extract LibraryPrefixContributor from imported reference contributor

pkg/analysis_server/lib/src/services/completion/dart_completion_cache.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 services.completion.dart.cache;
 
 import 'dart:async';
 import 'dart:collection';
 
 import 'package:analysis_server/src/protocol_server.dart'
@@ skipping 13 matching lines @@
  * completion operation.
  */
 class DartCompletionCache extends CompletionCache {
   /**
    * A hash of the import directives
    * or `null` if nothing has been cached.
    */
   String _importKey;
 
   /**
-   * Library prefix suggestions based upon imports,
-   * or `null` if nothing has been cached.
-   */
-  List<CompletionSuggestion> libraryPrefixSuggestions;
-
-  /**
    * Type suggestions based upon imports,
    * or `null` if nothing has been cached.
    */
   List<CompletionSuggestion> importedTypeSuggestions;
 
   /**
    * Suggestions for methods and functions that have void return type,
    * or `null` if nothing has been cached.
    */
   List<CompletionSuggestion> importedVoidReturnSuggestions;
@@ skipping 57 matching lines @@
    * If [shouldWaitForLowPrioritySuggestions] is `true` then the returned
    * future will complete when the cache is fully populated. If `false`,
    * the returned future will complete sooner, but the cache will not include
    * the lower priority suggestions added as a result of a global search.
    * In this case, those lower priority suggestions will be added later
    * when the index has been updated and the global search completes.
    */
   Future<bool> computeImportInfo(CompilationUnit unit,
       SearchEngine searchEngine, bool shouldWaitForLowPrioritySuggestions) {
     importedTypeSuggestions = <CompletionSuggestion>[];
-    libraryPrefixSuggestions = <CompletionSuggestion>[];
     otherImportedSuggestions = <CompletionSuggestion>[];
     importedConstructorSuggestions = <CompletionSuggestion>[];
     importedVoidReturnSuggestions = <CompletionSuggestion>[];
     importedClassMap = new Map<String, ClassElement>();
     _importedCompletions = new HashSet<String>();
 
     // Assert that the compilation unit is resolved
     // and represents the expected source
     assert(unit.element.source == source);
 
@@ skipping 105 matching lines @@
               // Include top level elements
               importNamespace.definedNames.forEach((String name, Element elem) {
                 if (elem is ClassElement) {
                   importedClassMap[name] = elem;
                 }
                 _addSuggestion(elem, DART_RELEVANCE_DEFAULT);
               });
             } else {
               // Exclude elements from prefixed imports
               // because they are provided by PrefixedElementContributor
-              _addLibraryPrefixSuggestion(importElem);
-              excludedLibs.add(importElem.importedLibrary);
+              // Suggested by LibraryPrefixContributor
+              // _addLibraryPrefixSuggestion(importElem);
+              // excludedLibs.add(importElem.importedLibrary);
             }
           }
         } else if (directive is PartDirective) {
           CompilationUnitElement partElem = directive.element;
           if (partElem != null && partElem.source != source) {
             partElem.accept(new _NonLocalElementCacheVisitor(this));
           }
         }
       });
       if (libSource != source) {
         libUnit.element.accept(new _NonLocalElementCacheVisitor(this));
       }
     }
   }
 
-  void _addLibraryPrefixSuggestion(ImportElement importElem) {
-    CompletionSuggestion suggestion = null;
-    String completion = importElem.prefix.displayName;
-    if (completion != null && completion.length > 0) {
-      suggestion = new CompletionSuggestion(
-          CompletionSuggestionKind.INVOCATION,
-          DART_RELEVANCE_DEFAULT,
-          completion,
-          completion.length,
-          0,
-          importElem.isDeprecated,
-          false);
-      LibraryElement lib = importElem.importedLibrary;
-      if (lib != null) {
-        suggestion.element = convertElement(lib);
-      }
-      libraryPrefixSuggestions.add(suggestion);
-      _importedCompletions.add(suggestion.completion);
-    }
-  }
-
   /**
    * Add suggestions for all top level elements in the context
    * excluding those elemnents for which suggestions have already been added.
    */
   void _addNonImportedElementSuggestions(
       List<SearchMatch> matches, Set<LibraryElement> excludedLibs) {
     // Exclude internal Dart SDK libraries
     for (var lib in context.sourceFactory.dartSdk.sdkLibraries) {
       if (lib.isInternal) {
         Source libUri = context.sourceFactory.forUri(lib.shortName);
@@ skipping 122 matching lines @@
   @override
   void visitFunctionTypeAliasElement(FunctionTypeAliasElement element) {
     cache._addSuggestion(element, DART_RELEVANCE_DEFAULT);
   }
 
   @override
   void visitTopLevelVariableElement(TopLevelVariableElement element) {
     cache._addSuggestion(element, DART_RELEVANCE_DEFAULT);
   }
 }