10-14-2010
Well, if you dislike but must apply the three regex in sequence, you might try this simple heurism: Put the three regex in as list, and apply them in the current order; if one misses, removing a line from contention, move it to the top of the list if not already, sliding the others down. For instance, consider c e q as three regex. The q will reject more lines than c, usually, and the e less, but by letting the best rejecters float to the top, you save a lot of second and third regex searches.
I have a name for this, but it is not politically correct, something about how a dictator selects a military commander -- death at first failure. It came to me one day as a text editor took very long to find instances of 'equal': it did a character scan and for every first character, it stopped and did a sting compare, tragically missing the filtering power of q. If I searched for 'qual', it was quick (Borland Sprint on I386 dos emulation under UNIX SVR3).
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LEARN ABOUT DEBIAN
re_comp
RE_COMP(3) Linux Programmer's Manual RE_COMP(3)
NAME
re_comp, re_exec - BSD regex functions
SYNOPSIS
#define _REGEX_RE_COMP
#include <sys/types.h>
#include <regex.h>
char *re_comp(char *regex);
int re_exec(char *string);
DESCRIPTION
re_comp() is used to compile the null-terminated regular expression pointed to by regex. The compiled pattern occupies a static area, the
pattern buffer, which is overwritten by subsequent use of re_comp(). If regex is NULL, no operation is performed and the pattern buffer's
contents are not altered.
re_exec() is used to assess whether the null-terminated string pointed to by string matches the previously compiled regex.
RETURN VALUE
re_comp() returns NULL on successful compilation of regex otherwise it returns a pointer to an appropriate error message.
re_exec() returns 1 for a successful match, zero for failure.
CONFORMING TO
4.3BSD.
NOTES
These functions are obsolete; the functions documented in regcomp(3) should be used instead.
SEE ALSO
regcomp(3), regex(7), GNU regex manual
COLOPHON
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU
1995-07-14 RE_COMP(3)