util.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
*/


/**
 * fuck_text() generates brainfuck code from $text. The resulting code will use the current
 * register p for looping and the register p+1 for the resulting character. Thus, make sure
 * these two registers are zero (prepend "[-]>[-]<<" to clear the first two registers).
 *
 * I suggest you to use this function in conjunction with wordwrap:
 *
 * $bf = wordwrap(fuck_text("Hello World"), 75, "\n", 1));
 *
 * wich will generate nice, formatted output.
 *
 * @param string $text
 */
function fuck_text($text)
{
    /* value of current pointer */
    $value = 0;
    $result = '';

    for ($_t = 0; $_t < strlen($text); ++$_t) {

        /* ordinal difference between current char and the one we want to have */
        $diff = ord($text[$_t]) - $value;

        /* it's easier like this than always computing this value - saves some cpu cycles*/
        $value = ord($text[$_t]);

        /* repeat current character */
        if ($diff == 0) {
            $result .= ">.<";
            continue;
        }

        /* is it worth making a loop?
           No. A bunch of + or - consume less space than the loop. */
        if (abs($diff) < 10) {

            /* output a bunch of + or - */
            if ($diff > 0)
                $result .= ">" . str_repeat("+", $diff);
            else if ($diff < 0)
                $result .= ">" . str_repeat("-", abs($diff));

        } /* Yes, create a loop. This will make the resulting code more compact. */
        else {

            /*  we strictly use ints, as PHP has some bugs with floating point operations
               (even if no division is involved) */
            $loop = (int)sqrt(abs($diff));

            /* set loop counter */
            $result .= str_repeat("+", $loop);

            /* execute loop, then add reminder */
            if ($diff > 0) {
                $result .= "[->" . str_repeat("+", $loop) . "<]";
                $result .= ">" . str_repeat("+", $diff - pow($loop, 2));
            } else if ($diff < 0) {
                $result .= "[->" . str_repeat("-", $loop) . "<]";
                $result .= ">" . str_repeat("-", abs($diff) - pow($loop, 2));
            }

        } /* end: if loop */

        $result .= ".<";

    } /* end: for */

    /* cleanup */
    return str_replace("<>", "", $result);
}

/**
 * This function checks whether the brackets are balanced.
 *
 * Make sure you get the return value correctly, as 0 means "OK" and not "false":
 *
 * positive return value: this many [ too much = this many ] missing
 * zero: balanced
 * negative return value: this many ] too much = this many [ missing
 *
 * @param string $bf Brainfuck source
 * @return int
 */
function bf_brackets_balance($bf)
{
    $histogram = count_chars($bf);
    return $histogram[91] - $histogram[93];
}

/**
 * This returns the real number of brainfuck commands when all other characters
 * are ignored.
 *
 * @param string $bf
 * @return int
 */
function bf_count_chars($bf)
{
    return count(preg_split("/[\[\]+\-<>.,]/", $bf)) - 1;
}

/**
 * removes all unnecessary characters from a brainfuck source
 *
 * only actual instructions are kept
 *
 * @param string $bf
 * @return string
 */
function bf_reduce($bf)
{
    preg_match_all("/[\[\]+\-<>.,]/", $bf, $matches);
    return join("", $matches[0]);
}