lib/ccan/htable/_info

   1 #include <string.h>
   2 #include <stdio.h>
   3
   4 /**
   5  * htable - hash table routines
   6  *
   7  * A hash table is an efficient structure for looking up keys.  This version
   8  * grows with usage and allows efficient deletion.
   9  *
  10  * Example:
  11  *      #include <ccan/htable/htable.h>
  12  *      #include <ccan/hash/hash.h>
  13  *      #include <stdio.h>
  14  *      #include <err.h>
  15  *      #include <string.h>
  16  *
  17  *      struct name_to_digit {
  18  *              const char *name;
  19  *              unsigned int val;
  20  *      };
  21  *
  22  *      static struct name_to_digit map[] = {
  23  *              { "zero", 0},
  24  *              { "one", 1 },
  25  *              { "two", 2 },
  26  *              { "three", 3 },
  27  *              { "four", 4 },
  28  *              { "five", 5 },
  29  *              { "six", 6 },
  30  *              { "seven", 7 },
  31  *              { "eight", 8 },
  32  *              { "nine", 9 }
  33  *      };
  34  *
  35  *      // Wrapper for rehash function pointer.
  36  *      static size_t rehash(const void *e, void *unused)
  37  *      {
  38  *              return hash_string(((struct name_to_digit *)e)->name);
  39  *      }
  40  *
  41  *      // Comparison function.
  42  *      static bool streq(const void *e, void *string)
  43  *      {
  44  *              return strcmp(((struct name_to_digit *)e)->name, string) == 0;
  45  *      }
  46  *
  47  *      // We let them add their own aliases, eg. --alias=v=5
  48  *      static void add_alias(struct htable *ht, const char *alias)
  49  *      {
  50  *              char *eq;
  51  *              struct name_to_digit *n;
  52  *
  53  *              n = malloc(sizeof(*n));
  54  *              n->name = strdup(alias);
  55  *
  56  *              eq = strchr(n->name, '=');
  57  *              if (!eq || ((n->val = atoi(eq+1)) == 0 && !strcmp(eq+1, "0")))
  58  *                      errx(1, "Usage: --alias=<name>=<value>");
  59  *              *eq = '\0';
  60  *              htable_add(ht, hash_string(n->name), n);
  61  *      }
  62  *
  63  *      int main(int argc, char *argv[])
  64  *      {
  65  *              struct htable ht;
  66  *              unsigned int i;
  67  *              unsigned long val;
  68  *
  69  *              if (argc < 2)
  70  *                      errx(1, "Usage: %s [--alias=<name>=<val>]... <str>...",
  71  *                           argv[0]);
  72  *
  73  *              // Create and populate hash table.
  74  *              htable_init(&ht, rehash, NULL);
  75  *              for (i = 0; i < sizeof(map)/sizeof(map[0]); i++)
  76  *                      htable_add(&ht, hash_string(map[i].name), &map[i]);
  77  *
  78  *              // Add any aliases to the hash table.
  79  *              for (i = 1; i < argc; i++) {
  80  *                      if (!strncmp(argv[i], "--alias=", strlen("--alias=")))
  81  *                              add_alias(&ht, argv[i] + strlen("--alias="));
  82  *                      else
  83  *                              break;
  84  *              }
  85  *
  86  *              // Find the other args in the hash table.
  87  *              for (val = 0; i < argc; i++) {
  88  *                      struct name_to_digit *n;
  89  *                      n = htable_get(&ht, hash_string(argv[i]),
  90  *                                     streq, argv[i]);
  91  *                      if (!n)
  92  *                              errx(1, "Invalid digit name %s", argv[i]);
  93  *                      // Append it to the value we are building up.
  94  *                      val *= 10;
  95  *                      val += n->val;
  96  *              }
  97  *              printf("%lu\n", val);
  98  *              return 0;
  99  *      }
 100  *
 101  * License: LGPL (v2.1 or any later version)
 102  * Author: Rusty Russell <rusty@rustcorp.com.au>
 103  */
 104 int main(int argc, char *argv[])
 105 {
 106         if (argc != 2)
 107                 return 1;
 108
 109         if (strcmp(argv[1], "depends") == 0) {
 110                 printf("ccan/compiler\n");
 111                 return 0;
 112         }
 113
 114         return 1;
 115 }