File Coverage

blib/lib/PPIx/Regexp/Token/Operator.pm

Criterion	Covered	Total	%
statement	42	48	87.5
branch	10	14	71.4
condition	4	5	80.0
subroutine	11	13	84.6
pod	2	2	100.0
total	69	82	84.1

=head1 NAME

PPIx::Regexp::Token::Operator - Represent an operator.

=head1 SYNOPSIS

 use PPIx::Regexp::Dumper;
 PPIx::Regexp::Dumper->new( 'qr{foo|bar}smx' )
     ->print();

=head1 INHERITANCE

C is a
L.

C has no descendants.

=head1 DESCRIPTION

This class represents an operator. In a character class, it represents
the negation (C<^>) and range (C<->) operators. Outside a character
class, it represents the alternation (C<|>) operator.

=head1 METHODS

This class provides no public methods beyond those provided by its
superclass.

=cut

package PPIx::Regexp::Token::Operator;

use strict;
use warnings;

use base qw{ PPIx::Regexp::Token };

use PPIx::Regexp::Constant qw{
    COOKIE_CLASS COOKIE_REGEX_SET
    LITERAL_LEFT_CURLY_ALLOWED
    TOKEN_LITERAL
    @CARP_NOT
};
use PPIx::Regexp::Util qw{ __instance };

our $VERSION = '0.087';

use constant TOKENIZER_ARGUMENT_REQUIRED => 1;

sub __new {
    my ( $class, $content, %arg ) = @_;

    my $self = $class->SUPER::__new( $content, %arg )
	or return;

    $self->{operation} = $self->_compute_operation_name(
	$arg{tokenizer} ) || 'unknown';

    return $self;
}

# Return true if the token can be quantified, and false otherwise
# sub can_be_quantified { return };

sub explain {
    my ( $self ) = @_;
    my $expl = ucfirst "$self->{operation} operator";
    $expl =~ s/ _ / /smxg;
    return $expl;
}

=head2 operation

This method returns the name of the operation performed by the operator.
This depends not only on the operator itself but its context:

=over

=item In a bracketed character class

    '-' => 'range',
    '^' => 'inversion',

=item In an extended bracketed character class

    '&' => 'intersection',
    '+' => 'union',
    '|' => 'union',
    '-' => 'subtraction',
    '^' => 'symmetric_difference',
    '!' => 'complement',

=item Outside any sort of bracketed character class

    '|' => 'alternation',

=back

=cut

sub operation {
    my ( $self ) = @_;
    return $self->{operation};
}

# These will be intercepted by PPIx::Regexp::Token::Literal if they are
# really literals, so here we may process them unconditionally.

# Note that if we receive a '-' we unconditionally make it an operator,
# relying on the lexer to turn it back into a literal if necessary.

my %operator = map { $_ => 1 } qw{ | - };

sub _treat_as_literal {
    my ( $token ) = @_;
    return __instance( $token, 'PPIx::Regexp::Token::Literal' ) ||
	__instance( $token, 'PPIx::Regexp::Token::Interpolation' );
}

{

    my %operation = (
	COOKIE_CLASS()	=> {
	    '-'	=> 'range',
	    '^'	=> 'inversion',
	},
	COOKIE_REGEX_SET()		=> {
	    '&'	=> 'intersection',
	    '+'	=> 'union',
	    '|'	=> 'union',
	    '-'	=> 'subtraction',
	    '^'	=> 'symmetric_difference',
	    '!'	=> 'complement',
	},
	''	=> {
	    '|'	=> 'alternation',
	},
    );

    sub _compute_operation_name {
	my ( $self, $tokenizer ) = @_;

	my $content = $self->content();

	if ( $tokenizer->cookie( COOKIE_CLASS ) ) {
	    return $operation{ COOKIE_CLASS() }{$content};
	} elsif ( $tokenizer->cookie( COOKIE_REGEX_SET ) ) {
	    return $operation{ COOKIE_REGEX_SET() }{$content};
	} else {
	    return $operation{''}{$content};
	}
    }

}

{
    my $removed_in = {
	'|'	=> LITERAL_LEFT_CURLY_ALLOWED,	# Allowed after alternation
    };

    sub __following_literal_left_curly_disallowed_in {
	my ( $self ) = @_;
	my $content = $self->content();
	exists $removed_in->{$content}
	    and return $removed_in->{$content};
	return $self->SUPER::__following_literal_left_curly_disallowed_in();
    }
}

sub __PPIX_TOKENIZER__regexp {
    my ( undef, $tokenizer, $character ) = @_;

    # We only receive the '-' if we are inside a character class. But it
    # is only an operator if it is preceded and followed by literals. We
    # can use prior() because there are no insignificant tokens inside a
    # character class.
    if ( $character eq '-' ) {

	_treat_as_literal( $tokenizer->prior_significant_token() )
	    or return $tokenizer->make_token( 1, TOKEN_LITERAL );

	my @tokens = ( $tokenizer->make_token( 1 ) );
	push @tokens, $tokenizer->get_token();

	_treat_as_literal( $tokens[1] )
	    or TOKEN_LITERAL->__PPIX_ELEM__rebless( $tokens[0] );

	return ( @tokens );
    }

    return $operator{$character};
}

1;

__END__