Re: [top-level] C++-friendly allocators for libiberty

[Bernardo Innocenti <bernie@develer.com>]

Falk Hueffner wrote:
> Zack Weinberg <zack@codesourcery.com> writes:
> 
> 
>>Alexandre Oliva <aoliva@redhat.com> writes:
>>
>>
>>>>+#define xcnewvec(T, N)		(T *) xcalloc (N, sizeof (T))
>>>>+#define xresize(T, P, S)	(T *) xrealloc (P, S)
>>>>+#define xresizevec(T, P, N)	(T *) xrealloc (P, sizeof (T) * (N))
>>>>+#define xobnew(O, T)		(T *) obstack_alloc (O, sizeof (T))
>>>
>>>You're missing parentheses around N, P (twice), S and O.
>>
>>They're not actually necessary in this context.
> 
> 
> How about parentheses around the whole cast? Somebody might want to
> write
> 
> &xnew(T)->el
> 
> Not very likely, but IMHO it's not really worth the trouble to try to
> think of every possible or sensible use instead of just adding a bunch
> of parentheses.

Agreed.  This is the full patch again updated with your suggestions
and a proposed fix for the realloc() interface.


include/
2004-06-26  Bernardo Innocenti  <bernie@develer.com>

	* include/libiberty.h (xnew, xcnew, xnewvec, xcnewvec, xobnew): Move
	here from libcpp/internal.h.
	(xdelete, xresizevec, xdeletevec, xnewvar, xcnewvar, xresizevar): New
	macros.

diff -u -p -r1.35 libiberty.h
--- include/libiberty.h	15 May 2003 19:02:12 -0000	1.35
+++ include/libiberty.h	26 Jun 2004 16:35:34 -0000
@@ -250,6 +250,37 @@ extern PTR xmemdup PARAMS ((const PTR, s
 extern double physmem_total PARAMS ((void));
 extern double physmem_available PARAMS ((void));
 
+
+/* These macros provide a K&R/C89/C++-friendly way of allocating structures
+   with nice encapsulation.  The xdelete*() macros are technically
+   superfluous, but provided here for symmetry.  Using them consistently
+   makes it easier to update client code to use different allocators such
+   as new/delete and new[]/delete[].  */
+
+/* Scalar allocators.  */
+
+#define xnew(T)			((T *) xmalloc (sizeof (T)))
+#define xcnew(T)		((T *) xcalloc (1, sizeof (T)))
+#define xdelete(P)		free (P)
+
+/* Array allocators.  */
+
+#define xnewvec(T, N)		((T *) xmalloc (sizeof (T) * (N)))
+#define xcnewvec(T, N)		((T *) xcalloc (N, sizeof (T)))
+#define xresizevec(T, P, N)	((T *) xrealloc (P, sizeof (T) * (N)))
+#define xdeletevec(P)		free (P)
+
+/* Allocators for variable-sized structures and raw buffers.  */
+
+#define xnewvar(T, S)		((T *) xmalloc (S))
+#define xcnewvar(T, S)		((T *) xcalloc (1, S))
+#define xresizevar(T, P, S)	((T *) xrealloc (P, S))
+
+/* Type-safe obstack allocator.  */
+
+#define xobnew(O, T)		((T *) obstack_alloc (O, sizeof (T)))
+
+
 /* hex character manipulation routines */
 
 #define _hex_array_size 256

-- 
  // Bernardo Innocenti - Develer S.r.l., R&D dept.
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