Suggest enum constants for imported enums.

So, you can complete `Column(crossAxisAlignment: ^)` and get all of
the CrossAxisAlignment right away for selection. Or you can start
typing `center` and by the time when you typed first letters, you get
several completion suggestions. There are several enums with `center`,
but because we give compatible types higher relevance, the correct
one is always the first.

[email protected], [email protected]

Bug: flutter/flutter-intellij#998
Change-Id: I6c2082668c6b25bf23e070915b5df03081ff0d5c
Reviewed-on: https://dart-review.googlesource.com/43485
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

pkg/analysis_server/lib/src/services/completion/dart/local_library_contributor.dart

@@ -61,6 +61,21 @@ class LibraryElementSuggestionBuilder extends GeneralizingElementVisitor
         _addConstructorSuggestions(element, relevance);
       }
     }
+    if (optype.includeReturnValueSuggestions) {
+      if (element.isEnum) {
+        String enumName = element.displayName;
+        int relevance = optype.returnValueSuggestionsFilter(
+            element.type, DART_RELEVANCE_DEFAULT);
+        for (var field in element.fields) {
+          if (field.isEnumConstant) {
+            addSuggestion(field,
+                prefix: prefix,
+                relevance: relevance,
+                elementCompletion: '$enumName.${field.name}');
+          }
+        }
+      }
+    }
   }
 
   @override

pkg/analysis_server/lib/src/services/completion/dart/suggestion_builder.dart

@@ -147,13 +147,15 @@ abstract class ElementSuggestionBuilder {
    * Add a suggestion based upon the given element.
    */
   void addSuggestion(Element element,
-      {String prefix, int relevance: DART_RELEVANCE_DEFAULT}) {
+      {String prefix,
+      int relevance: DART_RELEVANCE_DEFAULT,
+      String elementCompletion}) {
     if (element.isPrivate) {
       if (element.library != containingLibrary) {
         return;
       }
     }
-    String completion = element.displayName;
+    String completion = elementCompletion ?? element.displayName;
     if (prefix != null && prefix.length > 0) {
       if (completion == null || completion.length <= 0) {
         completion = prefix;

pkg/analysis_server/test/services/completion/dart/imported_reference_contributor_test.dart

@@ -1849,6 +1849,33 @@ int myFunc() {}
     assertNotSuggested('two');
   }
 
+  test_enum_filter() async {
+    addSource('/a.dart', '''
+enum E { one, two }
+enum F { three, four }
+''');
+    addTestSource('''
+import 'a.dart';
+
+void foo({E e}) {}
+
+main() {
+  foo(e: ^);
+}
+''');
+    await computeSuggestions();
+
+    assertSuggestEnum('E');
+    assertSuggestEnumConst('E.one',
+        relevance: DART_RELEVANCE_DEFAULT + DART_RELEVANCE_BOOST_TYPE);
+    assertSuggestEnumConst('E.two',
+        relevance: DART_RELEVANCE_DEFAULT + DART_RELEVANCE_BOOST_TYPE);
+
+    assertSuggestEnum('F');
+    assertSuggestEnumConst('F.three');
+    assertSuggestEnumConst('F.four');
+  }
+
   test_ExpressionStatement_identifier() async {
     // SimpleIdentifier  ExpressionStatement  Block
     resolveSource('/testA.dart', '''

pkg/analysis_server/test/services/completion/dart/local_reference_contributor_test.dart

@@ -2167,10 +2167,13 @@ main() {
 ''');
     await computeSuggestions();
 
+    assertSuggestEnum('E');
     assertSuggestEnumConst('E.one',
         relevance: DART_RELEVANCE_DEFAULT + DART_RELEVANCE_BOOST_TYPE);
     assertSuggestEnumConst('E.two',
         relevance: DART_RELEVANCE_DEFAULT + DART_RELEVANCE_BOOST_TYPE);
+
+    assertSuggestEnum('F');
     assertSuggestEnumConst('F.three');
     assertSuggestEnumConst('F.four');
   }