Question

I’m using the PHP-FineDiff class as a service in my project. Creating diff works fine, however, when I try to restore the diffs using e.g. FineDiff::renderToTextFromOpcodes(), nothing happens.

I digged a little in the code and found that a callback doesn’t work. After commenting out some

if ( !is_callable($callback) ) {
    return;
}

I run into the error:

Warning: call_user_func() expects parameter 1 to be a valid callback, class ‘FineDiff’ not found in /var/www/sopos-blog/src/Sopos/WikiBundle/Services/FineDiff.php line 321.

These are some relevant lines of code:

public static function renderToTextFromOpcodes($from, $opcodes) {
    ob_start();
    FineDiff::renderFromOpcodes($from, $opcodes, array('FineDiff','renderToTextFromOpcode'));
    return ob_get_clean();
}

// ...

public static function renderFromOpcodes($from, $opcodes, $callback) {
    if ( !is_callable($callback) ) {
        return;
        }
    $opcodes_len = strlen($opcodes);
    $from_offset = $opcodes_offset = 0;
    while ( $opcodes_offset <  $opcodes_len ) {
        $opcode = substr($opcodes, $opcodes_offset, 1);
        $opcodes_offset++;
        $n = intval(substr($opcodes, $opcodes_offset));
        if ( $n ) {
            $opcodes_offset += strlen(strval($n));
            }
        else {
            $n = 1;
            }
        if ( $opcode === 'c' ) { // copy n characters from source
            call_user_func($callback, 'c', $from, $from_offset, $n, '');
            $from_offset += $n;
            }

// ...

Answer 1

I guess your class’s FQCN is Sopos\WikiBundle\Services\FineDiff, so the callback must be one these:

$arrayCallback = array(__NAMESPACE__.'\FineDiff','renderToTextFromOpcode');
$stringCallback = __NAMESPACE__.'\FineDiff::renderToTextFromOpcode';

You could also replace __NAMESPACE__ by the real namespace.