NAME¶
PPIx::Regexp::Token::Modifier - Represent modifiers.
SYNOPSIS¶
use PPIx::Regexp::Dumper;
PPIx::Regexp::Dumper->new( 'qr{foo}smx' )
->print();
The trailing "smx" will be represented by this class.
This class also represents the whole of things like "(?ismx)". But the
modifiers in something like "(?i:foo)" are represented by a
PPIx::Regexp::Token::GroupType::Modifier.
INHERITANCE¶
"PPIx::Regexp::Token::Modifier" is a PPIx::Regexp::Token.
"PPIx::Regexp::Token::Modifier" is the parent of
PPIx::Regexp::Token::GroupType::Modifier.
DESCRIPTION¶
This class represents modifier characters at the end of the regular expression.
For example, in "qr{foo}smx" this class would represent the terminal
"smx".
The "a", "aa", "d", "l", and "u" modifiers¶
The "a", "aa", "d", "l", and
"u" modifiers, introduced starting in Perl 5.13.6, are used to force
either Unicode pattern semantics ("u"), locale semantics
("l") default semantics ("d" the traditional Perl
semantics, which can also mean 'dual' since it means Unicode if the string's
UTF-8 bit is on, and locale if the UTF-8 bit is off), or restricted default
semantics ("a"). These are mutually exclusive, and only one can be
asserted at a time. Asserting any of these overrides the inherited value of
any of the others. The "asserted()" method reports as asserted the
last one it sees, or none of them if it has seen none.
For example, given "PPIx::Regexp::Token::Modifier" $elem representing
the invalid regular expression fragment "(?dul)",
"$elem->asserted( 'l' )" would return true, but
"$elem->asserted( 'u' )" would return false. Note that
"$elem->negated( 'u' )" would also return false, since
"u" is not explicitly negated.
If $elem represented regular expression fragment "(?i)",
"$elem->asserted( 'd' )" would return false, since even though
"d" represents the default behavior it is not explicitly asserted.
The caret ("^") modifier¶
Calling "^" a modifier is a bit of a misnomer. The "(?^...)"
construction was introduced in Perl 5.13.6, to prevent the inheritance of
modifiers. The documentation calls the caret a shorthand equivalent for
"d-imsx", and that it the way this class handles it.
For example, given "PPIx::Regexp::Token::Modifier" $elem representing
regular expression fragment "(?^i)", "$elem->asserted( 'd'
)" would return true, since in the absence of an explicit "l"
or "u" this class considers the "^" to explicitly assert
"d".
Note that if this is retracted before Perl 5.14 is released, this support
will disappear. See "NOTICE" in PPIx::Regexp for some explanation.
METHODS¶
This class provides the following public methods. Methods not documented here
are private, and unsupported in the sense that the author reserves the right
to change or remove them without notice.
asserts¶
$token->asserts( 'i' ) and print "token asserts i";
foreach ( $token->asserts() ) { print "token asserts $_\n" }
This method returns true if the token explicitly asserts the given modifier. The
example would return true for the modifier in "(?i:foo)", but false
for "(?-i:foo)".
If called without an argument, or with an undef argument, all modifiers
explicitly asserted by this token are returned.
match_semantics¶
my $sem = $token->match_semantics();
defined $sem or $sem = 'undefined';
print "This token has $sem match semantics\n";
This method returns the match semantics asserted by the token, as one of the
strings 'a', 'aa', 'd', 'l', or 'u'. If no explicit match semantics are
asserted, this method returns "undef".
modifiers¶
my %mods = $token->modifiers();
Returns all modifiers asserted or negated by this token, and the values set
(true for asserted, false for negated). If called in scalar context, returns a
reference to a hash containing the values.
negates¶
$token->negates( 'i' ) and print "token negates i\n";
foreach ( $token->negates() ) { print "token negates $_\n" }
This method returns true if the token explicitly negates the given modifier. The
example would return true for the modifier in "(?-i:foo)", but false
for "(?i:foo)".
If called without an argument, or with an undef argument, all modifiers
explicitly negated by this token are returned.
SUPPORT¶
Support is by the author. Please file bug reports at <
http://rt.cpan.org>,
or in electronic mail to the author.
AUTHOR¶
Thomas R. Wyant, III
wyant at cpan dot org
COPYRIGHT AND LICENSE¶
Copyright (C) 2009-2014 by Thomas R. Wyant, III
This program is free software; you can redistribute it and/or modify it under
the same terms as Perl 5.10.0. For more details, see the full text of the
licenses in the directory LICENSES.
This program is distributed in the hope that it will be useful, but without any
warranty; without even the implied warranty of merchantability or fitness for
a particular purpose.