Implement @singleton also as BooleanTag subclass.

require "jsduck/builtins/tag"

require "jsduck/builtins/boolean_tag"

module JsDuck::Builtins

  class Singleton < Tag

  class Singleton < BooleanTag

    def initialize

      @pattern = "singleton"

      @key = :singleton

      @ext_define_pattern = "singleton"

    end

    # @singleton

    def parse(p)

      p.add_tag(:singleton)

      super

    end

    def parse_ext_define(cls, ast)

        :mixins => detect_list(:mixins, doc_map),

        :alternateClassNames => detect_list(:alternateClassNames, doc_map),

        :aliases => detect_aliases(doc_map),

        :singleton => !!doc_map[:singleton],

        :requires => detect_list(:requires, doc_map),

        :uses => detect_list(:uses, doc_map),

        :enum => detect_enum(doc_map),