JSON to S-Expressions

j2sexp.rb

#!/usr/bin/env ruby

# The following script translates a JSON file into S-Expressions. I wrote this after I learned about
# attempts to use Scheme as the lingua franca of Web in the early 90s. Someone told me S-Expressions
# are bascilly XML and well, he's right.
# You can either pass a JSON file as the first argument, or pipe it via STDIN. The translated S-Expression
# data will be written to STDOUT. A regular session would look like:
#     cat my_file.json | ruby j2sexp.rb > my_file.sexp
# What is the use of this program? Well, basically, consider this: It's much easier to parse S-Expressions
# that it is to parse JSON. There, I don't need any further explanations!

require 'json'

input_file = ARGV[0]

unless input_file
   json_data = STDIN.read
else
   json_data = File.read(input_file)
end

parsed_data = JSON.parse(json_data)

def to_sexp_integer(integer)
  print "(:integer: #{integer})"
end

def to_sexp_float(float)
  print "(:float: #{float})"
end

def to_sexp_string(string)
  print "(:string: #{string})"
end

def to_sexp_array(array)
    print "(:array: "
    array.each do |element|
      print " "
      to_sexp_element element
      print " "
    end
    print ")"
end

def to_sexp_hash(hash)
  print "[:hash: "
  hash.each do |key, value|
    print "(:key::#{key}:)"
    print " "
    print "(:value: "
    to_sexp_element value
    print ")"
  end
  print "]\n"
end

def to_sexp_element(element)
  if element.is_a?(Hash)
    to_sexp_hash element
  elsif element.is_a?(Array)
    to_sexp_array element
  elsif element.is_a?(Integer)
    to_sexp_integer element
  elsif element.is_a?(Float)
    to_sexp_float element
  elsif element.is_a?(String)
    to_sexp_string element
  else
    print "()"
  end
end


to_sexp_hash(parsed_data)