Create binstubs for executables when activating a package.

sdk/lib/_internal/pub_generated/lib/src/pubspec.dart

 library pub.pubspec;
 import 'package:path/path.dart' as path;
 import 'package:source_span/source_span.dart';
 import 'package:yaml/yaml.dart';
 import 'barback/transformer_config.dart';
 import 'exceptions.dart';
 import 'io.dart';
 import 'package.dart';
 import 'source_registry.dart';
 import 'utils.dart';
@@ skipping 153 matching lines @@
             span,
             () => Uri.parse(publishTo));
       }
     }
     _parsedPublishTo = true;
     _publishTo = publishTo;
     return _publishTo;
   }
   bool _parsedPublishTo = false;
   String _publishTo;
+  Map<String, String> get executables {
+    if (_executables != null) return _executables;
+    var yaml = fields['executables'];
+    if (yaml == null) {
+      _executables = {};
+      return _executables;
+    }
+    if (yaml is! Map) {
+      _error(
+          '"executables" field must be a map.',
+          fields.nodes['executables'].span);
+    }
+    yaml.nodes.forEach((key, value) {
+      validateName(name, description) {
+        final validName = new RegExp(r"^[a-zA-Z0-9_-]+$");
+        if (!validName.hasMatch(name.value)) {
+          _error(
+              '"executables" $description may only contain letters, '
+                  'numbers, hyphens and underscores.',
+              name.span);
+        }
+      }
+      if (key.value is! String) {
+        _error('"executables" keys must be strings.', key.span);
+      }
+      validateName(key, "keys");
+      if (value.value == null) return;
+      if (value.value is! String) {
+        _error('"executables" values must be strings or null.', value.span);
+      }
+      validateName(value, "values");
+    });
+    _executables = yaml;
+    return _executables;
+  }
+  Map<String, String> _executables;
   bool get isPrivate => publishTo == "none";
   bool get isEmpty =>
       name == null && version == Version.none && dependencies.isEmpty;
   factory Pubspec.load(String packageDir, SourceRegistry sources,
       {String expectedName}) {
     var pubspecPath = path.join(packageDir, 'pubspec.yaml');
     var pubspecUri = path.toUri(pubspecPath);
     if (!fileExists(pubspecPath)) {
       throw new FileException(
           'Could not find a file named "pubspec.yaml" in "$packageDir".',
@@ skipping 194 matching lines @@
 class PubspecEnvironment {
   final VersionConstraint sdkVersion;
   PubspecEnvironment([VersionConstraint sdk])
       : sdkVersion = sdk != null ? sdk : VersionConstraint.any;
 }
 class PubspecException extends SourceSpanFormatException implements
     ApplicationException {
   PubspecException(String message, SourceSpan span) : super(message, span);
 }
 bool _isFileUri(Uri uri) => uri.scheme == 'file' || uri.scheme == '';