More cases to optimize linq

ChangeLog.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add SECURITY.md ([#1147](https://github.com/josefpihrt/roslynator/pull/1147))
 - Add custom FixAllProvider for [RCS1014](https://github.com/JosefPihrt/Roslynator/blob/main/docs/analyzers/RCS1014.md) ([#1070](https://github.com/JosefPihrt/Roslynator/pull/1070)).
+- Support for more linq optimizations ([#1157](https://github.com/josefpihrt/roslynator/pull/1157))
 
 ### Fixed
 

src/Analyzers.CodeFixes/CSharp/CodeFixes/OptimizeLinqMethodCallCodeFixProvider.cs

@@ -332,8 +332,17 @@ private static Task<Document> SimplifyLinqMethodChainAsync(
         InvocationExpressionSyntax invocation = invocationInfo.InvocationExpression;
         InvocationExpressionSyntax invocation2 = invocationInfo2.InvocationExpression;
 
+        SimpleNameSyntax name = (invocationInfo2.NameText, invocationInfo.NameText) switch
+        {
+            ("OrderBy", "FirstOrDefault") => (SimpleNameSyntax)ParseName("MinBy"),
+            ("OrderByDescending", "FirstOrDefault") => (SimpleNameSyntax)ParseName("MaxBy"),
+            ("OrderBy", "First") => (SimpleNameSyntax)ParseName("MinBy"),
+            ("OrderByDescending", "First") => (SimpleNameSyntax)ParseName("MaxBy"),
+            _ => invocationInfo.Name
+        };
+
         InvocationExpressionSyntax newNode = invocation2.WithExpression(
-            invocationInfo2.MemberAccessExpression.WithName(invocationInfo.Name.WithTriviaFrom(invocationInfo2.Name)));
+            invocationInfo2.MemberAccessExpression.WithName(name.WithTriviaFrom(invocationInfo2.Name)));
 
         IEnumerable<SyntaxTrivia> trivia = invocation.DescendantTrivia(TextSpan.FromBounds(invocation2.Span.End, invocation.Span.End));
 

src/Analyzers.CodeFixes/CSharp/CodeFixes/SimplifyLogicalNegationCodeFixProvider.cs

@@ -97,9 +97,11 @@ private static ExpressionSyntax GetNewNode(PrefixUnaryExpressionSyntax logicalNo
 
                     SingleParameterLambdaExpressionInfo lambdaInfo = SyntaxInfo.SingleParameterLambdaExpressionInfo(lambdaExpression);
 
-                    var logicalNot2 = (PrefixUnaryExpressionSyntax)SimplifyLogicalNegationAnalyzer.GetReturnExpression(lambdaInfo.Body).WalkDownParentheses();
+                    ExpressionSyntax logicalNot2 = SimplifyLogicalNegationAnalyzer.GetReturnExpression(lambdaInfo.Body).WalkDownParentheses();
 
-                    InvocationExpressionSyntax newNode = invocationExpression.ReplaceNode(logicalNot2, logicalNot2.Operand.WithTriviaFrom(logicalNot2));
+                    ExpressionSyntax invertedExperssion = SyntaxLogicalInverter.GetInstance(document).LogicallyInvert(logicalNot2);
+
+                    InvocationExpressionSyntax newNode = invocationExpression.ReplaceNode(logicalNot2, invertedExperssion.WithTriviaFrom(logicalNot2));
 
                     return SyntaxRefactorings.ChangeInvokedMethodName(newNode, (memberAccessExpression.Name.Identifier.ValueText == "All") ? "Any" : "All");
                 }

src/Analyzers/CSharp/Analysis/InvocationExpressionAnalyzer.cs

@@ -129,6 +129,7 @@ private static void AnalyzeInvocationExpression(SyntaxNodeAnalysisContext contex
 
                                     OptimizeLinqMethodCallAnalysis.AnalyzeWhere(context, invocationInfo);
                                     OptimizeLinqMethodCallAnalysis.AnalyzeFirst(context, invocationInfo);
+                                    OptimizeLinqMethodCallAnalysis.AnalyzerOrderByAndFirst(context, invocationInfo, shouldThrowIfEmpty: true);
                                 }
 
                                 break;
@@ -184,6 +185,7 @@ private static void AnalyzeInvocationExpression(SyntaxNodeAnalysisContext contex
                                 {
                                     OptimizeLinqMethodCallAnalysis.AnalyzeWhere(context, invocationInfo);
                                     OptimizeLinqMethodCallAnalysis.AnalyzeFirstOrDefault(context, invocationInfo);
+                                    OptimizeLinqMethodCallAnalysis.AnalyzerOrderByAndFirst(context, invocationInfo, shouldThrowIfEmpty: false);
                                 }
 
                                 break;

src/Analyzers/CSharp/Analysis/OptimizeLinqMethodCallAnalysis.cs

@@ -199,6 +199,90 @@ private static void SimplifyLinqMethodChain(
         Report(context, invocation, span, checkDirectives: true, properties: properties);
     }
 
+
+    // for reference types
+    // items.OrderBy(selector).FirstOrDefault() >>> items.MaxBy(selector)
+    // items.OrderByDescending(selector).FirstOrDefault() >>> items.MaxBy(selector)
+    // for value types:
+    // items.OrderBy(selector).First() >>> items.MaxBy(selector)
+    // items.OrderByDescending(selector).First() >>> items.MaxBy(selector)
+    public static void AnalyzerOrderByAndFirst(SyntaxNodeAnalysisContext context, in SimpleMemberInvocationExpressionInfo invocationInfo, bool shouldThrowIfEmpty)
+    {
+        // MinBy / MaxBy are only supported for net6.0 onwards
+        INamedTypeSymbol enumerableSymbol = context.Compilation.GetTypeByMetadataName("System.Linq.Enumerable");
+
+        if (enumerableSymbol.FindMember<IMethodSymbol>("MinBy") is null)
+            return;
+
+        SimpleMemberInvocationExpressionInfo previousInvocationInfo = SyntaxInfo.SimpleMemberInvocationExpressionInfo(invocationInfo.Expression);
+
+        if (!previousInvocationInfo.Success)
+            return;
+
+        if (previousInvocationInfo.Arguments.Count != 1)
+            return;
+
+        if (previousInvocationInfo.NameText != "OrderBy" && previousInvocationInfo.NameText != "OrderByDescending")
+            return;
+
+        InvocationExpressionSyntax invocation = invocationInfo.InvocationExpression;
+
+        SemanticModel semanticModel = context.SemanticModel;
+        CancellationToken cancellationToken = context.CancellationToken;
+
+        IMethodSymbol methodSymbol = semanticModel.GetExtensionMethodInfo(invocation, cancellationToken).Symbol;
+
+        if (methodSymbol is null)
+            return;
+
+        if (!SymbolUtility.IsLinqExtensionOfIEnumerableOfTWithoutParameters(methodSymbol, invocationInfo.NameText))
+            return;
+
+        IMethodSymbol methodSymbol2 = semanticModel.GetExtensionMethodInfo(previousInvocationInfo.InvocationExpression, cancellationToken).Symbol;
+
+        if (methodSymbol2 is null)
+            return;
+
+
+        switch (previousInvocationInfo.NameText)
+        {
+            case "OrderBy":
+                {
+                    if (!SymbolUtility.IsLinqOrderBy(methodSymbol2, allowImmutableArrayExtension: true))
+                        return;
+
+                    break;
+                }
+            case "OrderByDescending":
+                {
+                    if (!SymbolUtility.IsLinqOrderByDescending(methodSymbol2, allowImmutableArrayExtension: true))
+                        return;
+
+                    break;
+                }
+            default:
+                {
+                    throw new InvalidOperationException();
+                }
+        }
+
+        // First throws if no values found. MaxBy/MinBy match this behaviour if TSource is a not reference type.
+        var lambda = previousInvocationInfo.InvocationExpression.ArgumentList.Arguments[0].Expression;
+        var delegateType = semanticModel.GetTypeInfo(lambda).ConvertedType;
+        if (delegateType is not INamedTypeSymbol { TypeKind: TypeKind.Delegate } namedDelegateType)
+            return;
+
+        var tSource = namedDelegateType.TypeArguments.First();
+
+        if (tSource.IsReferenceType == shouldThrowIfEmpty)
+            return;
+
+        TextSpan span = TextSpan.FromBounds(previousInvocationInfo.Name.SpanStart, invocation.Span.End);
+
+        Report(context, invocation, span, checkDirectives: true, properties: Properties.SimplifyLinqMethodChain);
+    }
+
+
     public static void AnalyzeFirstOrDefault(SyntaxNodeAnalysisContext context, in SimpleMemberInvocationExpressionInfo invocationInfo)
     {
         InvocationExpressionSyntax invocation = invocationInfo.InvocationExpression;

src/Analyzers/CSharp/Analysis/SimplifyLogicalNegationAnalyzer.cs

@@ -173,9 +173,7 @@ public static void Analyze(SyntaxNodeAnalysisContext context, in SimpleMemberInv
         if (!lambdaInfo.Success)
             return;
 
-        ExpressionSyntax expression = GetReturnExpression(lambdaInfo.Body)?.WalkDownParentheses();
-
-        if (expression?.IsKind(SyntaxKind.LogicalNotExpression) != true)
+        if (GetReturnExpression(lambdaInfo.Body) is null)
             return;
 
         IMethodSymbol methodSymbol = context.SemanticModel.GetReducedExtensionMethodInfo(invocationInfo.InvocationExpression, context.CancellationToken).Symbol;

src/Core/SymbolUtility.cs

@@ -305,6 +305,20 @@ internal static bool IsLinqWhere(
         return IsLinqExtensionOfIEnumerableOfTWithPredicate(methodSymbol, "Where", parameterCount: 2, allowImmutableArrayExtension: allowImmutableArrayExtension);
     }
 
+    internal static bool IsLinqOrderBy(
+        IMethodSymbol methodSymbol,
+        bool allowImmutableArrayExtension = false)
+    {
+        return IsLinqExtensionOfIEnumerableOfT(methodSymbol, "OrderBy", parameterCount: 2, allowImmutableArrayExtension: allowImmutableArrayExtension);
+    }
+
+    internal static bool IsLinqOrderByDescending(
+        IMethodSymbol methodSymbol,
+        bool allowImmutableArrayExtension = false)
+    {
+        return IsLinqExtensionOfIEnumerableOfT(methodSymbol, "OrderByDescending", parameterCount: 2, allowImmutableArrayExtension: allowImmutableArrayExtension);
+    }
+
     internal static bool IsLinqWhereWithIndex(IMethodSymbol methodSymbol)
     {
         if (!IsLinqExtensionOfIEnumerableOfT(methodSymbol, "Where", parameterCount: 2, allowImmutableArrayExtension: false))

src/Tests/Analyzers.Tests/RCS1068SimplifyLogicalNegationTests2.cs

@@ -120,6 +120,40 @@ void M()
 ");
     }
 
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.SimplifyLogicalNegation)]
+    public async Task Test_NotAny4()
+    {
+        await VerifyDiagnosticAndFixAsync(@"
+using System.Linq;
+using System.Collections.Generic;
+
+class C
+{
+    void M()
+    {
+        bool f1 = false;
+        var items = new List<int>();
+
+        f1 = [|!items.Any(i => i % 2 == 0)|];
+    }
+}
+", @"
+using System.Linq;
+using System.Collections.Generic;
+
+class C
+{
+    void M()
+    {
+        bool f1 = false;
+        var items = new List<int>();
+
+        f1 = items.All(i => i % 2 != 0);
+    }
+}
+");
+    }
+
     [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.SimplifyLogicalNegation)]
     public async Task Test_NotAll()
     {
@@ -225,6 +259,40 @@ void M()
         f1 = items.Any<string>(s => s.Equals(s));
     }
 }
+");
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.SimplifyLogicalNegation)]
+    public async Task Test_NotAll4()
+    {
+        await VerifyDiagnosticAndFixAsync(@"
+using System.Linq;
+using System.Collections.Generic;
+
+class C
+{
+    void M()
+    {
+        bool f1 = false;
+        var items = new List<int>();
+
+        f1 = [|!items.All(i => i % 2 == 0)|];
+    }
+}
+", @"
+using System.Linq;
+using System.Collections.Generic;
+
+class C
+{
+    void M()
+    {
+        bool f1 = false;
+        var items = new List<int>();
+
+        f1 = items.Any(i => i % 2 != 0);
+    }
+}
 ");
     }
 }

src/Tests/Analyzers.Tests/RCS1077OptimizeLinqMethodCallTests.cs

@@ -282,6 +282,94 @@ void M()
 ", source, expected);
     }
 
+    [Theory, Trait(Traits.Analyzer, DiagnosticIdentifiers.OptimizeLinqMethodCall)]
+    [InlineData("OrderBy(f => f.Length).FirstOrDefault()", "MinBy(f => f.Length)")]
+    [InlineData("OrderByDescending(f => f.Length).FirstOrDefault()", "MaxBy(f => f.Length)")]
+    public async Task Test_CombineOrderByFirstOrDefault(string source, string expected)
+    {
+        await VerifyDiagnosticAndFixAsync(@"
+using System.Collections.Generic;
+using System.Linq;
+
+namespace N
+{
+    class C
+    {
+        string M()
+        {
+            var items = new List<string>();
+
+            return items.[||];
+        }
+    }
+}", source, expected);
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.OptimizeLinqMethodCall)]
+    public async Task Test_CombineOrderByFirstOrDefault_NoDiagnosticIfTsourceIsValueType()
+    {
+        await VerifyNoDiagnosticAsync(@"
+using System.Collections.Generic;
+using System.Linq;
+
+namespace N
+{
+    class C
+    {
+        void M()
+        {
+            var items = new List<int>();
+
+            var y = items.OrderBy(x=>x).FirstOrDefault();
+        }
+    }
+}");
+    }
+
+    [Theory, Trait(Traits.Analyzer, DiagnosticIdentifiers.OptimizeLinqMethodCall)]
+    [InlineData("OrderBy(f => f).First()", "MinBy(f => f)")]
+    [InlineData("OrderByDescending(f => f).First()", "MaxBy(f => f)")]
+    public async Task Test_CombineOrderByFirst(string source, string expected)
+    {
+        await VerifyDiagnosticAndFixAsync(@"
+using System.Collections.Generic;
+using System.Linq;
+
+namespace N
+{
+    class C
+    {
+        int M()
+        {
+            var items = new List<int>();
+
+            return items.[||];
+        }
+    }
+}", source, expected);
+    }
+
+    [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.OptimizeLinqMethodCall)]
+    public async Task Test_CombineOrderByFirst_NoDiagnosticIfTsourceIsReferenceType()
+    {
+        await VerifyNoDiagnosticAsync(@"
+using System.Collections.Generic;
+using System.Linq;
+
+namespace N
+{
+    class C
+    {
+        void M()
+        {
+            var items = new List<string>();
+
+            var y = items.OrderBy(x=>x.Length).First();
+        }
+    }
+}");
+    }
+
     [Theory, Trait(Traits.Analyzer, DiagnosticIdentifiers.OptimizeLinqMethodCall)]
     [InlineData(@"Where(f => f.StartsWith(""a"")).Any(f => f.StartsWith(""b""))", @"Any(f => f.StartsWith(""a"") && f.StartsWith(""b""))")]
     [InlineData(@"Where((f) => f.StartsWith(""a"")).Any(f => f.StartsWith(""b""))", @"Any((f) => f.StartsWith(""a"") && f.StartsWith(""b""))")]