real' enclosure character or if it is an embedded character that
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* has been escaped within the field.
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*/
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register char previous_char = 0x00;
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if (char_pos > 0U)
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{
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/* The escaped char will have to be the 2rd or later character. */
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previous_char = line[char_pos - 1];
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if (previous_char == escaped_char)
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{
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--current_state;
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}
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}
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if (current_state == 1U && previous_char != escaped_char)
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{
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/* This marks the beginning of the column */
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field_start = char_pos;
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} else if (current_state == 2U)
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{
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/* We have found the end of the current field */
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field_end = char_pos;
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/* We do not need the enclosure characters */
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const char * field_starts_at = line + field_start + 1U;
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/* Field width must exclude beginning and ending enclosure characters */
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const unsigned int field_width = field_end - field_start - 1U;
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/* Copy exactly field_width bytes from field_starts_at to field */
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memcpy(field, field_starts_at, field_width);
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/* This must be a null-terminated character array */
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field[field_width] = 0x00;
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string field_string_obj = field;
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row->push_back(field_string_obj);
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/* Reset the state to zero value for the next field */
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current_state = 0U;
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}
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}
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/* Move to the next character in the current line */
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char_pos++;
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}
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/* If no enclosures were found in this line, the entire line becomes the only field. */
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if (0 == row->size())
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{
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string entire_line = line;
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row->push_back(entire_line);
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} else if (current_state == 1U)
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{
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/* The beginning enclosure character was found but
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* we could not locate the closing enclosure in the current line
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* So we need to copy the remainder of the line into the last field.
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*/
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/* We do not need the starting enclosure character */
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const char * field_starts_at = line + field_start + 1U;
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/* Field width must exclude beginning characters */
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const unsigned int field_width = *line_length - field_start - 1U;
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/* Copy exactly field_width bytes from field_starts_at to field */
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memcpy(field, field_starts_at, field_width);
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/* This must be a null-terminated character array */
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field[field_width] = 0x00;
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string field_string_obj = field;
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row->push_back(field_string_obj);
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}
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/* Release the buffer for the field */
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CSV_PARSER_FREE_BUFFER_PTR(field);
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}
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}
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void csv_parser::_get_fields_with_optional_enclosure(csv_row_ptr row, const char * line, const unsigned int * line_length)
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{
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char * field = NULL;
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/*
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* How to extract the fields, when the enclosure char is optional.
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*
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* This is very similar to parsing the document without enclosure but with the following conditions.
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*
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* If the beginning char is an enclosure character, adjust the starting position of the string by + 1.
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* If the ending char is an enclosure character, adjust the ending position by -1
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*/
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if (*line_length > 0)
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{
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field = (char *) malloc(*line_length);
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memset(field, 0, *line_length);
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register unsigned int field_start = 0U;
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register unsigned int field_end = 0U;
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register unsigned int char_pos = 0U;
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while(char_pos < *line_length)
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{
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char curr_char = line[char_pos];
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if (curr_char == field_term_char)
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{
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field_end = char_pos;
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const char * field_starts_at = line + field_start;
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/* Field width must exclude field delimiter characters */
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unsigned int field_width = field_end - field_start;
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const char line_first_char = field_starts_at[0];
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const char line_final_char = field_starts_at[field_width - 1];
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/* If the enclosure char is found at either ends of the string */
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unsigned int first_adjustment = (line_first_char == enclosed_char) ? 1U : 0U;
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unsigned int final_adjustment = (line_final_char == enclosed_char) ? 2U : 0U;
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/* We do not want to have any negative or zero field widths */
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field_width = (field_width > 2U) ? (field_width - final_adjustment) : field_width;
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/* Copy exactly field_width bytes from field_starts_at to field */
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memcpy(field, field_starts_at + first_adjustment, field_width);
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/* This must be a null-terminated character array */
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field[field_width] = 0x00;
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string field_string_obj = field;
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row->push_back(field_string_obj);
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/* This is the starting point of the next field */
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field_start = char_pos + 1;
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} else if (curr_char == line_term_char)
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{
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field_end = char_pos;
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const char * field_starts_at = line + field_start;
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/* Field width must exclude line terminating characters */
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unsigned int field_width = field_end - field_start;
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const char line_first_char = field_starts_at[0];
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const char line_final_char = field_starts_at[field_width - 1];
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/* If the enclosure char is found at either ends of the string */
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unsigned int first_adjustment = (line_first_char == enclosed_char) ? 1U : 0U;
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unsigned int final_adjustment = (line_final_char == enclosed_char) ? 2U : 0U;
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/* We do not want to have any negative or zero field widths */
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field_width = (field_width > 2U) ? (field_width - final_adjustment) : field_width;
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/* Copy exactly field_width bytes from field_starts_at to field */
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memcpy(field, field_starts_at + first_adjustment, field_width);
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/* This must be a null-terminated character array */
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field[field_width] = 0x00;
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string field_string_obj = field;
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row->push_back(field_string_obj);
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}
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/* Move to the next character in the current line */
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char_pos++;
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}
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/* Deallocate memory for field buffer */
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CSV_PARSER_FREE_BUFFER_PTR(field);
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}
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}
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void csv_parser::_read_single_line(char ** buffer, unsigned int * buffer_len)
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{
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long int original_pos = ftell(input_fp);
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long int current_pos = original_pos;
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register int current_char = 0;
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/* Checking one character at a time until the end of a line is found */
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while(true)
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{
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current_char = fgetc(input_fp);
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if (current_char == EOF)
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{
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/* We have reached the end of the file */
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more_rows = false;
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break;
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} else if (current_char == line_term_char)
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{
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/* We have reached the end of the row */
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current_pos++;
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break;
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} else {
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current_pos++;
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}
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}
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/* Let's try to peek one character ahead to see if we are at the end of the file */
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if (more_rows)
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{
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current_char = fgetc(input_fp);
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more_rows = (current_char == EOF) ? false : true;
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}
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/* Find out how long this row is */
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const size_t length_of_row = current_pos - original_pos;
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if (length_of_row > 0)
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{
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*buffer_len = length_of_row * sizeof(char) + 1;
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*buffer = (char *) realloc(*buffer, *buffer_len);
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memset(*buffer, 0, *buffer_len);
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/* Reset the internal pointer to the original position */
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fseek(input_fp, original_pos, SEEK_SET);
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/* Copy the contents of the line into the buffer */
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fread(*buffer, 1, length_of_row, input_fp);
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}
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}
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