C#实现接口base调用示例详解

public interface IService
{
    void Proccess()
    {
        Console.WriteLine("Proccessing");
    }
}
public class Service : IService
{
    public void Proccess()
    {
        Console.WriteLine("Before Proccess");
        base(IService).Proccess(); // 目前不支持，也是本文需要探讨的部分
        Console.WriteLine("End Proccess");
    }
}

public static void Base<TInterface>(this TInterface instance, Expression<Action<TInterface>> selector);
public static TReturn Base<TInterface, TReturn>(this TInterface instance, Expression<Func<TInterface, TReturn>> selector);

public class Service : IService
{
    public void Proccess()
    {
        Console.WriteLine("Before Proccess");
        this.Base<IService>(m => m.Proccess());
        Console.WriteLine("End Proccess");
    }
}

private static (MethodInfo method, IReadOnlyList<Expression> args) GetMethodAndArguments(Expression exp) => exp switch
{
    LambdaExpression lambda => GetMethodAndArguments(lambda.Body),
    UnaryExpression unary => GetMethodAndArguments(unary.Operand),
    MethodCallExpression methodCall => (methodCall.Method!, methodCall.Arguments),
    MemberExpression { Member: PropertyInfo prop } => (prop.GetGetMethod(true) ?? throw new MissingMethodException($"No getter in propery {prop.Name}"), Array.Empty<Expression>()),
    _ => throw new InvalidOperationException("The expression refers to neither a method nor a readable property.")
};

internal readonly record struct InterfaceMethodInfo(Type InstanceType, Type InterfaceType, MethodInfo Method);
private static MethodInfo GetInterfaceMethod(InterfaceMethodInfo info)
{
    var (instanceType, interfaceType, method) = info;
    var parameters = method.GetParameters();
    var genericArguments = method.GetGenericArguments();
    var interfaceMethods = instanceType
        .GetInterfaceMap(interfaceType)
        .InterfaceMethods
        .Where(m => IfMatch(method, genericArguments, parameters, m))
        .ToArray();
    var interfaceMethod = interfaceMethods.Length switch
    {
        0 => throw new MissingMethodException($"Can not find method {method.Name} in type {instanceType.Name}"),
        > 1 => throw new AmbiguousMatchException($"Found more than one method {method.Name} in type {instanceType.Name}"),
        1 when interfaceMethods[0].IsAbstract => throw new InvalidOperationException($"The method {interfaceMethods[0].Name} is abstract"),
        _ => interfaceMethods[0]
    };
    if (method.IsGenericMethod)
        interfaceMethod = interfaceMethod.MakeGenericMethod(method.GetGenericArguments());
    return interfaceMethod;
}

private static DynamicMethod GetDynamicMethod(Type interfaceType, MethodInfo method, IEnumerable<Type> argumentTypes)
{
    var dynamicMethod = new DynamicMethod(
        name: "__IL_" + method.GetFullName(),
        returnType: method.ReturnType,
        parameterTypes: new[] { interfaceType, typeof(object[]) },
        owner: typeof(object),
        skipVisibility: true);
    var il = dynamicMethod.GetILGenerator();
    il.Emit(OpCodes.Ldarg_0);
    var i = 0;
    foreach (var argumentType in argumentTypes)
    {
        il.Emit(OpCodes.Ldarg_1);
        il.Emit(OpCodes.Ldc_I4, i);
        il.Emit(OpCodes.Ldelem, typeof(object));
        if (argumentType.IsValueType)
        {
            il.Emit(OpCodes.Unbox_Any, argumentType);
        }
        ++i;
    }
    il.Emit(OpCodes.Call, method);
    il.Emit(OpCodes.Ret);
    return dynamicMethod;
}