parser: use faster, unsafe nreverse.

* lib.c (us_nreverse): New function.

* lib.h (us_nreverse): Declared.

* parser.y (clauses_opt, n_exprs, r_exprs): Use us_nreverse
instead of nreverse to rorder lists built in reverse into
final shape.

1 files changed, 14 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index c288c8fc..4883f37d 100644
--- a/lib.c
+++ b/lib.c
@@ -1349,6 +1349,20 @@ val reverse(val seq_in)
   }
 }
 
+val us_nreverse(val in)
+{
+  val rev = nil;
+
+  while (in) {
+    val temp = us_cdr(in);
+    us_rplacd(in, rev);
+    rev = in;
+    in = temp;
+  }
+
+  return rev;
+}
+
 val append2(val list1, val list2)
 {
   list_collect_decl (out, ptail);