added parser code, no specs yet

motion/rss_parser.rb

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+# Asynchronous and non blocking RSS Parser based on NSXMLParser.
+# The parser will progressively parse a feed and yield each item to the provided block.
+#
+# The parser can also trigger delegate methods, you can define the following delegate method on the receiving object:
+# def when_parser_initializes; end
+# def when_parser_parses; end
+# def when_parser_is_done; end
+#
+# @see https://developer.apple.com/library/ios/#documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/Reference/Reference.html
+#
+# @usage example:
+#   feed = RSSParser.new(URL)
+#   feed.delegate = self
+#   feed.parse do |item|
+#     print item.link
+#   end
+#   def when_parser_is_done
+#     App.alert('parsing complete')
+#   end
+#
+class RSSParser
+  include BW::KVO
+
+  attr_accessor :parser, :xml_url, :doc, :debug, :state, :delegate
+
+  def initialize(input, data=false)
+    if data
+      data_to_parse = input.respond_to?(:to_data) ? input.to_data : input
+      @parser = NSXMLParser.alloc.initWithData(data_to_parse)
+    else
+      url = NSURL.alloc.initWithString(input)
+      @parser = NSXMLParser.alloc.initWithContentsOfURL(url)
+    end
+    observe(self, 'state') do |old_state, new_state|
+      meth = "when_parser_#{new_state}"
+      if self.delegate && self.delegate.respond_to?(meth)
+        self.delegate.send(meth)
+      end
+    end
+    self.state = :initializes
+    @parser.shouldProcessNamespaces = true
+    @parser.delegate = self
+    self
+  end
+
+  # RSSItem is a simple class that holds all of RSS items.
+  # Extend this class to display/process the item differently.
+  class RSSItem
+    attr_accessor :title, :description, :link, :guid, :pubDate, :enclosure
+    def initialize
+      @title, @description, @link, @pubDate, @guid = '', '', '', '', ''
+    end
+
+    def to_hash
+      {
+        :title        => title,
+        :description  => description,
+        :link         => link,
+        :pubDate      => pubDate,
+        :guid         => guid,
+        :enclosure    => enclosure
+      }
+    end
+  end
+
+  # Starts the parsing and send each parsed item through its block.
+  #
+  # Usage:
+  #   feed.parse do |item|
+  #     puts item.link
+  #   end
+  def parse(&block)
+    @block = block
+    puts "Parsing #{xml_url}" if debug
+    @parser.parse
+  end
+
+  # Delegate getting called when parsing starts
+  def parserDidStartDocument(parser)
+    self.state = :parses
+    puts "starting parsing.." if debug
+  end
+
+  # Delegate being called when an element starts being processed
+  def parser(parser, didStartElement:element, namespaceURI:uri, qualifiedName:name, attributes:attrs)
+    if element == 'item'
+      @current_item = RSSItem.new
+    elsif element == 'enclosure'
+      @current_item.enclosure = attrs
+    end
+    @current_element = element
+  end
+
+  # as the parser finds characters, this method is being called
+  def parser(parser, foundCharacters:string)
+    if @current_item && @current_item.respond_to?(@current_element)
+      el = @current_item.send(@current_element) 
+      el << string if el.respond_to?(:<<)
+    end
+  end
+
+  # method called when an element is done being parsed
+  def parser(parser, didEndElement:element, namespaceURI:uri, qualifiedName:name)
+    if element == 'item'
+      @block.call(@current_item) if @block
+    end
+  end
+
+  # delegate getting called when the parsing is done
+  # If a block was set, it will be called on each parsed items
+  def parserDidEndDocument(parser)
+    self.state = :is_done
+    puts "done parsing" if debug
+  end
+
+end