show all available import completion suggestions - fixes #23955

pkg/analysis_server/lib/src/services/completion/import_uri_contributor.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.contributor.dart.importuri;
 
 import 'dart:async';
-import 'dart:collection';
 import 'dart:core' hide Resource;
 
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:path/path.dart';
 
 import '../../protocol_server.dart'
@@ skipping 13 matching lines @@
   }
 
   @override
   Future<bool> computeFull(DartCompletionRequest request) {
     return new Future.value(false);
   }
 }
 
 class _ImportUriSuggestionBuilder extends SimpleAstVisitor {
   final DartCompletionRequest request;
-  HashSet<String> _importedUris;
 
   _ImportUriSuggestionBuilder(this.request);
 
   bool computeFast(AstNode node) {
     node.accept(this);
     return true;
   }
 
   @override
   visitImportDirective(ImportDirective node) {
     StringLiteral uri = node.uri;
     if (uri is SimpleStringLiteral) {
       int offset = request.offset;
       if (uri.offset < offset &&
           (offset < uri.end || offset == uri.offset + 1)) {
         // Handle degenerate case where import is only line in file
         // and there is no semicolon
         visitSimpleStringLiteral(uri);
       }
     }
   }
 
   @override
   visitSimpleStringLiteral(SimpleStringLiteral node) {
     AstNode parent = node.parent;
     if (parent is ImportDirective && parent.uri == node) {
       String partial = node.literal.lexeme.substring(
           node.contentsOffset - node.offset, request.offset - node.offset);
-      _computeImportedUris();
       request.replacementOffset = node.contentsOffset;
       request.replacementLength = node.contentsEnd - node.contentsOffset;
       _addDartSuggestions();
       _addPackageSuggestions(partial);
       _addFileSuggestions(partial);
     } else if (parent is PartDirective && parent.uri == node) {
       String partial = node.literal.lexeme.substring(
           node.contentsOffset - node.offset, request.offset - node.offset);
-      _computeImportedUris();
       request.replacementOffset = node.contentsOffset;
       request.replacementLength = node.contentsEnd - node.contentsOffset;
       _addFileSuggestions(partial);
     }
   }
 
   void _addDartSuggestions() {
     _addSuggestion('dart:');
     SourceFactory factory = request.context.sourceFactory;
     for (SdkLibrary lib in factory.dartSdk.sdkLibraries) {
       if (!lib.isInternal && !lib.isImplementation) {
         if (!lib.shortName.startsWith('dart:_')) {
-          _addSuggestion(lib.shortName);
+          _addSuggestion(lib.shortName,
+              relevance: lib.shortName == 'dart:core'
+                  ? DART_RELEVANCE_LOW
+                  : DART_RELEVANCE_DEFAULT);
         }
       }
     }
   }
 
   void _addFileSuggestions(String partial) {
     Source source = request.source;
     String sourceFullName = source.fullName;
     String sourceShortName = source.shortName;
     String dirPath = (partial.endsWith('/') || partial.endsWith(separator))
@@ skipping 49 matching lines @@
         _addSuggestion(prefix);
         for (Folder folder in folders) {
           if (folder.exists) {
             _addPackageFolderSuggestions(partial, prefix, folder);
           }
         }
       });
     }
   }
 
-  void _addSuggestion(String completion) {
-    if (!_importedUris.contains(completion)) {
-      request.addSuggestion(new CompletionSuggestion(
-          CompletionSuggestionKind.IMPORT, DART_RELEVANCE_DEFAULT, completion,
-          completion.length, 0, false, false));
-    }
-  }
-
-  void _computeImportedUris() {
-    _importedUris = new HashSet<String>();
-    _importedUris.add('dart:core');
-    for (Directive directive in request.unit.directives) {
-      if (directive is ImportDirective) {
-        String uri = directive.uriContent;
-        if (uri != null && uri.length > 0) {
-          _importedUris.add(uri);
-        }
-      }
-    }
+  void _addSuggestion(String completion,
+      {int relevance: DART_RELEVANCE_DEFAULT}) {
+    request.addSuggestion(new CompletionSuggestion(
+        CompletionSuggestionKind.IMPORT,
+        relevance,
+        completion,
+        completion.length,
+        0,
+        false,
+        false));
   }
 }