BrainFuck 解释器（C语言实现）

码农的业余休闲活动就是去学习一门冷门的语言或者研究一项非主流的技术。BrainFuck 是一门小巧的编程语言，顾名思义，阅读这门语言的代码就像在强奸你的大脑一样。事实证明开发它的解释器比读懂它的 Hello World 要快。

BrainFuck只有八条指令：

解释器代码如下：

#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#define TOKENS "><+-.,[]"

#define CODE_SEGMENT_SIZE 30000
#define STACK_SEGMENT_SIZE 1000
#define DATA_SEGMENT_SIZE 30000

typedef void (*Callback)(void);

struct {
  char cs[CODE_SEGMENT_SIZE];   /* Code Segment */
  long ip;                      /* Instruction Pointer */

  char ss[STACK_SEGMENT_SIZE];  /* Stack Segment */
  long sp;                      /* Stack Pointer */

  char ds[DATA_SEGMENT_SIZE];   /* Data Segment */
  long bp;                      /* Base Pointer */

  Callback fn[128];
} vm;

void vm_forward() {
  vm.bp = (vm.bp + 1) % DATA_SEGMENT_SIZE;
}

void vm_backward() {
  vm.bp = (vm.bp + DATA_SEGMENT_SIZE - 1) % DATA_SEGMENT_SIZE;
}

void vm_increment() {
  vm.ds[vm.bp]++;
}

void vm_decrement() {
  vm.ds[vm.bp]--;
}

void vm_input() {
  vm.ds[vm.bp] = getchar();
}

void vm_output() {
  putchar(vm.ds[vm.bp]);
}

void vm_while_entry() {
  if (vm.ds[vm.bp]) {
    vm.ss[vm.sp] = vm.ip - 1;
    vm.sp++;
  } else {
    int c = 1;
    for (vm.ip++; vm.cs[vm.ip] && c; vm.ip++) {
      if (vm.cs[vm.ip] == '[') {
        c++;
      } else if (vm.cs[vm.ip] == ']') {
        c--;
      }
    }
  }
}

void vm_while_exit() {
  if (vm.ds[vm.bp]) {
    vm.sp--;
    vm.ip = vm.ss[vm.sp];
  }
}

void setup() {
  int c;
  int i;

  memset(&vm, 0, sizeof(vm));
  vm.fn['>'] = vm_forward;
  vm.fn['<'] = vm_backward;
  vm.fn['+'] = vm_increment;
  vm.fn['-'] = vm_decrement;
  vm.fn['.'] = vm_output;
  vm.fn[','] = vm_input;
  vm.fn['['] = vm_while_entry;
  vm.fn[']'] = vm_while_exit;

  for (i = 0; (c = getchar()) != EOF;) {
    if (strchr(TOKENS, c)) {
      vm.cs[i] = c;
      i++;
    }
  }
}

void run() {
  while (vm.cs[vm.ip]) {
    vm.fn[vm.cs[vm.ip]]();
    vm.ip++;
  }
}

int main(int argc, char* argv[]) {
  if (argc > 1) {
    freopen(argv[1], "r", stdin);
  }

  setup();
  run();

  return 0;
}

Hello world:

brainfuc$ cat helloword.bf
++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.
brainfuc$ ./bf helloword.bf
Hello World!
brainfuc$