move linkheader.php to core

lib/linkheader.php

@@ -0,0 +1,66 @@
+<?php
+/**
+ * @todo Add file header and documentation.
+ */
+
+class LinkHeader
+{
+    var $href;
+    var $rel;
+    var $type;
+
+    function __construct($str)
+    {
+        preg_match('/^<[^>]+>/', $str, $uri_reference);
+        //if (empty($uri_reference)) return;
+
+        $this->href = trim($uri_reference[0], '<>');
+        $this->rel = array();
+        $this->type = null;
+
+        // remove uri-reference from header
+        $str = substr($str, strlen($uri_reference[0]));
+
+        // parse link-params
+        $params = explode(';', $str);
+
+        foreach ($params as $param) {
+            if (empty($param)) continue;
+            list($param_name, $param_value) = explode('=', $param, 2);
+            $param_name = trim($param_name);
+            $param_value = preg_replace('(^"|"$)', '', trim($param_value));
+
+            // for now we only care about 'rel' and 'type' link params
+            // TODO do something with the other links-params
+            switch ($param_name) {
+            case 'rel':
+                $this->rel = trim($param_value);
+                break;
+
+            case 'type':
+                $this->type = trim($param_value);
+            }
+        }
+    }
+
+    static function getLink($response, $rel=null, $type=null)
+    {
+        $headers = $response->getHeader('Link');
+        if ($headers) {
+            // Can get an array or string, so try to simplify the path
+            if (!is_array($headers)) {
+                $headers = array($headers);
+            }
+
+            foreach ($headers as $header) {
+                $lh = new LinkHeader($header);
+
+                if ((is_null($rel) || $lh->rel == $rel) &&
+                    (is_null($type) || $lh->type == $type)) {
+                    return $lh->href;
+                }
+            }
+        }
+        return null;
+    }
+}