> * Yitzchak Scott-Thoennes <[EMAIL PROTECTED]> [2004-01-17 21:04:50 -0800]: > > On Thu, Jan 15, 2004 at 03:14:57PM -0500, Sam Steingold <[EMAIL PROTECTED]> wrote: >> the cygwin regex is not POSIX. >> backrefs are not available by default (apparently you need REG_BACKR for >> that), "(a|)*" cannot be compiled because of "empty (sub)expression", >> &c &c. > > SUSv3 says: > A vertical-line appearing first or last in an ERE, or immediately > following a vertical-line or a left-parenthesis, or immediately > preceding a right-parenthesis, produces undefined results.
Thanks, you are right, complaint is withdrawn. > Also, it says backrefs part of basic regular expressions but not > exteneded ones. From your mention of | I assume you are using > REG_EXTENDED. If REG_EXTENDED|REG_BACKR allows backrefs, it doesn't > appear to be documented. I am not sure what you mean here. I would like to interpret your words as follows, so that I can agree with you: <http://www.opengroup.org/onlinepubs/007904975/basedefs/xbd_chap09.html> does not mention REG_BACKR, so it's mere presence can probably be contrued as a violation of the standard (unless it is enabled whenever REG_EXTENDED is). REG_BACKR is also not mentioned in "man regex", so it is not documented. Right? Now, whether I add REG_BACKR to cflags (together with REG_EXTENDED) or eflags, I do not get back references: "^(x)+\\1$" does not match "xx" (should be "xx" for whole and "x" for the group). Finally, a common extension appears to be the use or "?" after a repetition specification to mean non-greedy matching, e.g. "a+?" will match only the first "a" in "aaaa". -- Sam Steingold (http://www.podval.org/~sds) running w2k <http://www.camera.org> <http://www.iris.org.il> <http://www.memri.org/> <http://www.mideasttruth.com/> <http://www.honestreporting.com> When C++ is your hammer, everything looks like a thumb. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
