URL dissector that splits up a query string - php

Question

Ok so basically I am reading through this piece of source code and do not understand the purpose of a specific area.
class URL_Processor
{
private static $urlPath;
private static $urlBits = array();
/*
Gets data from the current URL
#return Void
*/
public function getURLData()
{
$urldata = (isset($_GET['page'])) ? $_GET['page'] : '' ;
self::$urlPath = $urldata;
if( $urldata == '' )
{
self::$urlBits[] = 'home';
self::$urlPath = 'home';
}
else
{
$data = explode( '/', $urldata );
while ( !empty( $data ) && strlen( reset( $data ) ) === 0 )
{
array_shift( $data );
}
while ( !empty( $data ) && strlen( end( $data ) ) === 0)
{
array_pop($data);
}
self::$urlBits = $this->array_trim( $data );
}
}
private function array_trim( $array )
{
while ( ! empty( $array ) && strlen( reset( $array ) ) === 0)
{
array_shift( $array );
}
while ( !empty( $array ) && strlen( end( $array ) ) === 0)
{
array_pop( $array );
}
return $array;
}
}
So basically from my understanding the two while loops with 'array_shift' in the getURLData method empty out the array but according to my logic the second while loop wont even be able to empty anything out because the first while loop already did.
Then the last line of the method getURLData
self::$urlBits = $this->array_trim( $data );
does the same thing but how if the passed in argument is empty already?
Very confused!!!

Answer 1

The first while loop removes all leading elements in the array where their string length is zero, the second one does the same with trailing elements. reset($array) will point to the first, end($array) to the last element.
Why he mushes it through a second time? I don't know.