1 files changed, 24 insertions, 0 deletions
diff --git a/src/2geom/utils.h b/src/2geom/utils.h
index bc0ad74b8..3e0dd4717 100644
--- a/src/2geom/utils.h
+++ b/src/2geom/utils.h
@@ -71,6 +71,30 @@ struct NullIterator
     void operator=(T const &v) {}
 };
 
+/** @brief Get the next iterator in the container with wrap-around.
+ * If the iterator would become the end iterator after incrementing,
+ * return the begin iterator instead. */
+template <typename Iter, typename Container>
+Iter cyclic_next(Iter i, Container &c) {
+    ++i;
+    if (i == c.end()) {
+        i = c.begin();
+    }
+    return i;
+}
+
+/** @brief Get the previous iterator in the container with wrap-around.
+ * If the passed iterator is the begin iterator, return the iterator
+ * just before the end iterator instead. */
+template <typename Iter, typename Container>
+Iter cyclic_prior(Iter i, Container &c) {
+    if (i == c.begin()) {
+        i = c.end();
+    }
+    --i;
+    return i;
+}
+
 } // end namespace Geom
 
 #endif // LIB2GEOM_SEEN_UTILS_H