interactivenovel.rb

#!/usr/bin/env ruby
=begin
> An interactive novel

> This program parses formatted text files and turns them into an interactive
> novel. Currently, the text files support two types of lines: display lines, or
> lines beginning with a greater than sign. Those lines will be printed out to
> the console. This program also supports prompt lines. These lines will take
> user input and store it in a variable. All other lines are ignored. This file
> can be run as an interactive novel. For completeness, please enter your name
> (to test prompting):
prompt ${name}
> Variables can be included on display lines. Just use a dollar sign and then
> curly braces. For example, your name is ${name}.
>
> By RC Howe (rchowe)
=end

if ARGV.length != 1
	puts "Usage: #{$0} novel"
	Process.exit
end

begin
	file = File.open( ARGV[0], File::RDONLY )
rescue Errno::ENOENT
	puts "Novel file does not exist."
	Process.exit
end

lines = []
variables = {}
file.each do |line|
	next if line.nil?
	if line[0].chr == ">"
		lines.push( Proc.new { l = line[1..(line.length)].lstrip.chomp.gsub(/\$\{(.*?)\}/) { |m| variables[m]}; "#{l} " } ) 
	elsif line.match(/^prompt \$\{(.*)\}/i)
		a = String.new $1
		p = Proc.new { if $last_line.nil? or $last_line.empty? then print "Sorry, I didn't catch that: "; $last_line = $stdin.gets.chomp; p.call; else variables["${#{a}}"] = $last_line; end; nil }
		lines.push p
	end
end

lines.each do |line|
	l = line.call line
	unless l.nil?
		print l
		$last_line = $stdin.gets.chomp
	end
end