module Nokogiri::ClassResolver - nokogiri-1.15.2 Documentation

# module Nokogiri::ClassResolver

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.

### Constants

VALID_NAMESPACES

  `related_class` restricts matching namespaces to those matching this set.

### Public Instance Methods

related_class(class_name) → Class click to toggle source

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

    # File lib/nokogiri/class_resolver.rb, line 46
    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