MT940 treetop grammar - (proof of concept)

mt940.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'treetop'
require 'active_support/all'
Treetop.load 'mt940'

parser = MT940Parser.new
parser.parse(':61:foo:86:bar:86:bza:61:baz:61:fogoo').elements.each do |st|
  st.elements.each do |st|
    if st.try(:entry?)
      puts "Statement: #{st.text_value}"
    elsif st.elements.any?
      puts "-> Additions: #{st.elements.map(&:text_value)}"
    end
  end
  puts "--"
end

mt940.treetop

# my_grammar.treetop
grammar MT940
  rule statement
    (entry (additions)* )+
  end

  rule entry
    ':61:' ([a-zA-Z])+ {
      def content
        [:text, text_value]
      end

      def entry?
        true
      end
    }
  end

  rule additions
    ':86:' ([a-zA-Z])+ {
      def entry?
        false
      end
    }
  end
end