S1479: Update RSPEC (#9458)

analyzers/rspec/cs/S1479.html

@@ -1,77 +1,120 @@
 <h2>Why is this an issue?</h2>
 <p>When <a href="https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/selection-statements#the-switch-statement">switch</a>
-statements have large sets of case clauses, it is usually an attempt to map two sets of data. A <a
-href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2">Dictionary</a> should be used instead to make the code
-more readable and maintainable.</p>
+statements have large sets of multi-line <code>case</code> clauses, the code becomes hard to read and maintain.</p>
+<p>For example, the <a href="https://www.sonarsource.com/docs/CognitiveComplexity.pdf">Cognitive Complexity</a> is going to be particularly high.</p>
+<p>In such scenarios, it’s better to refactor the <code>switch</code> to only have single-line case clauses.</p>
+<p>When all the <code>case</code> clauses of a <code>switch</code> statement are single-line, the readability of the code is not affected. Moreover,
+<code>switch</code> statements with single-line <code>case</code> clauses can easily be converted into <a
+href="https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/switch-expression"><code>switch</code> expressions</a>, which are
+more concise for assignment and avoid the need for <code>break</code> statements.</p>
 <h3>Exceptions</h3>
-<p>This rule ignores <code>switch</code> statements over <code>Enum</code> arguments and empty, fall-through cases.</p>
+<p>This rule ignores:</p>
+<ul>
+  <li> <code>switch</code> statements over <code>Enum</code> arguments </li>
+  <li> fall-through cases </li>
+  <li> <code>return</code>, <code>break</code> and <code>throw</code> statements in case clauses </li>
+</ul>
 <h2>How to fix it</h2>
-<p>Store all the cases apart from the <code>default</code> one in a dictionary and try to get the matching value by calling the <a
-href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2.trygetvalue">TryGetValue</a> method.</p>
+<p>Extract the logic of multi-line <code>case</code> clauses into separate methods.</p>
 <h3>Code examples</h3>
-<p>The example below are using the "Maximum number of case" property set to <code>4</code>.</p>
+<p>The examples below use the "Maximum number of case" property set to <code>4</code>.</p>
+<p>Note that from C# 8, you can use <a
+href="https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/switch-expression"><code>switch</code> expression</a>.</p>
 <h4>Noncompliant code example</h4>
 <pre data-diff-id="1" data-diff-type="noncompliant">
-public class TooManyCase
+public int MapChar(char ch, int value)
 {
-    public int mapValues(char ch)
+    switch(ch) // Noncompliant
     {
-        switch(ch) {  // Noncompliant: 5 cases, "default" excluded, more than maximum = 4
-            case 'a':
-                return 1;
-            case 'b':
-            case 'c':
-                return 2;
-            case 'd':
-                return 3;
-            case 'e':
-                return 4;
-            case 'f':
-            case 'g':
-            case 'h':
-                return 5;
-            default:
-                return 6;
-        }
+        case 'a':
+            return 1;
+        case 'b':
+            return 2;
+        case 'c':
+            return 3;
+        // ...
+        case '-':
+            if (value &gt; 10)
+            {
+                return 42;
+            }
+            else if (value &lt; 5 &amp;&amp; value &gt; 1)
+            {
+                return 21;
+            }
+            return 99;
+        default:
+            return 1000;
     }
 }
 </pre>
 <h4>Compliant solution</h4>
 <pre data-diff-id="1" data-diff-type="compliant">
-using System.Collections.Generic;
+public int MapChar(char ch, int value)
+{
+    switch(ch) // Compliant: All 5 cases are single line statements
+    {
+        case 'a':
+            return 1;
+        case 'b':
+            return 2;
+        case 'c':
+            return 3;
+        // ...
+        case '-':
+            return HandleDash(value);
+        default:
+            return 1000;
+    }
+}
 
-public class TooManyCase
+private int HandleDash(int value)
 {
-    Dictionary&lt;char, int&gt; matching = new Dictionary&lt;char, int&gt;()
+    if (value &gt; 10)
+    {
+        return 42;
+    }
+    else if (value &lt; 5 &amp;&amp; value &gt; 1)
     {
-        { 'a', 1 },
-        { 'b', 2 },
-        { 'c', 2 },
-        { 'd', 3 },
-        { 'e', 4 },
-        { 'f', 5 },
-        { 'g', 5 },
-        { 'h', 5 }
+        return 21;
+    }
+    return 99;
+}
+</pre>
+<p>For this example, a <code>switch</code> expression is more concise and clear:</p>
+<pre>
+public int MapChar(char ch, int value) =&gt;
+    ch switch // Compliant
+    {
+        'a' =&gt; 1,
+        'b' =&gt; 2,
+        'c' =&gt; 3,
+        // ...
+        '-' =&gt; HandleDash(value),
+        _ =&gt; 1000,
     };
 
-    public int mapValues(char ch)
+private int HandleDash(int value)
+{
+    if (value &gt; 10)
+    {
+        return 42;
+    }
+    else if (value &lt; 5 &amp;&amp; value &gt; 1)
     {
-        int value;
-        if (this.matching.TryGetValue(ch, out value)) {
-            return value;
-        } else {
-            return 6;
-        }
+        return 21;
     }
+    return 99;
 }
 </pre>
 <h2>Resources</h2>
 <h3>Documentation</h3>
 <ul>
-  <li> <a href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2">Dictionary&lt;TKey,TValue&gt; Class</a> </li>
-  <li> <a
-  href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2.trygetvalue">Dictionary&lt;TKey,TValue&gt;.TryGetValue(TKey, TValue) Method</a> </li>
-  <li> <a href="https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/selection-statements#the-switch-statement">The
+  <li> Sonar - <a href="https://www.sonarsource.com/docs/CognitiveComplexity.pdf">Cognitive Complexity</a> </li>
+  <li> Microsoft Learn - <a
+  href="https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/statements/selection-statements#the-switch-statement">The
   <code>switch</code> statement</a> </li>
+  <li> Microsoft Learn - <a href="https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/switch-expression">C#: Switch
+  Expression</a> </li>
 </ul>
 

analyzers/rspec/cs/S1479.json

@@ -1,5 +1,5 @@
 {
-  "title": "\"switch\" statements should not have too many \"case\" clauses",
+  "title": "\"switch\" statements with many \"case\" clauses should have only one statement",
   "type": "CODE_SMELL",
   "code": {
     "impacts": {

analyzers/rspec/vbnet/S1479.html

@@ -1,70 +1,75 @@
 <h2>Why is this an issue?</h2>
 <p>When <a href="https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/statements/select-case-statement">Select Case</a> statements
-have large sets of case clauses, it is usually an attempt to map two sets of data. A <a
-href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2">Dictionary</a> should be used instead to make the code
-more readable and maintainable.</p>
+have large sets of multi-line <code>Case</code> clauses, the code becomes hard to read and maintain.</p>
+<p>For example, the <a href="https://www.sonarsource.com/docs/CognitiveComplexity.pdf">Cognitive Complexity</a> is going to be particularly high.</p>
+<p>In such scenarios, it’s better to refactor the <code>Select Case</code> to only have single-line case clauses.</p>
+<p>When all the <code>Case</code> clauses of a <code>Select Case</code> statement are single-line, the readability of the code is not affected.</p>
 <h3>Exceptions</h3>
-<p>This rule ignores <code>Select Case</code> statements over <code>Enum</code> arguments and empty, fall-through cases.</p>
+<p>This rule ignores:</p>
+<ul>
+  <li> <code>Select Case</code> statements over <code>Enum</code> arguments </li>
+  <li> fall-through cases </li>
+  <li> <code>Return</code> and <code>Throw</code> statements in <code>Case</code> clauses </li>
+</ul>
 <h2>How to fix it</h2>
-<p>Store all the cases apart from the <code>Case Else</code> one in a dictionary and try to get the matching value by calling the <a
-href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2.trygetvalue">TryGetValue</a> method.</p>
+<p>Extract the logic of multi-line <code>Case</code> clauses into separate methods.</p>
 <h3>Code examples</h3>
+<p>The examples below use the "Maximum number of case" property set to <code>4</code>.</p>
 <h4>Noncompliant code example</h4>
 <pre data-diff-id="1" data-diff-type="noncompliant">
-Public Class TooManyCase
-
-    Public Function MapValues(Ch As Char) As Integer
-        Select Case Ch ' Noncompliant: 5 cases, "Case Else" excluded, more than maximum = 4
-            Case "a"c
-                Return 1
-            Case "b"c, "c"c
-                Return 2
-            Case "d"c
-                Return 3
-            Case "e"c
-                Return 4
-            Case "f"c, "g"c, "h"c
-                Return 5
-            Case Else
-                Return 6
-        End Select
-    End Function
-
-End Class
+Public Function MapChar(ch As Char, value As Integer) As Integer ' Noncompliant
+    Select Case ch
+        Case "a"c
+            Return 1
+        Case "b"c
+            Return 2
+        Case "c"c
+            Return 3
+        ' ...
+        Case "-"c
+            If value &gt; 10 Then
+                Return 42
+            ElseIf value &lt; 5 AndAlso value &gt; 1 Then
+                Return 21
+            End If
+            Return 99
+        Case Else
+            Return 1000
+    End Select
+End Function
 </pre>
 <h4>Compliant solution</h4>
 <pre data-diff-id="1" data-diff-type="compliant">
-Public Class TooManyCase
-
-    Private fMatching As New Dictionary(Of Char, Integer) From {
-            { "a"c, 1 },
-            { "b"c, 2 },
-            { "c"c, 2 },
-            { "d"c, 3 },
-            { "e"c, 4 },
-            { "f"c, 5 },
-            { "g"c, 5 },
-            { "h"c, 5 },
-        }
-
-    Public Function MapValues(Ch As Char) As Integer
-        Dim Value As Integer
-        If fMatching.TryGetValue(Ch, Value) Then
-            Return Value
-        Else
-            Return 6
-        End If
-    End Function
+Public Function MapChar(ch As Char, value As Integer) As Integer
+    Select Case ch
+        Case "a"c
+            Return 1
+        Case "b"c
+            Return 2
+        Case "c"c
+            Return 3
+        ' ...
+        Case "-"c
+            Return HandleDash(value)
+        Case Else
+            Return 1000
+    End Select
+End Function
 
-End Class
+Private Function HandleDash(value As Integer) As Integer
+    If value &gt; 10 Then
+        Return 42
+    ElseIf value &lt; 5 AndAlso value &gt; 1 Then
+        Return 21
+    End If
+    Return 99
+End Function
 </pre>
 <h2>Resources</h2>
 <h3>Documentation</h3>
 <ul>
-  <li> <a href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2">Dictionary&lt;TKey,TValue&gt; Class</a> </li>
-  <li> <a
-  href="https://learn.microsoft.com/en-us/dotnet/api/system.collections.generic.dictionary-2.trygetvalue">Dictionary&lt;TKey,TValue&gt;.TryGetValue(TKey, TValue) Method</a> </li>
-  <li> <a href="https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/statements/select-case-statement">Select…​Case Statement</a>
-  </li>
+  <li> Sonar - <a href="https://www.sonarsource.com/docs/CognitiveComplexity.pdf">Cognitive Complexity</a> </li>
+  <li> Microsoft Learn - <a
+  href="https://learn.microsoft.com/en-us/dotnet/visual-basic/language-reference/statements/select-case-statement">Select…​Case Statement</a> </li>
 </ul>
 

analyzers/rspec/vbnet/S1479.json

@@ -1,5 +1,5 @@
 {
-  "title": "\"Select Case\" statements should not have too many \"Case\" clauses",
+  "title": "\"Select Case\" statement with many \"Case\" clauses should have only one statement",
   "type": "CODE_SMELL",
   "code": {
     "impacts": {

analyzers/src/SonarAnalyzer.CSharp/sonarpedia.json

@@ -3,7 +3,7 @@
   "languages": [
     "CSH"
   ],
-  "latest-update": "2024-06-24T12:09:48.416439100Z",
+  "latest-update": "2024-06-24T13:02:32.572091600Z",
   "options": {
     "no-language-in-filenames": true
   }

analyzers/src/SonarAnalyzer.VisualBasic/sonarpedia.json

@@ -3,7 +3,7 @@
   "languages": [
     "VBNET"
   ],
-  "latest-update": "2024-06-24T12:10:12.271374400Z",
+  "latest-update": "2024-06-24T13:03:10.676891100Z",
   "options": {
     "no-language-in-filenames": true
   }