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.

2 files changed, 16 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) {
diff --git a/lib.h b/lib.h
index adf88b3c..9e1405a0 100644
--- a/lib.h
+++ b/lib.h
@@ -971,6 +971,8 @@ val rcons(val from, val to);
 val rangep(val obj);
 val from(val range);
 val to(val range);
+val set_from(val range, val from);
+val set_to(val range, val to);
 val env(void);
 void out_str_char(wchar_t ch, val out, int *semi_flag);
 val obj_print_impl(val obj, val out, val pretty);