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Andy Wardley >
Badger >
Badger::Logic

Badger::Logic - parse and evaluate simple logical expressions

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"; }

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.

This is a shortcut alias to `Badger::Logic`

.

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

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);

Constructor method to create a new `Badger::Logic`

object from an expression.

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

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"; }

Returns a reference to the root of a tree of `Badger::Logic::Node`

objects that represent the parsed expression.

Returns a text representation of the logic expression.

Main method to parse a logical expression. This calls parse_expr() and then checks that all of the text has been successfully parsed. It returns a reference to a `Badger::Logic::Node`

object.

Method to parse a binary expression.

Method to parse a unary expression.

Method to parse a single term in a logical expression.

Andy Wardley http://wardley.org

Copyright (C) 2007-2009 Andy Wardley. All Rights Reserved.

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

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