NAME

Badger::Logic - parse and evaluate simple logical expressions

SYNOPSIS

    use Badger::Logic 'Logic';
    my $logic  = Logic('animal and (eats_nuts or eats_berries)');
    my $values = {
        animal    => 1,
        eats_nuts => 1,
    }
    if ($logic->test($values)) {
        print "This is an animal that eats nuts or berries\n";
    }

DESCRIPTION

This module implements a simple parser and evaluator for boolean logic expressions. It evolved from a piece of code that I originally wrote to handle role-based authentication in web applications.

EXPORTABLE SUBROUTINES

LOGIC

This is a shortcut alias to "Badger::Logic".

    use Badger::Logic 'LOGIC';
    my $logic = LOGIC->new($expr);      # same as Badger::Logic->new($expr);

Logic()

This subroutine returns the name of the "Badger::Logic" class when called without arguments. Thus it can be used as an alias for "Badger::Logic" as per LOGIC.

    use Badger::Logic 'Logic';
    my $logic = Logic->new($expr);      # same as Badger::Logic->new($expr);

When called with arguments, it creates a new "Badger::Logic" object.

    my $logic = Logic($expr);           # same as Badger::Logic->new($expr);

METHODS

new($expr)

Constructor method to create a new "Badger::Logic" object from an expression.

    my $logic = Badger::Logic->new('animal and (cat or dog)');

evaluate($values) / test($values)

Method to evaluate the expression. A reference to a hash array should be passed containing the values that the expression can test.

    my $values = {
        animal => 1,
        cat    => 1,
    };
    if ($logic->evaluate($values)) {
        print "This animal is a cat or a dog\n";
    }

tree()

Returns a reference to the root of a tree of "Badger::Logic::Node" objects that represent the parsed expression.

text()

Returns a text representation of the logic expression.

INTERNAL METHODS

AUTHOR

Andy Wardley <http://wardley.org>

COPYRIGHT

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.