COMMENT(!MOD!zsh/regex
Interface to the POSIX regex library.
!MOD!)
cindex(regular expressions)
cindex(regex)
The tt(zsh/regex) module makes available the following test condition:

startitem()
findex(regex-match)
item(var(expr) tt(-regex-match) var(regex))(
Matches a string against a POSIX extended regular expression.
On successful match,
matched portion of the string will normally be placed in the tt(MATCH)
variable.  If there are any capturing parentheses within the regex, then
the tt(match) array variable will contain those.
If the match is not successful, then the variables will not be altered.

For example,

example([[ alphabetical -regex-match ^a+LPAR()[^a]PLUS()+RPAR()a+LPAR()[^a]+PLUS()+RPAR()a ]] &&
print -l $MATCH X $match)

If the option tt(REMATCH_PCRE) is not set, then the tt(=~) operator will
automatically load this module as needed and will invoke the
tt(-regex-match) operator.

If tt(BASH_REMATCH) is set, then the array tt(BASH_REMATCH) will be set
instead of tt(MATCH) and tt(match).

Note that the tt(zsh/regex) module logic relies on the host system. The 
same var(expr) and var(regex) pair could produce different results on different
platforms if a var(regex) with non-standard syntax is given.

For example, no syntax for matching a word boundary is defined in the POSIX
extended regular expression standard. GNU tt(libc) and BSD tt(libc) both provide 
such syntaxes as extensions (tt(\b) and tt([[:<:]])/tt([[:>:]]) respectively), 
but neither of these syntaxes is supported by both of these implementations.

Refer to the manref(regcomp)(3) and manref(re_format)(7) manual pages on your
system for locally-supported syntax.
)
enditem()