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hashmap: adjust documentation to reflect reality

The hashmap API is just complicated enough that even at least one
long-time Git contributor has to look up how to use it every time he
finds a new use case. When that happens, it is really useful if the
provided example code is correct...

While at it, "fix a memory leak", avoid statements before variable
declarations, fix a const -> no-const cast, several %l specifiers (which
want to be %ld), avoid using an undefined constant, call scanf()
correctly, use FLEX_ALLOC_STR() where appropriate, and adjust the style
here and there.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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dscho committed Nov 29, 2017
1 parent 81ab034 commit 5d5baf91824ec7750b103c8b7c4827ffac202feb
Showing with 29 additions and 31 deletions.
  1. +29 −31 hashmap.h
@@ -18,82 +18,80 @@
*
* #define COMPARE_VALUE 1
*
* static int long2string_cmp(const struct long2string *e1,
* static int long2string_cmp(const void *hashmap_cmp_fn_data,
* const struct long2string *e1,
* const struct long2string *e2,
* const void *keydata, const void *userdata)
* const void *keydata)
* {
* char *string = keydata;
* unsigned *flags = (unsigned*)userdata;
* const char *string = keydata;
* unsigned flags = *(unsigned *)hashmap_cmp_fn_data;
*
* if (flags & COMPARE_VALUE)
* return !(e1->key == e2->key) || (keydata ?
* strcmp(e1->value, keydata) : strcmp(e1->value, e2->value));
* return e1->key != e2->key ||
* strcmp(e1->value, string ? string : e2->value);
* else
* return !(e1->key == e2->key);
* return e1->key != e2->key;
* }
*
* int main(int argc, char **argv)
* {
* long key;
* char *value, *action;
*
* unsigned flags = ALLOW_DUPLICATE_KEYS;
* char value[255], action[32];
* unsigned flags = 0;
*
* hashmap_init(&map, (hashmap_cmp_fn) long2string_cmp, &flags, 0);
*
* while (scanf("%s %l %s", action, key, value)) {
* while (scanf("%s %ld %s", action, &key, value)) {
*
* if (!strcmp("add", action)) {
* struct long2string *e;
* e = malloc(sizeof(struct long2string) + strlen(value));
* FLEX_ALLOC_STR(e, value, value);
* hashmap_entry_init(e, memhash(&key, sizeof(long)));
* e->key = key;
* memcpy(e->value, value, strlen(value));
* hashmap_add(&map, e);
* }
*
* if (!strcmp("print_all_by_key", action)) {
* flags &= ~COMPARE_VALUE;
*
* struct long2string k;
* struct long2string k, *e;
* hashmap_entry_init(&k, memhash(&key, sizeof(long)));
* k.key = key;
*
* struct long2string *e = hashmap_get(&map, &k, NULL);
* flags &= ~COMPARE_VALUE;
* e = hashmap_get(&map, &k, NULL);
* if (e) {
* printf("first: %l %s\n", e->key, e->value);
* while (e = hashmap_get_next(&map, e))
* printf("found more: %l %s\n", e->key, e->value);
* printf("first: %ld %s\n", e->key, e->value);
* while ((e = hashmap_get_next(&map, e)))
* printf("found more: %ld %s\n", e->key, e->value);
* }
* }
*
* if (!strcmp("has_exact_match", action)) {
* flags |= COMPARE_VALUE;
*
* struct long2string *e;
* e = malloc(sizeof(struct long2string) + strlen(value));
* FLEX_ALLOC_STR(e, value, value);
* hashmap_entry_init(e, memhash(&key, sizeof(long)));
* e->key = key;
* memcpy(e->value, value, strlen(value));
*
* printf("%s found\n", hashmap_get(&map, e, NULL) ? "" : "not");
* flags |= COMPARE_VALUE;
* printf("%sfound\n", hashmap_get(&map, e, NULL) ? "" : "not ");
* free(e);
* }
*
* if (!strcmp("has_exact_match_no_heap_alloc", action)) {
* flags |= COMPARE_VALUE;
*
* struct long2string e;
* hashmap_entry_init(e, memhash(&key, sizeof(long)));
* e.key = key;
* struct long2string k;
* hashmap_entry_init(&k, memhash(&key, sizeof(long)));
* k.key = key;
*
* printf("%s found\n", hashmap_get(&map, e, value) ? "" : "not");
* flags |= COMPARE_VALUE;
* printf("%sfound\n", hashmap_get(&map, &k, value) ? "" : "not ");
* }
*
* if (!strcmp("end", action)) {
* hashmap_free(&map, 1);
* break;
* }
* }
*
* return 0;
* }
*/

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