Selectively trim text

gistfile1.php

<?php

$examples[] = 'This is text with no trim components';
$examples[] = 'This text is short but has /--trim components --/ too.';
$examples[] = 'This text is going to be quite long and has some parts that can be removed, /--such as this one, --/ and some that can\'t.';
$examples[] = 'This text is /-2-quite --/long and has some parts that can be removed, /-1-such as this one, --/ and some that can\'t.';

$trimLength = 100;

foreach($examples as $example) {
	echo '<hr />';
	
	if(strlen($example) > $trimLength) {
		if(preg_match_all('#/-([0-9]{0,2})-(.+?)--/#', $example, $matches)) {
			$trimmed = $example;

			$j = 0;
			$removalCandidates = array();
			foreach($matches[0] as $i=>$m) {
				if($matches[1][$i] != '') {
					$k = intval($matches[1][$i]);
				}
				else {
					$k = count($removalCandidates);
				}

				$removalCandidates[$k] = $m;
			}

			ksort($removalCandidates);
			$tmp = array();
			foreach($removalCandidates as $r)
				$tmp[] = $r;
			$removalCandidates = $tmp;
			
			$i = 0;
			while(strlen(removeTrimTags($trimmed)) > $trimLength && $i < count($removalCandidates)) {
				$trimmed = str_replace($removalCandidates[$i], '', $trimmed);
				$i++;
			}
			
		}
	} else {
		$matches = 'not trimmed';
		$trimmed = $example;
	}
	
	// Remove any remaining trim tags
	$trimmed = removeTrimTags($trimmed);

	echo $example . '<br />';
	#echo '<pre>'; print_r($matches); echo '</pre>';
	echo $trimmed . '<br />';
}

function removeTrimTags($text) {
	return preg_replace(array('#/-([0-9]{0,2})-#','#--/#'), '', $text);
}

/**

Output:

This is text with no trim components
This is text with no trim components

This text is short but has /--trim components --/ too.
This text is short but has trim components too.

This text is going to be quite long and has some parts that can be removed, /--such as this one, --/ and some that can't.
This text is going to be quite long and has some parts that can be removed, and some that can't.

This text is /-2-quite --/long and has some parts that can be removed, /-1-such as this one, --/ and some that can't.
This text is quite long and has some parts that can be removed, and some that can't.

**/