lighttroupe/luz

# Mixin: EasyDSL simplifies creating Domain Specific Languages.

# Provides class-level methods for defining other class-level methods.
require 'set'

module EasyDSL
    def self.included(base) #:nodoc:
        base.extend(ClassMethods)
    end

    ###################################################################
    # Class-level methods
    ###################################################################

    module ClassMethods
        def dsl_string(*names)
            names.to_a.each { |name|
                self.class_eval <<-end_class_eval
                    def self.#{name}(value = nil)
                        @#{name} = value if value
                        return @#{name} || ''
                    end
                end_class_eval
            }
        end

        def dsl_flag(*names)
            names.to_a.each { |name|
                self.class_eval <<-end_class_eval
                    def self.#{name}(rhs = true)
                        @#{name} = rhs
                    end
                    def self.#{name}?
                        @#{name} || false
                    end
                end_class_eval
            }
        end

        def dsl_set(singular, plural)
            self.class_eval <<-end_class_eval
                def self.#{singular}(value)
                    @#{plural} ||= Set.new    # NOTE: singular form adds to set
                    @#{plural} << value
                    @#{plural}
                end

                def self.#{plural}(*values)
                    @#{plural} = Set.new        # NOTE: plural form clears existing values
                    if values
                        values.each { |v|
                            @#{plural} << v
                        }
                    end
                    @#{plural}
                end

                def self.in_#{singular}?(value)
                    (@#{plural} && @#{plural}.include?(value))
                end
            end_class_eval
        end
    end
end