Add analyzer 'Add/remove blank line between switch sections' (#1302)

ChangeLog.md

@@ -7,6 +7,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add analyzer "Add/remove blank line between switch sections" ([RCS0061](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS0061)) ([PR](https://github.com/dotnet/roslynator/pull/1302))
+  - Option (required): `roslynator_blank_line_between_switch_sections = include|omit|omit_after_block` 
+  - Make analyzer [RCS0014](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS0014) obsolete
+
 ### Changed
 
 - Replace type declaration's empty braces with semicolon ([RCS1251](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1251) ([PR](https://github.com/dotnet/roslynator/pull/1323))
@@ -18,6 +24,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Add analyzer "Dispose resource asynchronously" ([RCS1261](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1261)) ([PR](https://github.com/dotnet/roslynator/pull/1285))
 - Add analyzer "Unnecessary raw string literal" ([RCS1262](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1262)) ([PR](https://github.com/dotnet/roslynator/pull/1293))
 - Add analyzer "Invalid reference in a documentation comment" ([RCS1263](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1263)) ([PR](https://github.com/dotnet/roslynator/pull/1295))
+- Add analyzer "Add/remove blank line between switch sections" ([RCS0061](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS0061)) ([PR](https://github.com/dotnet/roslynator/pull/1302))
+  - Option (required): `roslynator_blank_line_between_switch_sections = include|omit|omit_after_block` 
+  - Make analyzer [RCS0014](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS0014) obsolete
 
 ### Changed
 

src/Analyzers.xml

@@ -388,6 +388,8 @@ object this[int index] { get; }]]></After>
   <Analyzer>
     <Id>RCS0014</Id>
     <Identifier>AddBlankLineBetweenSwitchSections</Identifier>
+    <Status>Obsolete</Status>
+    <ObsoleteMessage>Use RCS0061 instead</ObsoleteMessage>
     <Title>Add blank line between switch sections</Title>
     <DefaultSeverity>Info</DefaultSeverity>
     <IsEnabledByDefault>false</IsEnabledByDefault>
@@ -1530,6 +1532,103 @@ public class C
       </Link>
     </Links>
   </Analyzer>
+  <Analyzer>
+    <Id>RCS0061</Id>
+    <Identifier>BlankLineBetweenSwitchSections</Identifier>
+    <Title>Add/remove blank line between switch sections</Title>
+    <MessageFormat>{0} blank line between switch sections</MessageFormat>
+    <DefaultSeverity>Info</DefaultSeverity>
+    <IsEnabledByDefault>false</IsEnabledByDefault>
+    <ConfigOptions>
+      <Option Key="blank_line_between_switch_sections" IsRequired="true" />
+    </ConfigOptions>
+    <Samples>
+      <Sample>
+        <ConfigOptions>
+          <Option Key="blank_line_between_switch_sections" Value="include" />
+        </ConfigOptions>
+        <Before><![CDATA[switch (x)
+{
+    case "foo":
+        return true;
+    case "bar":
+        return false;
+    default:
+        throw new InvalidOperationException();
+}
+]]></Before>
+        <After><![CDATA[switch (x)
+{
+    case "foo":
+        return true;
+
+    case "bar":
+        return false;
+
+    default:
+        throw new InvalidOperationException();
+}
+]]></After>
+      </Sample>
+      <Sample>
+        <ConfigOptions>
+          <Option Key="blank_line_between_switch_sections" Value="omit" />
+        </ConfigOptions>
+        <Before><![CDATA[switch (x)
+{
+    case "foo":
+        return true;
+
+    case "bar":
+        return false;
+
+    default:
+        throw new InvalidOperationException();
+}
+]]></Before>
+        <After><![CDATA[switch (x)
+{
+    case "foo":
+        return true;
+    case "bar":
+        return false;
+    default:
+        throw new InvalidOperationException();
+}
+]]></After>
+      </Sample>
+      <Sample>
+        <ConfigOptions>
+          <Option Key="blank_line_between_switch_sections" Value="omit_after_block" />
+        </ConfigOptions>
+        <Before><![CDATA[switch (x)
+{
+    case "foo":
+      {
+        return true;
+      }
+
+    case "bar":
+      {
+        return false;
+      }
+}
+]]></Before>
+        <After><![CDATA[switch (x)
+{
+    case "foo":
+      {
+        return true;
+      }
+    case "bar":
+      {
+        return false;
+      }
+}
+]]></After>
+      </Sample>
+    </Samples>
+  </Analyzer>
   <Analyzer>
     <Id>RCS1001</Id>
     <Identifier>AddBracesWhenExpressionSpansOverMultipleLines</Identifier>

src/Analyzers/CSharp/Analysis/RemoveUnnecessaryBlankLineAnalyzer.cs

@@ -38,7 +38,6 @@ public override void Initialize(AnalysisContext context)
         context.RegisterSyntaxNodeAction(f => AnalyzeInterfaceDeclaration(f), SyntaxKind.InterfaceDeclaration);
         context.RegisterSyntaxNodeAction(f => AnalyzeEnumDeclaration(f), SyntaxKind.EnumDeclaration);
         context.RegisterSyntaxNodeAction(f => AnalyzeNamespaceDeclaration(f), SyntaxKind.NamespaceDeclaration);
-        context.RegisterSyntaxNodeAction(f => AnalyzeSwitchStatement(f), SyntaxKind.SwitchStatement);
         context.RegisterSyntaxNodeAction(f => AnalyzeTryStatement(f), SyntaxKind.TryStatement);
         context.RegisterSyntaxNodeAction(f => AnalyzeElseClause(f), SyntaxKind.ElseClause);
 
@@ -147,35 +146,6 @@ private static void AnalyzeNamespaceDeclaration(SyntaxNodeAnalysisContext contex
             AnalyzeEnd(context, members.Last(), namespaceDeclaration.CloseBraceToken);
     }
 
-    private static void AnalyzeSwitchStatement(SyntaxNodeAnalysisContext context)
-    {
-        var switchStatement = (SwitchStatementSyntax)context.Node;
-
-        SyntaxList<SwitchSectionSyntax> sections = switchStatement.Sections;
-
-        if (sections.Any())
-        {
-            AnalyzeStart(context, sections[0], switchStatement.OpenBraceToken);
-            AnalyzeEnd(context, sections.Last(), switchStatement.CloseBraceToken);
-
-            if (sections.Count > 1
-                && context.GetBlankLineBetweenClosingBraceAndSwitchSection() == false)
-            {
-                SwitchSectionSyntax prevSection = sections[0];
-
-                for (int i = 1; i < sections.Count; i++)
-                {
-                    SwitchSectionSyntax section = sections[i];
-
-                    if (prevSection.Statements.LastOrDefault() is BlockSyntax block)
-                        Analyze(context, block.CloseBraceToken, section);
-
-                    prevSection = section;
-                }
-            }
-        }
-    }
-
     private static void AnalyzeTryStatement(SyntaxNodeAnalysisContext context)
     {
         var tryStatement = (TryStatementSyntax)context.Node;

src/Common/CSharp/CodeStyle/BlankLineBetweenSwitchSections.cs

@@ -0,0 +1,11 @@
+// Copyright (c) .NET Foundation and Contributors. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Roslynator.CSharp.CodeStyle;
+
+internal enum BlankLineBetweenSwitchSections
+{
+    None,
+    Include,
+    Omit,
+    OmitAfterBlock,
+}

src/Common/CSharp/Extensions/CodeStyleExtensions.cs

@@ -581,6 +581,23 @@ public static BlankLineStyle GetBlankLineAfterFileScopedNamespaceDeclaration(thi
         return null;
     }
 
+    public static BlankLineBetweenSwitchSections GetBlankLineBetweenSwitchSections(this SyntaxNodeAnalysisContext context)
+    {
+        if (ConfigOptions.TryGetValue(context.GetConfigOptions(), ConfigOptions.BlankLineBetweenSwitchSections, out string rawValue))
+        {
+            if (string.Equals(rawValue, ConfigOptionValues.BlankLineBetweenSwitchSections_Include, StringComparison.OrdinalIgnoreCase))
+                return BlankLineBetweenSwitchSections.Include;
+
+            if (string.Equals(rawValue, ConfigOptionValues.BlankLineBetweenSwitchSections_Omit, StringComparison.OrdinalIgnoreCase))
+                return BlankLineBetweenSwitchSections.Omit;
+
+            if (string.Equals(rawValue, ConfigOptionValues.BlankLineBetweenSwitchSections_OmitAfterBlock, StringComparison.OrdinalIgnoreCase))
+                return BlankLineBetweenSwitchSections.OmitAfterBlock;
+        }
+
+        return BlankLineBetweenSwitchSections.None;
+    }
+
     public static NewLinePosition GetEqualsSignNewLinePosition(this SyntaxNodeAnalysisContext context)
     {
         return context.GetConfigOptions().GetEqualsTokenNewLinePosition();

src/Common/ConfigOptionKeys.Generated.cs

@@ -14,6 +14,7 @@ internal static partial class ConfigOptionKeys
         public const string BlankLineAfterFileScopedNamespaceDeclaration      = "roslynator_blank_line_after_file_scoped_namespace_declaration";
         public const string BlankLineBetweenClosingBraceAndSwitchSection      = "roslynator_blank_line_between_closing_brace_and_switch_section";
         public const string BlankLineBetweenSingleLineAccessors               = "roslynator_blank_line_between_single_line_accessors";
+        public const string BlankLineBetweenSwitchSections                    = "roslynator_blank_line_between_switch_sections";
         public const string BlankLineBetweenUsingDirectives                   = "roslynator_blank_line_between_using_directives";
         public const string BlockBracesStyle                                  = "roslynator_block_braces_style";
         public const string BodyStyle                                         = "roslynator_body_style";

src/Common/ConfigOptionValues.Generated.cs

@@ -17,6 +17,9 @@ internal static partial class ConfigOptionValues
         public const string ArrowTokenNewLine_Before                                                    = "before";
         public const string BinaryOperatorNewLine_After                                                 = "after";
         public const string BinaryOperatorNewLine_Before                                                = "before";
+        public const string BlankLineBetweenSwitchSections_Include                                      = "include";
+        public const string BlankLineBetweenSwitchSections_Omit                                         = "omit";
+        public const string BlankLineBetweenSwitchSections_OmitAfterBlock                               = "omit_after_block";
         public const string BlankLineBetweenUsingDirectives_Never                                       = "never";
         public const string BlankLineBetweenUsingDirectives_SeparateGroups                              = "separate_groups";
         public const string BlockBracesStyle_MultiLine                                                  = "multi_line";

src/Common/ConfigOptions.Generated.cs

@@ -57,6 +57,12 @@ public static partial class ConfigOptions
             defaultValuePlaceholder: "true|false", 
             description:             "Add/remove blank line between single-line accessors");
 
+        public static readonly ConfigOptionDescriptor BlankLineBetweenSwitchSections = new(
+            key:                     ConfigOptionKeys.BlankLineBetweenSwitchSections, 
+            defaultValue:            null, 
+            defaultValuePlaceholder: "include|omit|omit_after_block", 
+            description:             "Include/omit blank line between switch sections");
+
         public static readonly ConfigOptionDescriptor BlankLineBetweenUsingDirectives = new(
             key:                     ConfigOptionKeys.BlankLineBetweenUsingDirectives, 
             defaultValue:            null, 
@@ -240,6 +246,7 @@ public static partial class ConfigOptions
             yield return new KeyValuePair<string, string>("RCS0058", JoinOptionKeys(ConfigOptionKeys.NewLineAtEndOfFile));
             yield return new KeyValuePair<string, string>("RCS0059", JoinOptionKeys(ConfigOptionKeys.NullConditionalOperatorNewLine));
             yield return new KeyValuePair<string, string>("RCS0060", JoinOptionKeys(ConfigOptionKeys.BlankLineAfterFileScopedNamespaceDeclaration));
+            yield return new KeyValuePair<string, string>("RCS0061", JoinOptionKeys(ConfigOptionKeys.BlankLineBetweenSwitchSections));
             yield return new KeyValuePair<string, string>("RCS1014", JoinOptionKeys(ConfigOptionKeys.ArrayCreationTypeStyle));
             yield return new KeyValuePair<string, string>("RCS1016", JoinOptionKeys(ConfigOptionKeys.BodyStyle, ConfigOptionKeys.UseBlockBodyWhenDeclarationSpansOverMultipleLines, ConfigOptionKeys.UseBlockBodyWhenExpressionSpansOverMultipleLines));
             yield return new KeyValuePair<string, string>("RCS1018", JoinOptionKeys(ConfigOptionKeys.AccessibilityModifiers));

src/ConfigOptions.xml

@@ -217,6 +217,14 @@
       <Value>omit_when_single_line</Value>
     </Values>
   </Option>
+  <Option Id="BlankLineBetweenSwitchSections">
+    <Description>Include/omit blank line between switch sections</Description>
+    <Values>
+      <Value>include</Value>
+      <Value>omit</Value>
+      <Value>omit_after_block</Value>
+    </Values>
+  </Option>
   <!--
   <Option Id="">
     <Key></Key>

src/Directory.Build.props

@@ -74,8 +74,4 @@
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All"/>
   </ItemGroup>
 
-  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|AnyCPU'">
-    <NoWarn>$(NoWarn);1573</NoWarn>
-  </PropertyGroup>
-
 </Project>

src/Formatting.Analyzers.CodeFixes/CSharp/SwitchSectionCodeFixProvider.cs

@@ -16,7 +16,12 @@ public sealed class SwitchSectionCodeFixProvider : BaseCodeFixProvider
 {
     public override ImmutableArray<string> FixableDiagnosticIds
     {
-        get { return ImmutableArray.Create(DiagnosticIdentifiers.AddBlankLineBetweenSwitchSections); }
+        get
+        {
+            return ImmutableArray.Create(
+                DiagnosticIdentifiers.AddBlankLineBetweenSwitchSections,
+                DiagnosticIdentifiers.BlankLineBetweenSwitchSections);
+        }
     }
 
     public override Task RegisterCodeFixesAsync(CodeFixContext context)

src/Formatting.Analyzers/CSharp/BlankLineBetweenSwitchSectionsAnalyzer.cs

@@ -0,0 +1,95 @@
+// Copyright (c) .NET Foundation and Contributors. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Immutable;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+using Roslynator.CSharp;
+using Roslynator.CSharp.CodeStyle;
+
+namespace Roslynator.Formatting.CSharp;
+
+[DiagnosticAnalyzer(LanguageNames.CSharp)]
+public sealed class BlankLineBetweenSwitchSectionsAnalyzer : BaseDiagnosticAnalyzer
+{
+    private static ImmutableArray<DiagnosticDescriptor> _supportedDiagnostics;
+
+    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics
+    {
+        get
+        {
+            if (_supportedDiagnostics.IsDefault)
+                Immutable.InterlockedInitialize(ref _supportedDiagnostics, DiagnosticRules.BlankLineBetweenSwitchSections);
+
+            return _supportedDiagnostics;
+        }
+    }
+
+    public override void Initialize(AnalysisContext context)
+    {
+        base.Initialize(context);
+
+        context.RegisterSyntaxNodeAction(c => AnalyzeSwitchStatement(c), SyntaxKind.SwitchStatement);
+    }
+
+    private static void AnalyzeSwitchStatement(SyntaxNodeAnalysisContext context)
+    {
+        var switchStatement = (SwitchStatementSyntax)context.Node;
+
+        BlankLineBetweenSwitchSections option = context.GetBlankLineBetweenSwitchSections();
+
+        if (option == BlankLineBetweenSwitchSections.None)
+            return;
+
+        SyntaxList<SwitchSectionSyntax> sections = switchStatement.Sections;
+        SyntaxList<SwitchSectionSyntax>.Enumerator en = sections.GetEnumerator();
+
+        if (!en.MoveNext())
+            return;
+
+        SwitchSectionSyntax previousSection = en.Current;
+        StatementSyntax previousLastStatement = previousSection.Statements.LastOrDefault();
+
+        while (en.MoveNext())
+        {
+            TriviaBlockAnalysis analysis = TriviaBlockAnalysis.FromBetween(previousSection, en.Current);
+
+            if (!analysis.Success)
+                continue;
+
+            if (analysis.Kind == TriviaBlockKind.BlankLine)
+            {
+                if (option == BlankLineBetweenSwitchSections.Omit)
+                {
+                    ReportDiagnostic(context, analysis, "Remove");
+                }
+                else if (option == BlankLineBetweenSwitchSections.OmitAfterBlock
+                    && previousLastStatement.IsKind(SyntaxKind.Block))
+                {
+                    ReportDiagnostic(context, analysis, "Remove");
+                }
+            }
+            else if (option == BlankLineBetweenSwitchSections.Include)
+            {
+                ReportDiagnostic(context, analysis, "Add");
+            }
+            else if (option == BlankLineBetweenSwitchSections.OmitAfterBlock
+                && !previousLastStatement.IsKind(SyntaxKind.Block))
+            {
+                ReportDiagnostic(context, analysis, "Add");
+            }
+
+            previousSection = en.Current;
+            previousLastStatement = previousSection.Statements.LastOrDefault();
+        }
+    }
+
+    private static void ReportDiagnostic(SyntaxNodeAnalysisContext context, TriviaBlockAnalysis analysis, string messageArg)
+    {
+        context.ReportDiagnostic(
+            DiagnosticRules.BlankLineBetweenSwitchSections,
+            analysis.GetLocation(),
+            messageArg);
+    }
+}

src/Formatting.Analyzers/CSharp/DiagnosticIdentifiers.Generated.cs

@@ -60,5 +60,6 @@ public static partial class DiagnosticIdentifiers
         public const string NormalizeWhitespaceAtEndOfFile = "RCS0058";
         public const string PlaceNewLineAfterOrBeforeNullConditionalOperator = "RCS0059";
         public const string BlankLineAfterFileScopedNamespaceDeclaration = "RCS0060";
+        public const string BlankLineBetweenSwitchSections = "RCS0061";
     }
 }