hashmap.h: compare function has access to a data field

When using the hashmap a common need is to have access to caller provided
data in the compare function. A couple of times we abuse the keydata field
to pass in the data needed. This happens for example in patch-ids.c.

This patch changes the function signature of the compare function
to have one more void pointer available. The pointer given for each
invocation of the compare function must be defined in the init function
of the hashmap and is just passed through.

Documentation of this new feature is deferred to a later patch.
This is a rather mechanical conversion, just adding the new pass-through
parameter.  However while at it improve the naming of the fields of all
compare functions used by hashmaps by ensuring unused parameters are
prefixed with 'unused_' and naming the parameters what they are (instead
of 'unused' make it 'unused_keydata').

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 12 insertions, 7 deletions

diff --git a/t/helper/test-hashmap.c b/t/helper/test-hashmap.c
index 7aa9440..095d739 100644
--- a/t/helper/test-hashmap.c
+++ b/t/helper/test-hashmap.c
@@ -13,14 +13,18 @@ static const char *get_value(const struct test_entry *e)
 	return e->key + strlen(e->key) + 1;
 }
 
-static int test_entry_cmp(const struct test_entry *e1,
-		const struct test_entry *e2, const char* key)
+static int test_entry_cmp(const void *unused_cmp_data,
+			  const struct test_entry *e1,
+			  const struct test_entry *e2,
+			  const char* key)
 {
 	return strcmp(e1->key, key ? key : e2->key);
 }
 
-static int test_entry_cmp_icase(const struct test_entry *e1,
-		const struct test_entry *e2, const char* key)
+static int test_entry_cmp_icase(const void *unused_cmp_data,
+				const struct test_entry *e1,
+				const struct test_entry *e2,
+				const char* key)
 {
 	return strcasecmp(e1->key, key ? key : e2->key);
 }
@@ -92,7 +96,8 @@ static void perf_hashmap(unsigned int method, unsigned int rounds)
 	if (method & TEST_ADD) {
 		/* test adding to the map */
 		for (j = 0; j < rounds; j++) {
-			hashmap_init(&map, (hashmap_cmp_fn) test_entry_cmp, 0);
+			hashmap_init(&map, (hashmap_cmp_fn) test_entry_cmp,
+				     NULL, 0);
 
 			/* add entries */
 			for (i = 0; i < TEST_SIZE; i++) {
@@ -104,7 +109,7 @@ static void perf_hashmap(unsigned int method, unsigned int rounds)
 		}
 	} else {
 		/* test map lookups */
-		hashmap_init(&map, (hashmap_cmp_fn) test_entry_cmp, 0);
+		hashmap_init(&map, (hashmap_cmp_fn) test_entry_cmp, NULL, 0);
 
 		/* fill the map (sparsely if specified) */
 		j = (method & TEST_SPARSE) ? TEST_SIZE / 10 : TEST_SIZE;
@@ -147,7 +152,7 @@ int cmd_main(int argc, const char **argv)
 	/* init hash map */
 	icase = argc > 1 && !strcmp("ignorecase", argv[1]);
 	hashmap_init(&map, (hashmap_cmp_fn) (icase ? test_entry_cmp_icase
-			: test_entry_cmp), 0);
+			: test_entry_cmp), NULL, 0);
 
 	/* process commands from stdin */
 	while (fgets(line, sizeof(line), stdin)) {