X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/20eb516fdebd2fb901e6a09ffa7e741cfb8e3a83..1ecb4530757072f552439ee4798929b3a4a6b89d:/darray.h

diff --git a/darray.h b/darray.h
index b8f17eb..a768c1d 100644
--- a/darray.h
+++ b/darray.h
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: darray.h,v 1.5 2000/06/17 10:37:39 mdw Exp $
+ * $Id: darray.h,v 1.7 2004/04/08 01:36:11 mdw Exp $
  *
  * Dynamically growing dense arrays
  *
@@ -27,26 +27,6 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: darray.h,v $
- * Revision 1.5  2000/06/17 10:37:39  mdw
- * Add support for arena management.
- *
- * Revision 1.4  1999/12/10 23:42:04  mdw
- * Change header file guard names.
- *
- * Revision 1.3  1999/11/05 14:32:43  mdw
- * Minor change in argument naming.
- *
- * Revision 1.2  1999/10/29 22:59:22  mdw
- * New array adjustment macros for unsigned arguments.
- *
- * Revision 1.1  1999/10/22 22:37:26  mdw
- * New dynamic array implementation replaces `dynarray.h'.
- *
- */
-
 #ifndef MLIB_DARRAY_H
 #define MLIB_DARRAY_H
 
@@ -410,6 +390,26 @@ typedef struct da_base {
 
 /*----- Stack-like operations ---------------------------------------------*/
 
+/* --- @DA_FIRST@ --- *
+ *
+ * Arguments:	@a@ = pointer to an array block (multiply evaluated)
+ *
+ * Use:		Evaluates to the initial element in array @a@.  It is unsafe
+ *		to do this if the array is empty.  The array is not changed. 
+ */
+
+#define DA_FIRST(a) (DA(a)[0])
+
+/* --- @DA_LAST@ --- *
+ *
+ * Arguments:	@a@ = pointer to an array block (multiply evaluated)
+ *
+ * Use:		Evaluates to the final element in array @a@.  It is unsafe
+ *		to do this if the array is empty.  The array is not changed.
+ */
+
+#define DA_LAST(a) (DA(a)[(a)->b.len - 1])
+
 /* --- @DA_PUSH@ --- *
  *
  * Arguments:	@a@ = pointer to an array block (multiply evaluated)
@@ -462,7 +462,7 @@ typedef struct da_base {
  */
 
 #define DA_SHIFT(a) 							\
-  ((a)->b.len ? ((void)0) : THROW(DAEXC_UFLOW),			\
+  ((a)->b.len ? ((void)0) : THROW(DAEXC_UFLOW),				\
    (a)->b.len--,							\
    (a)->b.sz--,								\
    (a)->b.off++,							\