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# frozen_string_literal: true
require 'singleton' # Use the Singleton design pattern
require_relative 'builtin_datatype'
module Loxxy
module Datatype
# Class for representing a Lox nil "value".
class Nil < BuiltinDatatype
include Singleton # Make a singleton class
# Build the sole instance
def initialize
super(nil)
end
# Check the equality with another object.
# @param other [Datatype::BuiltinDatatype, NilClass, Object]
# @return [Datatype::Boolean]
def ==(other)
is_nil = other.kind_of?(Nil) || other.kind_of?(NilClass)
is_nil ? True.instance : False.instance
end
# Is the value considered falsey in Lox?
# Rule: false and nil are falsey and everything else is truthy.
# This test used in conditional statements (i.e. if, while)
def falsey?
true
end
# Is the value considered truthy in Lox?
# Rule: false and nil are falsey and everything else is truthy.
# This test used in conditional statements (i.e. if, while)
def truthy?
false
end
# Method called from Lox to obtain the text representation of nil.
# @return [String]
def to_str
'nil'
end
end # class
Nil.instance.freeze # Make the sole instance immutable
end # module
end # module
Version data entries
50 entries across 50 versions & 1 rubygems