Re-add missed files

pkg/analyzer/lib/src/plugin/plugin_impl.dart

Index: pkg/analyzer/lib/src/plugin/plugin_impl.dart
diff --git a/pkg/analyzer/lib/src/plugin/plugin_impl.dart b/pkg/analyzer/lib/src/plugin/plugin_impl.dart
new file mode 100644
index 0000000000000000000000000000000000000000..5b9e8a2a48e7d6b2904c40a94731a5b02c560802
--- /dev/null
+++ b/pkg/analyzer/lib/src/plugin/plugin_impl.dart
@@ -0,0 +1,125 @@
+// Copyright (c) 2015, 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 analyzer.src.plugin.plugin_impl;
+
+import 'dart:collection';
+
+import 'package:analyzer/plugin/plugin.dart';
+
+/**
+ * An object that manages the extension points for a single instance of the
+ * analysis server.
+ */
+class ExtensionManager {
+  /**
+   * A table mapping the id's of extension points to the corresponding
+   * extension points.
+   */
+  Map<String, ExtensionPointImpl> extensionPoints =
+      new HashMap<String, ExtensionPointImpl>();
+
+  /**
+   * Process each of the given [plugins] by allowing them to register extension
+   * points and extensions.
+   *
+   * An [ExtensionError] will be thrown if any of the plugins throws such an
+   * exception while registering with this manager.
+   */
+  void processPlugins(List<Plugin> plugins) {
+    for (Plugin plugin in plugins) {
+      plugin.registerExtensionPoints((String identifier,
+              [ValidateExtension validateExtension]) =>
+          registerExtensionPoint(plugin, identifier, validateExtension));
+    }
+    for (Plugin plugin in plugins) {
+      plugin.registerExtensions(registerExtension);
+    }
+  }
+
+  /**
+   * Register an [extension] to the extension point with the given unique
+   * [identifier].
+   */
+  void registerExtension(String identifier, Object extension) {
+    ExtensionPointImpl extensionPoint = extensionPoints[identifier];
+    if (extensionPoint == null) {
+      throw new ExtensionError(
+          'There is no extension point with the id "$identifier"');
+    }
+    extensionPoint.add(extension);
+  }
+
+  /**
+   * Register an extension point being defined by the given [plugin] with the
+   * given simple [identifier] and [validateExtension].
+   */
+  ExtensionPoint registerExtensionPoint(
+      Plugin plugin, String identifier, ValidateExtension validateExtension) {
+    String uniqueIdentifier = Plugin.buildUniqueIdentifier(plugin, identifier);
+    if (extensionPoints.containsKey(uniqueIdentifier)) {
+      throw new ExtensionError(
+          'There is already an extension point with the id "$identifier"');
+    }
+    ExtensionPointImpl extensionPoint =
+        new ExtensionPointImpl(plugin, identifier, validateExtension);
+    extensionPoints[uniqueIdentifier] = extensionPoint;
+    return extensionPoint;
+  }
+}
+
+/**
+ * A concrete representation of an extension point.
+ */
+class ExtensionPointImpl implements ExtensionPoint {
+  @override
+  final Plugin plugin;
+
+  @override
+  final String simpleIdentifier;
+
+  /**
+   * The function used to validate extensions to this extension point.
+   */
+  final ValidateExtension validateExtension;
+
+  /**
+   * The list of extensions to this extension point.
+   */
+  final List<Object> _extensions = <Object>[];
+
+  /**
+   * Initialize a newly create extension point to belong to the given [plugin]
+   * and have the given [simpleIdentifier]. If [validateExtension] is non-`null`
+   * it will be used to validate extensions associated with this extension
+   * point.
+   */
+  ExtensionPointImpl(
+      this.plugin, this.simpleIdentifier, this.validateExtension);
+
+  /**
+   * Return a list containing all of the extensions that have been registered
+   * for this extension point.
+   */
+  List<Object> get extensions => new UnmodifiableListView(_extensions);
+
+  /**
+   * Return the identifier used to uniquely identify this extension point. The
+   * unique identifier is the identifier for the plugin, followed by a period
+   * (`.`), followed by the [simpleIdentifier] for the extension point.
+   */
+  String get uniqueIdentifier =>
+      Plugin.buildUniqueIdentifier(plugin, simpleIdentifier);
+
+  /**
+   * Validate that the given [extension] is appropriate for this extension
+   * point, and if it is then add it to the list of registered exceptions.
+   */
+  void add(Object extension) {
+    if (validateExtension != null) {
+      validateExtension(extension);
+    }
+    _extensions.add(extension);
+  }
+}