Clarify nomenclature of "ancestor" and "root" in context manager.

pkg/analysis_server/lib/src/context_manager.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 context.directory.manager;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
 import 'dart:core' hide Resource;
@@ skipping 87 matching lines @@
       : folder = folder,
         pathFilter = new PathFilter(folder.path, null) {
     packageDescriptionPath = packagespecFile.path;
     parent.children.add(this);
   }
 
   /**
    * Create the virtual [ContextInfo] which acts as an ancestor to all other
    * [ContextInfo]s.
    */
-  ContextInfo._ancestor()
+  ContextInfo._root()
       : folder = null,
         pathFilter = null;
 
   /**
-   * Returns `true` if the folder associated with this context is not contained
-   * within any other folders that have an associated context.
+   * Returns `true` if this is a "top level" context, meaning that the folder
+   * associated with it is not contained within any other folders that have an
+   * associated context.
    */
-  bool get isRoot => parent.parent == null;
+  bool get isTopLevel => parent.parent == null;
 
   /**
    * Returns `true` if [path] is excluded, as it is in one of the children.
    */
   bool excludes(String path) {
     return children.any((child) {
       return child.folder.contains(path);
     });
   }
 
@@ skipping 229 matching lines @@
    */
   final InstrumentationService _instrumentationService;
 
   @override
   ContextManagerCallbacks callbacks;
 
   /**
    * Virtual [ContextInfo] which acts as the ancestor of all other
    * [ContextInfo]s.
    */
-  final ContextInfo _ancestorInfo = new ContextInfo._ancestor();
+  final ContextInfo _rootInfo = new ContextInfo._root();
 
   ContextManagerImpl(this.resourceProvider, this.packageResolverProvider,
       this._packageMapProvider, this._instrumentationService) {
     pathContext = resourceProvider.pathContext;
   }
 
   @override
   List<AnalysisContext> contextsInAnalysisRoot(Folder analysisRoot) {
     List<AnalysisContext> contexts = <AnalysisContext>[];
     _contexts.forEach((Folder contextFolder, ContextInfo info) {
@@ skipping 120 matching lines @@
         info.packageRoot = newPackageRoot;
         _recomputePackageUriResolver(info);
       }
     });
     // create new contexts
     for (Folder includedFolder in includedFolders) {
       bool wasIncluded = contextFolders.any((folder) {
         return folder.isOrContains(includedFolder.path);
       });
       if (!wasIncluded) {
-        _createContexts(_ancestorInfo, includedFolder, false);
+        _createContexts(_rootInfo, includedFolder, false);
       }
     }
     // remove newly excluded sources
     _contexts.forEach((folder, info) {
       // prepare excluded sources
       Map<String, Source> excludedSources = new HashMap<String, Source>();
       info.sources.forEach((String path, Source source) {
         if (_isExcludedBy(excludedPaths, path) &&
             !_isExcludedBy(oldExcludedPaths, path)) {
           excludedSources[path] = source;
@@ skipping 393 matching lines @@
         if (_isInPackagesDir(path, folder)) {
           return;
         }
 
         Resource resource = resourceProvider.getResource(path);
 
         if (ENABLE_PACKAGESPEC_SUPPORT) {
           String directoryPath = pathContext.dirname(path);
 
           // Check to see if we need to create a new context.
-          if (info.isRoot) {
+          if (info.isTopLevel) {
 
             // Only create a new context if this is not the same directory
             // described by our info object.
             if (info.folder.path != directoryPath) {
               if (_isPubspec(path)) {
                 // Check for a sibling .packages file.
                 if (!resourceProvider.getFile(
                     pathos.join(directoryPath, PACKAGE_SPEC_NAME)).exists) {
                   _extractContext(info, resource);
                   return;
                 }
               }
               if (_isPackagespec(path)) {
                 // Check for a sibling pubspec.yaml file.
                 if (!resourceProvider
                     .getFile(pathos.join(directoryPath, PUBSPEC_NAME)).exists) {
                   _extractContext(info, resource);
                   return;
                 }
               }
             }
           }
         } else {
           // pubspec was added in a sub-folder, extract a new context
           if (_isPubspec(path) &&
-              info.isRoot &&
+              info.isTopLevel &&
               !info.isPathToPackageDescription(path)) {
             _extractContext(info, resource);
             return;
           }
         }
 
         // If the file went away and was replaced by a folder before we
         // had a chance to process the event, resource might be a Folder.  In
         // that case don't add it.
         if (resource is File) {
           File file = resource;
           if (callbacks.shouldFileBeAnalyzed(file)) {
             ChangeSet changeSet = new ChangeSet();
             Source source = createSourceInContext(info.context, file);
             changeSet.addedSource(source);
             callbacks.applyChangesToContext(folder, changeSet);
             info.sources[path] = source;
           }
         }
         break;
       case ChangeType.REMOVE:
 
         // If package spec info is removed, check to see if we can merge contexts.
         // Note that it's important to verify that there is NEITHER a .packages nor a
         // lingering pubspec.yaml before merging.
-        if (!info.isRoot) {
+        if (!info.isTopLevel) {
           if (ENABLE_PACKAGESPEC_SUPPORT) {
             String directoryPath = pathContext.dirname(path);
 
             // Only merge if this is the same directory described by our info object.
             if (info.folder.path == directoryPath) {
               if (_isPubspec(path)) {
                 // Check for a sibling .packages file.
                 if (!resourceProvider.getFile(
                     pathos.join(directoryPath, PACKAGE_SPEC_NAME)).exists) {
                   _mergeContext(info);
@@ skipping 166 matching lines @@
    */
   final List<AnalysisContext> removed;
 
   /**
    * Initialize a newly created event to indicate which contexts have changed.
    */
   ContextsChangedEvent({this.added: AnalysisContext.EMPTY_LIST,
       this.changed: AnalysisContext.EMPTY_LIST,
       this.removed: AnalysisContext.EMPTY_LIST});
 }