From 05b2717b9ea5e799b268ac1f2ca6c0a413e33434 Mon Sep 17 00:00:00 2001
From: Yuichi Nishiwaki <yuichi.nishiwaki@gmail.com>
Date: Thu, 21 Nov 2013 06:32:56 -0800
Subject: [PATCH] less memory usage of pic_reverse

---
 src/pair.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/pair.c b/src/pair.c
index d3ebc772..c1c78af1 100644
--- a/src/pair.c
+++ b/src/pair.c
@@ -96,10 +96,16 @@ pic_length(pic_state *pic, pic_value obj)
 pic_value
 pic_reverse(pic_state *pic, pic_value list)
 {
-  pic_value v, acc = pic_nil_value();
+  int ai = pic_gc_arena_preserve(pic);
+  pic_value v, acc;
 
+  acc = pic_nil_value();
   for (v = list; ! pic_nil_p(v); v = pic_cdr(pic ,v)) {
     acc = pic_cons(pic, pic_car(pic, v), acc);
+
+    pic_gc_arena_restore(pic, ai);
+    pic_gc_protect(pic, acc);
+    pic_gc_protect(pic, v);
   }
   return acc;
 }