Add URL parsing library to libkj-http.

c++/src/kj/compat/url.h

+// Copyright (c) 2017 Cloudflare, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#ifndef KJ_COMPAT_URL_H_
+#define KJ_COMPAT_URL_H_
+
+#include <kj/string.h>
+#include <inttypes.h>
+
+namespace kj {
+
+struct Url {
+  String scheme;
+  // E.g. "http", "https".
+
+  struct UserInfo {
+    String username;
+    Maybe<String> password;
+  };
+
+  Maybe<UserInfo> userInfo;
+  // Username / password.
+
+  String host;
+  // Hostname, including port if specified. We choose not to parse out the port because KJ's
+  // network address parsing functions already accept addresses containing port numbers, and
+  // because most web standards don't actually want to separate host and port.
+
+  Array<String> path;
+  bool hasTrailingSlash = false;
+  // Path, split on '/' characters. Note that the individual components of `path` could contain
+  // '/' characters if they were percent-encoded in the original URL.
+
+  struct QueryParam {
+    String name;
+    String value;
+  };
+  Array<QueryParam> query;
+  // Query, e.g. from "?key=value&key2=value2". If a component of the query contains no '=' sign,
+  // it will be parsed as a key with an empty value.
+
+  Maybe<String> fragment;
+  // The stuff after the '#' character (not including the '#' character itself), if present.
+
+  // ---------------------------------------------------------------------------
+
+  Url() = default;
+  Url(Url&&) = default;
+  ~Url() noexcept(false);
+
+  Url clone() const;
+
+  enum Context {
+    GENERAL,
+    // The full URL.
+
+    HTTP_PROXY_REQUEST,
+    // The URL to place in the first line of an HTTP proxy request. This includes scheme, host,
+    // path, and query, but omits userInfo (which should be used to construct the Authorization
+    // header) and fragment (which should not be transmitted).
+
+    HTTP_REQUEST
+    // The path to place in the first line of a regular HTTP request. This includes only the path
+    // and query. Scheme, user, host, and fragment are omitted.
+  };
+
+  kj::String toString(Context context = GENERAL) const;
+  // Convert the URL to a string.
+
+  static Url parse(StringPtr text, Context context = GENERAL);
+  static Maybe<Url> tryParse(StringPtr text, Context context = GENERAL);
+  // Parse an absolute URL.
+
+  Url parseRelative(StringPtr relative) const;
+  Maybe<Url> tryParseRelative(StringPtr relative) const;
+  // Parse a relative URL string with this URL as the base.
+};
+
+} // namespace kj
+
+#endif // KJ_COMPAT_URL_H_