class Regexp::Syntax::Base

def added_features
  @added_features ||= {}
end

def excludes(type, tokens)
  tokens.each { |tok| features[type].delete(tok) }
  removed_features[type] = tokens
end

def implementations(type)
  features[type] || []
end

def implements(type, tokens)
  (features[type] ||= []).concat(tokens)
  added_features[type] = tokens
end

def implements!(type, token)
  raise NotImplementedError.new(self, type, token) unless
    implements?(type, token)
end

def implements?(type, token)
  implementations(type).include?(token)
end

def inherited(subclass)
  super
  subclass.features = features.to_h.map { |k, v| [k, v.dup] }.to_h
end

def initialize
  warn 'Using instances of Regexp::Parser::Syntax is deprecated ' \
       "and will no longer be supported in v3.0.0."
end

def method_missing(name, *args)
  if self.class.respond_to?(name)
    warn 'Using instances of Regexp::Parser::Syntax is deprecated ' \
         "and will no longer be supported in v3.0.0. Please call "\
         "methods on the class directly, e.g.: #{self.class}.#{name}"
    self.class.send(name, *args)
  else
    super
  end
end

def normalize(type, token)
  case type
  when :group
    normalize_group(type, token)
  when :backref
    normalize_backref(type, token)
  else
    [type, token]
  end
end

def normalize_backref(type, token)
  case token
  when :name_ref_ab, :name_ref_sq
    %i[backref name_ref]
  when :name_call_ab, :name_call_sq
    %i[backref name_call]
  when :name_recursion_ref_ab, :name_recursion_ref_sq
    %i[backref name_recursion_ref]
  when :number_ref_ab, :number_ref_sq
    %i[backref number_ref]
  when :number_call_ab, :number_call_sq
    %i[backref number_call]
  when :number_rel_ref_ab, :number_rel_ref_sq
    %i[backref number_rel_ref]
  when :number_rel_call_ab, :number_rel_call_sq
    %i[backref number_rel_call]
  when :number_recursion_ref_ab, :number_recursion_ref_sq
    %i[backref number_recursion_ref]
  else
    [type, token]
  end
end

def normalize_group(type, token)
  case token
  when :named_ab, :named_sq
    %i[group named]
  else
    [type, token]
  end
end

def removed_features
  @removed_features ||= {}
end

def respond_to_missing?(name, include_private = false)
  self.class.respond_to?(name) || super
end