run Brainf*ck on PHP

bf_on_php.php

<?php

if (isset($argv[1]) && file_exists($argv[1])) {
    $code = file_get_contents($argv[1]);
} else {
    fputs(STDERR, "no source (follow output is fizzbuzz demo)\n\n");
    $code = file_get_contents(__FILE__, 0, null, __COMPILER_HALT_OFFSET__);
}

$buffer = array_pad(array(), 30, 0);
$ptr = 0;
$nest_pos = array();
$nest_level = 0;

$length = strlen($code);
$pos = 0;
while($pos < $length) {

    //printf('%03d.%s|ptr:%-3d(%-3d) / nest:%-2d [%s]%s', $pos, $code[$pos], $ptr, $buffer[$ptr], $nest_level, implode(', ', $buffer), "\n");

    switch($code[$pos++]) {
        case '>':
            ++$ptr;
            break;
        case '<':
            --$ptr;
            break;
        case '+':
            ++$buffer[$ptr];
            break;
        case '-':
            --$buffer[$ptr];
            break;
        case '.':
            fwrite(STDOUT, chr($buffer[$ptr]), 1);
            break;
        case ',':
            $buffer[$ptr] = fread(STDIN, 1);
            break;
        case '[':
            if (0 === $buffer[$ptr]) {
                if ($pos < $length) {
                    $nest = 1;
                    do {
                        if ('[' === $code[$pos]) { ++$nest; }
                        elseif (']' === $code[$pos]) { --$nest; }
                    } while(++$pos < $length && 0 < $nest);
                }
            } else {
                $nest_pos[$nest_level++] = $pos;
            }
            break;
        case ']':
            if (0 !== $buffer[$ptr]) {
                $pos = $nest_pos[$nest_level-1];
            } else {
                --$nest_level;
                if ($nest_level < 0) { die("error at {$pos}\n"); }
            }
            break;
    }
}

__halt_compiler();
>++++++++++[<++++++++++>-]>>>+++>+++++<<<<<[>>>>>>>+[<<<<<+<+>>>>>>-]<<<<<[>>>>>
+<<<<<-]++++++++++<[>-<-]>>+<[>[-]<[-]]>[>>>>[-]>+<<<<<-]>>>>>[<<<<<<+<+>>>>>>>-
]<<<<<<[>>>>>>+<<<<<<-]++++++++++<[>-<-]>>+<[>[-]<[-]]>[>>>>>[-]>+<<<<<<-]>>>+<<
-[<<+<+>>>-]<<<[>>>+<<<-]>>+<[>[-]<[-]]>[>+++<<+++++++[<++++++++++>-]<.>+++++[<+
++++++>-]<.>+++[<+++++>-]<++..[-]>>>>>[-]<<<-]>>-[<<<+<+>>>>-]<<<[>>>+<<<-]>+<<[
>>[-]<<[-]]>>[>>+++++<<<++++++++[<++++++++>-]<++.>++++++[<++++++++>-]<+++.+++++.
.[-]>>>>>[-]<<<-]>>>[>>>++++++++++++++++++++++++++++++++++++++++++++++++.-------
-----------------------------------------<++++++++++++++++++++++++++++++++++++++
++++++++++.------------------------------------------------<++++++++++++++++++++
++++++++++++++++++++++++++++.------------------------------------------------<-]
<<<<++++[<+++++++++++>-]<.>+++[<---->-]<.[-]<-]