Support completion in switch expressions

Change-Id: I21df4780eed21043b3d97ea0e55c50285e4c9b28
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/282700
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

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

@@ -826,6 +826,13 @@ class _KeywordVisitor extends GeneralizingAstVisitor<void> {
     return super.visitSwitchCase(node);
   }
 
+  @override
+  void visitSwitchExpression(SwitchExpression node) {
+    if (entity == node.expression) {
+      _addExpressionKeywords(node);
+    }
+  }
+
   @override
   void visitSwitchPatternCase(SwitchPatternCase node) {
     final entity = this.entity;
@@ -861,22 +868,16 @@ class _KeywordVisitor extends GeneralizingAstVisitor<void> {
     if (entity == node.expression) {
       _addExpressionKeywords(node);
     } else if (entity == node.rightBracket) {
-      if (node.members.isEmpty) {
-        _addSuggestion(Keyword.CASE);
-        _addSuggestion2(DEFAULT_COLON);
-      } else {
-        _addSuggestion(Keyword.CASE);
-        _addSuggestion2(DEFAULT_COLON);
+      _addSuggestion(Keyword.CASE);
+      _addSuggestion2(DEFAULT_COLON);
+      if (node.members.isNotEmpty) {
         _addStatementKeywords(node);
       }
     }
     if (node.members.contains(entity)) {
-      if (entity == node.members.first) {
-        _addSuggestion(Keyword.CASE);
-        _addSuggestion2(DEFAULT_COLON);
-      } else {
-        _addSuggestion(Keyword.CASE);
-        _addSuggestion2(DEFAULT_COLON);
+      _addSuggestion(Keyword.CASE);
+      _addSuggestion2(DEFAULT_COLON);
+      if (entity != node.members.first) {
         _addStatementKeywords(node);
       }
     }

pkg/analysis_server/test/services/completion/dart/location/switch_expression_test.dart

@@ -0,0 +1,98 @@
+// Copyright (c) 2023, 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.
+
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../../../../client/completion_driver_test.dart';
+
+void main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(SwitchExpressionTest1);
+    defineReflectiveTests(SwitchExpressionTest2);
+  });
+}
+
+@reflectiveTest
+class SwitchExpressionTest1 extends AbstractCompletionDriverTest
+    with SwitchExpressionTestCases {
+  @override
+  TestingCompletionProtocol get protocol => TestingCompletionProtocol.version1;
+}
+
+@reflectiveTest
+class SwitchExpressionTest2 extends AbstractCompletionDriverTest
+    with SwitchExpressionTestCases {
+  @override
+  TestingCompletionProtocol get protocol => TestingCompletionProtocol.version2;
+}
+
+// mixin SwitchCaseTestCases on AbstractCompletionDriverTest {
+// }
+
+mixin SwitchExpressionTestCases on AbstractCompletionDriverTest {
+  Future<void> test_body_afterArrow() async {
+    await computeSuggestions('''
+int f(Object p01) {
+  return switch (p01) {
+    1 => ^
+  };
+}
+''');
+    assertResponse('''
+suggestions
+  p01
+    kind: parameter
+''');
+  }
+
+  Future<void> test_body_afterComma() async {
+    await computeSuggestions('''
+int f(Object p01) {
+  return switch (p01) {
+    1 => 2,
+    ^
+  };
+}
+''');
+    assertResponse('''
+suggestions
+''');
+  }
+
+  Future<void> test_body_empty() async {
+    await computeSuggestions('''
+int f(Object p01) {
+  return switch (p01) {
+    ^
+  };
+}
+''');
+    assertResponse('''
+suggestions
+''');
+  }
+
+  Future<void> test_expression() async {
+    await computeSuggestions('''
+int f(Object p01) {
+  return switch (^) {};
+}
+''');
+    assertResponse('''
+suggestions
+  const
+    kind: keyword
+  false
+    kind: keyword
+  null
+    kind: keyword
+  p01
+    kind: parameter
+  switch
+    kind: keyword
+  true
+    kind: keyword
+''');
+  }
+}

pkg/analysis_server/test/services/completion/dart/location/test_all.dart

@@ -24,6 +24,7 @@ import 'record_pattern_test.dart' as record_pattern;
 import 'record_type_annotation_test.dart' as record_type_annotation;
 import 'relational_pattern_test.dart' as relational_pattern;
 import 'super_formal_parameter_test.dart' as super_formal_parameter;
+import 'switch_expression_test.dart' as switch_expression;
 import 'switch_pattern_case_test.dart' as switch_pattern_case;
 import 'type_argument_list_test.dart' as type_argument_list;
 import 'variable_declaration_list_test.dart' as variable_declaration_list;
@@ -51,6 +52,7 @@ void main() {
     record_type_annotation.main();
     relational_pattern.main();
     super_formal_parameter.main();
+    switch_expression.main();
     switch_pattern_case.main();
     type_argument_list.main();
     variable_declaration_list.main();

pkg/analyzer_plugin/lib/src/utilities/completion/optype.dart

@@ -1388,6 +1388,24 @@ class _OpTypeAstVisitor extends GeneralizingAstVisitor<void> {
     }
   }
 
+  @override
+  void visitSwitchExpression(SwitchExpression node) {
+    if (identical(entity, node.expression)) {
+      optype.completionLocation = 'SwitchExpression_expression';
+      optype.includeReturnValueSuggestions = true;
+      optype.includeTypeNameSuggestions = true;
+    }
+  }
+
+  @override
+  void visitSwitchExpressionCase(SwitchExpressionCase node) {
+    if (identical(entity, node.expression)) {
+      optype.completionLocation = 'SwitchExpressionCase_expression';
+      optype.includeReturnValueSuggestions = true;
+      optype.includeTypeNameSuggestions = true;
+    }
+  }
+
   @override
   void visitSwitchPatternCase(SwitchPatternCase node) {
     if (identical(entity, node.colon)) {