Provide functions to alter range objects.

Ranges continue to be immutable; but a
backdoor is needed for upcoming support for
circular notation.

* lib.c (set_from, set_to): New functions.

* lib.h (set_from, set_to): Declared.

1 files changed, 14 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index c032bde1..46033a21 100644
--- a/lib.c
+++ b/lib.c
@@ -8712,6 +8712,20 @@ val to(val range)
   return range->rn.to;
 }
 
+val set_from(val range, val from)
+{
+  type_check(range, RNG);
+  set(mkloc(range->rn.from, range), from);
+  return range;
+}
+
+val set_to(val range, val to)
+{
+  type_check(range, RNG);
+  set(mkloc(range->rn.to, range), to);
+  return range;
+}
+
 val env(void)
 {
   if (env_list) {