Relative to absolute path

new_gist_file.php

function make_absolute($url, $base) 
{
    // Return base if no url
    if( ! $url) return $base;

    // Return if already absolute URL
    if(parse_url($url, PHP_URL_SCHEME) != '') return $url;
    
    // Urls only containing query or anchor
    if($url[0] == '#' || $url[0] == '?') return $base.$url;
    
    // Parse base URL and convert to local variables: $scheme, $host, $path
    extract(parse_url($base));

    // If no path, use /
    if( ! isset($path)) $path = '/';
 
    // Remove non-directory element from path
    $path = preg_replace('#/[^/]*$#', '', $path);
 
    // Destroy path if relative url points to root
    if($url[0] == '/') $path = '';
    
    // Dirty absolute URL
    $abs = "$host$path/$url";
 
    // Replace '//' or '/./' or '/foo/../' with '/'
    $re = array('#(/\.?/)#', '#/(?!\.\.)[^/]+/\.\./#');
    for($n = 1; $n > 0; $abs = preg_replace($re, '/', $abs, -1, $n)) {}
    
    // Absolute URL is ready!
    return $scheme.'://'.$abs;
}