Class: DMAP::Element

Inherits:
Object
  • Object
show all
Defined in:
lib/dmap.rb

Overview

Represents any DMAP tag and its content. Will have methods appropriate to the dmap specified

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(tag_or_dmap, new_content = nil) ⇒ Element

Accepts a string or an IO. The first four bytes (in either case) should be the tag you wish to make.

If you have a big dmap file this is your lucky day, this class only processes the parts needed for any queries you’re making, so its all on-the-fly.

NB. if you specify ‘content` while passing a dmap tag you will overwrite anything that was in the dmap!



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# File 'lib/dmap.rb', line 23

def initialize(tag_or_dmap,new_content = nil)    
  # Assume we have an IO object, if this fails then we probably have a string instead
  begin
    @tag = tag_or_dmap.read(4)
    @io = tag_or_dmap if new_content.nil?
  rescue NoMethodError
    @tag = tag_or_dmap[0..3]
  end
  
  # Find out the details of this tag
  begin
    @name,type = DMAP::TAGS[@tag.to_sym]
  rescue NameError
    raise NameError, "I don't know how to interpret the tag '#{@tag}'. Please extend the DMAP module!"
  end
  
  self.send("parse_#{type}",new_content)
  fudge = @real_class
  eigenclass = class<<self; self; end
  eigenclass.class_eval do
    extend Forwardable
    def_delegators :@real_class,*fudge.methods - ['__send__','__id__','to_dmap']
    def inspect
      "<#{@tag}: #{@real_class.inspect}>"
    end
  end
end

Instance Attribute Details

#real_class ⇒ Object (readonly)

Returns the value of attribute real_class.



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# File 'lib/dmap.rb', line 13

def real_class
  @real_class
end

#tag ⇒ Object (readonly)

Returns the value of attribute tag.



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# File 'lib/dmap.rb', line 12

def tag
  @tag
end

Instance Method Details

#close_stream ⇒ Object 



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# File 'lib/dmap.rb', line 55

def close_stream
  begin
    @io.close
  rescue NoMethodError
    # There was no IO or its already been closed
  end
end

#is_dmap? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dmap.rb', line 51

def is_dmap?
  true
end

#to_dmap ⇒ Object

Adds the tag to a request to create the dmap



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# File 'lib/dmap.rb', line 64

def to_dmap
  begin
    "#{@tag.downcase}#{@real_class.to_dmap}"
  rescue
    warn("Error while putting #{@tag} to dmap")
    raise
  end
end