Add helper macros for ring walking (APR_RING_FOREACH and APR_RING_FOREACH_SAFE).

git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@555640 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 24 insertions, 0 deletions

diff --git a/include/apr_ring.h b/include/apr_ring.h
index eab1e69a8..a796816dc 100644
--- a/include/apr_ring.h
+++ b/include/apr_ring.h
@@ -377,6 +377,30 @@
 #define APR_RING_REMOVE(ep, link)					\
     APR_RING_UNSPLICE((ep), (ep), link)
 
+/**
+ * Iterate over a ring
+ * @param ep The current element
+ * @param head The head of the ring
+ * @param elem The name of the element struct
+ * @param link The name of the APR_RING_ENTRY in the element struct
+ */
+#define APR_RING_FOREACH(ep, head, elem, link)                          \
+    for (ep = APR_RING_FIRST(head);                                     \
+         ep != APR_RING_SENTINEL(head, elem, link);                     \
+         ep = APR_RING_NEXT(ep, link))
+
+/**
+ * Iterate over a ring safe against removal of the current element
+ * @param ep1 The current element
+ * @param ep2 Iteration cursor
+ * @param head The head of the ring
+ * @param elem The name of the element struct
+ * @param link The name of the APR_RING_ENTRY in the element struct
+ */
+#define APR_RING_FOREACH_SAFE(ep1, ep2, head, elem, link)               \
+    for (ep1 = APR_RING_FIRST(head), ep2 = APR_RING_NEXT(ep1, link);    \
+         ep1 != APR_RING_SENTINEL(head, elem, link);                    \
+         ep1 = ep2, ep2 = APR_RING_NEXT(ep1, link))
 
 /* Debugging tools: */