map: introduce map_contains utility function

2 files changed, 8 insertions, 0 deletions

diff --git a/map.c b/map.c
index 9906e42..4e727f4 100644
--- a/map.c
+++ b/map.c
@@ -73,6 +73,11 @@ void *map_closest(const Map *map, const char *prefix)
 	return m->v;
 }
 
+bool map_contains(const Map *map, const char *prefix)
+{
+	return !map_empty(map_prefix(map, prefix));
+}
+
 bool map_put(Map *map, const char *k, const void *value)
 {
 	size_t len = strlen(k);
diff --git a/map.h b/map.h
index ed42393..078c9c6 100644
--- a/map.h
+++ b/map.h
@@ -12,6 +12,9 @@ void *map_get(const Map*, const char *key);
 /* Returns the corresponding value if the given prefix is unique.
  * Otherwise NULL, if no such prefix exists then errno is set to ENOENT. */
 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);
 /* 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);