Improve the detection lockfile freshness.

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:package_config/packages_file.dart' as packages_file;
 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.
   final SourceRegistry _sources;
 
   /// The packages this lockfile pins.
   final Map<String, PackageId> packages;
 
+  /// The intersection of all SDK constraints for all locked packages.
+  final VersionConstraint sdkConstraint;
+
   /// Creates a new lockfile containing [ids].
-  factory LockFile(Iterable<PackageId> ids, SourceRegistry sources) {
-    var packages = new Map.fromIterable(
-        ids.where((id) => !id.isRoot),
-        key: (id) => id.name);
-    return new LockFile._(packages, sources);
-  }
+  ///
+  /// If passed, [sdkConstraint] represents the intersection of all SKD
+  /// constraints for all locked packages. It defaults to
+  /// [VersionConstraint.any].
+  LockFile(Iterable<PackageId> ids, SourceRegistry sources,
+          {VersionConstraint sdkConstraint})
+      : this._(
+          new Map.fromIterable(
+              ids.where((id) => !id.isRoot),
+              key: (id) => id.name),
+          sdkConstraint ?? VersionConstraint.any,
+          sources);
 
-  LockFile._(Map<String, PackageId> packages, this._sources)
+  LockFile._(Map<String, PackageId> packages, this.sdkConstraint, this._sources)
       : packages = new UnmodifiableMapView(packages);
 
   LockFile.empty(this._sources)
-      : packages = const {};
+      : packages = const {},
+        sdkConstraint = VersionConstraint.any;
 
   /// 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 = {};
-
     if (contents.trim() == '') return new LockFile.empty(sources);
 
     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 sdkConstraint = VersionConstraint.any;
+    var sdkConstraintText = parsed['sdk'];
+    if (sdkConstraintText != null) {
+      _validate(sdkConstraintText is String, 'The "sdk" field must be a string.',

[Bob Nystrom, 2015/12/21 20:55:03]

Long line.

[nweiz, 2016/01/04 23:27:29]

Done.

+          parsed.nodes['sdk']);
+
+      sdkConstraint = _wrapFormatException(
+          'version constraint',
+          parsed.nodes['sdk'],
+          () => new VersionConstraint.parse(sdkConstraintText));
+    }
+
+    var packages = {};
     var packageEntries = parsed['packages'];
     if (packageEntries != null) {
       _validate(packageEntries is Map, 'The "packages" field must be a map.',
           parsed.nodes['packages']);
 
       packageEntries.forEach((name, spec) {
         // Parse the version.
         _validate(spec.containsKey('version'),
             'Package $name is missing a version.', spec);
         var version = new Version.parse(spec['version']);
@@ skipping 18 matching lines @@
         }
 
         // Validate the name.
         _validate(name == id.name,
             "Package name $name doesn't match ${id.name}.", spec);
 
         packages[name] = id;
       });
     }
 
-    return new LockFile._(packages, sources);
+    return new LockFile._(packages, sdkConstraint, sources);
+  }
+
+  /// Runs [fn] and wraps any [FormatException] it throws in a
+  /// [SourceSpanFormatException].
+  ///
+  /// [description] should be a noun phrase that describes whatever's being
+  /// parsed or processed by [fn]. [span] should be the location of whatever's
+  /// being processed within the pubspec.
+  static _wrapFormatException(String description, SourceSpan span, fn()) {
+    try {
+      return fn();
+    } on FormatException catch (e) {
+      throw new SourceSpanFormatException(
+          'Invalid $description: ${e.message}', span);
+    }
   }

[Bob Nystrom, 2015/12/21 20:55:03]

Do we do this elsewhere? Maybe move it into utils?

[nweiz, 2016/01/04 23:27:29]

We do something similar in pubspec.dart, but it throws a different type of
exception so we wouldn't be able to re-use code.

 
   /// 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 a copy of this LockFile with [id] added.
   ///
   /// If there's already an ID with the same name as [id] in the LockFile, it's
   /// overwritten.
   LockFile setPackage(PackageId id) {
     if (id.isRoot) return this;
 
     var packages = new Map.from(this.packages);
     packages[id.name] = id;
-    return new LockFile._(packages, _sources);
+    return new LockFile._(packages, sdkConstraint, _sources);
   }
 
   /// Returns a copy of this LockFile with a package named [name] removed.
   ///
   /// Returns an identical [LockFile] if there's no package named [name].
   LockFile removePackage(String name) {
     if (!this.packages.containsKey(name)) return this;
 
     var packages = new Map.from(this.packages);
     packages.remove(name);
-    return new LockFile._(packages, _sources);
+    return new LockFile._(packages, sdkConstraint, _sources);
   }
 
   /// Returns the contents of the `.packages` file generated from this lockfile.
   ///
   /// If [entrypoint] is passed, a relative entry is added for its "lib/"
   /// directory.
   String packagesFile([String entrypoint]) {
     var header = "Generated by pub on ${new DateTime.now()}.";
 
     var map = new Map.fromIterable(ordered(packages.keys), value: (name) {
       var id = packages[name];
       var source = _sources[id.source];
       return p.toUri(p.join(source.getDirectory(id), "lib"));
     });
 
     if (entrypoint != null) map[entrypoint] = Uri.parse("lib/");
 
     var text = new StringBuffer();
     packages_file.write(text, map, comment: header);
     return text.toString();
   }
 
   /// 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) {
     // Convert the dependencies to a simple object.
-    var data = {};
+    var packageMap = {};
     packages.forEach((name, package) {
       var description = _sources[package.source]
           .serializeDescription(packageDir, package.description);
 
-      data[name] = {
+      packageMap[name] = {
         'version': package.version.toString(),
         'source': package.source,
         'description': description
       };
     });
 
+    var data = {'sdk': sdkConstraint.toString(), 'packages': packageMap};
     return """
 # Generated by pub
 # See http://pub.dartlang.org/doc/glossary.html#lockfile
-${yamlToString({'packages': data})}
+${yamlToString(data)}
 """;
   }
 }