【PHP】相対パスを絶対パス(URL)に変換する

function pathToUrl($pPath, $pUrl)
{
    $path = trim($pPath);    // 変換対象パス
    $url = trim($pUrl);      // 基準URL

    //-- 変換不要
    if ($path === '') { return $url; }

    if (stripos($path, 'http://') === 0 ||
        stripos($path, 'https://') === 0 ||
        stripos($path, 'mailto:') === 0 ||
        stripos($path, 'tel:') === 0) { return $path; }

    //-- #anchor
    if (strpos($path, '#') === 0) { return $url . $path; }

    //-- 基準URLを分解
    $urlAry = explode('/', $url);
    if (!isset($urlAry[2])) { return false; }

    //-- //path
    if (strpos($path, '//') === 0) { return $urlAry[0] . $path; }

    //-- 基準URLのHOME(scheme://host)
    $urlHome = $urlAry[0] . '//' . $urlAry[2];

    //-- 基準URLのパス
    if (!$pathBase = parse_url($url, PHP_URL_PATH)) { $pathBase = '/'; }

    //-- ?query
    if (strpos($path, '?') === 0) { return $urlHome . $pathBase . $path; }

    //-- /path
    if (strpos($path, '/') === 0) { return $urlHome . $path; }

    //-- ./path or ../path
    $pathBaseAry = array_filter(explode('/', $pathBase), 'strlen');
    if (strpos(end($pathBaseAry), '.') !== false) { array_pop($pathBaseAry); }

    foreach (explode('/', $path) as $pathElem) {
        if ($pathElem === '.') { continue; }
        if ($pathElem === '..') { array_pop($pathBaseAry); continue; }
        if ($pathElem !== '') { $pathBaseAry[] = $pathElem; }
    }

    return (substr($path, -1) === '/') ? $urlHome . '/' . implode('/', $pathBaseAry) . '/'
                                       : $urlHome . '/' . implode('/', $pathBaseAry);
}

$url = 'http://user:[email protected]/base/path/here/index.php?p=q';

$testAry = array(
    'URL' => 'https://www.google.com/gmail/',
    'mailto:' => 'mailto:[email protected]',
    'クエリのみ' => '?aaa=bbb&ccc=ddd',
    'パス＋クエリ' => 'new.php?aaa=bbb',
    'アンカーのみ' => '#anchor',
    'パス＋アンカー' => 'new.html#anchor',
    '絶対パス1' => '/new/path/abs.html',
    '絶対パス2' => '//new/path/abs.html',
    '相対パス1' => './',
    '相対パス2' => './new/path/rel2/',
    '相対パス3' => './new/path/rel3.html',
    '相対パス4' => '../../rel4.html',
    '相対パス5' => '.././/new/../././rel5.html',
);

foreach ($testAry as $title => $test) {
    echo "{$title}('{$test}') ⇒ ", pathToUrl($test, $url), "\n";
}

URL('https://www.google.com/gmail/') ⇒ https://www.google.com/gmail/
mailto:('mailto:[email protected]') ⇒ mailto:[email protected]

クエリのみ('?aaa=bbb&ccc=ddd') ⇒ http://user:[email protected]/base/path/here/index.php?aaa=bbb&ccc=ddd
パス＋クエリ('new.php?aaa=bbb') ⇒ http://user:[email protected]/base/path/here/new.php?aaa=bbb

アンカーのみ('#anchor') ⇒ http://user:[email protected]/base/path/here/index.php?p=q#anchor
パス＋アンカー('new.html#anchor') ⇒ http://user:[email protected]/base/path/here/new.html#anchor

絶対パス1('/new/path/abs.html') ⇒ http://user:[email protected]/new/path/abs.html
絶対パス2('//new/path/abs.html') ⇒ http://new/path/abs.html

相対パス1('./') ⇒ http://user:[email protected]/base/path/here/
相対パス2('./new/path/rel2/') ⇒ http://user:[email protected]/base/path/here/new/path/rel2/
相対パス3('./new/path/rel3.html') ⇒ http://user:[email protected]/base/path/here/new/path/rel3.html
相対パス4('../../rel4.html') ⇒ http://user:[email protected]/base/rel4.html
相対パス5('.././/new/../././rel5.html') ⇒ http://user:[email protected]/base/path/rel5.html