Fix 2011-12-03 regression. The freeform directive code

relies on lazy_str_get_trailing_list and the behavior
of that function changed because (split-str "" any-separator)
changed from returning nil to returning the empty string.
The resulting behavior change of lazy_str_get_trailing_list was later
described in the documentation, thereby codifying it.

This patch changes the lazy_str_get_trailing_list behavior,
which is poor, and causes infinite looping. We do not want
an extra empty string prepended, because it looks like
a spurious line.

* lib.c (lazy_str_get_trailing_list): if split_str produces
a the list (""), then just return the unmaterialized list from
the lazy string without prepending that one-element list to it.

* txr.1: Updated documentation for lazy-str-get-trailing-list.

1 files changed, 3 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index 0b107c93..d121177a 100644
--- a/lib.c
+++ b/lib.c
@@ -4987,6 +4987,9 @@ val lazy_str_get_trailing_list(val lstr, val index)
     val split_suffix = split_str(sub_str(lstr->ls.prefix, index, nil),
                                  or2(car(lstr->ls.opts), lit("\n")));
 
+    if (!cdr(split_suffix) && equal(car(split_suffix), null_string))
+      return lstr->ls.list;
+
     return nappend2(split_suffix, lstr->ls.list);
   }
 }