使用Roslyn确定类是否为抽象类

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using System;

class Program
{
    static void Main()
    {
        string code = @"
            using System;

            namespace MyNamespace
            {
                public abstract class MyClass
                {
                    public abstract void MyMethod();
                }

                public class MyDerivedClass : MyClass
                {
                    public override void MyMethod()
                    {
                        Console.WriteLine(""Hello, World!"");
                    }
                }
            }
        ";

        SyntaxTree syntaxTree = CSharpSyntaxTree.ParseText(code);
        var root = syntaxTree.GetRoot();

        var walker = new ClassDeclarationWalker();
        walker.Visit(root);
    }
}

class ClassDeclarationWalker : CSharpSyntaxWalker
{
    public override void VisitClassDeclaration(ClassDeclarationSyntax node)
    {
        if (node.Modifiers.Any(SyntaxKind.AbstractKeyword))
        {
            Console.WriteLine($"{node.Identifier.ValueText} is an abstract class.");
        }
        else
        {
            Console.WriteLine($"{node.Identifier.ValueText} is not an abstract class.");
        }

        base.VisitClassDeclaration(node);
    }
}

MyClass is an abstract class.
MyDerivedClass is not an abstract class.