Created
March 6, 2012 22:32
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A quick, dirty and *untested* brainfuck interpreter.
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| import scala.collection.mutable.Queue | |
| object Brainfuck { | |
| def main(args: Array[String]) { | |
| val code = io.Source.fromFile("src.txt") filter ("[]<>.,+-" contains _) toSeq | |
| exec(code) | |
| } | |
| def exec(code: Seq[Char]) { | |
| val program = parse(code) | |
| program(new World()) | |
| System.out.println() | |
| } | |
| def parse(code: Seq[Char]): Block = { | |
| val c = Queue[Instruction]() | |
| var ip = 0 | |
| while (ip < code.size) { | |
| code(ip) match { | |
| case '-' => { c += Inc(-1) } | |
| case '+' => { c += Inc(1) } | |
| case '<' => { c += Right(-1) } | |
| case '>' => { c += Right(1) } | |
| case '.' => { c += Print() } | |
| case '[' => { | |
| var nest = 1 | |
| var tip = ip | |
| while (code(tip) != ']' && nest != 0) { | |
| tip += 1 | |
| if (code(tip) == '[') { nest += 1 } | |
| if (code(tip) == ']') { nest -= 1 } | |
| } | |
| c += While(parse(code.slice(ip + 1, tip))) | |
| ip = tip | |
| } | |
| case _ => () | |
| } | |
| ip += 1 | |
| } | |
| Block(c) | |
| } | |
| } | |
| class World { | |
| val data = Array.fill(30000)(0) | |
| var dp = 0 | |
| def eqz: Boolean = { data(dp) == 0 } | |
| def inc(n: Int) { data(dp) += n } | |
| def right(n: Int) { dp += n } | |
| def print { System.out.print(data(dp) toChar) } | |
| } | |
| sealed abstract class Instruction { | |
| def apply(w: World) | |
| } | |
| case class Inc(n: Int) extends Instruction { | |
| def apply(w: World) { w.inc(n) } | |
| override def toString: String = { | |
| if (n < 0) { | |
| "-" * -n | |
| } else { | |
| "+" * n | |
| } | |
| } | |
| } | |
| case class Right(n: Int) extends Instruction { | |
| def apply(w: World) { w.right(n) } | |
| override def toString: String = { | |
| if (n < 0) { | |
| "<" * -n | |
| } else { | |
| ">" * n | |
| } | |
| } | |
| } | |
| case class Print() extends Instruction { | |
| def apply(w: World) { w.print } | |
| override def toString: String = "." | |
| } | |
| case class Block(code: Seq[Instruction]) extends Instruction { | |
| def apply(w: World) { | |
| for (i <- code) { | |
| i(w) | |
| } | |
| } | |
| override def toString: String = { | |
| code map { _.toString } mkString "" | |
| } | |
| } | |
| case class While(block: Block) extends Instruction { | |
| def apply(w: World) { | |
| while (!w.eqz) { | |
| block(w) | |
| } | |
| } | |
| override def toString: String = { | |
| "[%s]" format block.toString | |
| } | |
| } |
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