Write a brainfuck translator

Brainfuck, 5 + 540 = 545 bytes

5 bytes of code, 540 from output of given test file (assuming got the count right from my paste of that code).

,[.,]

Assuming EOF is 0.

Perl - 177 (source) + 172 (output) = 349

#!perl -p0
y/-+><.,[]
-~/p-w/d;s/(.)\K\1+|rs|wv[^v]*(?=w)/$+&&length$&/ge;$_="eval'r$_'=~".'s/.(\d*)/(qw(--$ ++$ -- ++ print+chr$ $$i=ord+getc; while($$i){ })[$&&v63].q($i;))x($++1)/ger'

Counting the shebang as 2 bytes, one for each option. First, each of the eight commands is translated onto the range p-w, while at the same time removing all other characters. This string is then run-length encoded and output with a minimal decoder/interpreter. A few things are optimized away: the string >< obviously does nothing, and a for loop that follows directly after another may be removed entirely, as it will never be entered.

Output for the test program:

eval'rq4vpwq9vrq6rq9rq2s2pwrq1trqtq6t1q2trq1tsq7tp7tq2tp5tp7trqtp32vt44wsps1'=~s/.(\d*)/(qw(--$ ++$ -- ++ print+chr$ $$i=ord+getc; while($$i){ })[$&&v63].q($i;))x($++1)/ger

A sample run:

$ perl brainfusk.pl < in.bf | perl
Hello world!

---

Perl - 232 (source) + 21 (output) = 253

#!perl -p0
y/-+><.,[]
-~/0-7/d;$_="eval'2$_'=~".'s/./qw(--$ ++$ -- ++ print+chr$ $$i=ord+getc; while($$i){ })[$&].q($i;)/ger';
/5/||fork?(wait,$?||exit):($SIG{ALRM}=sub{exit 1},alarm 9,$S=select(open 1,'>',\$o),eval,print$S "print\"\Q$o\E\"")

This one is based on FIQ's observation that if the original program doesn't contain an input statement, the output will be static, and therefore can be reduced to a single print statement. If you like this one, be sure to give his answer a +1.

So what we can do is pipe stdout to a variable, eval the code we would have output, and wrap the result in a print.

...that won't always work, though. Whenever the code to be translated would have resulted in an infinite loop, (e.g. +[.]), this cannot be reduced to a single print statement, for obvious reasons. So instead, we launch the eval in a child process with a short timeout, and if it doesn't finish executing within that time we output the translated program as before.

Structured and commented:

if(!/5/) { # no `,` in program

  if(fork) { # parent process

    # wait for child
    wait;
    # no child error, terminate without output
    $?||exit

  } else { # child process

    # alarm handler, exit with error
    $SIG{ALRM}=sub{exit 1};
    # set an alarm in 9 seconds
    alarm 9;
    # redirect STDOUT to variable $o
    $S=select open 1,'>',\$o;
    # execute translated code
    eval;
    # wrap the result in a print statement
    print$S "print\"\Q$o\E\""
  }
}

Output for sample program:

print"Hello\ world\!"

Output for ,[.]:

eval'25647'=~s/./qw(--$ ++$ -- ++ print+chr$ $$i=ord+getc; while($$i){ })[$&].q($i;)/ger

Output for +[.] (after 9 seconds):

eval'21647'=~s/./qw(--$ ++$ -- ++ print+chr$ $$i=ord+getc; while($$i){ })[$&].q($i;)/ger

PHP, 553 + 27 = 580 bytes

(553 bytes with all whitespaces, i.e. newlines and spaces, removed)

I suck badly at golfing PHP, so this approach can be heavily optimized. I mostly wanted to show my approach to the solution in something not BF.

<?php
echo "<?php ";
$x = 'if (!$b) $c = $_GET[c];
$x=$y=$n[0]=$p=0;$o[0]=1;$d="";
while($a=$c[$x++]){
    if($o[$p]){
        if($a=="-")$m[$y]--;
        if($a=="+")$m[$y]++;
        $m[$y]=$m[$y]%256;
        if($a=="<")$y--;
        if($a==">")$y++;
        if($a=="."){
            $e=chr($m[$y]);
            if ($b) echo $e;
            else $d.=addslashes($e);
        }
        if($a==",")$m[$y]=($b=$_GET[i])?ord($b):0;
    }if($a=="["){
        $p++;
        $n[$p]=$x-1;
        $o[$p]=$o[$p-1]?$m[$y]:0;
    }
    if($a=="]"){
        if($o[$p])$x=$n[$p];
        $p--;
        if($p=-1)$p=0;
    }
}
if (!$b) echo "echo \'$d\';";';
if (strstr($_GET['c'],",")) {
    $x = '$b=1;'.$x;
    echo '$c="'.addslashes($_GET[c]).'";'.$x;
    return;
}
eval($x);

Error reporting must be off, otherwise PHP will hate you. Usage: throw this up as a page, and run it with script.php?c=CODE (if the resulting script requires input, you run it as out.php?i=INPUT). Remember to url escape the input!

What this does is basically this - if the BF script contains ",", it pretty much embeds itself as the resulting script with an attached $b=1; at the top. If it does NOT contain ",", it optimizes it down to "echo '<BF output>'". Conveniently, the test script in the OP does NOT require any input. The addslashes() is just there for escaping ' and \.