Text_Diff_Renderer_inline::_changed

    function _changed($orig, $final)
    {
        /* If we've already split on characters, just display. */
        if ($this->_split_level == 'characters') {
            return $this->_deleted($orig)
                . $this->_added($final);
        }

        /* If we've already split on words, just display. */
        if ($this->_split_level == 'words') {
            $prefix = '';
            while ($orig[0] !== false && $final[0] !== false &&
                   substr($orig[0], 0, 1) == ' ' &&
                   substr($final[0], 0, 1) == ' ') {
                $prefix .= substr($orig[0], 0, 1);
                $orig[0] = substr($orig[0], 1);
                $final[0] = substr($final[0], 1);
            }
            return $prefix . $this->_deleted($orig) . $this->_added($final);
        }

        $text1 = implode("\n", $orig);
        $text2 = implode("\n", $final);

        /* Non-printing newline marker. */
        $nl = "\0";

        if ($this->_split_characters) {
            $diff = new Text_Diff('native',
                                  array(preg_split('//', $text1),
                                        preg_split('//', $text2)));
        } else {
            /* We want to split on word boundaries, but we need to preserve
             * whitespace as well. Therefore we split on words, but include
             * all blocks of whitespace in the wordlist. */
            $diff = new Text_Diff('native',
                                  array($this->_splitOnWords($text1, $nl),
                                        $this->_splitOnWords($text2, $nl)));
        }

        /* Get the diff in inline format. */
        $renderer = new Text_Diff_Renderer_inline
            (array_merge($this->getParams(),
                         array('split_level' => $this->_split_characters ? 'characters' : 'words')));

        /* Run the diff and get the output. */
        return str_replace($nl, "\n", $renderer->render($diff)) . "\n";
    }