diff options
Diffstat (limited to 'libc/regexp/patch.3')
| -rw-r--r-- | libc/regexp/patch.3 | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/libc/regexp/patch.3 b/libc/regexp/patch.3 new file mode 100644 index 0000000..36bafd4 --- /dev/null +++ b/libc/regexp/patch.3 @@ -0,0 +1,46 @@ +Subject: regexp(3) improvement +Newsgroups: mod.sources +Approved: jpn@panda.UUCP + +Mod.sources: Volume 4, Issue 49 +Submitted by: utzoo!henry (Henry Spencer) + +One flaw of my regexp(3) as distributed is that there is no way to get +a literal `&' or '\n' (n a digit) past regsub(). The V8 manual page +made no mention of an escape convention. It turns out that this is a +deficiency in the documentation rather than the software. Accordingly, +the following update should be applied to my regexp(3) to preserve full +compatibility and to add this useful facility. + +In regsub.c, change the following (line numbers approximate only): + +67,69c67,71 +< if (no < 0) /* Ordinary character. */ +< *dst++ = c; +< else if (prog->startp[no] != NULL && prog->endp[no] != NULL) { +--- +> if (no < 0) { /* Ordinary character. */ +> if (c == '\\' && (*src == '\\' || *src == '&')) +> c = *src++; +> *dst++ = c; +> } else if (prog->startp[no] != NULL && prog->endp[no] != NULL) { + +In regexp.3, add the following sentence to the end of the paragraph +describing regsub: + +To get a literal `&' or `\e\fIn\fR' into \fIdest\fR, prefix it with `\e'; +to get a literal `\e' preceding `&' or `\e\fIn\fR', prefix it with +another `\e'. + +And add the following two lines to the "tests" file: + +abcd abcd y &-\&-\\& abcd-&-\abcd +a(bc)d abcd y \1-\\1-\\\1 bc-\1-\bc + +My thanks to Mike Lutz at Rochester Institute of Technology for noticing +this issue and alerting me to it. + + Henry Spencer @ U of Toronto Zoology + {allegra,ihnp4,decvax,pyramid}!utzoo!henry + + |