vector: add a reference iterator foreach loop

For storage of types larger than native types a ref based iterated loop
is handy to avoid copy.

include/vlc_vector.h

@@ -665,7 +665,21 @@ vlc_vector_move_(char *array, size_t index, size_t count, size_t target)
          ++vlc_vector_idx_##item)
 
 /**
- * Returns a reference to the vector's first element.
+ * For-each loop with a reference iterator.
+ *
+ * Should be used for vector holding non-trivially copyable data.
+ *
+ * \param[out] ref The reference iterator
+ * \param[in] pv a pointer to the vector
+ */
+#define vlc_vector_foreach_ref(ref, pv) \
+    for (size_t vlc_vector_idx_##ref = 0; \
+         vlc_vector_idx_##ref < (pv)->size && \
+             ((ref) = &(pv)->data[vlc_vector_idx_##ref], true); \
+         ++vlc_vector_idx_##ref)
+
+/**
+ * Returns the vector's last element.
  */
 #define vlc_vector_last(pv) \
 ( \

src/test/vector.c

@@ -257,6 +257,15 @@ static void test_vector_foreach(void)
     }
     assert(count == 10);
 
+    count = 0;
+    const int *ref;
+    vlc_vector_foreach_ref(ref, &vec)
+    {
+        assert(*ref == count);
+        assert(ref == &vec.data[count]);
+        count++;
+    }
+
     vlc_vector_destroy(&vec);
 }