ESA match finder with some additional code

main.c

//
// Created by caleb on 6/19/22.
//

#include "esa_matchfinder.h"
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>

long long multi_pass_optimal_parse(const char *buffer, int size) {
  long long total_matches = 0;

  void *mf = esa_matchfinder_create(size, /*min_match_length*/ 2,
                                    /*max_match_length*/ 256);
  if (mf != NULL &&
      esa_matchfinder_parse(mf, buffer, size) == ESA_MATCHFINDER_NO_ERROR) {
    for (int pass = 0; pass < 2; pass += 1) {
      ESA_MATCHFINDER_MATCH matches[ESA_MATCHFINDER_MAX_MATCH_LENGTH];

      esa_matchfinder_rewind(mf, /*position*/ 0);

      ESA_MATCHFINDER_MATCH mt;
      //      int pos = 0;
      for (int position = 0; position < size;) {
        mt = esa_matchfinder_find_best_match(mf);
        if (mt.length != 0) {
          printf("pos=%d \t length=%d \t offset=%d\n", position, mt.length,
                 mt.offset);
        }
        position += 1;
        position += mt.length;

        esa_matchfinder_advance(mf, mt.length);
        //        total_matches += esa_matchfinder_find_all_matches(mf, matches)
        //        - matches;
      }
    }
  }

  esa_matchfinder_destroy(mf);

  return total_matches;
}

typedef struct Buf {
  size_t size;
  char *buf;

} Buf;

Buf open(const char *file_name) {
  char *source = NULL;
  Buf buf;

  FILE *fp = fopen(file_name, "r");
  if (fp != NULL) {
    /* Go to the end of the file. */
    if (fseek(fp, 0L, SEEK_END) == 0) {
      /* Get the size of the file. */
      long bufsize = ftell(fp);

      if (bufsize == -1) { /* Error */
      }

      buf.size = bufsize;

      /* Allocate our buffer to that size. */
      source = malloc(sizeof(char) * (bufsize + 1));

      /* Go back to the start of the file. */
      if (fseek(fp, 0L, SEEK_SET) != 0) { /* Error */
      }

      /* Read the entire file into memory. */
      size_t newLen = fread(source, sizeof(char), bufsize, fp);
      if (ferror(fp) != 0) {
        fputs("Error reading file", stderr);
      } else {
        source[newLen++] = '\0'; /* Just to be safe. */
      }
    }
    fclose(fp);
  }
  buf.buf = source;

  return buf;
}
int main() {
  // Your file HERE.
  Buf buf = open("/home/caleb/Projects/Data/silesia/xml");
  printf("%lld ,", multi_pass_optimal_parse(buf.buf, buf.size));

  free(buf.buf);
}

I try to graps this thing and, therefore, have two questions:

1. Why is there `position += 1;' in line 31? Don't you miss one byte every time you search?
2. Also, in line 34 you advance by `mt.length'. How is that take into account that `esa_matchfinder_find_best_match()' advances by 1 byte on it's own?

Hi, I do not claim the code is 100% accurate, I hacked it in some few minutes to see some statistics for myself
It's probably buggy/error prone

Why is there `position += 1;' in line 31? Don't you miss one byte every time you search?

It was to avoid redundancies when mt didn't find a match, hence it would be 0, notice I'm maintingin my own position variable independent of the esa_matchfinder_advancements, so there was no way of me knowing they advanced

Also, in line 34 you advance by mt.length'. How is that take into account that esa_matchfinder_find_best_match()' advances by 1 byte on it's own?

It is taken into account, by position+=1, the matchfinder advances by 1, we also advance by 1, so they remain in sync, we loose matches at some positions due to this tho