From: Martin Hansen <mail@...>
Date: 2010-04-16T22:13:05+09:00
Subject: Re: Writing a parser

Ah, of cause I am creating record of class Hash and not class Record. 
This does not Err (I wonder if it is sane though):

class Record < Hash
  SEPERATOR = "\n---\n"

  include Enumerable

  def initialize(path=nil)
    @path = path
    @ios  = File.open(@path, 'r') if @path
  end

  # Reads the next 'record' from the I/O stream. The records are 
separated by
  # lines of "---" and each record consists of a varying number of lines 
with
  # a key/value pair separated by ": ". The record is returned as a 
hash.
  def get_record
    block = @ios.gets(SEPERATOR).chomp!(SEPERATOR)

    record = Record.new

    block.each_line do |line|
      fields = line.split(": ")
      raise ArgumentError, "Bad record line: #{line}" if fields.length 
!= 2

      record.add(fields[0],fields[1])
    end

    record
  end

  # Add a key value pair to this record.
  def add(key, value)
    raise ArgumentError, "Bad key contains ': ' or '\n' ->#{key}"     if 
key.match(": |\n")
    raise ArgumentError, "Bad value contains ': ' or '\n' ->#{value}" if 
value.match(": |\n")

    self[key] = value
  end

  # Return the content of this record as a string.
  def to_s
    return nil if empty?
    self.map { | key, val | "#{ key }: #{ val }" }.join( "\n" ) + 
SEPERATOR
  end
end
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