Update IfToSwitch refactoring for switch expressions

src/Compilers/Core/Portable/InternalUtilities/EnumerableExtensions.cs

@@ -546,5 +546,24 @@ public static bool SequenceEqual<T>(this IEnumerable<T> first, IEnumerable<T> se
 
  return true;
  }
+
+ public static T AggregateOrDefault<T>(this IEnumerable<T> source, Func<T, T, T> func)
+ {
+ using (var e = source.GetEnumerator())
+ {
+ if (!e.MoveNext())
+ {
+ return default;
+ }
+
+ var result = e.Current;
+ while (e.MoveNext())
+ {
+ result = func(result, e.Current);
+ }
+
+ return result;
+ }
+ }
  }
 }

src/EditorFeatures/CSharpTest/CodeActions/ConvertIfToSwitch/ConvertIfToSwitchTests.cs

@@ -341,7 +341,7 @@ void M(object o)
  {
  switch (o)
  {
- case string s when s.Length > 5 && s.Length < 10:
+ case string s when (s.Length > 5 && s.Length < 10):
  return;
  case int i:
  return;
@@ -380,7 +380,7 @@ void M(object o)
  }
 
  [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsConvertIfToSwitch)]
- public async Task TestPreserveTrivia()
+ public async Task TestComplexExpression_01()
  {
  await TestInRegularAndScriptAsync(
 @"class C
@@ -405,8 +405,7 @@ void M(object o)
  {
  switch (o)
  {
- case string s when s.Length > 5 &&
- s.Length < 10:
+ case string s when s.Length > 5 && s.Length < 10:
  M(o: 0);
  break;
  case int i:
@@ -562,12 +561,40 @@ int M(int? i)
  return 5;
  case 0:
  return 6;
+ default:
+ return 7;
  }
- return 7;
  }
 }");
  }
 
+ [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsConvertIfToSwitch)]
+ public async Task TestSwitchExpression_01()
+ {
+ await TestInRegularAndScriptAsync(
+ @"class C
+{
+ int M(int? i)
+ {
+ [||]if (i == null) return 5;
+ if (i == 0) return 6;
+ return 7;
+ }
+}",
+@"class C
+{
+ int M(int? i)
+ {
+ return i switch
+ {
+ null => 5,
+ 0 => 6,
+ _ => 7
+ };
+ }
+}", index: 1);
+ }
+
  [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsConvertIfToSwitch)]
  public async Task TestSubsequentIfStatements_02()
  {
@@ -810,7 +837,7 @@ public async Task TestTrivia1()
  await TestInRegularAndScriptAsync(
 @"class C
 {
- int M(int i)
+ int M(int x, int z)
  {
 #if TRUE
  Console.WriteLine();
@@ -828,7 +855,7 @@ int M(int i)
 }",
 @"class C
 {
- int M(int i)
+ int M(int x, int z)
  {
 #if TRUE
  Console.WriteLine();
@@ -854,7 +881,7 @@ public async Task TestTrivia2()
  await TestInRegularAndScriptAsync(
 @"class C
 {
- int M(int i)
+ int M(int i, string[] args)
  {
  [||]if (/* t0 */args.Length /* t1*/ == /* t2 */ 2)
  return /* t3 */ 0 /* t4 */; /* t5 */
@@ -864,7 +891,7 @@ int M(int i)
 }",
 @"class C
 {
- int M(int i)
+ int M(int i, string[] args)
  {
  switch (/* t0 */args.Length /* t1*/ )
  {
@@ -1168,7 +1195,7 @@ void M(int i)
  {
  switch (i)
  {
- case 1 when i == 2 && i == 3:
+ case 1 when (i == 2 && i == 3):
  return;
  case 10:
  return;
@@ -1318,7 +1345,7 @@ void M(int i)
  {
  switch (i)
  {
- case 1 when (i == 2) && i == 3:
+ case 1 when ((i == 2) && i == 3):
  return;
  case 10:
  return;
@@ -1348,12 +1375,46 @@ void M(int i)
  {
  switch (i)
  {
- case 1 when i == 2 && (i == 3):
+ case 1 when (i == 2 && (i == 3)):
  return;
  case 10:
  return;
  }
  }
+}");
+ }
+
+ [WorkItem(37035, "https:/dotnet/roslyn/issues/37035")]
+ [Fact, Trait(Traits.Feature, Traits.Features.CodeActionsConvertIfToSwitch)]
+ public async Task TestComplexExpression_02()
+ {
+ await TestInRegularAndScriptAsync(
+@"class C
+{
+ void M(object o)
+ {
+ [||]if (o is string text &&
+ int.TryParse(text, out var n) &&
+ n < 5 && n > -5)
+ {
+ }
+ else
+ {
+ }
+ }
+}",
+@"class C
+{
+ void M(object o)
+ {
+ switch (o)
+ {
+ case string text when int.TryParse(text, out var n) && n < 5 && n > -5:
+ break;
+ default:
+ break;
+ }
+ }
 }");
  }
  }

src/EditorFeatures/VisualBasicTest/CodeActions/ConvertIfToSwitch/ConvertIfToSwitchTests.vb

@@ -220,8 +220,9 @@ End Class",
  Return 5
  Case 20
  Return 6
+ Case Else
+ Return 7
  End Select
- Return 7
  End Function
 End Class")
  End Function

src/Features/CSharp/Portable/ConvertIfToSwitch/CSharpConvertIfToSwitchCodeRefactoringProvider.Analyzer.cs

@@ -0,0 +1,42 @@
+// Copyright (c) Microsoft. All Rights Reserved. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Linq;
+using Microsoft.CodeAnalysis.LanguageServices;
+using Microsoft.CodeAnalysis.Operations;
+
+namespace Microsoft.CodeAnalysis.CSharp.ConvertIfToSwitch
+{
+ internal sealed partial class CSharpConvertIfToSwitchCodeRefactoringProvider
+ {
+ private sealed class CSharpAnalyzer : Analyzer
+ {
+ public override bool SupportsSwitchExpression => true;
+ public override bool SupportsCaseGuard => true;
+ public override bool SupportsRangePattern => false;
+ public override bool SupportsTypePattern => true;
+ public override bool SupportsSourcePattern => true;
+ public override bool SupportsRelationalPattern => false;
+
+ public CSharpAnalyzer(ISyntaxFactsService syntaxFacts)
+ : base(syntaxFacts)
+ {
+ }
+
+ public override bool HasUnreachableEndPoint(IOperation operation)
+ => !operation.SemanticModel.AnalyzeControlFlow(operation.Syntax).EndPointIsReachable;
+
+ // We do not offer a fix if the if-statement contains a break-statement, e.g.
+ //
+ // while (...)
+ // {
+ // if (...) {
+ // break;
+ // }
+ // }
+ //
+ // When the 'break' moves into the switch, it will have different flow control impact.
+ public override bool CanConvert(IConditionalOperation operation)
+ => !operation.SemanticModel.AnalyzeControlFlow(operation.Syntax).ExitPoints.Any(n => CodeAnalysis.CSharpExtensions.IsKind((SyntaxNode)n, SyntaxKind.BreakStatement));
+ }
+ }
+}