Self-modifying esoteric language interpreter in Ruby

Question

I recently created Copy, an esoteric language, and wrote an implementation in Ruby.

The language has only 7 instructions:

• copy <a> <b> <c> Copy the code block from a to b at c
• remove <a> <b> Remove the code block from a to b
• skip <value> Skip the next instruction if value is not 0
• add <var> <value> Add value to var
• negate <var> Negate var
• print <value> Print value as an ASCII character
• getch <var> Read a character and store it character code in var

All addresses are relative and values can be variables or signed integers,

require "io/console"
class Copy
 def initialize(code)
 @code = code.lines.map &:chomp
 @len = @code.length*2
 @i = 0
 @vars = {}
 end
 def value(s)
 if s =~ /-?\d+/
 s.to_i
 else
 @vars[s] or 0
 end
 end
 def step
 while @code.length > @len do
 @code.shift
 @i -= 1
 end
 line = @code[@i].split " "
 case line[0]
 when "copy"
 @code.insert(
 @i + value(line[3]),
 *@code.slice((@i + value(line[1]))..(@i + value(line[2])))
 )
 when "remove"
 @code.slice!((@i + value(line[1]))..(@i + value(line[2])))
 when "skip"
 if value(line[1]) != 0
 @i += 1
 end
 when "add"
 @vars[line[1]] = (@vars[line[1]] or 0) + value(line[2])
 when "negate"
 @vars[line[1]] *= -1
 when "print"
 STDOUT.write value(line[1]).chr
 when "getch"
 @vars[line[1]] = STDIN.getch.ord
 end
 @i += 1
 end
 def run
 while @i < @code.length
 step
 end
 end
end
if __FILE__ == 0ドル
 unless ARGV[0]
 puts "Copy interpreter in Ruby"
 puts "Usage: #{0ドル} <file>"
 end
 c = Copy.new File.read(ARGV[0])
 c.run
end

Truth machine (If the input is 0, print 0 and exit, if the input is 1, print 1 in an infinite loop):

getch a
add b a
add b -48
print a
skip b
skip 1
copy -4 0 1

I am not really good at Ruby, can someone review this?

• Conor O'Brien: I personally would change step to self.step to increase readability.

Answer 1

I would suggest refactoring the switch. This would make scaling easier

 def remove_callback
 @code.slice!((@i + value(line[1]))..(@i + value(line[2])))
 end
 ...
 line = @code[@i].split " "
 self.send("#{line[0]}_callback")