Make LockFile immutable.

lib/src/lock_file.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 pub.lock_file;
 
+import 'dart:collection';
+
 import 'package:path/path.dart' as p;
 import 'package:pub_semver/pub_semver.dart';
 import 'package:source_span/source_span.dart';
 import 'package:yaml/yaml.dart';
 
 import 'io.dart';
 import 'package.dart';
 import 'source_registry.dart';
 import 'utils.dart';
 
 /// A parsed and validated `pubspec.lock` file.
 class LockFile {
+  /// The source registry with which the lock file's IDs are interpreted.
+  ///
+  /// This is `null` for an empty lock file, since there are no IDs to
+  /// interpret.
+  final SourceRegistry _sources;
+
   /// The packages this lockfile pins.
-  Map<String, PackageId> packages;
+  final Map<String, PackageId> packages;
 
   /// Creates a new lockfile containing [ids].
-  factory LockFile(List<PackageId> ids) {
-    var lockFile = new LockFile.empty();
+  ///
+  /// Throws an [ArgumentError] if any package has an undefined source according
+  /// to [sources] or an unresolved ID according to [Source.isResolved].
+  factory LockFile(Iterable<PackageId> ids, SourceRegistry sources) {
+    var packages = {};
     for (var id in ids) {
-      if (!id.isRoot) lockFile.packages[id.name] = id;
+      if (id.isRoot) continue;
+
+      var source = sources[id.source];
+      if (source == null) {
+        throw new ArgumentError('Undefined source "$source" for package "$id".');

[Bob Nystrom, 2015/08/07 21:50:56]

Long line.

Also, does this do the right thing on old lock files that may still have SDK
sources? Do we care? The rest of pub has the concept of an "unknown" source to
handle this. Should we do that here?

[nweiz, 2015/08/07 22:16:07]

Done.
Removed. I had forgotten about UnknownSource. That means that this will never
return null anyway.

+      }
+
+      if (!source.isResolved(id)) {
+        throw new ArgumentError('ID "$id" is not resolved.');
+      }
+
+      packages[id.name] = id;
     }
 
-    return lockFile;
+    return new LockFile._(packages, sources);
   }
 
-  LockFile._(this.packages);
+  LockFile._(Map<String, PackageId> packages, this._sources)
+      : packages = new UnmodifiableMapView(packages);
 
   LockFile.empty()
-    : packages = <String, PackageId>{};
+      : packages = const {},
+        _sources = null;
 
   /// Loads a lockfile from [filePath].
   factory LockFile.load(String filePath, SourceRegistry sources) {
     return LockFile._parse(filePath, readTextFile(filePath), sources);
   }
 
   /// Parses a lockfile whose text is [contents].
   factory LockFile.parse(String contents, SourceRegistry sources) {
     return LockFile._parse(null, contents, sources);
   }
 
   /// Parses the lockfile whose text is [contents].
   ///
   /// [filePath] is the system-native path to the lockfile on disc. It may be
   /// `null`.
   static LockFile _parse(String filePath, String contents,
       SourceRegistry sources) {
-    var packages = <String, PackageId>{};
+    var packages = {};
 
     if (contents.trim() == '') return new LockFile.empty();
 
     var sourceUrl;
     if (filePath != null) sourceUrl = p.toUri(filePath);
     var parsed = loadYamlNode(contents, sourceUrl: sourceUrl);
 
     _validate(parsed is Map, 'The lockfile must be a YAML mapping.', parsed);
 
     var packageEntries = parsed['packages'];
@@ skipping 29 matching lines @@
         var id = new PackageId(name, sourceName, version, description);
 
         // Validate the name.
         _validate(name == id.name,
             "Package name $name doesn't match ${id.name}.", spec);
 
         packages[name] = id;
       });
     }
 
-    return new LockFile._(packages);
+    return new LockFile._(packages, sources);
   }
 
   /// If [condition] is `false` throws a format error with [message] for [node].
   static void _validate(bool condition, String message, YamlNode node) {
     if (condition) return;
     throw new SourceSpanFormatException(message, node.span);
   }
 
   /// Returns the serialized YAML text of the lock file.
   ///
   /// [packageDir] is the containing directory of the root package, used to
   /// properly serialize package descriptions.
-  String serialize(String packageDir, SourceRegistry sources) {
+  String serialize(String packageDir) {
     // Convert the dependencies to a simple object.
     var data = {};
     packages.forEach((name, package) {
-      var description = sources[package.source].serializeDescription(packageDir,
-          package.description);
+      var description = _sources[package.source]
+          .serializeDescription(packageDir, package.description);
 
       data[name] = {
         'version': package.version.toString(),
         'source': package.source,
         'description': description
       };
     });
 
     return """
 # Generated by pub
 # See http://pub.dartlang.org/doc/glossary.html#lockfile
 ${yamlToString({'packages': data})}
 """;
   }
 }