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# coding: utf-8
# frozen_string_literal: true
require "set"
module Nokogiri
#
# Some classes in Nokogiri are namespaced as a group, for example
# Document, DocumentFragment, and Builder.
#
# It's sometimes necessary to look up the related class, e.g.:
#
# XML::Builder → XML::Document
# HTML4::Builder → HTML4::Document
# HTML5::Document → HTML5::DocumentFragment
#
# This module is included into those key classes who need to do this.
#
module ClassResolver
# #related_class restricts matching namespaces to those matching this set.
VALID_NAMESPACES = Set.new(["HTML", "HTML4", "HTML5", "XML", "SAX"])
# :call-seq:
# related_class(class_name) → Class
#
# Find a class constant within the
#
# Some examples:
#
# Nokogiri::XML::Document.new.related_class("DocumentFragment")
# # => Nokogiri::XML::DocumentFragment
# Nokogiri::HTML4::Document.new.related_class("DocumentFragment")
# # => Nokogiri::HTML4::DocumentFragment
#
# Note this will also work for subclasses that follow the same convention, e.g.:
#
# Loofah::HTML::Document.new.related_class("DocumentFragment")
# # => Loofah::HTML::DocumentFragment
#
# And even if it's a subclass, this will iterate through the superclasses:
#
# class ThisIsATopLevelClass < Nokogiri::HTML4::Builder ; end
# ThisIsATopLevelClass.new.related_class("Document")
# # => Nokogiri::HTML4::Document
#
def related_class(class_name)
klass = nil
inspecting = self.class
while inspecting
namespace_path = inspecting.name.split("::")[0..-2]
inspecting = inspecting.superclass
next unless VALID_NAMESPACES.include?(namespace_path.last)
related_class_name = (namespace_path << class_name).join("::")
klass = begin
Object.const_get(related_class_name)
rescue NameError
nil
end
break if klass
end
klass
end
end
end
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