Module: Gecode::Constraints::IntEnum::Element::AdditionalEnumMethods

Included in:
FixnumEnumMethods, IntEnumMethods
Defined in:
lib/gecoder/interface/constraints/int_enum/element.rb

Overview

Methods needed to add support for element constraints to enums.

Class Method Summary collapse

Class Method Details

.included(enum_mod) ⇒ Object

This adds the adder for the methods in the modules including it. The reason for doing it so indirect is that the first #[] won’t be defined before the module that this is mixed into is mixed into an enum.



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# File 'lib/gecoder/interface/constraints/int_enum/element.rb', line 43

def self.included(enum_mod)
  enum_mod.module_eval do
    # Now we enter the module AdditionalEnumMethods is mixed into.
    class << self
      alias_method :pre_element_included, :included
      def included(mod)
        mod.module_eval do
          # Now we enter the module that the module possibly defining #[] 
          # is mixed into.
          if instance_methods.include? '[]'
            alias_method :pre_element_access, :[]
          end
        
          def [](*vars)
            # Hook in an element constraint if a variable is used for array 
            # access.
            if vars.first.kind_of? Gecode::FreeIntVar
              params = {:lhs => self, :position => vars.first}
              return Gecode::Constraints::IntEnum::Element::ExpressionStub.new(
                @model, params)
            else
              pre_element_access(*vars) if respond_to? :pre_element_access
            end
          end
        end
        pre_element_included(mod)
      end
    end
  end
end