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Versions: 7
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Contents
# frozen_string_literal: true
require_relative 'composite_term'
unless MiniKraken::Core.constants(false).include? :ConsCell
module MiniKraken
module Core
class ConsCell < CompositeTerm
attr_reader :car
attr_reader :cdr
def initialize(obj1, obj2 = nil)
@car = obj1
@cdr = obj2
end
def children
[car, cdr]
end
# Return true if it is an empty list, otherwise false.
# A list is empty, when both car and cdr fields are nil.
def null?
car.nil? && cdr.nil?
end
def ==(other)
return false unless other.respond_to?(:car)
(car == other.car) && (cdr == other.cdr)
end
def eql?(other)
(self.class == other.class) && car.eql?(other.car) && cdr.eql?(other.cdr)
end
def quote(anEnv)
return self if null?
new_car = car.nil? ? nil : car.quote(anEnv)
new_cdr = cdr.nil? ? nil : cdr.quote(anEnv)
ConsCell.new(new_car, new_cdr)
end
def append(another)
@cdr = another
end
end # class
# Constant representing the null (empty) list.
NullList = ConsCell.new(nil, nil).freeze
end # module
end # module
end # defined
Version data entries
7 entries across 7 versions & 1 rubygems