smap: New macro SMAP_CONST1 for initializing immutable 1-member smaps.

[cascardo/ovs.git] / lib / smap.h

diff --git a/lib/smap.h b/lib/smap.h
index 846e384..3bfbb71 100644 (file)
--- a/lib/smap.h
+++ b/lib/smap.h
@@ -39,6 +39,25 @@ struct smap_node {
 #define SMAP_FOR_EACH_SAFE(SMAP_NODE, NEXT, SMAP) \
     HMAP_FOR_EACH_SAFE (SMAP_NODE, NEXT, node, &(SMAP)->map)
 
+/* Initializer for an immutable struct smap 'SMAP' that contains a single
+ * 'KEY'-'VALUE' pair, e.g.
+ *
+ *     const struct smap smap = SMAP1_CONST1(&smap, "key", "value");
+ *
+ * An smap initialized this way must not be modified or destroyed.
+ *
+ * The 'KEY' argument is evaluated multiple times.
+ */
+#define SMAP_CONST1(SMAP, KEY, VALUE) {                                 \
+        HMAP_CONST1(&(SMAP)->map,                                       \
+                   (&(struct smap_node) SMAP_NODE_INIT(KEY, VALUE).node)) \
+            }
+#define SMAP_NODE_INIT(KEY, VALUE) {                \
+        HMAP_NODE_INIT(hash_string(KEY, 0)),        \
+                       CONST_CAST(char *, KEY),     \
+                       CONST_CAST(char *, VALUE) }
+
+
 void smap_init(struct smap *);
 void smap_destroy(struct smap *);