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我想将包含已知签名表达式的字符串转换为Func<dynamic, bool)我可以调用的动态函数。

(x) => x.Age > 18  //Typecastable to Func<dynamic, bool>

var function = (Func<dynamic, bool>) Lamdba.Parse("(x) => x.Age > 18")

我正在寻找相当于Lambda.Parse

我正在尝试实现的完整代码如下：

using System;
using System.Dynamic;
using System.Collections.Generic;

public class DynamicModelTests
{
    public static void Main()
    {
        //Illustration purpose... Working code
        dynamic model = new ExpandoObject();
        model.Age = 18;
        Func<dynamic, bool> isAdultRule = (x) => x.Age >= 18;
        IDictionary<string, object> dict = model;
        dict["IsAdult"] = (Func<bool>) (() => isAdultRule(model));
        Console.WriteLine($"Is Adult: {model.IsAdult()}");
        //Working code ends

        //Pseudo code starts... Pseudo only because it needs a working Lambda.Parse()
        Compose(model, "IsAdult",  "(x) => x.Age >= 18");
        Compose(model, "CanWatchRRated", "(x) => x.IsAdult()");
        bool isAdult = model.CanWatchRRated();
        bool result = ExecuteByName(model, "CanWatchRRated");
        Console.WriteLine($"Is Adult #2: {isAdult}");
        Console.WriteLine($"Same as Is Adult #2: {result}");
        //ends
    }

    public static void Compose(dynamic model, string ruleName, string expression)
    {
        var method = GetMethod(model, expression);
        var ruleCallExpression = $"() => method(model)";

        IDictionary<string, object> dict = model;
        dict[ruleName] = (Action) method;
    }

    public static Func<dynamic, T> GetMethod<T>(dynamic model, string expression)
    {
        return Lambda.Parse<dynamic, T>(expression); 
    }

    public static T Execute<T>(dynamic model, string expression)
    {
        return GetMethod(model, expression)(model);
    }

    //Should be called after compose... otherwise, throws MethodNotFound Exception
    public static T ExecuteByName<T>(dynamic model, string ruleName)
    {
        IDictionary<string, object> dictionary = model;
        if(!model.ContainsKey(ruleName))
        {
            throw new MethodNotFoundException();
        }

        return (T) model.Invoke(ruleName);

    }
}

public class MethodNotFoundException : Exception
{
}

有现成的Lambda.Parse()可以用吗？

注意＃1：模型必须是“ dynamic”类型。我正在使用Rick Strahl 的库而不是滚动我自己的DynamicObject实现

注意#2：解析表达式的所有示例System.Linq.Dynamic.DynamicExpression似乎仅适用于已知类型。他们不适合我的类型' dynamic'。如果它适合你，我会全力以赴。

谢谢！

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