update_homebrew: support version-formatted revisions

tools/apps/update_homebrew/bin/update_homebrew.dart

 // Copyright (c) 2014, 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 update_homebrew;
 
 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
@@ skipping 15 matching lines @@
   'sdk/dartsdk-macos-ia32-release.zip'
 ];
 
 const DARTIUM_FILES = const [
   'dartium/dartium-macos-ia32-release.zip',
   'dartium/content_shell-macos-ia32-release.zip'
 ];
 
 final FILES = []..addAll(SDK_FILES)..addAll(DARTIUM_FILES);
 
-Future<String> getHash256(String channel, int revision, String download) async {
+Future<String> getHash256(
+    String channel, String revision, String download) async {
   var client = new http.Client();
   try {
     var api = new storage.StorageApi(client);
     var media = await api.objects.get('dart-archive',
         'channels/$channel/release/$revision/$download.sha256sum',
         downloadOptions: DownloadOptions.FullMedia);
 
     var hashLine = await ASCII.decodeStream(media.stream);
     return new RegExp('[0-9a-fA-F]*').stringMatch(hashLine);
   } finally {
     client.close();
   }
 }
 
-Future<String> getVersion(String channel, int revision) async {
+Future<String> getVersion(String channel, String revision) async {
   var client = new http.Client();
   try {
     var api = new storage.StorageApi(client);
 
     var media = await api.objects.get(
         'dart-archive', 'channels/$channel/release/$revision/VERSION',
         downloadOptions: DownloadOptions.FullMedia);
 
     var versionObject = await JSON.fuse(ASCII).decoder.bind(media.stream).first;
     return versionObject['version'];
   } finally {
     client.close();
   }
 }
 
 Future setCurrentRevisions(Map revisions) async {
   var lines = await (new File('$repository/dart.rb')).readAsLines();
 
   for (var channel in CHANNELS) {
-    final regExp = new RegExp('channels/$channel/release/(\\d*)/sdk');
+    /// This RegExp between release/ and /sdk matches
+    /// * 1 digit followed by
+    /// * Any number of letters, numbers, dashes and dots
+    /// This covers both numeric- and version-formatted revisions
+    ///
+    /// Note: all of the regexp escape slashes `\` are double-escaped within the
+    /// Dart string
+    final regExp =
+        new RegExp('channels/$channel/release/(\\d[\\w\\d\\-\\.]*)/sdk');
+
     revisions[channel] =
         regExp.firstMatch(lines.firstWhere(regExp.hasMatch)).group(1);
   }
 }
 
 Future setHashes(Map revisions, Map hashes) {
   List waitOn = [];
   for (var channel in CHANNELS) {
     hashes[channel] = {};
     for (var file in FILES) {
       waitOn.add(getHash256(channel, revisions[channel], file).then((hash) {
         hashes[channel][file] = hash;
       }));
     }
   }
   return Future.wait(waitOn);
 }
 
-Future writeHomebrewInfo(String channel, int revision) async {
+Future writeHomebrewInfo(String channel, String revision) async {
   var revisions = {};
   var hashes = {};
 
   await setCurrentRevisions(revisions);
 
   if (revisions[channel] == revision) {
     print("Channel $channel is already at revision $revision in homebrew.");
     exit(0);
   }
   revisions[channel] = revision;
@@ skipping 173 matching lines @@
 
       await runGit(['push']);
     } finally {
       await tempDir.delete(recursive: true);
     }
   }, onError: (error, chain) {
     print(error);
     print(chain.terse);
   });
 }