Add the da_foreach macro

1 files changed, 13 insertions, 1 deletions

diff --git a/da.h b/da.h
index 888ac1a..9bda5df 100644
--- a/da.h
+++ b/da.h
@@ -14,7 +14,9 @@
  * You should include ‘err.h’ and ‘stdlib.h’ along with this file.  If you want
  * to use da_remove(), include ‘string.h’.  The da_remove() macro also doesn’t
  * bother with shrinking your array when the length is far lower than the
- * capacity.  If you care about that, do it yourself.
+ * capacity.  If you care about that, do it yourself.  To use the da_foreach()
+ * macro, you need to have ptrdiff_t defined; to be absolutely sure you can
+ * include ‘stddef.h’.
  *
  * Remember to call free() on your dynamic arrays ‘buf’ field after use.
  *
@@ -27,6 +29,8 @@
  * da_append(a, x)           Append the item ‘x’ to the array
  * da_remove(a, x)           Remove the item ‘x’ from the array
  * da_remove_range(a, x, y)  Remove the items between the range [x, y)
+ * da_foreach(a, t, i)       Iterate the pointer ‘i’ of type ‘t’ over each
+ *                           element of the array.
  *
  * The ‘da_append()’ macro will by default double the arrays capacity when it
  * gets full.  If you would like to use a different growth factor instead of 2,
@@ -50,6 +54,11 @@
  * da_append(&nums, 1337);
  * da_append(&nums, 420);
  *
+ * da_foreach (&nums, int *, n) {
+ *     int x = *n << 1;
+ *     printf("n = %d; n² = %d\n", *n, x);
+ * }
+ *
  * // Remove 1337 and 420 from nums
  * da_remove_range(&nums, 1, 3);
  *
@@ -94,4 +103,7 @@
 		(a)->len -= j - i; \
 	} while (0)
 
+#define da_foreach(a, t, i) \
+	for (t i = (a)->buf; i - (a)->buf < (ptrdiff_t)(a)->len; i++)
+
 #endif /* !MANGO_DA_H */