This will acquire its first user in an upcoming commit.
Signed-off-by: Ben Pfaff <[email protected]>
---
lib/sset.c | 14 ++++++++++++++
lib/sset.h | 3 +++
2 files changed, 17 insertions(+)
diff --git a/lib/sset.c b/lib/sset.c
index 33c4298..f9d4fc0 100644
--- a/lib/sset.c
+++ b/lib/sset.c
@@ -269,6 +269,20 @@ sset_at_position(const struct sset *set, uint32_t
*bucketp, uint32_t *offsetp)
return SSET_NODE_FROM_HMAP_NODE(hmap_node);
}
+/* Replaces 'a' by the intersection of 'a' and 'b'. That is, removes from 'a'
+ * all of the strings that are not also in 'b'. */
+void
+sset_intersect(struct sset *a, const struct sset *b)
+{
+ const char *name, *next;
+
+ SSET_FOR_EACH_SAFE (name, next, a) {
+ if (!sset_contains(b, name)) {
+ sset_delete(a, SSET_NODE_FROM_NAME(name));
+ }
+ }
+}
+
/* Returns a null-terminated array of pointers to the strings in 'set', in no
* particular order. The caller must free the returned array when it is no
* longer needed, but the strings in the array belong to 'set' and thus must
diff --git a/lib/sset.h b/lib/sset.h
index 35bf463..25d9c1c 100644
--- a/lib/sset.h
+++ b/lib/sset.h
@@ -67,6 +67,9 @@ bool sset_equals(const struct sset *, const struct sset *);
struct sset_node *sset_at_position(const struct sset *,
uint32_t *bucketp, uint32_t *offsetp);
+/* Set operations. */
+void sset_intersect(struct sset *, const struct sset *);
+
/* Iteration macros. */
#define SSET_FOR_EACH(NAME, SSET) \
for ((NAME) = SSET_FIRST(SSET); \
--
2.1.3
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