Module: SerialPacketModule

Included in:
SerialPacket
Defined in:
lib/serial_packet.rb

Overview

SerialPacket is used to define the format of Packets that can be sent and received over a serial link

they are essentially a description how to create a string representation from an array

a packet has the following properties:

data_format(string)
   this is a string that is passed to 'pack' and 'unpack'

header_format(string)   
   this is the format of the header of received packets
   this property is used with SerialPacket.matches?

header_data
   an array that is used to decide if a given String is

Class Method Summary collapse

Class Method Details

.included(other) ⇒ Object 



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# File 'lib/serial_packet.rb', line 25

def self.included(other)
  other.class_eval do 

    def initialize_from_packet(str)
      self.data = str.unpack(self.class.data_format)      
    end
    
    def initialize(*d)
      self.data = d
    end

    def to_str
      self.class.header_str << self.data.pack(self.class.data_format)
    end
    
    class << self

      # a packet can only be sent if it has a header
      #
      def sendable?
        (self.header && self.header_format) ? true : false
      end

      def header_str
        if sendable?
          h = self.header || []
          h.pack(self.header_format) || ""
        else
          ""
        end
      end
      
      # a packet can only be received, if it has a filter-expression
      def receiveable?
        defined? header_format and header_filter
      end

      # checks if some string conforms to the format of this packet
      #
      # this is tested by matching the packet "header" against the 
      # provided filter-expression
      #
      def matches?(str)
        header = str.unpack(header_format)
        filter = self.header_filter || []
        filter.zip(header) { |f,a| return false unless f === a }
        return true
      end

      def from_str(str) #:nodoc:
        p = self.allocate
        p.initialize_from_packet(str)
        p
      end

      def create(&block)
        klass = Class.new(self)
        klass.instance_eval(&block) if block
        return klass    
      end
    end
  end
end