Add swap function for maps

3 files changed, 77 insertions, 0 deletions

diff --git a/collections/map/map.adoc b/collections/map/map.adoc
index c42a99a..740df3c 100644
--- a/collections/map/map.adoc
+++ b/collections/map/map.adoc
@@ -119,6 +119,32 @@ assert(strcmp(tmp, "FOUR") == 0);
 free(tmp);
 ----
 
+[[map_swap]]
++void map_swap(map *self, void *i, void *j)+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Swaps values at keys +i+ and +j+, does nothing if +i+ or +j+ are invalid keys.
+
+Examples
+^^^^^^^^
+[source,c]
+----
+#include "map.h"
+#include <string.h>
+
+char *str1 = "ONE";
+char *str2 = "TWO";
+
+map *dict = map_new((cmp_func) strcmp);
+
+map_insert(dict, str1, strdup(str2));
+map_insert(dict, str2, strdup(str3));
+
+map_swap(dict, str1, str2);
+
+assert(strcmp(str1, map_index(dict, str1)) == 0);
+assert(strcmp(str2, map_index(dict, str2)) == 0);
+----
+
 [[map_set_val]]
 +void* map_set_val(map *self, void *key, void *val)+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/collections/map/map.c b/collections/map/map.c
index 5ad0b65..b0e095e 100644
--- a/collections/map/map.c
+++ b/collections/map/map.c
@@ -497,6 +497,55 @@ void *key;
 	return ret;
 }
 
+void map_swap(root, ikey, jkey)
+map *root;
+void *ikey, *jkey;
+{
+	struct map_node *tmp, *inode, *jnode;
+	void *tmp_val;
+	int cmp;
+
+	tmp = root->root;
+
+searchi:
+	if (!tmp)
+		return;
+
+	cmp = root->cmp(ikey, tmp->key);
+	if (cmp < 0) {
+		tmp = tmp->left;
+		goto searchi;
+	}
+	if (cmp > 0) {
+		tmp = tmp->right;
+		goto searchi;
+	}
+
+	inode = tmp;
+
+	tmp = root->root;
+searchj:
+	if (!tmp)
+		return;
+
+	cmp = root->cmp(jkey, tmp->key);
+	if (cmp < 0) {
+		tmp = tmp->left;
+		goto searchj;
+	}
+	if (cmp > 0) {
+		tmp = tmp->right;
+		goto searchj;
+	}
+
+	jnode = tmp;
+	tmp_val = jnode->val;
+	jnode->val = inode->val;
+	inode->val = tmp_val;
+
+	return;
+}
+
 void map_clear_aux(root)
 struct map_node *root;
 {
diff --git a/collections/map/map.h b/collections/map/map.h
index 81718c1..c6fb83d 100644
--- a/collections/map/map.h
+++ b/collections/map/map.h
@@ -17,6 +17,8 @@ void* map_remove(map*, void*);
 void* map_set_val(map*, void*, void*);
 void* map_index(map*, void*);
 
+void map_swap(map*, void*, void*);
+
 int map_check_key_ptr(map*, void*);
 void* map_set_key(map*, void*);