IDE0019 Use pattern matching

Author: vweijsters

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/Helpers/RenameHelper.cs

@@ -162,8 +162,7 @@ public static SyntaxNode GetParentDeclaration(SyntaxToken token)
                     return parent;
 
                 default:
-                    var declarationParent = parent as MemberDeclarationSyntax;
-                    if (declarationParent != null)
+                    if (parent is MemberDeclarationSyntax declarationParent)
                     {
                         return declarationParent;
                     }

StyleCop.Analyzers/StyleCop.Analyzers/ReadabilityRules/SA1122UseStringEmptyForEmptyStrings.cs

@@ -93,9 +93,7 @@ private static bool HasToBeConstant(LiteralExpressionSyntax literalExpression)
                     return true;
                 }
 
-                VariableDeclaratorSyntax variableDeclaratorSyntax = equalsValueClause.Parent as VariableDeclaratorSyntax;
-                VariableDeclarationSyntax variableDeclarationSyntax = variableDeclaratorSyntax?.Parent as VariableDeclarationSyntax;
-                if (variableDeclaratorSyntax == null || variableDeclarationSyntax == null)
+                if (!(equalsValueClause.Parent is VariableDeclaratorSyntax variableDeclaratorSyntax) || !(variableDeclaratorSyntax?.Parent is VariableDeclarationSyntax variableDeclarationSyntax))
                 {
                     return false;
                 }

StyleCop.Analyzers/StyleCop.Analyzers/ReadabilityRules/SA1130UseLambdaSyntax.cs

@@ -128,9 +128,7 @@ private static void HandleAnonymousMethodExpression(SyntaxNodeAnalysisContext co
         private static bool HandleMethodInvocation(SemanticModel semanticModel, AnonymousMethodExpressionSyntax anonymousMethod, ArgumentSyntax argumentSyntax)
         {
             // invocation -> argument list -> argument -> anonymous method
-            var argumentListSyntax = argumentSyntax?.Parent as BaseArgumentListSyntax;
-
-            if (argumentListSyntax != null)
+            if (argumentSyntax?.Parent is BaseArgumentListSyntax argumentListSyntax)
             {
                 var originalInvocableExpression = argumentListSyntax.Parent;
                 SymbolInfo originalSymbolInfo = semanticModel.GetSymbolInfo(originalInvocableExpression);