add keyword suggestions

pkg/analysis_services/lib/src/completion/keyword_computer.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.computer.dart.keyword;
+
+import 'dart:async';
+
+import 'package:analysis_services/completion/completion_computer.dart';
+import 'package:analysis_services/completion/completion_suggestion.dart';
+import 'package:analyzer/src/generated/ast.dart';
+import 'package:analyzer/src/generated/scanner.dart';
+
+/**
+ * A computer for calculating `completion.getSuggestions` request results
+ * for the local library in which the completion is requested.
+ */
+class KeywordComputer extends CompletionComputer {
+
+  @override
+  bool computeFast(CompilationUnit unit, AstNode node,
+      List<CompletionSuggestion> suggestions) {
+    node.accept(new _KeywordVisitor(suggestions));
+    return true;
+  }
+
+  @override
+  Future<bool> computeFull(CompilationUnit unit, AstNode node,
+      List<CompletionSuggestion> suggestions) {
+    return new Future.value(false);
+  }
+}
+
+/**
+ * A vistor for generating keyword suggestions.
+ */
+class _KeywordVisitor extends GeneralizingAstVisitor {

[Brian Wilkerson, 2014/08/12 15:33:37]

It seems unlikely that we'd ever want to add suggestions for all nodes, so
perhaps extend SimpleAstVisitor.

[danrubel, 2014/08/15 03:23:26]

I'm thinking that there may be some more general situations in which we want to
suggest such things as true, false, null, which is why I chose this base class.

+  final List<CompletionSuggestion> suggestions;
+
+  _KeywordVisitor(this.suggestions);
+
+  visitCompilationUnit(CompilationUnit node) {

[Brian Wilkerson, 2014/08/12 15:33:37]

Missing @override annotations.

[danrubel, 2014/08/15 03:23:26]

I wish that the tool would insert these automatically. I'll have to go through
all my visitors to add these missing annotations in a separate CL.

+    _addSuggestions(

[Brian Wilkerson, 2014/08/13 16:20:15]

This should check to see whether we are in the "directives" partition or the
"declarations" partition of the file and only suggest valid completions. For
example, given

  library lib;
  import 'dart:async';
  ab^
  import 'dart:unittest';

I would argue that we shouldn't suggest "abstract" because it isn't valid at
that point. Similarly, given

  class C {}
  im^

we shouldn't suggest "import" because it's also not valid.

[danrubel, 2014/08/15 03:23:26]

Good points. I'll add tests for these. This current implementation is very much
an incomplete first cut just to get things moving.

+        [
+            Keyword.ABSTRACT,
+            Keyword.CLASS,
+            Keyword.CONST,
+            Keyword.EXPORT,
+            Keyword.FINAL,
+            Keyword.IMPORT,
+            Keyword.LIBRARY,
+            Keyword.PART,
+            Keyword.VAR]);

[Brian Wilkerson, 2014/08/12 15:33:37]

Missing 'typedef'.

[danrubel, 2014/08/15 03:23:26]

Done.

+  }
+
+  visitClassDeclaration(ClassDeclaration node) {
+    _addSuggestions([Keyword.EXTENDS, Keyword.IMPLEMENTS, Keyword.WITH]);

[Brian Wilkerson, 2014/08/12 15:33:38]

This should check that we're not within the body of the class.

It should not suggest keywords that are already in use (for example "class C ^
implements A {}" shouldn't suggest "implements").

It should not suggest keywords that can't be used (for example "class C ^
extends B {}" shouldn't suggest any keywords because both "with" and
"implements" would need to follow the extends clause).

[danrubel, 2014/08/15 03:23:26]

Will definitely add these as a follow on CL. As stated this is an incomplete
first cut to get things rolling.

+  }
+
+  void _addSuggestions(List<Keyword> keywords) {
+    keywords.forEach((Keyword keyword) {
+      String completion = keyword.syntax;
+      suggestions.add(
+          new CompletionSuggestion(
+              CompletionSuggestionKind.KEYWORD,
+              CompletionRelevance.DEFAULT,
+              completion,
+              completion.length,
+              0,
+              false,
+              false));
+    });
+  }
+
+  visitNode(AstNode node) {}
+}