item_extractors.rb in html2rss-0.10.0

- old
+ new
@@ -1,23 +1,88 @@
+# frozen_string_literal: true
+
 module Html2rss
   ##
   # Provides a namespace for item extractors.
   module ItemExtractors
-    DEFAULT = 'text'.freeze
-    private_constant :DEFAULT
+    ##
+    # The Error class to be thrown when an unknown extractor name is requested.
+    class UnknownExtractorName < StandardError; end
 
-    def self.get_extractor(name)
-      @get_extractor ||= Hash.new do |extractors, key|
-        extractors[key] = Utils.get_class_from_name(key || DEFAULT, 'ItemExtractors')
-      end
+    ##
+    # Maps the extractor name to the class implementing the extractor.
+    #
+    # The key is the name to use in the feed config.
+    NAME_TO_CLASS = {
+      attribute: Attribute,
+      href: Href,
+      html: Html,
+      static: Static,
+      text: Text
+    }.freeze
 
-      @get_extractor[name]
+    ##
+    # Maps the extractor class to its corresponding options class.
+    ITEM_OPTION_CLASSES = Hash.new do |hash, klass|
+      hash[klass] = klass.const_get(:Options)
     end
 
+    DEFAULT_EXTRACTOR = :text
+
     ##
-    # @return [Nokogiri::XML::Element]
-    def self.element(xml, options)
-      selector = options[:selector]
+    # Retrieves an element from Nokogiri XML based on the selector.
+    #
+    # @param xml [Nokogiri::XML::Document]
+    # @param selector [String, nil]
+    # @return [Nokogiri::XML::ElementSet] selected XML elements
+    def self.element(xml, selector)
       selector ? xml.css(selector) : xml
+    end
+
+    ##
+    # Creates an instance of the requested item extractor.
+    #
+    # @param attribute_options [Hash<Symbol, Object>]
+    #   Should contain at least `:extractor` (the name) and required options for that extractor.
+    # @param xml [Nokogiri::XML::Document]
+    # @return [Object] instance of the specified item extractor class
+    def self.item_extractor_factory(attribute_options, xml)
+      extractor_name = attribute_options[:extractor]&.to_sym || DEFAULT_EXTRACTOR
+      extractor_class = find_extractor_class(extractor_name)
+      options_instance = build_options_instance(extractor_class, attribute_options)
+      create_extractor_instance(extractor_class, xml, options_instance)
+    end
+
+    ##
+    # Finds the extractor class based on the name.
+    #
+    # @param extractor_name [Symbol] the name of the extractor
+    # @return [Class] the class implementing the extractor
+    # @raise [UnknownExtractorName] if the extractor class is not found
+    def self.find_extractor_class(extractor_name)
+      NAME_TO_CLASS[extractor_name] || raise(UnknownExtractorName,
+                                             "Unknown extractor name '#{extractor_name}' requested in NAME_TO_CLASS")
+    end
+
+    ##
+    # Builds the options instance for the extractor class.
+    #
+    # @param extractor_class [Class] the class implementing the extractor
+    # @param attribute_options [Hash<Symbol, Object>] the attribute options
+    # @return [Object] an instance of the options class for the extractor
+    def self.build_options_instance(extractor_class, attribute_options)
+      options = attribute_options.slice(*extractor_class::Options.members)
+      ITEM_OPTION_CLASSES[extractor_class].new(options)
+    end
+
+    ##
+    # Creates an instance of the extractor class.
+    #
+    # @param extractor_class [Class] the class implementing the extractor
+    # @param xml [Nokogiri::XML::Document] the XML document
+    # @param options_instance [Object] the options instance
+    # @return [Object] an instance of the extractor class
+    def self.create_extractor_instance(extractor_class, xml, options_instance)
+      extractor_class.new(xml, options_instance)
     end
   end
 end