From: Robert Klemme <shortcutter@...>
Date: 2010-04-16T22:35:42+09:00
Subject: Re: Writing a parser

2010/4/16 Martin Hansen <mail@maasha.dk>:
> 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"

Inheriting from core classes is rarely a good idea.  Basically your
records do not need to be more than Hashes - you just need a proper
implementation of fetching records.

class RecordSource
  include Enumerable

  def self.foreach(file, &b)
    if block_given?
      File.open(file) do |io|
        rs = new(io)
        rs.each_record(&b)
      end
    else
      Enumerator.new(self, :foreach, file)
    end
  end

  def self.open(file)
    File.open(file) do |io|
      yield new(io)
    end
  end

  def initialize(io)
    @io = io
  end

  def each_record
    curr = {}

    @io.each_line do |line|
      case line
      when /^([^:]+):(.*)$/
        curr[$1] = $2
      when /^---$/
        yield curr unless curr.empty?
        curr = {}
      else
        raise "Illegal format: #{line}"
      end
    end

    yield curr unless curr.empty?

    self # conventionally
  end

  alias :each :each_record
end

# usage

RecordSource.open "myfile" do |rs|
  rs.each_record do |rec|
    p rec
  end
end

RecordSource.foreach("myfile") do |rec|
  p rec
end

p RecordSource.foreach("myfile").to_a


Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/