string-finish: new function.

* eval.c (eval_init): Register string-finish intrinsic.

* lib.c (string_finish): New function.

* lib.h (string_finish): Declared.

* txr.1: Documented.

* stdlib/doc-syms.tl: Updated.

1 files changed, 19 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index ee74ff89..cdfb5742 100644
--- a/lib.c
+++ b/lib.c
@@ -4843,6 +4843,25 @@ val string_extend(val str, val tail, val finish_in)
   return str;
 }
 
+val string_finish(val str)
+{
+  val self = lit("string-finish");
+  type_check(self, str, STR);
+
+  {
+    cnum len = c_fixnum(length_str(str), self);
+    cnum alloc = c_fixnum(str->st.alloc, self);
+
+    if (alloc > len + 1) {
+      alloc = len + 1;
+      str->st.str = chk_wrealloc(str->st.str, alloc);
+      set(mkloc(str->st.alloc, str), num_fast(alloc));
+    }
+  }
+
+  return str;
+}
+
 val stringp(val str)
 {
   switch (type(str)) {