Get codebase ready for actually supporting versioning.

utils/pub/pubspec.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_pubspec');
+
+#import('io.dart');
+#import('pub.dart');
+#import('utils.dart');
+#import('version.dart');
+#import('yaml/yaml.dart');
+
+/**
+ * The parsed and validated contents of a pubspec file.
+ */
+class Pubspec {
+  /**
+   * Parses the pubspec at the given path.
+   */
+  static Future<Pubspec> parse(String path, SourceRegistry sources) {
+    var version = Version.none;
+    var dependencies = <PackageRef>[];
+    var completer = new Completer<Pubspec>();
+    complete() => completer.complete(new Pubspec(version, dependencies));
+
+    // TODO(rnystrom): Handle the directory not existing.
+    // TODO(rnystrom): Error-handling.
+    var readFuture = readTextFile(path);
+    readFuture.handleException((error) {
+      // If there is no pubspec, we implicitly treat that as a package with no
+      // dependencies.
+      // TODO(rnystrom): Distinguish file not found from other real errors.
+      complete();
+      return true;
+    });
+
+    readFuture.then((pubspec) {
+      if (pubspec.trim() == '') {
+        complete();
+        return;
+      }
+
+      var parsedPubspec = loadYaml(pubspec);
+      if (parsedPubspec is! Map) {
+        completer.completeException('The pubspec must be a YAML mapping.');
+      }
+
+      if (parsedPubspec.containsKey('version')) {
+        version = new Version.parse(parsedPubspec['version']);
+      }
+
+      if (!parsedPubspec.containsKey('dependencies')) {
+        complete();
+        return;
+      }
+
+      var dependencyEntries = parsedPubspec['dependencies'];
+      if (dependencyEntries is! Map ||
+          dependencyEntries.getKeys().some((e) => e is! String)) {
+        completer.completeException(
+            'The pubspec dependencies must be a map of package names.');
+      }
+
+      dependencyEntries.forEach((name, spec) {
+        var description, source;
+        // TODO(nweiz): parse the version once we have version handling

[nweiz, 2012/05/18 00:08:24]

You can remove this now

[Bob Nystrom, 2012/05/18 20:02:38]

Done.

+        if (spec == null || spec is String) {

[nweiz, 2012/05/18 00:08:24]

If spec is a string, you should parse it as a version.

[Bob Nystrom, 2012/05/18 20:02:38]

Done.

+          description = name;
+          source = sources.defaultSource;
+        } else if (spec is Map) {
+          if (spec.containsKey('version')) {
+            // TODO(rnystrom): Support parsing version constraints like
+            // ">= 2.0.0 < 3.1.3".
+            version = new Version.parse(spec['version']);

[nweiz, 2012/05/18 00:08:24]

Replace spec['version'] here with spec.remove('version')

[Bob Nystrom, 2012/05/18 20:02:38]

Done.

+            spec.remove('version');
+          }
+
+          var sourceNames = spec.getKeys();
+          if (sourceNames.length > 1) {
+            completer.completeException(
+                'Dependency $name may not have multiple sources: '
+                '$sourceNames.');
+            return;
+          }
+
+          var sourceName = only(sourceNames);
+          if (sourceName is! String) {
+            completer.completeException(
+                'Source name $sourceName must be a string.');
+            return;
+          }
+          source = sources[sourceName];
+          description = spec[sourceName];
+        } else {
+          completer.completeException(
+              'Dependency specification $spec must be a string or a mapping.');
+          return;
+        }
+
+        dependencies.add(new PackageRef(
+            name, source, Version.none, description));
+      });
+
+      complete();
+    });
+
+    return completer.future;
+  }
+
+  /**
+   * This package's version. Defaults to [Version.none] if not present in
+   * the pubspec.

[nweiz, 2012/05/18 00:08:24]

I wouldn't document the default here when it only acquires that default if you
use Pubspec.parse. That actually probably belongs in the prose documentation.

[Bob Nystrom, 2012/05/18 20:02:38]

Done.

+   */
+  final Version version;
+
+  /**
+   * The packages this package depends on.
+   */
+  List<PackageRef> dependencies;
+
+  Pubspec(this.version, this.dependencies);
+}