Initial support for managing partial results from plugins

pkg/analysis_server/lib/src/plugin/result_collector.dart

+// Copyright (c) 2017, 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.
+
+/**
+ * An object used to collect partial results (of type [E]) where the partial
+ * results are contributed by plugins.
+ */
+class ResultCollector<E> {
+  /**
+   * The id used as a plugin id for contributions from the server.
+   */
+  final String serverId;
+
+  /**
+   * A multi-keyed map, where the first key is the (normalized and absolute)
+   * path to the file associated with the results, and the second is the id of
+   * the plugin that provided the partial results. The value is the partial
+   * results contrinuted by the plugin for the file.
+   */
+  Map<String, Map<String, E>> resultMap = <String, Map<String, E>>{};
+
+  /**
+   * Initialize a newly created result manager.
+   */
+  ResultCollector(this.serverId);
+
+  /**
+   * Clear any results that have been contributed for the file with the given
+   * [filePath], but continue to collect results for the file. This is used when
+   * the results for the specified file are known to be invalid, typically
+   * because the content of the file has been modified.
+   */
+  void clearResultsForFile(String filePath) {
+    resultMap[filePath].clear();
+  }
+
+  /**
+   * Clear any results that have been contributed by the plugin with the given
+   * [pluginId].
+   */
+  void clearResultsFromPlugin(String pluginId) {
+    for (Map<String, E> partialResults in resultMap.values) {
+      partialResults.remove(pluginId);
+    }
+  }
+
+  /**
+   * Return an iterator producing the partial results that have been contributed
+   * for the given [filePath],

[scheglov, 2017/02/04 03:05:16]

Did you want to continue writing?

[Brian Wilkerson, 2017/02/04 17:45:38]

No, just mistyped.

+   */
+  Iterable<E> getResults(String filePath) {
+    Map<String, E> partialResultMap = resultMap[filePath];
+    if (partialResultMap == null) {
+      return <E>[];
+    }
+    List<E> values = partialResultMap.values.toList();
+    //
+    // Ensure that the server's contributions are always first in the list.
+    //
+    E serverContributions = partialResultMap[serverId];
+    if (serverContributions != null && values.remove(serverContributions)) {
+      values.insert(0, serverContributions);
+    }
+    return values;
+  }
+
+  /**
+   * Record the [partialResults] as having been contributed for the given
+   * [filePath] by the plugin with the given [pluginId].
+   */
+  void putResults(String filePath, String pluginId, E partialResults) {
+    Map<String, E> fileResults = resultMap[filePath];
+    if (fileResults != null) {
+      fileResults[pluginId] = partialResults;
+    }
+  }
+
+  /**
+   * Start collecting results contributed for the file with the given
+   * [filePath]. Unless the collector is told to collect results for a file, any
+   * results that are contributed for that file are discarded.
+   */
+  void startCollectingFor(String filePath) {
+    resultMap.putIfAbsent(filePath, () => <String, E>{});
+  }
+
+  /**
+   * Stop collecting results contributed for the file with the given [filePath].
+   * Until the collector is told to start collecting results for the file, any
+   * results that are contributed for the file are discarded.
+   */
+  void stopCollectingFor(String filePath) {
+    resultMap.remove(filePath);
+  }
+}