Issue 7296 - Implement lightweight URL parsing

lib/url.js

Index: lib/url.js
===================================================================
--- a/lib/url.js
+++ b/lib/url.js
@@ -35,16 +35,94 @@
 
   for (let key in publicSuffixes)
     map.set(key, publicSuffixes[key]);
 
   return map;
 }
 
 /**
+ * A <code>URLInfo</code> object represents information about a URL. It is
+ * returned by <code>{@link parseURL}</code>.
+ */
+class URLInfo
+{
+  /**
+   * Creates a <code>URLInfo</code> object.
+   *
+   * @param {string} href The entire URL.
+   * @param {string} protocol The protocol scheme of the URL, including the
+   *   final <code>:</code>.
+   * @param {string} [hostname] The hostname of the URL.
+   *
+   * @private
+   */
+  constructor(href, protocol, hostname = "")
+  {
+    this._href = href;
+    this._protocol = protocol;
+    this._hostname = hostname;
+  }
+
+  /**
+   * The entire URL.
+   * @type {string}
+   */
+  get href()
+  {
+    return this._href;
+  }
+
+  /**
+   * The protocol scheme of the URL, including the final <code>:</code>.
+   * @type {string}
+   */
+  get protocol()
+  {
+    return this._protocol;
+  }
+
+  /**
+   * The hostname of the URL.
+   * @type {string}
+   */
+  get hostname()
+  {
+    return this._hostname;
+  }
+
+  /**
+   * Returns the entire URL.
+   * @returns {string} The entire URL.
+   */
+  toString()
+  {
+    return this._href;
+  }
+}
+
+/**
+ * Parses a URL to extract the protocol and the hostname. This is a lightweight
+ * alternative to the native <code>URL</code> object. Unlike the
+ * <code>URL</code> object, this function is not robust and will give incorrect
+ * results for invalid URLs. <em>Use this function with valid, normalized,
+ * properly encoded (IDNA and percent-encoding) URLs only.</em>
+ *
+ * @param {string} url The URL to parse.
+ * @returns {URLInfo} Information about the URL.
+ */
+function parseURL(url)
+{
+  let match = /^([^:]+:)(?:\/\/(?:[^/]*@)?(\[[^\]]*\]|[^:/]+))?/.exec(url);
+  return new URLInfo(url, match[1], match[2]);
+}
+
+exports.parseURL = parseURL;
+
+/**
  * Normalizes a hostname.
  * @param {string} hostname
  * @returns {string}
  */
 function normalizeHostname(hostname)
 {
   return (hostname[hostname.length - 1] == "." ?
             hostname.replace(/\.+$/, "") : hostname).toLowerCase();