brainfuck.php

<?php

/*

    Brainfuck interpreter in PHP
    Copyright (C) 2002 Daniel Lorch

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*/

/* Debug function displays valuable debug information.
   Rewrite this if desired. 
   
   $s, $_s  Source string and pointer (current position)
   $d, $_d  Data   array  and pointer
   $i, $_i  Input  string and pointer
   $o       Output string
   
   */

function brainfuck_debug(&$s, &$_s, &$d, &$_d, &$i, &$_i, &$o) {
	echo "<table>\n";
	echo "<tr><td><b>Position</b></td><td><b>Value</b></td><td><b>ASCII</b></td></tr>\n";
	
	foreach( $d as $element=>$value ) {
		echo "<tr>\n";
		echo "<td align=\"center\">" . $element . "</td>\n";
		echo "<td align=\"center\">" . ord( $value ) . "</td>\n";
		echo "<td align=\"center\">" . (ord( $value ) >= 32? htmlentities( $value ) : "&nbsp;") . "</td>\n";
		echo "</tr>\n";
	}
	
	echo "</table>\n";
}

/* The actual interpreter */

function brainfuck_interpret(&$s, &$_s, &$d, &$_d, &$i, &$_i, &$o) {
	do {
		switch($s[$_s]) {
			/* Execute brainfuck commands. Values are not stored as numbers, but as their
          representing characters in the ASCII table. This is perfect, as chr(256) is
          automagically converted to chr(0). */
			case '+':
				$d[$_d] = chr( ord( $d[$_d] ) + 1 );
				break;
			case '-':
				$d[$_d] = chr( ord( $d[$_d] ) - 1 );
				break;
			case '>':
				$_d++;
				if( !isset( $d[$_d] ) ) $d[$_d] = chr( 0 );
				break;
			case '<':
				$_d--;
				break;
			
			/* Output is stored in a variable. Change this to
            echo $d[$_d]; flush();
          if you would like to have a "live" output (when running long calculations, for example.
          Or if you are just terribly impatient). */
			case '.':
				$o .= $d[$_d];
				break;
			
			/* Due to PHP's non-interactive nature I have the whole input passed over in a string. 
          I successively read characters from this string and pass it over to BF every time a
          ',' command is executed. */
			case ',':
				$d[$_d] = $_i == strlen( $i )? chr( 0 ) : $i[$_i++];
				break;
			
			/* Catch loops */
			case '[':
         /* Skip loop (also nested ones) */
         if( (int)ord( $d[$_d] ) == 0 ) {
					$brackets = 1;
					while( $brackets && $_s++ < strlen( $s ) ) {
						if( $s[$_s] == '[' ) {
							$brackets++;
						}
						else 
							if( $s[$_s] == ']' ) {
								$brackets--;
							}
					}
				}
				/* Execute loop */
				else {
					$pos = $_s++ - 1;
					/* The closing ] returns true when the loop has to be executed again. If so, then return
              to the $pos(ition) where the opening [ is. */
					if( brainfuck_interpret( $s, $_s, $d, $_d, $i, $_i, $o ) ) $_s = $pos;
				}
				break;
			/* Return true when loop has to be executed again. It is redundant to the [ checking, but
          it will save some parsing time (otherwise the interpreter would have to return to [ only
          to skip all characters again) */
			case ']':
				return ((int)ord( $d[$_d] ) != 0);
			/* Call debug function */
			case '#':
				brainfuck_debug( $s, $_s, $d, $_d, $i, $_i, $o );
		}
	}
	while( ++$_s < strlen( $s ) );
	return '';
}

/* Call this one in order to interpret brainfuck code */

function brainfuck($source, $input = '') {
	
	/* Define needed variables:

     $data    Brainfuck's memory
     $source  Source data
     $input   Simulate STDIN
     $output  Save output in here
     
     Each with according index variables
  */
	
	$data = array();
	$data[0] = chr( 0 ); /* It is necessary to set every element explicitly, as 
                             PHP treats arrays as hashes */
	$data_index = 0;
	
	$source_index = 0;
	
	$input_index = 0;
	
	$output = '';
	
	/* Call the actual interpreter */
	brainfuck_interpret( $source, $source_index, $data, $data_index, $input, $input_index, $output );
	
	return $output;
}

/* modifications perso */

function brainfuck_regex_callback($value) {
	return str_repeat( $value[2], $value[0] );
}

function _brainfuck($source, $input = '') {
	$code = preg_replace_callback( '/(\d+)([><+-.,\[\]])/', 'brainfuck_regex_callback', $source );
	return brainfuck( $code, $input );
}

?>