Create a URI class in utils/ (based on client/util/).

dart/utils/uri/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.
+
+#library('uri');
+
+/**
+ * A parsed URI, inspired by:
+ * http://closure-library.googlecode.com/svn/docs/class_goog_Uri.html
+ */
+class Uri {
+  final String scheme;
+  final String userInfo;
+  final String domain;
+  final int port;
+  final String path;
+  final String query;
+  final String fragment;
+
+  /**
+   * Determines whether a URI is absolute.
+   *
+   * See: http://tools.ietf.org/html/rfc3986#section-4.3
+   */
+  bool isAbsolute() {
+    if ("" == scheme) return false;
+    if ("" != fragment) return false;
+    return true;
+
+    /* absolute-URI  = scheme ":" hier-part [ "?" query ]
+     * hier-part   = "//" authority path-abempty
+     *             / path-absolute
+     *             / path-rootless
+     *             / path-empty
+     *
+     * path          = path-abempty    ; begins with "/" or is empty
+     *               / path-absolute   ; begins with "/" but not "//"
+     *               / path-noscheme   ; begins with a non-colon segment
+     *               / path-rootless   ; begins with a segment
+     *               / path-empty      ; zero characters
+     *
+     * path-abempty  = *( "/" segment )
+     * path-absolute = "/" [ segment-nz *( "/" segment ) ]
+     * path-noscheme = segment-nz-nc *( "/" segment )
+     * path-rootless = segment-nz *( "/" segment )
+     * path-empty    = 0<pchar>
+     * segment       = *pchar
+     * segment-nz    = 1*pchar
+     * segment-nz-nc = 1*( unreserved / pct-encoded / sub-delims / "@" )
+     *               ; non-zero-length segment without any colon ":"
+     *
+     * pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"
+     */
+  }
+
+  Uri resolve(String uri) {
+    return resolveUri(new Uri.fromString(uri));
+  }
+
+  Uri resolveUri(Uri reference) {
+    // From RFC 3986.
+    String targetScheme;
+    String targetUserInfo;
+    String targetDomain;
+    int targetPort;
+    String targetPath;
+    String targetQuery;
+    if (reference.scheme != "") {
+      targetScheme = reference.scheme;
+      targetUserInfo = reference.userInfo;
+      targetDomain = reference.domain;
+      targetPort = reference.port;
+      targetPath = removeDotSegments(reference.path);
+      targetQuery = reference.query;
+    } else {
+      if (reference.hasAuthority()) {
+        targetUserInfo = reference.userInfo;
+        targetDomain = reference.domain;
+        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;
+        targetDomain = this.domain;
+        targetPort = this.port;
+      }
+      targetScheme = this.scheme;
+    }
+    return new Uri(targetScheme, targetUserInfo, targetDomain, targetPort,
+                   targetPath, targetQuery, reference.fragment);
+  }
+
+  bool hasAuthority() {
+    return (userInfo != "") || (domain != "") || (port != 0);
+  }
+
+  String toString() {
+    StringBuffer sb = new StringBuffer();
+    _addIfNonEmpty(sb, scheme, scheme, ':');
+    if (hasAuthority() || (scheme == "file")) {
+      sb.add("//");
+      _addIfNonEmpty(sb, userInfo, userInfo, "@");
+      sb.add(domain);
+      if (port != 0) {
+        sb.add(":");
+        sb.add(port.toString());
+      }
+    }
+    sb.add(path);
+    _addIfNonEmpty(sb, query, "?", query);
+    _addIfNonEmpty(sb, fragment, "#", fragment);
+    return sb.toString();
+  }
+
+  static void _addIfNonEmpty(StringBuffer sb, String test,
+                             String first, String second) {
+    if ("" != test) {
+      sb.add(first);
+      sb.add(second);
+    }
+  }
+
+  Uri.fromString(String uri) : this._fromMatch(_splitRe.firstMatch(uri));
+
+  Uri._fromMatch(Match m) : this(_emptyIfNull(m[_COMPONENT_SCHEME]),
+                                 _emptyIfNull(m[_COMPONENT_USER_INFO]),
+                                 _emptyIfNull(m[_COMPONENT_DOMAIN]),
+                                 _parseIntOrZero(m[_COMPONENT_PORT]),
+                                 _emptyIfNull(m[_COMPONENT_PATH]),
+                                 _emptyIfNull(m[_COMPONENT_QUERY_DATA]),
+                                 _emptyIfNull(m[_COMPONENT_FRAGMENT]));
+
+  const Uri([String this.scheme = "", String this.userInfo ="",
+             String this.domain = "", int this.port = 0,
+             String this.path = "", String this.query = "",
+             String this.fragment = ""]);
+
+  static String _emptyIfNull(String val) => val != null ? val : '';
+
+  static int _parseIntOrZero(String val) {
+    if (val !== null && val != '') {
+      return Math.parseInt(val);
+    } else {
+      return 0;
+    }
+  }
+
+  // NOTE: This code was ported from: closure-library/closure/goog/uri/utils.js
+  static RegExp _splitReLazy;
+
+  static RegExp get _splitRe() {
+    if (_splitReLazy == null) {
+      _splitReLazy = new RegExp(
+        '^' +
+        '(?:' +
+          '([^:/?#.]+)' +                 // scheme - ignore special characters
+                                          // used by other URL parts such as :,
+                                          // ?, /, #, and .
+        ':)?' +
+        '(?://' +
+          '(?:([^/?#]*)@)?' +             // userInfo
+          '([\\w\\d\\-\\u0100-\\uffff.%]*)' +
+                                          // domain - restrict to letters,
+                                          // digits, dashes, dots, percent
+                                          // escapes, and unicode characters.
+          '(?::([0-9]+))?' +              // port
+        ')?' +
+        '([^?#]+)?' +                     // path
+        '(?:\\?([^#]*))?' +               // query
+        '(?:#(.*))?' +                    // fragment
+        '\$');
+    }
+    return _splitReLazy;
+  }
+
+  static final _COMPONENT_SCHEME = 1;
+  static final _COMPONENT_USER_INFO = 2;
+  static final _COMPONENT_DOMAIN = 3;
+  static final _COMPONENT_PORT = 4;
+  static final _COMPONENT_PATH = 5;
+  static final _COMPONENT_QUERY_DATA = 6;
+  static final _COMPONENT_FRAGMENT = 7;
+}
+
+testUri(String uri, bool isAbsolute) {
+  Expect.equals(isAbsolute, new Uri.fromString(uri).isAbsolute());
+  Expect.stringEquals(uri, new Uri.fromString(uri).toString());
+}
+
+main() {

[ahe, 2012/01/29 14:38:00]

I'll move this method and testUri to a test case before submitting.

+  testUri("http:", true);
+  testUri("file://", true);
+  testUri("file", false);
+  testUri("http://user@example.com:80/fisk?query=89&hest=silas", true);
+  testUri("http://user@example.com:80/fisk?query=89&hest=silas#fragment",
+          false);
+  Expect.stringEquals("http://user@example.com:80/a/b/c?query#fragment",
+                      const Uri("http", "user", "example.com", 80, "/a/b/c",
+                                "query", "fragment").toString());
+  Expect.stringEquals("null://null@null/a/b/c/?null#null",
+                      const Uri(null, null, null, 0, "/a/b/c/",
+                                null, null).toString());
+  Expect.stringEquals("file://", new Uri.fromString("file:").toString());
+  Expect.stringEquals("/a/g", removeDotSegments("/a/b/c/./../../g"));
+  Expect.stringEquals("mid/6", removeDotSegments("mid/content=5/../6"));
+  Expect.stringEquals("a/b/e", removeDotSegments("a/b/c/d/../../e"));
+  Expect.stringEquals("a/b/e", removeDotSegments("../a/b/c/d/../../e"));
+  Expect.stringEquals("a/b/e", removeDotSegments("./a/b/c/d/../../e"));
+  Expect.stringEquals("a/b/e", removeDotSegments("../a/b/./c/d/../../e"));
+  Expect.stringEquals("a/b/e", removeDotSegments("./a/b/./c/d/../../e"));
+  Expect.stringEquals("a/b/e/", removeDotSegments("./a/b/./c/d/../../e/."));
+  Expect.stringEquals("a/b/e/", removeDotSegments("./a/b/./c/d/../../e/./."));
+  Expect.stringEquals("a/b/e/", removeDotSegments("./a/b/./c/d/../../e/././."));
+
+  // From RFC 3986.
+  Uri base = new Uri.fromString("http://a/b/c/d;p?q");
+  Expect.stringEquals("g:h", base.resolve("g:h").toString());
+  Expect.stringEquals("http://a/b/c/g", base.resolve("g").toString());
+  Expect.stringEquals("http://a/b/c/g", base.resolve("./g").toString());
+  Expect.stringEquals("http://a/b/c/g/", base.resolve("g/").toString());
+  Expect.stringEquals("http://a/g", base.resolve("/g").toString());
+  Expect.stringEquals("http://g", base.resolve("//g").toString());
+  Expect.stringEquals("http://a/b/c/d;p?y", base.resolve("?y").toString());
+  Expect.stringEquals("http://a/b/c/g?y", base.resolve("g?y").toString());
+  Expect.stringEquals("http://a/b/c/d;p?q#s", base.resolve("#s").toString());
+  Expect.stringEquals("http://a/b/c/g#s", base.resolve("g#s").toString());
+  Expect.stringEquals("http://a/b/c/g?y#s", base.resolve("g?y#s").toString());
+  Expect.stringEquals("http://a/b/c/;x", base.resolve(";x").toString());
+  Expect.stringEquals("http://a/b/c/g;x", base.resolve("g;x").toString());
+  Expect.stringEquals("http://a/b/c/g;x?y#s",
+                      base.resolve("g;x?y#s").toString());
+  Expect.stringEquals("http://a/b/c/d;p?q", base.resolve("").toString());
+  Expect.stringEquals("http://a/b/c/", base.resolve(".").toString());
+  Expect.stringEquals("http://a/b/c/", base.resolve("./").toString());
+  Expect.stringEquals("http://a/b/", base.resolve("..").toString());
+  Expect.stringEquals("http://a/b/", base.resolve("../").toString());
+  Expect.stringEquals("http://a/b/g", base.resolve("../g").toString());
+  Expect.stringEquals("http://a/", base.resolve("../..").toString());
+  Expect.stringEquals("http://a/", base.resolve("../../").toString());
+  Expect.stringEquals("http://a/g", base.resolve("../../g").toString());
+  Expect.stringEquals("http://a/g", base.resolve("../../../g").toString());
+  Expect.stringEquals("http://a/g", base.resolve("../../../../g").toString());
+  Expect.stringEquals("http://a/g", base.resolve("/./g").toString());
+  Expect.stringEquals("http://a/g", base.resolve("/../g").toString());
+  Expect.stringEquals("http://a/b/c/g.", base.resolve("g.").toString());
+  Expect.stringEquals("http://a/b/c/.g", base.resolve(".g").toString());
+  Expect.stringEquals("http://a/b/c/g..", base.resolve("g..").toString());
+  Expect.stringEquals("http://a/b/c/..g", base.resolve("..g").toString());
+  Expect.stringEquals("http://a/b/g", base.resolve("./../g").toString());
+  Expect.stringEquals("http://a/b/c/g/", base.resolve("./g/.").toString());
+  Expect.stringEquals("http://a/b/c/g/h", base.resolve("g/./h").toString());
+  Expect.stringEquals("http://a/b/c/h", base.resolve("g/../h").toString());
+  Expect.stringEquals("http://a/b/c/g;x=1/y",
+                      base.resolve("g;x=1/./y").toString());
+  Expect.stringEquals("http://a/b/c/y", base.resolve("g;x=1/../y").toString());
+  Expect.stringEquals("http://a/b/c/g?y/./x",
+                      base.resolve("g?y/./x").toString());
+  Expect.stringEquals("http://a/b/c/g?y/../x",
+                      base.resolve("g?y/../x").toString());
+  Expect.stringEquals("http://a/b/c/g#s/./x",
+                      base.resolve("g#s/./x").toString());
+  Expect.stringEquals("http://a/b/c/g#s/../x",
+                      base.resolve("g#s/../x").toString());

[Bill Hesse, 2012/01/31 10:37:57]

Should you also test parameters in the path elements?
resolve("../g;p/h;s")?

[ahe, 2012/01/31 11:43:00]

That's being tested on lines:

243-246
269-270

But your particular pattern isn't tested (leading ..) and I think it makes sense
to add it.

+  Expect.stringEquals("http:g", base.resolve("http:g").toString());
+}
+
+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("/")) {
+    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 Strings.join(output, "/");
+}