improve keyword suggestions - fixes #24016

pkg/analysis_server/lib/src/services/completion/keyword_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.keyword;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
@@ skipping 214 matching lines @@
   @override
   visitInstanceCreationExpression(InstanceCreationExpression node) {
     if (entity == node.constructorName) {
       // no keywords in 'new ^' expression
     } else {
       super.visitInstanceCreationExpression(node);
     }
   }
 
   @override
+  visitIsExpression(IsExpression node) {
+    if (entity == node.isOperator) {
+      _addSuggestion(Keyword.IS, DART_RELEVANCE_HIGH);
+    } else {
+      _addExpressionKeywords(node);
+    }
+  }
+
+  @override
   visitLibraryIdentifier(LibraryIdentifier node) {
     // no suggestions
   }
 
   @override
   visitMethodDeclaration(MethodDeclaration node) {
     if (entity == node.body) {
       if (node.body is EmptyFunctionBody) {
         _addClassBodyKeywords();
         _addSuggestion2(ASYNC);
@@ skipping 152 matching lines @@
     }
   }
 
   void _addStatementKeywords(AstNode node) {
     if (_inClassMemberBody(node)) {
       _addSuggestions([Keyword.SUPER, Keyword.THIS,]);
     }
     if (_inAsyncMethodOrFunction(node)) {
       _addSuggestion2(AWAIT);
     }
+    if (_inLoop(node)) {
+      _addSuggestions([Keyword.BREAK, Keyword.CONTINUE]);
+    }
+    if (_inSwitch(node)) {
+      _addSuggestions([Keyword.BREAK]);
+    }
     _addSuggestions([
       Keyword.ASSERT,
-      Keyword.CONTINUE,
       Keyword.DO,
       Keyword.FINAL,
       Keyword.FOR,
       Keyword.IF,
       Keyword.NEW,

[Brian Wilkerson, 2015/08/26 20:33:20]

If we suggest 'new', shouldn't we also suggest 'const'?

[danrubel, 2015/08/26 21:39:29]

Good suggestion. Done.

       Keyword.RETURN,
       Keyword.SWITCH,
       Keyword.THROW,
       Keyword.TRY,
       Keyword.VAR,
       Keyword.VOID,
       Keyword.WHILE
     ]);
     _addSuggestion(Keyword.RETHROW, DART_RELEVANCE_KEYWORD - 1);

[Brian Wilkerson, 2015/08/26 20:33:20]

Seems like we should only suggest this if we're inside a catch block, in which
case the relevance should be as high as any other keyword.

[danrubel, 2015/08/26 21:39:29]

Good point. I'll address this in a subsequent CL.
https://github.com/dart-lang/sdk/issues/24214

   }
 
   void _addSuggestion(Keyword keyword,
       [int relevance = DART_RELEVANCE_KEYWORD]) {
     _addSuggestion2(keyword.syntax, relevance: relevance);
   }
 
   void _addSuggestion2(String completion,
       {int offset, int relevance: DART_RELEVANCE_KEYWORD}) {
     if (offset == null) {
       offset = completion.length;
     }
     request.addSuggestion(new CompletionSuggestion(
-        CompletionSuggestionKind.KEYWORD, relevance, completion, offset, 0,
-        false, false));
+        CompletionSuggestionKind.KEYWORD,
+        relevance,
+        completion,
+        offset,
+        0,
+        false,
+        false));
   }
 
   void _addSuggestions(List<Keyword> keywords,
       [int relevance = DART_RELEVANCE_KEYWORD]) {
     keywords.forEach((Keyword keyword) {
       _addSuggestion(keyword, relevance);
     });
   }
 
   bool _inAsyncMethodOrFunction(AstNode node) {
     FunctionBody body = node.getAncestor((n) => n is FunctionBody);
     return body != null && body.isAsynchronous;
   }
 
   bool _inClassMemberBody(AstNode node) {
     while (true) {
       AstNode body = node.getAncestor((n) => n is FunctionBody);
       if (body == null) {
         return false;
       }
       AstNode parent = body.parent;
       if (parent is ConstructorDeclaration || parent is MethodDeclaration) {
         return true;

[Brian Wilkerson, 2015/08/26 20:33:20]

If we're inside a method declaration, given that this is used for 'this' and
'super', we should check that it doesn't have a 'super' modifier.

[danrubel, 2015/08/26 21:39:29]

Not sure what you mean here. Isn't this valid thus we should suggest super?

class A {
  var x;
}
class B extends A {
  B() : super() {super.x = 7;}
}

       }
       node = parent;
     }
   }
+
+  bool _inDoLoop(AstNode node) =>
+      node.getAncestor((p) => p is DoStatement) != null;
+
+  bool _inForLoop(AstNode node) =>
+      node.getAncestor((p) => p is ForStatement || p is ForEachStatement) !=
+          null;
+
+  bool _inLoop(AstNode node) =>
+      _inDoLoop(node) || _inForLoop(node) || _inWhileLoop(node);
+
+  bool _inSwitch(AstNode node) =>
+      node.getAncestor((p) => p is SwitchStatement) != null;
+
+  bool _inWhileLoop(AstNode node) =>
+      node.getAncestor((p) => p is WhileStatement) != null;
 }