PHP - simple shortcode parser, output order is wrong - php

Question

I have a simple function which parse shortcode tags and its attribute,
but it has some problem in output.
Like, this is my content in a string with a shortcode inside it:
$content = 'This is lorem ispium test [gallery image="10"] and text continues...'
I want the result output like this:
This is lorem ispium test
----------------------------------------------
| This is output of gallery |
-----------------------------------------------
and text continues...
But now shortcode is not rendering where the shortcode is called, instead of this shortcode render at the top. like:
----------------------------------------------
| This is output of gallery |
-----------------------------------------------
This is lorem ispium test and text continues...
Kindly tell how do I render shortcode where it was called
function shortcode($content) {
$shortcodes = implode('|', array_map('preg_quote', get('shortcodes')));
$pattern = "/(.?)\[($shortcodes)(.*?)(\/)?\](?(4)|(?:(.+?)\[\/\s*\\2\s*\]))?(.?)/s";
echo preg_replace_callback($pattern, array($this,'handleShortcode'), $content);
}
function handleShortcode($matches) {
$prefix = $matches[1];
$suffix = $matches[6];
$shortcode = .$matches[2];
// allow for escaping shortcodes by enclosing them in double brackets ([[shortcode]])
if($prefix == '[' && $suffix == ']') {
return substr($matches[0], 1, -1);
}
$attributes = array(); // Parse attributes into into this array.
if(preg_match_all('/(\w+) *= *(?:([\'"])(.*?)\\2|([^ "\'>]+))/', $matches[3], $match, PREG_SET_ORDER)) {
foreach($match as $attribute) {
if(!empty($attribute[4])) {
$attributes[strtolower($attribute[1])] = $attribute[4];
} elseif(!empty($attribute[3])) {
$attributes[strtolower($attribute[1])] = $attribute[3];
}
}
}
//callback to gallery
return $prefix. call_user_func(array($this,$shortcode), $attributes, $matches[5], $shortcode) . $suffix;
}
function gallery($att, $cont){
//gallery output
}
Please note: it is not related to wordpress, it is a custom script.

Answer 1

I believe that the problem may be in your function gallery($att, $cont).
If that function uses echo or print instead of return, then it makes perfect sense to show up before the actual content does.
EDIT:
If you can't change the gallery code, then yes, you can use output buffering.
function handleShortcode($matches) {
...
ob_start();
call_user_func(array($this,$shortcode), $attributes, $matches[5], $shortcode);
$gallery_output = ob_get_contents();
ob_end_clean();
return $prefix . $gallery_output . $suffix;
}
Related readings:
PHP ob_start
PHP ob_get_contents