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   1 #include "config.h"
   2 #include <string.h>
   3 #include <stdio.h>
   4
   5 /**
   6  * htable - hash table routines
   7  *
   8  * A hash table is an efficient structure for looking up keys.  This version
   9  * grows with usage and allows efficient deletion.
  10  *
  11  * Example:
  12  *      #include <ccan/htable/htable.h>
  13  *      #include <ccan/hash/hash.h>
  14  *      #include <stdio.h>
  15  *      #include <err.h>
  16  *      #include <string.h>
  17  *
  18  *      struct name_to_digit {
  19  *              const char *name;
  20  *              unsigned int val;
  21  *      };
  22  *
  23  *      static struct name_to_digit map[] = {
  24  *              { "zero", 0},
  25  *              { "one", 1 },
  26  *              { "two", 2 },
  27  *              { "three", 3 },
  28  *              { "four", 4 },
  29  *              { "five", 5 },
  30  *              { "six", 6 },
  31  *              { "seven", 7 },
  32  *              { "eight", 8 },
  33  *              { "nine", 9 }
  34  *      };
  35  *
  36  *      // Wrapper for rehash function pointer.
  37  *      static size_t rehash(const void *e, void *unused)
  38  *      {
  39  *              (void)unused;
  40  *              return hash_string(((struct name_to_digit *)e)->name);
  41  *      }
  42  *
  43  *      // Comparison function.
  44  *      static bool nameeq(const void *e, void *string)
  45  *      {
  46  *              return strcmp(((struct name_to_digit *)e)->name, string) == 0;
  47  *      }
  48  *
  49  *      // We let them add their own aliases, eg. --alias=v=5
  50  *      static void add_alias(struct htable *ht, const char *alias)
  51  *      {
  52  *              char *eq, *name;
  53  *              struct name_to_digit *n;
  54  *
  55  *              n = malloc(sizeof(*n));
  56  *              n->name = name = strdup(alias);
  57  *
  58  *              eq = strchr(name, '=');
  59  *              if (!eq || ((n->val = atoi(eq+1)) == 0 && !strcmp(eq+1, "0")))
  60  *                      errx(1, "Usage: --alias=<name>=<value>");
  61  *              *eq = '\0';
  62  *              htable_add(ht, hash_string(n->name), n);
  63  *      }
  64  *
  65  *      int main(int argc, char *argv[])
  66  *      {
  67  *              struct htable ht;
  68  *              int i;
  69  *              unsigned long val;
  70  *
  71  *              if (argc < 2)
  72  *                      errx(1, "Usage: %s [--alias=<name>=<val>]... <str>...",
  73  *                           argv[0]);
  74  *
  75  *              // Create and populate hash table.
  76  *              htable_init(&ht, rehash, NULL);
  77  *              for (i = 0; i < (int)(sizeof(map)/sizeof(map[0])); i++)
  78  *                      htable_add(&ht, hash_string(map[i].name), &map[i]);
  79  *
  80  *              // Add any aliases to the hash table.
  81  *              for (i = 1; i < argc; i++) {
  82  *                      if (!strncmp(argv[i], "--alias=", strlen("--alias=")))
  83  *                              add_alias(&ht, argv[i] + strlen("--alias="));
  84  *                      else
  85  *                              break;
  86  *              }
  87  *
  88  *              // Find the other args in the hash table.
  89  *              for (val = 0; i < argc; i++) {
  90  *                      struct name_to_digit *n;
  91  *                      n = htable_get(&ht, hash_string(argv[i]),
  92  *                                     nameeq, argv[i]);
  93  *                      if (!n)
  94  *                              errx(1, "Invalid digit name %s", argv[i]);
  95  *                      // Append it to the value we are building up.
  96  *                      val *= 10;
  97  *                      val += n->val;
  98  *              }
  99  *              printf("%lu\n", val);
 100  *              return 0;
 101  *      }
 102  *
 103  * License: LGPL (v2.1 or any later version)
 104  * Author: Rusty Russell <rusty@rustcorp.com.au>
 105  */
 106 int main(int argc, char *argv[])
 107 {
 108         if (argc != 2)
 109                 return 1;
 110
 111         if (strcmp(argv[1], "depends") == 0) {
 112                 printf("ccan/compiler\n");
 113                 printf("ccan/str\n");
 114                 return 0;
 115         }
 116
 117         return 1;
 118 }