Add a "cache add" command to download packages to the cache.

sdk/lib/_internal/pub/lib/src/command/cache_add.dart

Index: sdk/lib/_internal/pub/lib/src/command/cache_add.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command/cache_add.dart b/sdk/lib/_internal/pub/lib/src/command/cache_add.dart
new file mode 100644
index 0000000000000000000000000000000000000000..7cf0be437404a4785d56690d6c9bb386e71059de
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+++ b/sdk/lib/_internal/pub/lib/src/command/cache_add.dart
@@ -0,0 +1,98 @@
+// 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 pub.command.cache_add;
+
+import 'dart:async';
+
+import '../command.dart';
+import '../exit_codes.dart' as exit_codes;
+import '../io.dart';
+import '../log.dart' as log;
+import '../package.dart';
+import '../utils.dart';
+import '../version.dart';
+
+/// Handles the `cache add` pub command.
+class CacheAddCommand extends PubCommand {
+  String get description => "Install a package.";
+  String get usage =>
+      "pub cache add <package> [--version <constraint>] [--all]";
+  bool get requiresEntrypoint => false;
+  bool get takesArguments => true;
+
+  CacheAddCommand() {
+    commandParser.addFlag("all",
+        help: "Install all matching versions.",
+        negatable: false);
+
+    commandParser.addOption("version", abbr: "v",
+        help: "Version constraint.");
+  }
+
+  Future onRun() {
+    // Make sure there is a package.
+    if (commandOptions.rest.isEmpty) {
+      usageError("No package to add given.");
+    }
+
+    // Don't allow extra arguments.
+    if (commandOptions.rest.length > 1) {
+      var unexpected = commandOptions.rest.skip(1).map((arg) => '"$arg"');
+      var arguments = pluralize("argument", unexpected.length);
+      usageError("Unexpected $arguments ${toSentence(unexpected)}.");
+    }
+
+    var package = commandOptions.rest.single;
+
+    // Parse the version constraint, if there is one.
+    var constraint = VersionConstraint.any;
+    if (commandOptions["version"] != null) {
+      try {
+        constraint = new VersionConstraint.parse(commandOptions["version"]);
+      } on FormatException catch (error) {
+        usageError(error.message);
+      }
+    }
+
+    // TODO(rnystrom): Support installing from git too.
+    var source = this.cache.sources["hosted"];
+
+    // TODO(rnystrom): Allow specifying the server.
+    return source.getVersions(package, package).then((versions) {
+      versions = versions.where(constraint.allows).toList();
+
+      if (versions.isEmpty) {
+        // TODO(rnystrom): Show most recent unmatching version?
+        throw new ApplicationException(
+            "Package $package has no versions that match $constraint.");
+      }
+
+      downloadVersion(Version version) {
+        var id = new PackageId(package, source.name, version, package);
+        return cache.contains(id).then((contained) {
+          if (contained) {
+            // TODO(rnystrom): Include source and description if not hosted.
+            // See solve_report.dart for code to harvest.
+            log.message("Already cached ${id.name} ${id.version}.");
+            return null;
+          }
+
+          // Download it.
+          return cache.download(id);
+        });
+      }
+
+      if (commandOptions["all"]) {
+        // Install them in ascending order.
+        versions.sort();
+        return Future.forEach(versions, downloadVersion);
+      } else {
+        // Pick the best matching version.
+        versions.sort(Version.prioritize);
+        return downloadVersion(versions.last);
+      }
+    });
+  }
+}