cat-str/join/join-with: allow nested sequences

The measure/allocate/catenate functions which underlie
the cat-str implementation are streamlined, simplifying
the code. At the same time, they handle nested sequences
of string/character items.

* lib.c (struct cat_str): New member, seen_one. This flips
from 0 to 1 after the first item has been seen in the
cat_str_measure pass or cat_str_append pass. Each item
other than the first is preceded by a separator.
(cat_str_measure, cat_str_append): The more_p argument
is dropped. We account for the separator with the help
of the new seen_one flag, which allows us to easily
recurse over items that are sequences.
(cat_str_alloc): Reset the seen_one flag in preparation
for the cat_str_append pass.
(cat_str, vscat, scat2, scat3, join_with): Simplified.

* tests/015/split.tl: New tests.

* txr.1: Redocumented.

0 files changed, 0 insertions, 0 deletions