If the file belongs to any analysis root, check whether we're in it now.

pkg/analysis_server/lib/src/analysis_server.dart

 // Copyright (c) 2014, 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 analysis.server;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:math' show max;
 
@@ skipping 375 matching lines @@
 
   /**
    * Return the [AnalysisContext]s that are being used to analyze the analysis
    * roots.
    */
   Iterable<AnalysisContext> getAnalysisContexts() {
     return folderMap.values;
   }
 
   /**
+   * Return the [AnalysisContext] that contains the given [path].
+   * Return `null` if no context contains the [path].
+   */
+  AnalysisContext getContainingContext(String path) {
+    Folder containingFolder = null;
+    AnalysisContext containingContext = null;
+    folderMap.forEach((Folder folder, AnalysisContext context) {
+      if (folder.isOrContains(path)) {
+        if (containingFolder == null ||
+            containingFolder.path.length < folder.path.length) {
+          containingFolder = folder;
+          containingContext = context;
+        }
+      }
+    });
+    return containingContext;
+  }
+
+  /**
    * Return the primary [ContextSourcePair] representing the given [path].
    *
    * The [AnalysisContext] of this pair will be the context that explicitly
    * contains the path, if any such context exists, otherwise it will be the
    * first context that implicitly analyzes it.
    *
    * If the [path] is not analyzed by any context, a [ContextSourcePair] with
    * `null` context and `file` [Source] is returned.
    *
    * If the [path] dosn't represent a file, `null` is returned as a [Source].
    *
    * Does not return `null`.
    */
   ContextSourcePair getContextSourcePair(String path) {
     // try SDK
     {
       Uri uri = resourceProvider.pathContext.toUri(path);
       Source sdkSource = defaultSdk.fromFileUri(uri);
       if (sdkSource != null) {
         AnalysisContext anyContext = folderMap.values.first;
         return new ContextSourcePair(anyContext, sdkSource);
       }
     }
     // try to find the deep-most containing context
     Resource resource = resourceProvider.getResource(path);
     File file = resource is File ? resource : null;
     {
-      Folder containingFolder = null;
-      AnalysisContext containingContext = null;
-      folderMap.forEach((Folder folder, AnalysisContext context) {
-        if (folder.isOrContains(path)) {
-          if (containingFolder == null ||
-              containingFolder.path.length < folder.path.length) {
-            containingFolder = folder;
-            containingContext = context;
-          }
-        }
-      });
+      AnalysisContext containingContext = getContainingContext(path);
       if (containingContext != null) {
         Source source = file != null
             ? ContextManager.createSourceInContext(containingContext, file)
             : null;
         return new ContextSourcePair(containingContext, source);
       }
     }
     // try to find a context that analysed the file
     for (AnalysisContext context in folderMap.values) {
       Source source = file != null
@@ skipping 964 matching lines @@
   /**
    * The [PerformanceTag] for time spent in server request handlers.
    */
   static PerformanceTag serverRequests = new PerformanceTag('serverRequests');
 
   /**
    * The [PerformanceTag] for time spent in split store microtasks.
    */
   static PerformanceTag splitStore = new PerformanceTag('splitStore');
 }