test/turing.go

   1 // $G $F.go && $L $F.$A && ./$A.out
   2
   3 // Copyright 2009 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 package main
   8
   9 // brainfuck
  10
  11 var p, pc int
  12 var a [30000]byte
  13 const prog = "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.!"
  14
  15 func scan(dir int) {
  16         for nest := dir; dir*nest > 0; pc += dir {
  17                 switch prog[pc+dir] {
  18                         case ']':
  19                                 nest--
  20                         case '[':
  21                                 nest++
  22                 }
  23         }
  24 }
  25
  26 func main() {
  27         for {
  28                 switch prog[pc] {
  29                         case '>':
  30                                         p++
  31                         case '<':
  32                                         p--
  33                         case '+':
  34                                         a[p]++
  35                         case '-':
  36                                         a[p]--
  37                         case '.':
  38                                         print(string(a[p]))
  39                         case '[':
  40                                 if a[p] == 0 {
  41                                         scan(1)
  42                                 }
  43                         case ']':
  44                                 if a[p] != 0 {
  45                                         scan(-1)
  46                                 }
  47                         default:
  48                                         return
  49                 }
  50                 pc++
  51         }
  52 }