testsfx.c

后缀数存储算法

/*
 * example using the suffix tree library
 *
 * this example shows both how to store a new entry and how to retrieve it
 * usage: testsfx -i file.sft INDEX data
 *        to store a new entry (file.sft will be created or appended if
 *                              already existing)
 *        INDEX is the key and has to be upper case here as the sfxdisk.h
 *        only has upper case characters in the SThashtable
 *
 *        testsfx -l file.sft INDEX
 *        to retrieve the data
 *
 *        testsfx -d file.sfx INDEX data
 *        to delete the INDEX/data pair
 */

#include <stdio.h>
#include <stdlib.h>

#include "sfxdisk.h"

enum
{
  ACT_INSERT, ACT_READ, ACT_DELETE
};


int main(int argc, char *argv[])
{
  STFile *fichier;
  int action;
  offset_t pos;
  char *data = NULL;
  int tdata;


  if (argc < 3)
  {
    fprintf(stderr, "syntax: %s [-i][-l][-d] datafile.sft key [data]\n",
            argv[0]);
    return(1);
  }
  if (strcmp(argv[1], "-l") == 0)
    action = ACT_READ;
  else if (strcmp(argv[1], "-i") == 0)
    action = ACT_INSERT;
  else if (strcmp(argv[1], "-d") == 0)
    action = ACT_DELETE;
  else
  {
    fprintf(stderr, "unknown command\n");
    return(1);
  }

  switch (action)
  {
    case ACT_READ:
      if ((fichier = STopen(argv[2], ST_RDONLY)) == NULL)
      {
        perror(argv[2]);
        return(1);
      }
      /*
       * first step now that we have the file descriptor is to look for
       * the key with the STlookup() function, argv[3] being our key.
       * we retrieve the starting position, that will be necessary to read
       * our data with STreaddata, in pos
       * if STlookup() fails, it returns 0
       */
      if (!STlookup(fichier, argv[3], &pos))
      {
        return(2);
      }
      /*
       * each data node is linked, STreaddata() returns the position to the
       * next node, or -1 is at the end
       * data will be malloc()'d (realloc()'d actually) and tdata contains
       * the size of the retrieved data. data must be set to NULL before
       * calling the function (realloc() is used).
       */
      do
      {
	pos = STreaddata(fichier, pos, (void *)&data, &tdata);
        printf("%s\n", data);
      }
      while (pos != -1);
      break;

    case ACT_INSERT:
      if ((fichier = STopen(argv[2], ST_RDWRITE)) == NULL)
      {
	perror(argv[2]);
	return(1);
      }
      /*
       * now we insert with argv[3] as the key, argv[4] as data and the length
       * of the string as 4th argument
       */
      STinsert(fichier, argv[3], argv[4], strlen(argv[4]) + 1);
      /*
       * as the library uses a custom cache, this function has to be called
       * otherwise the library will be corrupted
       */
      STclose(fichier);
      break;

    case ACT_DELETE:
      if ((fichier = STopen(argv[2], ST_RDWRITE)) == NULL)
      {
	perror(argv[2]);
	return(1);
      }
      if (!STlookup(fichier, argv[3], &pos))
      {
        return(2);
      }
      do
      {
	pos = STreaddata(fichier, pos, (void *)&data, &tdata);
        if (strcmp(data, argv[4]) == 0)
          STdelete(fichier);
      }
      while (pos != -1);
      STclose(fichier);
      break;
  }

  return(0);
}