Hook in the version solver to pub install.

utils/pub/repo_source.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('dartlang_source');
 
 #import('dart:io');
+#import('dart:json');
 #import('dart:uri');
 #import('io.dart');
 #import('package.dart');
+#import('pubspec.dart');
 #import('source.dart');
+#import('source_registry.dart');
 #import('utils.dart');
+#import('version.dart');
 
 /**
  * A package source that installs packages from a package repository that uses
  * the same API as pub.dartlang.org.
  */
 class RepoSource extends Source {
   final String name = "repo";
 
   final bool shouldCache = true;
 
   // TODO(nweiz): update this comment once pub.dartlang.org is online
   /**
    * The URL of the default package repository.
    *
    * At time of writing, pub.dartlang.org is not yet online, but it should be
    * soon.
    */
   static final String defaultUrl = "http://pub.dartlang.org";
 
   RepoSource();
 
   /**
+   * Downloads a list of all versions of a package that have been uploaded to
+   * pub.dartlang.org.
+   */
+  Future<List<Version>> getVersions(description) {
+    var parsed = _parseDescription(description);
+    var fullUrl = "${parsed.last}/packages/${parsed.first}.json";
+    return consumeInputStream(httpGet(fullUrl)).transform((data) {
+      var doc = JSON.parse(new String.fromCharCodes(data));
+      return doc['versions'].map((version) => new Version.parse(version));
+    });
+  }
+
+  /**
+   * Downloads and parses the pubspec for a specific version of a package that
+   * has been uploaded to pub.dartlang.org.
+   */
+  Future<Pubspec> describe(PackageId id) {
+    var parsed = _parseDescription(id.description);
+    var fullUrl = "${parsed.last}/packages/${parsed.first}/versions/"
+      "${id.version}.yaml";
+    return consumeInputStream(httpGet(fullUrl)).transform((data) {
+      return new Pubspec.parse(
+          new String.fromCharCodes(data), systemCache.sources);
+    });
+  }
+
+  /**
    * Downloads a package from a package repository and unpacks it.
    */
   Future<bool> install(PackageId id, String destPath) {
     var parsedDescription = _parseDescription(id.description);
     var name = parsedDescription.first;
     var url = parsedDescription.last;
 
     return ensureDir(destPath).chain((destDir) {
       var fullUrl = "$url/packages/$name/versions/${id.version}.tar.gz";
       return extractTarGz(httpGet(fullUrl), destDir);
@@ skipping 55 matching lines @@
 
     var name = description["name"];
     if (name is! String) {
       throw new FormatException("The 'name' key must have a string value.");
     }
 
     var url = description.containsKey("url") ? description["url"] : defaultUrl;
     return new Pair<String, String>(name, url);
   }
 }