在运行时解析成员名称

Question

在运行时解析成员名称

xan*_*tos 6 c# reflection overload-resolution c#-5.0 c#-4.0

给定类型,名称和签名,如何使用7.4的C#规则(7.4是C#语言规范中的章节编号)对名称和签名签名的成员进行成员查找(或至少部分)其中......假设我可以在运行时使用完全匹配,无需转换/转换？我需要得到一个MethodInfo/ PropertyInfo/ ...因为那时我必须使用反射(更确切地说,我正在尝试构建一个Expression.ForEach构建器(一个能够创建表示树的表达式代表一个foreach语句的工厂),并且是使用C#完美像素foreach我必须能够进行鸭子输入并搜索GetEnumerator方法(在集合中),Current属性和MoveNext方法(在枚举器中),如8.8.4中所述)

问题(问题的一个例子)

class C1
{
    public int Current { get; set; }

    public object MoveNext()
    {
        return null;
    }
}

class C2 : C1
{
    public new long Current { get; set; }

    public new bool MoveNext()
    {
        return true;
    }
}

class C3 : C2
{
}

var m = typeof(C3).GetMethods(); // I get both versions of MoveNext()
var p = typeof(C3).GetProperties(); // I get both versions of Current

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显然,如果我尝试typeof(C3).GetProperty("Current")我得到一个AmbiguousMatchException例外.

接口存在类似但不同的问题:

interface I0
{
    int Current { get; set; }
}

interface I1 : I0
{
    new long Current { get; set; }
}

interface I2 : I1, I0
{
    new object Current { get; set; }
}

interface I3 : I2
{
}

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这里如果我尝试做一个typeof(I3).GetProperties()我没有得到Current属性(这是已知的,请参见例如GetProperties()以返回接口继承层次结构的所有属性),但我不能简单地展平接口,因为那时我不知道是谁隐藏谁.

我知道可能这个问题在Microsoft.CSharp.RuntimeBinder命名空间的某处解决(在Microsoft.CSharp程序集中声明).这是因为我正在尝试使用C#规则,当你进行动态方法调用时,成员查找是必要的,但是我找不到任何东西(然后我会得到的是一个Expression或者可能是直接调用).

经过一番思考后,很明显Microsoft.VisualBasic大会中有类似的东西.VB.NET支持后期绑定.它在Microsoft.VisualBasic.CompilerServices.NewLateBinding,但它没有暴露后期有界方法.

Answer 1

xan*_*tos 3

（注意：C# 中方法/属性/事件定义中的遮蔽 = 隐藏 = new）

没有人回复，所以我将同时发布我编写的代码。我讨厌发布 400 行代码，但我希望完整。主要有两种方法：GetVisibleMethods和GetVisibleProperties。它们是Type类的扩展方法。它们将返回类型的公共可见（非隐藏/非重写）方法/属性。它们甚至应该处理 VB.NET 程序集（VB.NET 通常使用hide-by-name遮蔽，而不是像hidebysigC# 那样）。他们将结果缓存在两个静态集合中（Methods和Properties）。该代码适用于 C# 4.0，因此我使用ConcurrentDictionary<T, U>. 如果您使用的是 C# 3.5，则可以将其替换为 a ，但在读取和写入时Dictionary<T, U>必须使用 () { } 来保护它。lock

它是如何运作的？它通过递归来工作（我知道递归通常是不好的，但我希望没有人会创建 1.000 级的继承链）。

对于“真实”类型（非接口），它向上一层（使用递归，因此这一层可以向上一层，依此类推），并且从返回的方法/属性列表中删除方法/属性它超载/隐藏。

对于接口来说，它有点复杂。Type.GetInterfaces()返回所有被继承的接口，忽略它们是直接继承还是间接继承。对于每个接口，都会计算声明的方法/属性的列表（通过递归）。该列表与接口隐藏的方法/属性列表配对（HashSet<MethodInfo>/ HashSet<PropertyInfo>）。这些被一个或另一个接口隐藏的方法/属性将从接口返回的所有其他方法/属性中删除（因此，如果您有I1with Method1(int)，I2则继承自I1该重新声明Method1(int)，并且这样做会隐藏I1.Method1并I3继承自I1and ，隐藏I2的事实将是应用于从 Explore 返回的方法，因此删除（发生这种情况是因为我没有为接口生成继承映射，我只是查看隐藏了什么））。I2I1.Method1I1I1.Method1(int)

从返回的方法/属性集合中，可以使用 Linq 来查找所查找的方法/属性。请注意，通过接口，您可以找到多个具有给定签名的方法/属性。一个例子：

interface I1
{
    void Method1();
}

interface I2
{
    void Method1();
}

interface I3 : I1, I2
{
}

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I3将返回两个Method1().

代码：

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

public static class TypeEx
{
    /// <summary>
    /// Type, Tuple&lt;Methods of type, (for interfaces)methods of base interfaces shadowed&gt;
    /// </summary>
    public static readonly ConcurrentDictionary<Type, Tuple<MethodInfo[], HashSet<MethodInfo>>> Methods = new ConcurrentDictionary<Type, Tuple<MethodInfo[], HashSet<MethodInfo>>>();

    /// <summary>
    /// Type, Tuple&lt;Properties of type, (for interfaces)properties of base interfaces shadowed&gt;
    /// </summary>
    public static readonly ConcurrentDictionary<Type, Tuple<PropertyInfo[], HashSet<PropertyInfo>>> Properties = new ConcurrentDictionary<Type, Tuple<PropertyInfo[], HashSet<PropertyInfo>>>();

    public static MethodInfo[] GetVisibleMethods(this Type type)
    {
        if (type.IsInterface)
        {
            return (MethodInfo[])type.GetVisibleMethodsInterfaceImpl().Item1.Clone();
        }

        return (MethodInfo[])type.GetVisibleMethodsImpl().Clone();
    }

    public static PropertyInfo[] GetVisibleProperties(this Type type)
    {
        if (type.IsInterface)
        {
            return (PropertyInfo[])type.GetVisiblePropertiesInterfaceImpl().Item1.Clone();
        }

        return (PropertyInfo[])type.GetVisiblePropertiesImpl().Clone();
    }

    private static MethodInfo[] GetVisibleMethodsImpl(this Type type)
    {
        Tuple<MethodInfo[], HashSet<MethodInfo>> tuple;

        if (Methods.TryGetValue(type, out tuple))
        {
            return tuple.Item1;
        }

        var methods = type.GetMethods(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public);

        if (type.BaseType == null)
        {
            Methods.TryAdd(type, Tuple.Create(methods, (HashSet<MethodInfo>)null));
            return methods;
        }

        var baseMethods = type.BaseType.GetVisibleMethodsImpl().ToList();

        foreach (var method in methods)
        {
            if (method.IsHideByName())
            {
                baseMethods.RemoveAll(p => p.Name == method.Name);
            }
            else
            {
                int numGenericArguments = method.GetGenericArguments().Length;
                var parameters = method.GetParameters();

                baseMethods.RemoveAll(p =>
                {
                    if (!method.EqualSignature(numGenericArguments, parameters, p))
                    {
                        return false;
                    }

                    return true;
                });
            }
        }

        if (baseMethods.Count == 0)
        {
            Methods.TryAdd(type, Tuple.Create(methods, (HashSet<MethodInfo>)null));
            return methods;
        }

        var methods3 = new MethodInfo[methods.Length + baseMethods.Count];

        Array.Copy(methods, 0, methods3, 0, methods.Length);
        baseMethods.CopyTo(methods3, methods.Length);

        Methods.TryAdd(type, Tuple.Create(methods3, (HashSet<MethodInfo>)null));
        return methods3;
    }

    private static Tuple<MethodInfo[], HashSet<MethodInfo>> GetVisibleMethodsInterfaceImpl(this Type type)
    {
        Tuple<MethodInfo[], HashSet<MethodInfo>> tuple;

        if (Methods.TryGetValue(type, out tuple))
        {
            return tuple;
        }

        var methods = type.GetMethods(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public);

        var baseInterfaces = type.GetInterfaces();

        if (baseInterfaces.Length == 0)
        {
            tuple = Tuple.Create(methods, new HashSet<MethodInfo>());
            Methods.TryAdd(type, tuple);
            return tuple;
        }

        var baseMethods = new List<MethodInfo>();

        var baseMethodsTemp = new MethodInfo[baseInterfaces.Length][];

        var shadowedMethods = new HashSet<MethodInfo>();

        for (int i = 0; i < baseInterfaces.Length; i++)
        {
            var tuple2 = baseInterfaces[i].GetVisibleMethodsInterfaceImpl();
            baseMethodsTemp[i] = tuple2.Item1;
            shadowedMethods.UnionWith(tuple2.Item2);
        }

        for (int i = 0; i < baseInterfaces.Length; i++)
        {
            baseMethods.AddRange(baseMethodsTemp[i].Where(p => !shadowedMethods.Contains(p)));
        }

        foreach (var method in methods)
        {
            if (method.IsHideByName())
            {
                baseMethods.RemoveAll(p =>
                {
                    if (p.Name == method.Name)
                    {
                        shadowedMethods.Add(p);
                        return true;
                    }

                    return false;
                });
            }
            else
            {
                int numGenericArguments = method.GetGenericArguments().Length;
                var parameters = method.GetParameters();

                baseMethods.RemoveAll(p =>
                {
                    if (!method.EqualSignature(numGenericArguments, parameters, p))
                    {
                        return false;
                    }

                    shadowedMethods.Add(p);
                    return true;
                });
            }
        }

        if (baseMethods.Count == 0)
        {
            tuple = Tuple.Create(methods, shadowedMethods);
            Methods.TryAdd(type, tuple);
            return tuple;
        }

        var methods3 = new MethodInfo[methods.Length + baseMethods.Count];

        Array.Copy(methods, 0, methods3, 0, methods.Length);
        baseMethods.CopyTo(methods3, methods.Length);

        tuple = Tuple.Create(methods3, shadowedMethods);
        Methods.TryAdd(type, tuple);
        return tuple;
    }

    private static PropertyInfo[] GetVisiblePropertiesImpl(this Type type)
    {
        Tuple<PropertyInfo[], HashSet<PropertyInfo>> tuple;

        if (Properties.TryGetValue(type, out tuple))
        {
            return tuple.Item1;
        }

        var properties = type.GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Static | BindingFlags.Public);

        if (type.BaseType == null)
        {
            Properties.TryAdd(type, Tuple.Create(properties, (HashSet<PropertyInfo>)null));
            return properties;
        }

        var baseProperties = type.BaseType.GetVisiblePropertiesImpl().ToList();

        foreach (var property in properties)
        {
            if (property.IsHideByName())
            {
                baseProperties.RemoveAll(p => p.Name == property.Name);
            }
            else
            {
                var indexers = property.GetIndexParameters();

                baseProperties.RemoveAll(p =>
                {
                    if (!property.EqualSignature(indexers, p))
                    {
                        return false;
                    }

                    return true;
                });
            }
        }

        if (baseProperties.Count == 0)
        {
            Properties.TryAdd(type, Tuple.Create(properties, (HashSet<PropertyInfo>)null));
            return properties;
        }

        var properties3 = new PropertyInfo[properties.Length + baseProperties.Count];

        Array.Copy(properties, 0, properties3, 0, properties.Length);
        baseProperties.CopyTo(properties3, properties.Length);

        Properties.TryAdd(type, Tuple.Create(properties3, (HashSet<PropertyInfo>)null));
        return properties3;
    }

    private static Tuple<PropertyInfo[], HashSet<PropertyInfo>> GetVisiblePropertiesInterfaceImpl(this Type type)
    {
        Tuple<PropertyInfo[], HashSet<PropertyInfo>> tuple;

        if (Properties.TryGetValue(type, out tuple))
        {
            return tuple;
        }

        var properties = type.GetProperties(BindingFlags.DeclaredOnly | BindingFlags.Instance | BindingFlags.Public);

        var baseInterfaces = type.GetInterfaces();

        if (baseInterfaces.Length == 0)
        {
            tuple = Tuple.Create(properties, new HashSet<PropertyInfo>());
            Properties.TryAdd(type, tuple);
            return tuple;
        }

        var baseProperties = new List<PropertyInfo>();

        var basePropertiesTemp = new PropertyInfo[baseInterfaces.Length][];

        var shadowedProperties = new HashSet<PropertyInfo>();

        for (int i = 0; i < baseInterfaces.Length; i++)
        {
            var tuple2 = baseInterfaces[i].GetVisiblePropertiesInterfaceImpl();
            basePropertiesTemp[i] = tuple2.Item1;
            shadowedProperties.UnionWith(tuple2.Item2);
        }

        for (int i = 0; i < baseInterfaces.Length; i++)
        {
            baseProperties.AddRange(basePropertiesTemp[i].Where(p => !shadowedProperties.Contains(p)));
        }

        foreach (var property in properties)
        {
            if (property.IsHideByName())
            {
                baseProperties.RemoveAll(p =>
                {
                    if (p.Name == property.Name)
                    {
                        shadowedProperties.Add(p);
                        return true;
                    }

                    return false;
                });
            }
            else
            {
                var indexers = property.GetIndexParameters();

                baseProperties.RemoveAll(p =>
                {
                    if (!property.EqualSignature(indexers, p))
                    {
                        return false;
                    }

                    shadowedProperties.Add(p);
                    return true;
                });
            }
        }

        if (baseProperties.Count == 0)
        {
            tuple = Tuple.Create(properties, shadowedProperties);
            Properties.TryAdd(type, tuple);
            return tuple;
        }

        var properties3 = new PropertyInfo[properties.Length + baseProperties.Count];

        Array.Copy(properties, 0, properties3, 0, properties.Length);
        baseProperties.CopyTo(properties3, properties.Length);

        tuple = Tuple.Create(properties3, shadowedProperties);
        Properties.TryAdd(type, tuple);
        return tuple;
    }

    private static bool EqualSignature(this MethodInfo method1, int numGenericArguments1, ParameterInfo[] parameters1, MethodInfo method2)
    {
        // To shadow by signature a method must have same name, same number of 
        // generic arguments, same number of parameters and same parameters' type
        if (method1.Name != method2.Name)
        {
            return false;
        }

        if (numGenericArguments1 != method2.GetGenericArguments().Length)
        {
            return false;
        }

        var parameters2 = method2.GetParameters();

        if (!parameters1.EqualParameterTypes(parameters2))
        {
            return false;
        }

        return true;
    }

    private static bool EqualSignature(this PropertyInfo property1, ParameterInfo[] indexers1, PropertyInfo property2)
    {
        // To shadow by signature a property must have same name, 
        // same number of indexers and same indexers' type
        if (property1.Name != property2.Name)
        {
            return false;
        }

        var parameters2 = property1.GetIndexParameters();

        if (!indexers1.EqualParameterTypes(parameters2))
        {
            return false;
        }

        return true;
    }

    private static bool EqualParameterTypes(this ParameterInfo[] parameters1, ParameterInfo[] parameters2)
    {
        if (parameters1.Length != parameters2.Length)
        {
            return false;
        }

        for (int i = 0; i < parameters1.Length; i++)
        {
            if (parameters1[i].IsOut != parameters2[i].IsOut)
            {
                return false;
            }

            if (parameters1[i].ParameterType.IsGenericParameter)
            {
                if (!parameters2[i].ParameterType.IsGenericParameter)
                {
                    return false;
                }

                if (parameters1[i].ParameterType.GenericParameterPosition != parameters2[i].ParameterType.GenericParameterPosition)
                {
                    return false;
                }
            }
            else if (parameters1[i].ParameterType != parameters2[i].ParameterType)
            {
                return false;
            }
        }

        return true;
    }

    private static bool IsHideByName(this MethodInfo method)
    {
        if (!method.Attributes.HasFlag(MethodAttributes.HideBySig) && (!method.Attributes.HasFlag(MethodAttributes.Virtual) || method.Attributes.HasFlag(MethodAttributes.NewSlot)))
        {
            return true;
        }

        return false;
    }

    private static bool IsHideByName(this PropertyInfo property)
    {
        var get = property.GetGetMethod();

        if (get != null && get.IsHideByName())
        {
            return true;
        }

        var set = property.GetSetMethod();

        if (set != null && set.IsHideByName())
        {
            return true;
        }

        return false;
    }
}

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