regex: new function, regex-prefix-match.

This new function allows a program to determine whether a
given string is the prefix of any of the strings denoted by a
regular expression; or, in alternative words, whether a given
string is the prefix of a possibly longer string which matches
a regular expression.

* regex.c (regex_machine_infer_init_state): New static
function.
(regex_prefix_match): New function.
(regex_init): regex-prefix-match intrinsic registered.

regex.h (regex_prefix_match): Declared.

* txr.1: Documented.

1 files changed, 1 insertions, 0 deletions

diff --git a/regex.h b/regex.h
index 77375454..3ad158ba 100644
--- a/regex.h
+++ b/regex.h
@@ -42,6 +42,7 @@ val match_regex_right(val str, val regex, val end);
 val search_regst(val haystack, val needle_regex, val start_num, val from_end);
 val match_regst(val str, val regex, val pos);
 val match_regst_right(val str, val regex, val end);
+val regex_prefix_match(val reg, val str, val pos);
 val regsub(val regex, val repl, val str);
 val read_until_match(val regex, val stream, val keep_match);
 val regex_match_full(val regex, val arg1, val arg2);