ccan/ccan/hashtable/_info

#include <string.h>

/**
 * hashtable - hash table routines
 *
 * A hash table is an efficient structure for looking up keys.  This version
 * grows with usage and allows efficient deletion.
 *
 * Caveat: pointers placed into the hash must be aligned to 64 bits.
 * ie. from malloc or because the structure they point to is aligned.
 * An assert will be raised if this isn't true.
 *
 * Example:
 *	#include <ccan/hashtable/hashtable.h>
 *	#include <ccan/hash/hash.h>
 *	#include <stdio.h>
 *	#include <err.h>
 *	#include <string.h>
 *	
 *	struct name_to_digit {
 *		const char *name;
 *		unsigned int val;
 *	};
 *	
 *	static struct name_to_digit map[] = { 
 *		{ "zero", 0},
 *		{ "one", 1 },
 *		{ "two", 2 },
 *		{ "three", 3 },
 *		{ "four", 4 },
 *		{ "five", 5 },
 *		{ "six", 6 },
 *		{ "seven", 7 },
 *		{ "eight", 8 },
 *		{ "nine", 9 }
 *	};
 *	
 *	// Wrapper for rehash function pointer.
 *	static unsigned long rehash(const void *e, void *unused)
 *	{
 *		return hash_string(((struct name_to_digit *)e)->name);
 *	}
 *	
 *	// Comparison function.
 *	static bool streq(const void *e, void *string)
 *	{
 *		return strcmp(((struct name_to_digit *)e)->name, string) == 0;
 *	}
 *	
 *	// We let them add their own aliases, eg. --alias=v=5
 *	static void add_alias(struct hashtable *ht, const char *alias)
 *	{
 *		char *eq;
 *		struct name_to_digit *n;
 *	
 *		n = malloc(sizeof(*n));
 *		n->name = strdup(alias);
 *	
 *		eq = strchr(n->name, '=');
 *		if (!eq || ((n->val = atoi(eq+1)) == 0 && !strcmp(eq+1, "0")))
 *			errx(1, "Usage: --alias=<name>=<value>");
 *		*eq = '\0';
 *		hashtable_add(ht, hash_string(n->name), n);
 *	}
 *	
 *	int main(int argc, char *argv[])
 *	{
 *		struct hashtable *ht;
 *		unsigned int i;
 *		unsigned long val;
 *	
 *		if (argc < 2)
 *			errx(1, "Usage: %s [--alias=<name>=<val>]... <str>...",
 *			     argv[0]);
 *	
 *		// Create and populate hash table.
 *		ht = hashtable_new(rehash, NULL);
 *		for (i = 0; i < sizeof(map)/sizeof(map[0]); i++)
 *			hashtable_add(ht, hash_string(map[i].name), &map[i]);
 *	
 *		// Add any aliases to the hash table.
 *		for (i = 1; i < argc; i++) {
 *			if (!strncmp(argv[i], "--alias=", strlen("--alias=")))
 *				add_alias(ht, argv[i] + strlen("--alias="));
 *			else
 *				break;
 *		}
 *	
 *		// Find the other args in the hash table.
 *		for (val = 0; i < argc; i++) {
 *			struct name_to_digit *n;
 *			n = hashtable_find(ht, hash_string(argv[i]),
 *					   streq, argv[i]);
 *			if (!n)
 *				errx(1, "Invalid digit name %s", argv[i]);
 *			// Append it to the value we are building up.
 *			val *= 10;
 *			val += n->val;
 *		}
 *		printf("%lu\n", val);
 *		return 0;
 *	}
 *
 * Licence: GPLv2 (or later)
 */
int main(int argc, char *argv[])
{
	if (argc != 2)
		return 1;

	if (strcmp(argv[1], "depends") == 0) {
		return 0;
	}

	return 1;
}