Please consult the manual of Regexp::Common for a general description of the works of this interface.
Do not use this module directly, but load it via Regexp::Common.
"$RE{balanced}{-parens}"
Returns a pattern that matches a string that starts with the nominated opening parenthesis or bracket,
contains characters and properly nested parenthesized subsequences, and ends in the matching parenthesis.
More than one type of parenthesis can be specified:
$RE{balanced}{-parens=>'(){}'}
in which case all specified parenthesis types must be correctly balanced within the string.
Since version 2013030901, $1 will always be set (to the entire matched substring), regardless whether
"{-keep}" is used or not.
"$RE{balanced}{-begin=>"begin"}{-end=>"end"}"
Returns a pattern that matches a string that is properly balanced using the begin and end strings as
start and end delimiters. Multiple sets of begin and end strings can be given by separating them by "|"s
(which can be escaped with a backslash).
qr/$RE{balanced}{-begin => "do|if|case"}{-end => "done|fi|esac"}/
will match properly balanced strings that either start with do and end with done, start with if and end
with fi, or start with case and end with esac.
If -end contains less cases than -begin, the last case of -end is repeated. If it contains more cases
than -begin, the extra cases are ignored. If either of -begin or -end isn't given, or is empty, -begin=>'(' and -end=>')' are assumed.
Since version 2013030901, $1 will always be set (to the entire matched substring), regardless whether
"{-keep}" is used or not.
Note
Since version 2013030901 the pattern will make of the recursive construct "(?-1)", instead of using the
problematic "(??{ })" construct. This fixes an problem that was introduced in the 5.17 development
track.