Merge the dart:uri library into dart:core and update the Uri class

sdk/lib/core/uri.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+part of dart.core;
+
+/**
+ * A parsed URI, as specified by RFC-3986, http://tools.ietf.org/html/rfc3986.

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

More documentation here, please.
Describe the parts (scheme, authority (I don't know what that means), etc).

[Søren Gjesse, 2013/05/28 13:33:26]

I absolutely agree. However I will like to postpone updating the comments to a
separate CL.

+ */
+class Uri {
+  int _port;
+
+  /**
+   * Returns the scheme.

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Returns the scheme component of this URI.

Generally, consider adding "component" after the component parts (and I think
it's event "fragment identifier component").

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+   *
+   * Returns the empty string if there is no scheme.
+   */
+  final String scheme;
+
+  /**
+   * Returns the authority.
+   *
+   * The authority is formatted from the [userInfo], [host] and [port]
+   * components.
+   *
+   * Returns the empty string if there is no authority.

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Why empty string and not, e.g., null?
(I assume it is because then you can just concatenate the parts to get the
whole, but maybe state that in the class documentation: we chose to return empty
strings because ...).

[Søren Gjesse, 2013/05/28 13:33:26]

This is not changed from the current behavior in dart:uri. I was tempted to
change it from the empty string to null. When this is landed I will try to see
if it is feasible.

+   */
+  String get authority {
+    if (!hasAuthority) return "";
+    var sb =  new StringBuffer();

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Two spaces after "=".

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+    _writeAuthority(sb);
+    return sb.toString();
+  }

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Add empty line.

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+  /**
+   * Returns the user info part of the authority.
+   *
+   * Returns the empty string if there is no user info in the authority.
+   */
+  final String userInfo;
+
+  /**
+   * Returns the host part of the authority.
+   *
+   * Returns the empty string if there is no authority and hence no host.
+   */
+  final String host;
+
+  /**
+   * Returns the port part of the authority.
+   *
+   * Returns 0 if there is no port in the authority.

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

I can see "port zero is a wildcard" as precedented by TCP/UDP bind function, but
I don't see it making a lot of sense as a URI default - it's never the correct
port at the other end. 
Are we sure there is no schemes where port zero may be a valid port?
How about using null?

[Søren Gjesse, 2013/05/28 13:33:26]

Again this is the behavior from the current dart:uir, and again it makes sense
to change it.

+   */
+  int get port => _port;
+
+  /**
+   * Returns the path.
+   *
+   * The returned path is encoded. To get direct access to the decoded

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Encoded how, and encoded from what?
The version that is not encoded is "uncoded" (or raw?), not "decoded". Referring
to both the "encoded" and the "decoded" in the same context makes it not obvious
what they are relative to, and if there is a third "normal" version as well.

[Søren Gjesse, 2013/05/28 13:33:26]

I agree. I think adding a general comment above about when components are
encoded/decoded and that the accessors (except for pathSegments and
queryParameters) return the literal URI component value.

+   * path use [pathSegments].
+   *
+   * Returns the empty string if there is no path.
+   */
+  final String path;
+
+  /**
+   * Returns the URI query. The returned query is encoded. To get

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Ditto for encoded: What has been encoded and how?

[Søren Gjesse, 2013/05/28 13:33:26]

See above.

+   * direct access to the decoded query use [queryParameters].
+   *
+   * Returns the empty string if there is no query.
+   */
+  final String query;
+
+  /**
+   * Returns the fragment.
+   *
+   * Returns the empty string if there is no fragment.

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Is there a way to distinguish:
  foo:bar#
from
  foo:bar
?
Is it relevant? :)

[Søren Gjesse, 2013/05/28 13:33:26]

No and I don't think so. We could use null vs. the empty string if we really
want, but that will be pretty subtle.

+   */
+  final String fragment;
+
+  /**
+   * Creates a new URI object by parsing a URI string.
+   */
+  static Uri parse(String uri) => new Uri._fromMatch(_splitRe.firstMatch(uri));
+
+  Uri._fromMatch(Match m) :
+    this(scheme: _emptyIfNull(m[_COMPONENT_SCHEME]),
+         userInfo: _emptyIfNull(m[_COMPONENT_USER_INFO]),
+         host: _eitherOf(
+         m[_COMPONENT_HOST], m[_COMPONENT_HOST_IPV6]),
+         port: _parseIntOrZero(m[_COMPONENT_PORT]),
+         path: _emptyIfNull(m[_COMPONENT_PATH]),
+         query: _emptyIfNull(m[_COMPONENT_QUERY_DATA]),
+         fragment: _emptyIfNull(m[_COMPONENT_FRAGMENT]));
+
+  /*
+   * Create a new URI from its components.
+   *
+   * Each component is set through a named argument. Any number of
+   * components can be provided. The default value for the components
+   * not provided is the empry string, except for [port] which has a
+   * default value of 0. The [path] and [query] components can be set
+   * using two different named arguments.
+   *
+   * The scheme component is set through [scheme]. The scheme is
+   * normalized to all lowercase letters.
+   *
+   * The user info part of the authority component is set through
+   * [userInfo].
+   *
+   * The host part of the authority component is set through
+   * [host]. The host can either be a hostname, a IPv4 address or an
+   * IPv6 address, contained in '[' and ']'. If the host contains a
+   * ':' character, the '[' and ']' are added if not already provided.
+   *
+   * The port part of the authority component is set through
+   * [port]. The port is normalized for scheme http and https where
+   * port 80 and port 443 respectively is set.
+   *
+   * The path component is set through either [path] or
+   * [pathSegments]. When [path] is used, the provided string is
+   * expected to be fully percent-encoded, and is used in its literal
+   * form. When [pathSegments] is used, each of the provided segments
+   * is percent-encoded and joined using the forward slash
+   * separator. The percent-encoding of the path segments encodes all
+   * characters except for the unreserved characters and the following
+   * list of characters: `!$&'()*+,;=:@`.
+   *
+   * The query component is set through either [query] or
+   * [queryParameters]. When [query] is used the provided string is
+   * expected to be fully percent-encoded and is used in its literal
+   * form. When [queryParameters] is used the query is built from the
+   * provided map. Each key and value in the map is percent-encoded
+   * and joined using equal and ampersand characters. The
+   * percent-encoding of the keys and values encodes all characters
+   * except for the unreserved characters.
+   *
+   * The fragment component is set through [fragment].
+   */
+  Uri({scheme,
+       this.userInfo: "",
+       this.host: "",
+       port: 0,
+       String path,
+       List<String> pathSegments,
+       String query,
+       Map<String, String> queryParameters,
+       fragment: ""}) :
+      scheme = _makeScheme(scheme),
+      path = _makePath(path, pathSegments),
+      query = _makeQuery(query, queryParameters),
+      fragment = _makeFragment(fragment) {
+    // Perform scheme specific normalization.
+    if (scheme == "http" && port == 80) {
+      _port = 0;
+    } else if (scheme == "https" && port == 443) {
+      _port =  0;
+    } else {
+      _port =  port;
+    }
+  }
+
+  /*
+   * Returns the URI path split into its segments. Each of the
+   * segments in the returned list have been decoded. If the path is
+   * empty the empty list will be returned.
+   */
+  List<String> get pathSegments {
+    if (path == "") return const<String>[];
+    return path.split("/").map(Uri.decodeComponent).toList(growable: false);
+  }
+
+  /*
+   * Returns the URI query split into a map according to the rules
+   * specified for FORM post in the HTML 4.01 specification. Each key
+   * and value in the returned map have been decoded. If there is no
+   * query the empty map will be returned.
+   */
+  Map<String, String> get queryParameters {
+    return query.split("&").fold({}, (map, element) {
+        int index = element.indexOf("=");
+        if (index == -1) {
+          if (!element.isEmpty) map[element] = "";
+        } else if (index != 0) {
+          var key = element.substring(0, index);
+          var value = element.substring(index + 1);
+          map[Uri.decodeQueryComponent(key)] = decodeQueryComponent(value);
+        }
+        return map;
+    });
+  }
+
+  static String _makeScheme(String scheme) {
+    bool isSchemeLowerCharacter(int ch) {
+      return ch < 128 &&
+             ((_schemeLowerTable[ch >> 4] & (1 << (ch & 0x0f))) != 0);
+    }
+
+    bool isSchemeCharacter(int ch) {
+      return ch < 128 && ((_schemeTable[ch >> 4] & (1 << (ch & 0x0f))) != 0);
+    }
+
+    if (scheme == null) return "";
+    bool allLowercase = true;
+    int length = scheme.length;
+    for (int i = 0; i < length; i++) {
+      int codeUnit = scheme.codeUnitAt(i);
+      if (!isSchemeLowerCharacter(codeUnit)) {
+        if (isSchemeCharacter(codeUnit)) {
+          allLowercase = false;
+        } else {
+          throw new ArgumentError('Illegal scheme: $scheme');
+        }
+      }
+    }
+
+    return allLowercase ? scheme : scheme.toLowerCase();
+  }
+
+  static String _makePath(String path, List<String> pathSegments) {
+    if (path == null && pathSegments == null) return "";
+    if (path != null && pathSegments != null) {
+      throw new ArgumentError('Both path and pathSegments specified');
+    }
+    if (path != null) return _normalize(path);
+
+    return pathSegments.map((s) => _uriEncode(_pathCharTable, s)).join("/");
+  }
+
+  static String _makeQuery(String query, Map<String, String> queryParameters) {
+    if (query == null && queryParameters == null) return "";
+    if (query != null && queryParameters != null) {
+      throw new ArgumentError('Both query and queryParameters specified');
+    }
+    if (query != null) return _normalize(query);
+
+    var result = new StringBuffer();
+    var first = true;
+    queryParameters.forEach((key, value) {
+      if (!first) {
+        result.write("&");
+      }
+      first = false;
+      result.write(Uri.encodeQueryComponent(key));
+      if (value != null && !value.isEmpty) {
+        result.write("=");
+        result.write(Uri.encodeQueryComponent(value));
+      }
+    });
+    return result.toString();
+  }
+
+  static String _makeFragment(String fragment) {
+    if (fragment == null) return "";
+    return _normalize(fragment);
+  }
+
+  static String _normalize(String component) {
+    bool isNormalizedHexDigit(int digit) {
+      return (_ZERO <= digit && digit <= _NINE) ||
+          (_UPPER_CASE_A <= digit && digit <= _UPPER_CASE_F);
+    }
+
+    bool isLowerCaseHexDigit(int digit) {
+      return _LOWER_CASE_A <= digit && digit <= _LOWER_CASE_F;
+    }
+
+    bool isUnreserved(int ch) {
+      return ch < 128 &&
+             ((_unreservedTable[ch >> 4] & (1 << (ch & 0x0f))) != 0);
+    }
+
+    int normalizeHexDigit(int index) {
+      var codeUnit = component.codeUnitAt(index);
+      if (isLowerCaseHexDigit(codeUnit)) {
+        return codeUnit - 0x20;
+      } else if (!isNormalizedHexDigit(codeUnit)) {
+        throw new ArgumentError("Invalid URI component: $component");
+      } else {
+        return codeUnit;
+      }
+    }
+
+    int decodeHexDigitPair(int index) {
+      int byte = 0;
+      for (int i = 0; i < 2; i++) {
+        var codeUnit = component.codeUnitAt(index + i);
+        if (_ZERO <= codeUnit && codeUnit <= _NINE) {
+          byte = byte * 16 + codeUnit - _ZERO;
+        } else {
+          // Check ranges A-F (0x41-0x46) and a-f (0x61-0x66).
+          codeUnit |= 0x20;
+          if (_LOWER_CASE_A <= codeUnit &&
+              codeUnit <= _LOWER_CASE_F) {
+            byte = byte * 16 + codeUnit - _LOWER_CASE_A + 10;
+          } else {
+            throw new ArgumentError(
+                "Invalid percent-encoding in URI component: $component");
+          }
+        }
+      }
+      return byte;
+    }
+
+    // Start building the normalized component string.
+    StringBuffer result;
+    int length = component.length;
+    int index = 0;
+    int prevIndex = 0;
+    while (index < length) {
+
+      // Copy a part of the component string to the result.
+      fillResult() {
+        if (result == null) {
+          assert(prevIndex == 0);
+          result = new StringBuffer(component.substring(prevIndex, index));
+        } else {
+          result.write(component.substring(prevIndex, index));
+        }
+      }
+
+      // Normalize percent encoding to uppercase and don't encode
+      // unreserved characters.
+      if (component.codeUnitAt(index) == _PERCENT) {
+        if (length < index + 2) {
+            throw new ArgumentError(
+                "Invalid percent-encoding in URI component: $component");
+        }
+
+        var codeUnit1 = component.codeUnitAt(index + 1);
+        var codeUnit2 = component.codeUnitAt(index + 2);
+        var decodedCodeUnit = decodeHexDigitPair(index + 1);
+        if (isNormalizedHexDigit(codeUnit1) &&
+            isNormalizedHexDigit(codeUnit2) &&
+            !isUnreserved(decodedCodeUnit)) {
+          index += 3;
+        } else {
+          fillResult();
+          if (isUnreserved(decodedCodeUnit)) {
+            result.writeCharCode(decodedCodeUnit);
+          } else {
+            result.write("%");
+            result.writeCharCode(normalizeHexDigit(index + 1));
+            result.writeCharCode(normalizeHexDigit(index + 2));
+          }
+          index += 3;
+          prevIndex = index;
+        }
+      } else {
+        index++;
+      }
+    }
+    assert(index == length);
+
+    if (result == null) return component;
+    return result.toString();
+  }
+
+  static String _emptyIfNull(String val) => val != null ? val : '';
+
+  static int _parseIntOrZero(String val) {
+    if (val != null && val != '') {
+      return int.parse(val);
+    } else {
+      return 0;
+    }
+  }
+
+  static String _eitherOf(String val1, String val2) {
+    if (val1 != null) return val1;
+    if (val2 != null) return val2;
+    return '';
+  }
+
+  // NOTE: This code was ported from: closure-library/closure/goog/uri/utils.js
+  static final RegExp _splitRe = new RegExp(
+      '^'
+      '(?:'
+        '([^:/?#.]+)'                   // scheme - ignore special characters
+                                        // used by other URL parts such as :,
+                                        // ?, /, #, and .
+      ':)?'
+      '(?://'
+        '(?:([^/?#]*)@)?'               // userInfo
+        '(?:'
+          r'([\w\d\-\u0100-\uffff.%]*)'
+                                        // host - restrict to letters,
+                                        // digits, dashes, dots, percent
+                                        // escapes, and unicode characters.

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Why are we restricting more than the RegExp in the RFC?

[Søren Gjesse, 2013/05/28 13:33:26]

Currently RegExp is also parsing the user info, host and port parts from the
authority.

+          '|'
+          // TODO(ajohnsen): Only allow a max number of parts?
+          r'\[([A-Fa-f0-9:.]*)\])'
+                                        // IPv6 host - restrict to hex,
+                                        // dot and colon.
+        '(?::([0-9]+))?'                // port
+      ')?'
+      r'([^?#[]+)?'                     // path
+      r'(?:\?([^#]*))?'                 // query
+      '(?:#(.*))?'                      // fragment
+      r'$');
+
+  static const _COMPONENT_SCHEME = 1;
+  static const _COMPONENT_USER_INFO = 2;
+  static const _COMPONENT_HOST = 3;
+  static const _COMPONENT_HOST_IPV6 = 4;
+  static const _COMPONENT_PORT = 5;
+  static const _COMPONENT_PATH = 6;
+  static const _COMPONENT_QUERY_DATA = 7;
+  static const _COMPONENT_FRAGMENT = 8;
+
+  /**
+   * Returns `true` if the URI is absolute.
+   */
+  bool get isAbsolute {
+    if ("" == scheme) return false;
+    if ("" != fragment) return false;
+    return true;

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

just:
  return scheme != "" && fragment == "";
More readable!

I don't think adding a fragment identifier will make an otherwise absolute URI
not absolute. Fragments are orthogonal to URIs (they don't specify the resource,
they refer to the content of the resource). I.e., change this to just:
  return scheme != "";

[Søren Gjesse, 2013/05/28 13:33:26]

Change the formatting.

The spec says "...calls for an absolute-URI syntax rule that does not allow a
fragment."

+  }
+
+  String _merge(String base, String reference) {
+    if (base == "") return "/$reference";
+    return "${base.substring(0, base.lastIndexOf("/") + 1)}$reference";
+  }
+
+  String _removeDotSegments(String path) {
+    List<String> output = [];
+    bool appendSlash = false;
+    for (String segment in path.split("/")) {

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Seems like overkill to split and rebuild every time.
How about checking for the occurrence of '/.' in the string first, 
and check if it is followed by '/' or './', and just return path
if nothing is found?

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+      appendSlash = false;
+      if (segment == "..") {
+        if (!output.isEmpty &&
+            ((output.length != 1) || (output[0] != ""))) output.removeLast();
+        appendSlash = true;
+      } else if ("." == segment) {
+        appendSlash = true;
+      } else {
+        output.add(segment);
+      }
+    }
+    if (appendSlash) output.add("");
+    return output.join("/");
+  }
+
+  Uri resolve(String uri) {
+    return resolveUri(Uri.parse(uri));
+  }
+
+  Uri resolveUri(Uri reference) {
+    // From RFC 3986.
+    String targetScheme;
+    String targetUserInfo;
+    String targetHost;
+    int targetPort;
+    String targetPath;
+    String targetQuery;
+    if (reference.scheme != "") {
+      targetScheme = reference.scheme;
+      targetUserInfo = reference.userInfo;
+      targetHost = reference.host;
+      targetPort = reference.port;
+      targetPath = _removeDotSegments(reference.path);
+      targetQuery = reference.query;
+    } else {
+      if (reference.hasAuthority) {
+        targetUserInfo = reference.userInfo;
+        targetHost = reference.host;
+        targetPort = reference.port;
+        targetPath = _removeDotSegments(reference.path);
+        targetQuery = reference.query;
+      } else {
+        if (reference.path == "") {
+          targetPath = this.path;
+          if (reference.query != "") {
+            targetQuery = reference.query;
+          } else {
+            targetQuery = this.query;
+          }
+        } else {
+          if (reference.path.startsWith("/")) {
+            targetPath = _removeDotSegments(reference.path);
+          } else {
+            targetPath = _removeDotSegments(_merge(this.path, reference.path));
+          }
+          targetQuery = reference.query;
+        }
+        targetUserInfo = this.userInfo;
+        targetHost = this.host;
+        targetPort = this.port;
+      }
+      targetScheme = this.scheme;
+    }
+    return new Uri(scheme: targetScheme,
+                   userInfo: targetUserInfo,
+                   host: targetHost,
+                   port: targetPort,
+                   path: targetPath,
+                   query: targetQuery,
+                   fragment: reference.fragment);
+  }
+
+  bool get hasAuthority => host != "";
+
+  /**
+   * Returns the origin of the URI in the form scheme://host:port for the
+   * schemes http and https.
+   *
+   * Throws StateError if the scheme is not http or https.

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Just say "It is an error if ...".
Quote "http" and "https".

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+   *
+   * See: http://www.w3.org/TR/2011/WD-html5-20110405/origin-0.html#origin
+   */
+  String get origin {
+    if (scheme == "" || host == null || host == "") {
+      throw new StateError("Cannot use origin without a scheme: $this");
+    }
+    if (scheme != "http" && scheme != "https") {
+      throw new StateError(
+        "Origin is only applicable schemes http and https: $this");
+    }
+    if (port == 0) return "$scheme://$host";
+    return "$scheme://$host:$port";
+  }
+
+  void _writeAuthority(StringSink ss) {
+    _addIfNonEmpty(ss, userInfo, userInfo, "@");
+    ss.write(host == null ? "null" :
+             host.contains(':') ? '[$host]' : host);
+    if (port != 0) {
+      ss.write(":");
+      ss.write(port.toString());
+    }
+  }
+
+  String toString() {
+    StringBuffer sb = new StringBuffer();
+    _addIfNonEmpty(sb, scheme, scheme, ':');
+    if (hasAuthority || (scheme == "file")) {
+      sb.write("//");
+      _writeAuthority(sb);
+    }
+    sb.write(path);
+    _addIfNonEmpty(sb, query, "?", query);
+    _addIfNonEmpty(sb, fragment, "#", fragment);
+    return sb.toString();
+  }
+
+  bool operator==(other) {
+    if (other is! Uri) return false;
+    Uri uri = other;
+    return scheme == uri.scheme &&
+        userInfo == uri.userInfo &&
+        host == uri.host &&
+        port == uri.port &&
+        path == uri.path &&
+        query == uri.query &&
+        fragment == uri.fragment;
+  }
+
+  int get hashCode {
+    int combine(part, current) {
+      // The sum is truncated to 30 bits to make sure it fits into a Smi.
+      return (current * 31 + part.hashCode) & 0x3FFFFFFF;
+    }
+    return combine(scheme, combine(userInfo, combine(host, combine(port,
+        combine(path, combine(query, combine(fragment, 1)))))));
+  }
+
+  static void _addIfNonEmpty(StringBuffer sb, String test,
+                             String first, String second) {
+    if ("" != test) {
+      sb.write(first == null ? "null" : first);

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Since null.toString() == "null", just write
  sb.write(first); 
  sb.write(second);

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+      sb.write(second == null ? "null" : second);
+    }
+  }
+
+  /**
+   * Encode the string [component] using percent-encoding to make it

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

I prefer "URL encoding" to "percent-encoding".
Is it worth writing that this is the URL-encoding of the UTF-8 encoded character
data?

[Søren Gjesse, 2013/05/28 13:33:26]

I would like to address the comments in a separate CL. Btw. the spec. calls it
percent-encoding.

+   * safe for literal use as a URI component.
+   *
+   * All characters except uppercase and lowercase letters, digits and
+   * the characters `!$&'()*+,;=:@` are percent-encoded. This is the
+   * set of characters specified in RFC 2396 and the which is
+   * specified for the encodeUriComponent in ECMA-262 version 5.1.
+   *
+   * When manually encoding path segments or query components remember
+   * to encode each part separately before building the path or query
+   * string.
+   *
+   * For encoding the query part consider using
+   * [encodeQueryComponent].
+   *
+   * To avoid the need for explicitly encoding use the [pathSegments]
+   * and [queryParameters] optional named arguments when constructing
+   * a Uri.

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Uri -> [Uri].

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+   */
+  static String encodeComponent(String component) {
+    return _uriEncode(_unreserved2396Table, component);
+  }
+
+  /*
+   * Encode the string [component] according to the HTML 4.01 rules
+   * for encoding the posting of a HTML form as a query string
+   * component.
+   *
+   * Spaces will be replaced with plus and all characters except for
+   * uppercase and lowercase letters, decimal digits and the
+   * characters `-._~`. Note that the set of characters encoded is a
+   * superset of what HTML 4.01 says as it refers to RFC 1738 for
+   * reserved characters.
+   *
+   * When manually encoding query components remember to encode each
+   * part separately before building the query string.
+   *
+   * To avoid the need for explicitly encoding the query use the
+   * [queryParameters] optional named arguments when constructing a
+   * URI.
+   *
+   * See http://www.w3.org/TR/html401/interact/forms.html#h-17.13.4.2 for more
+   * details.
+   */
+  static String encodeQueryComponent(String component) {
+    return _uriEncode(_unreservedTable, component, spaceToPlus: true);
+  }
+
+  /**
+   * Decodes the percent-encoding in [encodedComponent].
+   *
+   * Note that decoding a URI component might change its meaning as
+   * some of the decoded characters could be characters with are
+   * delimiters for a given URI componene type. Always split a URI
+   * component using the delimiters for the component before decoding
+   * the individual parts.
+   *
+   * For handling the [path] and [query] components consider using
+   * [pathSegments] and [queryParameters] to get the separated and
+   * decoded component.
+   */
+  static String decodeComponent(String encodedComponent) {
+    return _uriDecode(encodedComponent);
+  }
+
+  static String decodeQueryComponent(String encodedComponent) {
+    return _uriDecode(encodedComponent, plusToSpace: true);
+  }
+
+  /**
+   * Encode the string [uri] using percent-encoding to make it
+   * safe for literal use as a full URI.
+   *
+   * All characters except uppercase and lowercase letters, digits and
+   * the characters `!#$&'()*+,-./:;=?@_~` are percent-encoded. This
+   * is the set of characters specified in in ECMA-262 version 5.1 for
+   * the encodeURI function .
+   */
+  static String encodeFull(String uri) {
+    return _uriEncode(_encodeFullTable, uri);
+  }
+
+  /**
+   * Decodes the percent-encoding in [uri].
+   *
+   * Note that decoding a full URI might change its meaning as some of
+   * the decoded characters could be reserved characters. In most
+   * cases an encoded URI should be parsed into components using
+   * [Uri.parse] before decoding the separate components.
+   */
+  static String decodeFull(String uri) {
+    return _uriDecode(uri);
+  }
+
+  // Frequently used character codes.
+  static const int _PERCENT = 0x25;
+  static const int _ZERO = 0x30;
+  static const int _NINE = 0x39;
+  static const int _UPPER_CASE_A = 0x41;
+  static const int _UPPER_CASE_F = 0x46;
+  static const int _LOWER_CASE_A = 0x61;
+  static const int _LOWER_CASE_F = 0x66;
+
+  /**
+   * This is the internal implementation of JavaScript's encodeURI function.
+   * It encodes all characters in the string [text] except for those
+   * that appear in [canonicalTable], and returns the escaped string.
+   */
+  static String _uriEncode(List<int> canonicalTable,
+                    String text,
+                    {bool spaceToPlus: false}) {
+    byteToHex(int v) {
+      final String hex = '0123456789ABCDEF';
+      return '%${hex[v >> 4]}${hex[v & 0x0f]}';
+    }
+
+    StringBuffer result = new StringBuffer();
+    for (int i = 0; i < text.length; i++) {
+      int ch = text.codeUnitAt(i);
+      if (ch < 128 && ((canonicalTable[ch >> 4] & (1 << (ch & 0x0f))) != 0)) {
+        result.write(text[i]);
+      } else if (spaceToPlus && text[i] == " ") {
+        result.write("+");
+      } else {
+        if (ch >= 0xD800 && ch < 0xDC00) {
+          // Low surrogate. We expect a next char high surrogate.
+          ++i;
+          int nextCh = text.length == i ? 0 : text.codeUnitAt(i);
+          if (nextCh >= 0xDC00 && nextCh < 0xE000) {
+            // convert the pair to a U+10000 codepoint
+            ch = 0x10000 + ((ch - 0xD800) << 10) + (nextCh - 0xDC00);
+          } else {
+            throw new ArgumentError('Malformed URI');
+          }
+        }
+        for (int codepoint in codepointsToUtf8([ch])) {
+          result.write(byteToHex(codepoint));
+        }
+      }
+    }
+    return result.toString();
+  }
+
+  /**
+   * Convert a byte (2 character hex sequence) in string [s] starting
+   * at position [pos] to its ordinal value
+   */
+  static int _hexCharPairToByte(String s, int pos) {
+    int byte = 0;
+    for (int i = 0; i < 2; i++) {
+      var charCode = s.codeUnitAt(pos + i);
+      if (0x30 <= charCode && charCode <= 0x39) {
+        byte = byte * 16 + charCode - 0x30;
+      } else {
+        // Check ranges A-F (0x41-0x46) and a-f (0x61-0x66).
+        charCode |= 0x20;
+        if (0x61 <= charCode && charCode <= 0x66) {
+          byte = byte * 16 + charCode - 0x57;
+        } else {
+          throw new ArgumentError("Invalid URL encoding");
+        }
+      }
+    }
+    return byte;
+  }
+
+  /**
+   * A JavaScript-like decodeURI function. It unescapes the string [text] and
+   * returns the unescaped string.
+   */
+  static String _uriDecode(String text, {bool plusToSpace: false}) {
+    StringBuffer result = new StringBuffer();
+    List<int> codepoints = new List<int>();
+    for (int i = 0; i < text.length;) {
+    String ch = text[i];

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

Consider using text.codeUnitAt(i) and work with code units instead of singleton
strings.
I know the VM will optimize singleton strings, but I'd still want to see if it's
faster to work on integers.

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+    if (ch != '%') {
+      if (plusToSpace && ch == '+') {
+        result.write(" ");
+      } else {
+        result.write(ch);
+      }
+      i++;
+    } else {
+      codepoints.clear();
+      while (ch == '%') {
+        if (++i > text.length - 2) {
+          throw new ArgumentError('Truncated URI');
+        }
+        codepoints.add(_hexCharPairToByte(text, i));
+        i += 2;
+        if (i == text.length)
+          break;

[Lasse Reichstein Nielsen, 2013/05/28 08:45:33]

break on line above, or add braces.

[Søren Gjesse, 2013/05/28 13:33:26]

Done.

+        ch = text[i];
+      }
+      result.write(decodeUtf8(codepoints));
+    }
+    }
+    return result.toString();
+  }
+
+  // Tables of char-codes organized as a bit vector of 128 bits where
+  // each bit indicate whether a character code on the 0-127 needs to
+  // be escaped or not.
+
+  // The unreserved characters of RFC 3986.
+  static const _unreservedTable = const [
+                //             LSB            MSB
+                //              |              |
+      0x0000,   // 0x00 - 0x0f  0000000000000000
+      0x0000,   // 0x10 - 0x1f  0000000000000000
+                //                           -.
+      0x6000,   // 0x20 - 0x2f  0000000000000110
+                //              0123456789
+      0x03ff,   // 0x30 - 0x3f  1111111111000000
+                //               ABCDEFGHIJKLMNO
+      0xfffe,   // 0x40 - 0x4f  0111111111111111
+                //              PQRSTUVWXYZ    _
+      0x87ff,   // 0x50 - 0x5f  1111111111100001
+                //               abcdefghijklmno
+      0xfffe,   // 0x60 - 0x6f  0111111111111111
+                //              pqrstuvwxyz   ~
+      0x47ff];  // 0x70 - 0x7f  1111111111100010
+
+  // The unreserved characters of RFC 2396.
+  static const _unreserved2396Table = const [
+                //             LSB            MSB
+                //              |              |
+      0x0000,   // 0x00 - 0x0f  0000000000000000
+      0x0000,   // 0x10 - 0x1f  0000000000000000
+                //               !     '()*  -.
+      0x6782,   // 0x20 - 0x2f  0100000111100110
+                //              0123456789
+      0x03ff,   // 0x30 - 0x3f  1111111111000000
+                //               ABCDEFGHIJKLMNO
+      0xfffe,   // 0x40 - 0x4f  0111111111111111
+                //              PQRSTUVWXYZ    _
+      0x87ff,   // 0x50 - 0x5f  1111111111100001
+                //               abcdefghijklmno
+      0xfffe,   // 0x60 - 0x6f  0111111111111111
+                //              pqrstuvwxyz   ~
+      0x47ff];  // 0x70 - 0x7f  1111111111100010
+
+  // Table of reserved characters specified by ECMAScript 5.
+  static const _encodeFullTable = const [
+                //             LSB            MSB
+                //              |              |
+      0x0000,   // 0x00 - 0x0f  0000000000000000
+      0x0000,   // 0x10 - 0x1f  0000000000000000
+                //               ! #$ &'()*+,-./
+      0xf7da,   // 0x20 - 0x2f  0101101111101111
+                //              0123456789:; = ?
+      0xafff,   // 0x30 - 0x3f  1111111111110101
+                //              @ABCDEFGHIJKLMNO
+      0xffff,   // 0x40 - 0x4f  1111111111111111
+                //              PQRSTUVWXYZ    _
+      0x87ff,   // 0x50 - 0x5f  1111111111100001
+                //               abcdefghijklmno
+      0xfffe,   // 0x60 - 0x6f  0111111111111111
+                //              pqrstuvwxyz   ~
+      0x47ff];  // 0x70 - 0x7f  1111111111100010
+
+  // Characters allowed in the scheme.
+  static const _schemeTable = const [
+                //             LSB            MSB
+                //              |              |
+      0x0000,   // 0x00 - 0x0f  0000000000000000
+      0x0000,   // 0x10 - 0x1f  0000000000000000
+                //                         + -.
+      0x6800,   // 0x20 - 0x2f  0000000000010110
+                //              0123456789
+      0x03ff,   // 0x30 - 0x3f  1111111111000000
+                //               ABCDEFGHIJKLMNO
+      0xfffe,   // 0x40 - 0x4f  0111111111111111
+                //              PQRSTUVWXYZ
+      0x07ff,   // 0x50 - 0x5f  1111111111100001
+                //               abcdefghijklmno
+      0xfffe,   // 0x60 - 0x6f  0111111111111111
+                //              pqrstuvwxyz
+      0x07ff];  // 0x70 - 0x7f  1111111111100010
+
+  // Characters allowed in scheme except for upper case letters.
+  static const _schemeLowerTable = const [
+                //             LSB            MSB
+                //              |              |
+      0x0000,   // 0x00 - 0x0f  0000000000000000
+      0x0000,   // 0x10 - 0x1f  0000000000000000
+                //                         + -.
+      0x6800,   // 0x20 - 0x2f  0000000000010110
+                //              0123456789
+      0x03ff,   // 0x30 - 0x3f  1111111111000000
+                //
+      0x0000,   // 0x40 - 0x4f  0111111111111111
+                //
+      0x0000,   // 0x50 - 0x5f  1111111111100001
+                //               abcdefghijklmno
+      0xfffe,   // 0x60 - 0x6f  0111111111111111
+                //              pqrstuvwxyz
+      0x07ff];  // 0x70 - 0x7f  1111111111100010
+
+  // Sub delimiter characters combined with unreserved as of 3986.
+  // sub-delims  = "!" / "$" / "&" / "'" / "(" / ")"
+  //             / "*" / "+" / "," / ";" / "="
+  // RFC 3986 section 2.3.
+  // unreserved  = ALPHA / DIGIT / "-" / "." / "_" / "~"
+  static const _subDelimitersTable = const [
+                //             LSB            MSB
+                //              |              |
+      0x0000,   // 0x00 - 0x0f  0000000000000000
+      0x0000,   // 0x10 - 0x1f  0000000000000000
+                //               !  $ &'()*+,-.
+      0x7fd2,   // 0x20 - 0x2f  0100101111111110
+                //              0123456789 ; =
+      0x2bff,   // 0x30 - 0x3f  1111111111010100
+                //               ABCDEFGHIJKLMNO
+      0xfffe,   // 0x40 - 0x4f  0111111111111111
+                //              PQRSTUVWXYZ    _
+      0x87ff,   // 0x50 - 0x5f  1111111111100001
+                //               abcdefghijklmno
+      0xfffe,   // 0x60 - 0x6f  0111111111111111
+                //              pqrstuvwxyz   ~
+      0x47ff];  // 0x70 - 0x7f  1111111111100010
+
+  // Characters allowed in the path as of RFC 3986.
+  // RFC 3986 section 3.3.
+  // pchar = unreserved / pct-encoded / sub-delims / ":" / "@"
+  static const _pathCharTable = const [
+                //             LSB            MSB
+                //              |              |
+      0x0000,   // 0x00 - 0x0f  0000000000000000
+      0x0000,   // 0x10 - 0x1f  0000000000000000
+                //               !  $ &'()*+,-.
+      0x7fd2,   // 0x20 - 0x2f  0100101111111110
+                //              0123456789:; =
+      0x2fff,   // 0x30 - 0x3f  1111111111110100
+                //              @ABCDEFGHIJKLMNO
+      0xffff,   // 0x40 - 0x4f  1111111111111111
+                //              PQRSTUVWXYZ    _
+      0x87ff,   // 0x50 - 0x5f  1111111111100001
+                //               abcdefghijklmno
+      0xfffe,   // 0x60 - 0x6f  0111111111111111
+                //              pqrstuvwxyz   ~
+      0x47ff];  // 0x70 - 0x7f  1111111111100010
+
+  // Characters allowed in the query as of RFC 3986.
+  // RFC 3986 section 3.4.
+  // query = *( pchar / "/" / "?" )
+  static const _queryCharTable = const [
+                //             LSB            MSB
+                //              |              |
+      0x0000,   // 0x00 - 0x0f  0000000000000000
+      0x0000,   // 0x10 - 0x1f  0000000000000000
+                //               !  $ &'()*+,-./
+      0xffd2,   // 0x20 - 0x2f  0100101111111111
+                //              0123456789:; = ?
+      0xafff,   // 0x30 - 0x3f  1111111111110101
+                //              @ABCDEFGHIJKLMNO
+      0xffff,   // 0x40 - 0x4f  1111111111111111
+                //              PQRSTUVWXYZ    _
+      0x87ff,   // 0x50 - 0x5f  1111111111100001
+                //               abcdefghijklmno
+      0xfffe,   // 0x60 - 0x6f  0111111111111111
+                //              pqrstuvwxyz   ~
+      0x47ff];  // 0x70 - 0x7f  1111111111100010
+}