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| // run
|
| // Copyright 2009 The Go Authors. All rights reserved.
| // Use of this source code is governed by a BSD-style
| // license that can be found in the LICENSE file.
|
| // Test simulating a Turing machine, sort of.
|
| package main
|
| // brainfuck
|
| var p, pc int
| var a [30000]byte
|
| const prog = "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.!"
|
| func scan(dir int) {
| for nest := dir; dir*nest > 0; pc += dir {
| switch prog[pc+dir] {
| case ']':
| nest--
| case '[':
| nest++
| }
| }
| }
|
| func main() {
| r := ""
| for {
| switch prog[pc] {
| case '>':
| p++
| case '<':
| p--
| case '+':
| a[p]++
| case '-':
| a[p]--
| case '.':
| r += string(a[p])
| case '[':
| if a[p] == 0 {
| scan(1)
| }
| case ']':
| if a[p] != 0 {
| scan(-1)
| }
| default:
| if r != "Hello World!\n" {
| panic(r)
| }
| return
| }
| pc++
| }
| }
|
|
