Response to https://gist.github.com/jjbohn/29e17a0df5435047eea8

ruby_parser.rb

class RubyParser
  
  #Creates a hash table as the parser object given a file name.
  def initialize(filename)
    #open the file
    @filename = filename
    toparse = File.open(@filename,"r")
	
	#build the hash table
    @sections = Hash.new
    section = ""
	key = ""
	value = ""
    toparse.each_line {|thisline|
      if thisline.start_with?("[")  
	    # brackets denote a section, so they'll be the highest level of our hash table
        section = thisline.sub("[","")
        section = section.sub("]","")
        section = section.strip
        @sections[section.dup] = Hash.new
      else
	    # first we need to deal with the fact that the value part of key : value pairs can run over multiple lines
		has_key = thisline.match(":")
		if has_key.nil?
		  value = @sections[section.dup][key.dup]
		  @sections[section.dup][key.dup][value.dup] = @sections[section.dup][key.dup][value.dup] + " " + thisline.strip
		else
		  # this line has a key, so we'll add it to our hashtable
          parts = thisline.partition(":")
          key = parts[0]
		  key = key.strip
          value = parts[2]
		  value = value.strip
		  details = Hash[key.dup,value.dup]
  		  if key != ""
		    @sections[section.dup]= @sections[section.dup].merge(details.dup)
		  end
		end
      end
    }
    toparse.close
		
    rescue Exception => e		
      puts "error running #{__method__} : " + e.message
  end

  # Get a string value associated with a given section and key names.
  def get_string_value(section,key)
    if @sections.has_key?(section) && @sections[section].has_key?(key)
      value = String.try_convert(@sections[section][key])
    else
      value = nil
    end  
		
    return value

    rescue Exception => e		
      puts "error running #{__method__} : " + e.message  
  end

  # Get an integer value associated with a given section and key names.
  def get_integer_value(section,key)
    if @sections.has_key?(section) && @sections[section].has_key?(key)
      value = @sections[section][key].to_i
    else
      value = nil
    end  
		
    return value

    rescue Exception => e		
      puts "error running #{__method__} : " + e.message  
  end

  # Get a floating point value associated with a given section and key names.
  def get_float_value(section,key)
    if @sections.has_key?(section) && @sections[section].has_key?(key)
      value = @sections[section][key].to_f
    else
      value = nil
    end  
		
    return value

    rescue Exception => e		
      puts "error running #{__method__} : " + e.message  
  end

  #Writes the information stored in @sections to a new file
  def write_to_file(newfile)
    to_write = File.open(newfile,"w")
    @sections.each{|section,key_values| 
      to_write.write("[#{section}]\r\n")
	  @sections[section].each{|key,value|
        to_write.write("#{key}:#{value}\r\n")
	  }
    }
	to_write.close  
	
    rescue Exception => e
      puts "error running #{__method__} : " + e.message
  end

  #Sets a value (regardless of type) for a given section and key names
  def set_value(section,key,value)
    unless @sections.has_key?(section)
      @sections[section] = Hash.new
    end	
    @sections[section][key] = value
	
    rescue Exception => e
      puts "error running #{__method__} : " + e.message
  end

  # Set a string value for a given section and key names, writing the new file to disk.
  def set_string_value(section,key,value,filename)
    value = String.try_convert(value)
    set_value(section,key,value)
    write_to_file(filename)
    
	rescue Exception => e
      puts "error running #{__method__} : " + e.message
  end
  
  # Set an integer value for a given section and key names, writing the new file to disk.
  def set_integer_value(section,key,value,filename)
    value = value.to_i
    set_value(section,key,value)
    write_to_file(filename)
    
	rescue Exception => e
      puts "error running #{__method__} : " + e.message
  end
  
  # Set a floating point value for a given section and key names, writing the new file to disk.
  def set_float_value(section,key,value,filename)
    value = value.to_f
    set_value(section,key,value)
    write_to_file(filename)
    
	rescue Exception => e
      puts "error running #{__method__} : " + e.message
  end
  

end

# testing functionality
puts "Testing creation of a hash table as the parser object given a file name.\n"
rp = RubyParser.new("testfile.txt")
puts rp.instance_variable_get(:@filename)
puts rp.instance_variable_get(:@sections)
puts "\n"
puts "Getting a string value associated with a given section and key names.\n"
puts rp.get_string_value("trailer","budget")
puts "\n"
puts "Getting integer values associated with a given section and key names.\n"
puts rp.get_integer_value("header","budget")
puts rp.get_integer_value("trailer","budget")
puts "\n"
puts "Getting float values associated with a given section and key names.\n"
puts rp.get_float_value("header","budget")
puts rp.get_float_value("header","accessed")
puts rp.get_float_value("trailer","budget")
puts "\n"
puts "Testing helper functions.\n"
rp.write_to_file("test_one.txt")
rp.set_value("trailer","director","BJW")
puts rp.instance_variable_get(:@sections)
puts "\n"
puts "Testing setting string, integer and floating point values for a given section and name, writing the new file to disc.\n"
rp.set_string_value("trailer","key grip","that guy","test_two.txt")
rp.set_integer_value("trailer","cost",3.14,"test_three.txt")
rp.set_float_value("trailer","gaffer",3.14,"test_four.txt")

testfile.txt

[header]
project: Programming Test
budget : 4.5
accessed :205

[meta data]
description : This is a tediously long description of the Lonely Planet
  programming test that you are taking. Tedious isn't the right word, but
  it's the first word that comes to mind.

correction text: I meant 'moderately,' not 'tediously,' above.

[ trailer ]
budget:all out of budget.