Implement command "unpack"

lib/src/command/unpack.dart

@@ -0,0 +1,192 @@
+// Copyright (c) 2024, 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.
+
+import 'package:path/path.dart' as p;
+import 'package:pub_semver/pub_semver.dart';
+import 'package:yaml/yaml.dart';
+
+import '../command.dart';
+import '../command_runner.dart';
+import '../entrypoint.dart';
+import '../io.dart';
+import '../log.dart' as log;
+import '../package_name.dart';
+import '../pubspec.dart';
+import '../sdk.dart';
+import '../solver/type.dart';
+import '../source/hosted.dart';
+import '../utils.dart';
+
+class UnpackCommand extends PubCommand {
+  @override
+  String get name => 'unpack';
+
+  @override
+  String get description => '''
+Downloads a package and unpacks it in place.
+
+For example:
+
+  $topLevelProgram pub unpack foo
+
+Downloads and extracts the latest stable package:foo from pub.dev in a
+directory `foo-<version>`.
+
+  $topLevelProgram pub unpack foo:1.2.3-pre --no-resolve
+
+Downloads and extracts package:foo version 1.2.3-pre in a directory
+`foo-1.2.3-pre` without running running implicit `pub get`.
+
+  $topLevelProgram pub unpack foo --output=archives
+
+Downloads and extracts latest stable version of package:foo in a directory
+`archives/foo-<version>`.
+
+  $topLevelProgram pub unpack 'foo:{hosted:"https://my_repo.org"}'
+
+Downloads and extracts latest stable version of package:foo from my_repo.org
+in a directory `foo-<version>`.
+''';
+
+  @override
+  String get argumentsDescription => 'package-name[:constraint]';
+
+  @override
+  String get docUrl => 'https://dart.dev/tools/pub/cmd/pub-unpack';
+
+  @override
+  bool get takesArguments => true;
+
+  UnpackCommand() {
+    argParser.addFlag(
+      'resolve',
+      help: 'Whether to do pub get in the downloaded folder',
+      defaultsTo: true,
+      hide: log.verbosity != log.Verbosity.all,
+    );
+    argParser.addFlag(
+      'force',
+      abbr: 'f',
+      help: 'overwrites an existing folder if it exists',
+    );
+    argParser.addOption(
+      'output',
+      abbr: 'o',
+      help: 'Download and extract the package in this dir',
+      defaultsTo: '.',
+    );
+  }
+
+  static final _argRegExp = RegExp(
+    r'^(?<name>[a-zA-Z0-9_.]+)'
+    r'(?::(?<descriptor>.*))?$',
+  );
+
+  @override
+  Future<void> runProtected() async {
+    if (argResults.rest.isEmpty) {
+      usageException('Provide a package name');
+    }
+    if (argResults.rest.length > 1) {
+      usageException('Please provide only a single package name');
+    }
+    final arg = argResults.rest[0];
+    final match = _argRegExp.firstMatch(arg);
+    if (match == null) {
+      usageException('Use the form package:constraint to specify the package.');
+    }
+    final parseResult = _parseDescriptor(
+      match.namedGroup('name')!,
+      match.namedGroup('descriptor'),
+    );
+
+    if (parseResult.description is! HostedDescription) {
+      fail('Can only fetch hosted packages.');
+    }
+    final versions = await parseResult.source
+        .doGetVersions(parseResult.toRef(), null, cache);
+    final constraint = parseResult.constraint;
+    versions.removeWhere((id) => !constraint.allows(id.version));
+    if (versions.isEmpty) {
+      fail('No matching versions of ${parseResult.name}.');
+    }
+    versions.sort((id1, id2) => id1.version.compareTo(id2.version));
+
+    final id = versions.last;
+    final name = id.name;
+
+    final outputArg = argResults['output'] as String;
+    final destinationDir = p.join(outputArg, '$name-${id.version}');
+    if (entryExists(destinationDir)) {
+      if (argResults.flag('force')) {
+        deleteEntry(destinationDir);
+      } else {
+        fail(
+          'Target directory `$destinationDir` already exists. Use --force to overwrite',
+        );
+      }
+    }
+    await log.progress(
+      'Downloading $name ${id.version} to `$destinationDir`',
+      () async {
+        await cache.hosted.downloadInto(id, destinationDir, cache);
+      },
+    );
+    final e = Entrypoint(
+      destinationDir,
+      cache,
+    );
+    if (argResults['resolve'] as bool) {
+      try {
+        await e.acquireDependencies(SolveType.get);
+      } finally {
+        log.message('To explore type: cd $destinationDir');
+        if (e.example != null) {
+          log.message('To explore the example type: cd ${e.example!.rootDir}');
+        }
+      }
+    }
+  }
+
+  PackageRange _parseDescriptor(
+    String packageName,
+    String? descriptor,
+  ) {
+    late final defaultDescription =
+        HostedDescription(packageName, cache.hosted.defaultUrl);
+    if (descriptor == null) {
+      return PackageRange(
+        PackageRef(packageName, defaultDescription),
+        VersionConstraint.any,
+      );
+    }
+    try {
+      // An unquoted version constraint is not always valid yaml.
+      // But we want to allow it here anyways.
+      final constraint = VersionConstraint.parse(descriptor);
+      return PackageRange(
+        PackageRef(packageName, defaultDescription),
+        constraint,
+      );
+    } on FormatException {
+      final parsedDescriptor = loadYaml(descriptor);
+      // Use the pubspec parsing mechanism for parsing the descriptor.
+      final Pubspec dummyPubspec;
+      try {
+        dummyPubspec = Pubspec.fromMap(
+          {
+            'dependencies': {packageName: parsedDescriptor},
+            'environment': {'sdk': sdk.version.toString()},
+          },
+          cache.sources,
+          // Resolve relative paths relative to current, not where the pubspec.yaml is.
+          location: p.toUri(p.join(p.current, 'descriptor')),
+        );
+      } on FormatException catch (e) {
+        usageException('Failed parsing package specification: ${e.message}');
+      }
+      return dummyPubspec.dependencies[packageName]!;
+    }
+  }
+}

lib/src/command_runner.dart

@@ -23,6 +23,7 @@ import 'command/outdated.dart';
 import 'command/remove.dart';
 import 'command/run.dart';
 import 'command/token.dart';
+import 'command/unpack.dart';
 import 'command/upgrade.dart';
 import 'command/uploader.dart';
 import 'command/version.dart';
@@ -148,6 +149,7 @@ class PubCommandRunner extends CommandRunner<int> implements PubTopLevel {
     addCommand(RemoveCommand());
     addCommand(RunCommand());
     addCommand(UpgradeCommand());
+    addCommand(UnpackCommand());
     addCommand(UploaderCommand());
     addCommand(LoginCommand());
     addCommand(LogoutCommand());

lib/src/pub_embeddable_command.dart

@@ -17,6 +17,7 @@ import 'command/outdated.dart';
 import 'command/remove.dart';
 import 'command/run.dart';
 import 'command/token.dart';
+import 'command/unpack.dart';
 import 'command/upgrade.dart';
 import 'command/uploader.dart';
 import 'log.dart' as log;
@@ -77,6 +78,7 @@ class PubEmbeddableCommand extends PubCommand implements PubTopLevel {
     addSubcommand(OutdatedCommand());
     addSubcommand(RemoveCommand());
     addSubcommand(RunCommand(deprecated: true, alwaysUseSubprocess: true));
+    addSubcommand(UnpackCommand());
     addSubcommand(UpgradeCommand());
     addSubcommand(UploaderCommand());
     addSubcommand(LoginCommand());

lib/src/source/hosted.dart

@@ -1353,6 +1353,13 @@ class HostedSource extends CachedSource {
         .toList();
   }
 
+  Future<void> downloadInto(
+    PackageId id,
+    String destPath,
+    SystemCache cache,
+  ) =>
+      _download(id, destPath, cache);
+
   /// Downloads package [package] at [version] from the archive_url and unpacks
   /// it into [destPath].
   ///

test/testdata/goldens/embedding/embedding_test/--help.txt

@@ -26,6 +26,7 @@ Available subcommands:
   publish   Publish the current package to pub.dev.
   remove   Removes dependencies from `pubspec.yaml`.
   token   Manage authentication tokens for hosted pub repositories.
+  unpack   Downloads a package and unpacks it in place.
   upgrade   Upgrade the current package's dependencies to latest versions.
 
 Run "pub_command_runner help" to see global options.

test/testdata/goldens/help_test/pub unpack --help.txt

@@ -0,0 +1,38 @@
+# GENERATED BY: test/help_test.dart
+
+## Section 0
+$ pub unpack --help
+Downloads a package and unpacks it in place.
+
+For example:
+
+  dart pub unpack foo
+
+Downloads and extracts the latest stable package:foo from pub.dev in a
+directory `foo-<version>`.
+
+  dart pub unpack foo:1.2.3-pre --no-resolve
+
+Downloads and extracts package:foo version 1.2.3-pre in a directory
+`foo-1.2.3-pre` without running running implicit `pub get`.
+
+  dart pub unpack foo --output=archives
+
+Downloads and extracts latest stable version of package:foo in a directory
+`archives/foo-<version>`.
+
+  dart pub unpack 'foo:{hosted:"https://my_repo.org"}'
+
+Downloads and extracts latest stable version of package:foo from my_repo.org
+in a directory `foo-<version>`.
+
+
+Usage: pub unpack package-name[:constraint]
+-h, --help          Print this usage information.
+-f, --[no-]force    overwrites an existing folder if it exists
+-o, --output        Download and extract the package in this dir
+                    (defaults to ".")
+
+Run "pub help" to see global options.
+See https://dart.dev/tools/pub/cmd/pub-unpack for detailed documentation.
+