[analysis_server] Support folding switch statements/expressions/cases

Fixes Dart-Code/Dart-Code#4506.

Change-Id: Idd5924d04e9ffffc49f088ca6884393ea72e9bea
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/298120
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: DanTup

pkg/analysis_server/lib/src/computer/computer_folding.dart

@@ -395,6 +395,44 @@ class _DartUnitFoldingComputerVisitor extends RecursiveAstVisitor<void> {
     super.visitSetOrMapLiteral(node);
   }
 
+  @override
+  void visitSwitchCase(SwitchCase node) {
+    _computer._addRegion(node.colon.end, node.end, FoldingKind.BLOCK);
+    super.visitSwitchCase(node);
+  }
+
+  @override
+  void visitSwitchDefault(SwitchDefault node) {
+    _computer._addRegion(node.colon.end, node.end, FoldingKind.BLOCK);
+    super.visitSwitchDefault(node);
+  }
+
+  @override
+  void visitSwitchExpression(SwitchExpression node) {
+    _computer._addRegion(
+        node.leftBracket.end, node.rightBracket.end, FoldingKind.BLOCK);
+    super.visitSwitchExpression(node);
+  }
+
+  @override
+  void visitSwitchExpressionCase(SwitchExpressionCase node) {
+    _computer._addRegion(node.arrow.end, node.end, FoldingKind.BLOCK);
+    super.visitSwitchExpressionCase(node);
+  }
+
+  @override
+  void visitSwitchPatternCase(SwitchPatternCase node) {
+    _computer._addRegion(node.colon.end, node.end, FoldingKind.BLOCK);
+    super.visitSwitchPatternCase(node);
+  }
+
+  @override
+  void visitSwitchStatement(SwitchStatement node) {
+    _computer._addRegion(
+        node.leftBracket.end, node.rightBracket.end, FoldingKind.BLOCK);
+    super.visitSwitchStatement(node);
+  }
+
   @override
   void visitWhileStatement(WhileStatement node) {
     var body = node.body;

pkg/analysis_server/test/lsp/folding_test.dart

@@ -340,6 +340,89 @@ void f/*[0*/() {
     });
   }
 
+  Future<void> test_switchExpression() async {
+    final content = '''
+void f(int a) {
+  var b = switch (a) {/*[0*/
+    1 => '',
+    2 =>/*[1*/ '1234567890'
+        '1234567890'/*1]*/,
+    _ =>/*[2*/ '1234567890'
+        '1234567890'
+        '1234567890'
+        '1234567890'/*2]*/
+  }/*0]*/;
+}
+    ''';
+
+    await computeRanges(content);
+    expectRanges(
+      {
+        0: noFoldingKind,
+        1: noFoldingKind,
+        2: noFoldingKind,
+      },
+      requireAll: false,
+    );
+  }
+
+  Future<void> test_switchPattern() async {
+    final content = '''
+void f(int a) {
+  switch (a) {/*[0*/
+    case 0:/*[1*/
+      print('');/*1]*/
+    case 1:
+    case 2:/*[2*/
+      print('');/*2]*/
+    default:/*[3*/
+      print('');/*3]*/
+  }/*0]*/
+}
+    ''';
+
+    await computeRanges(content);
+    expectRanges(
+      {
+        0: noFoldingKind,
+        1: noFoldingKind,
+        2: noFoldingKind,
+        3: noFoldingKind,
+      },
+      requireAll: false,
+    );
+  }
+
+  Future<void> test_switchStatement() async {
+    final content = '''
+// @dart = 2.19
+
+void f(int a) {
+  switch (a) {/*[0*/
+    case 0:/*[1*/
+      print('');
+      break;/*1]*/
+    case 1:
+    case 2:/*[2*/
+      print('');/*2]*/
+    default:/*[3*/
+      print('');/*3]*/
+  }/*0]*/
+}
+    ''';
+
+    await computeRanges(content);
+    expectRanges(
+      {
+        0: noFoldingKind,
+        1: noFoldingKind,
+        2: noFoldingKind,
+        3: noFoldingKind,
+      },
+      requireAll: false,
+    );
+  }
+
   Future<void> test_whileLoop() async {
     final content = '''
     f(int i) {