7.1 Matching newlines with the . subpattern

By default the dot subpattern . matches any character but newlines; to enable newline matching we have to enable the s flag using the special subpattern ‘(?<flags>)’ or ‘(?<flags>:<re>)’, where <flags> is a sequence of characters, one character for each flag, and <re> is a regexp subpattern. Notice that the parentheses in (?:) are non–capturing.

So let’s consider the text ciao\nhello:

• The regexp ciao.hello does not match because s is disabled.
• The regexp (?s)ciao.hello matches because the subpattern (?s) has enabled flag s for the rest of the pattern, including the dot.
• The regexp ciao(?s).hello matches because the subpattern (?s) has enabled flag s for the rest of the pattern, including the dot.
• The regexp ciao(?s:.)hello matches because the subpattern (?s:.) has enabled flag s for the subpattern . which is the dot.

This document describes version 0.4.0-devel.2 of CRE2.