vis

commit cc2fd27b88a22dd31ea13f644160df4b8f28d477
parent 72a801898acdc01ff1a9189c29ee1fed4d50b269
Author: Marc André Tanner <mat@brain-dump.org>
Date:   Thu, 15 Dec 2016 20:21:27 +0100

map: add map_leaf utility function

Tests whether the given prefix can be extended to exactly one map element
i.e. true iff the prefix map contains exactly one element.

Diffstat:
M
map.c
 | 
13
+++++++++++++
M
map.h
 | 
3
+++

2 files changed, 16 insertions(+), 0 deletions(-)
diff --git a/map.c b/map.c
@@ -78,6 +78,19 @@ bool map_contains(const Map *map, const char *prefix)
 	return !map_empty(map_prefix(map, prefix));
 }
 
+static bool leaf(const char *key, void *value, void *data)
+{
+	int *nodes = data;
+	return (*nodes)++ < 1;
+}
+
+bool map_leaf(const Map *map, const char *prefix)
+{
+	int nodes = 0;
+	map_iterate(map_prefix(map, prefix), leaf, &nodes);
+	return nodes == 1;
+}
+
 bool map_put(Map *map, const char *k, const void *value)
 {
 	size_t len = strlen(k);
diff --git a/map.h b/map.h
@@ -17,6 +17,9 @@ void *map_closest(const Map*, const char *prefix);
 /* check whether the map contains the given prefix, i.e. whether it can
  * be extended to match a key of an element stored in the map. */
 bool map_contains(const Map*, const char *prefix);
+/* Test whether the given prefix can be extended to exactly one map element
+ * i.e. true iff the prefix map contains exactly one element. */
+bool map_leaf(const Map*, const char *prefix);
 /* Place a member in the map. This returns false if we run out of memory
  * (errno = ENOMEM), or if that key already appears in the map (errno = EEXIST). */
 bool map_put(Map*, const char *key, const void *value);