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($values)) {
print "This animal is a cat or a dog\n";
}tree()
Returns a reference to the root of a tree of Badger::Logic::Node objects that represent the parsed expression.
text()
Returns a text representation of the logic expression.
INTERNAL METHODS
parse($text)
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.
parse_expr($text)
Method to parse a binary expression.
parse_unary($text)
Method to parse a unary expression.
parse_term($text)
Method to parse a single term in a logical expression.
AUTHOR
Andy Wardley http://wardley.org
COPYRIGHT
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.