使用反射查看方法内部是否调用了方法

Question

我正在使用反射，目前有一个 MethodBody。如何检查 MethodBody 内部是否调用了特定方法？

Assembly assembly = Assembly.Load("Module1");
Type type = assembly.GetType("Module1.ModuleInit");
MethodInfo mi = type.GetMethod("Initialize");
MethodBody mb = mi.GetMethodBody();

Answer 1

使用Mono.Cecil。它是一个独立的程序集，可以在 Microsoft .NET 和 Mono 上运行。 （我想当我编写下面的代码时，我使用了 0.6 版或大约版本）

假设您有许多程序集

IEnumerable<AssemblyDefinition> assemblies;

使用 AssemblyFactory 获取这些程序集（加载一个？）

以下代码片段将枚举这些程序集的所有类型中方法的所有用法

methodUsages = assemblies
            .SelectMany(assembly => assembly.MainModule.Types.Cast<TypeDefinition>())
            .SelectMany(type => type.Methods.Cast<MethodDefinition>())
            .Where(method => null != method.Body) // allow abstracts and generics
            .SelectMany(method => method.Body.Instructions.Cast<Instruction>())
            .Select(instr => instr.Operand)
            .OfType<MethodReference>();

这将返回对方法的所有引用（因此包括在反射中使用，或构造可能执行或不执行的表达式）。因此，这可能不是很有用，只是向您展示无需太多努力即可使用 Cecil API 完成的操作 :)

请注意，此示例假定 Cecil 版本稍旧（主流单声道版本中的版本）。新版本

• 更简洁（通过使用强类型泛型集合）
• 更快

当然，在您的情况下，您可以将单个方法引用作为起点。假设您想检测何时可以在“startingpoint”内直接调用“mytargetmethod”实际上：

MethodReference startingpoint; // get it somewhere using Cecil
MethodReference mytargetmethod; // what you are looking for

bool isCalled = startingpoint    
    .GetOriginalMethod() // jump to original (for generics e.g.)
    .Resolve()           // get the definition from the IL image
    .Body.Instructions.Cast<Instruction>()
    .Any(i => i.OpCode == OpCodes.Callvirt && i.Operand == (mytargetmethod));

调用树搜索

这是一个工作片段，允许您递归搜索到相互调用的（选定的）方法（间接）。

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using Mono.Cecil;
using Mono.Cecil.Cil;

namespace StackOverflow
{
    /*
     * breadth-first lazy search across a subset of the call tree rooting in startingPoint
     * 
     * methodSelect selects the methods to recurse into
     * resultGen generates the result objects to be returned by the enumerator
     * 
     */
    class CallTreeSearch<T> : BaseCodeVisitor, IEnumerable<T> where T : class
    {
        private readonly Func<MethodReference, bool> _methodSelect;
        private readonly Func<Instruction, Stack<MethodReference>, T> _transform;

        private readonly IEnumerable<MethodDefinition> _startingPoints;
        private readonly IDictionary<MethodDefinition, Stack<MethodReference>> _chain = new Dictionary<MethodDefinition, Stack<MethodReference>>();
        private readonly ICollection<MethodDefinition> _seen = new HashSet<MethodDefinition>(new CompareMembers<MethodDefinition>());
        private readonly ICollection<T> _results = new HashSet<T>();
        private Stack<MethodReference> _currentStack;

        private const int InfiniteRecursion = -1;
        private readonly int _maxrecursiondepth;
        private bool _busy;

        public CallTreeSearch(IEnumerable<MethodDefinition> startingPoints,
                              Func<MethodReference, bool> methodSelect,
                              Func<Instruction, Stack<MethodReference>, T> resultGen)
            : this(startingPoints, methodSelect, resultGen, InfiniteRecursion)
        {

        }

        public CallTreeSearch(IEnumerable<MethodDefinition> startingPoints,
                              Func<MethodReference, bool> methodSelect,
                              Func<Instruction, Stack<MethodReference>, T> resultGen,
                              int maxrecursiondepth)
        {
            _startingPoints = startingPoints.ToList();

            _methodSelect = methodSelect;
            _maxrecursiondepth = maxrecursiondepth;
            _transform = resultGen;
        }

        public override void VisitMethodBody(MethodBody body)
        {
            _seen.Add(body.Method); // avoid infinite recursion
            base.VisitMethodBody(body);
        }

        public override void VisitInstructionCollection(InstructionCollection instructions)
        {
            foreach (Instruction instr in instructions)
                VisitInstruction(instr);

            base.VisitInstructionCollection(instructions);
        }

        public override void VisitInstruction(Instruction instr)
        {
            T result = _transform(instr, _currentStack);
            if (result != null)
                _results.Add(result);

            var methodRef = instr.Operand as MethodReference; // TODO select calls only?
            if (methodRef != null && _methodSelect(methodRef))
            {
                var resolve = methodRef.Resolve();
                if (null != resolve && !(_chain.ContainsKey(resolve) || _seen.Contains(resolve)))
                    _chain.Add(resolve, new Stack<MethodReference>(_currentStack.Reverse()));
            }

            base.VisitInstruction(instr);
        }

        public IEnumerator<T> GetEnumerator()
        {
            lock (this) // not multithread safe
            {
                if (_busy)
                    throw new InvalidOperationException("CallTreeSearch enumerator is not reentrant");
                _busy = true;

                try
                {
                    int recursionLevel = 0;
                    ResetToStartingPoints();

                    while (_chain.Count > 0 &&
                           ((InfiniteRecursion == _maxrecursiondepth) || recursionLevel++ <= _maxrecursiondepth))
                    {

                        // swapout the collection because Visitor will modify
                        var clone = new Dictionary<MethodDefinition, Stack<MethodReference>>(_chain);
                        _chain.Clear();

                        foreach (var call in clone.Where(call => HasBody(call.Key)))
                        {
//                          Console.Error.Write("\rCallTreeSearch: level #{0}, scanning {1,-20}\r", recursionLevel, call.Key.Name + new string(' ',21));
                            _currentStack = call.Value;
                            _currentStack.Push(call.Key);
                            try
                            {
                                _results.Clear();
                                call.Key.Body.Accept(this); // grows _chain and _results
                            }
                            finally
                            {
                                _currentStack.Pop();
                            }
                            _currentStack = null;

                            foreach (var result in _results)
                                yield return result;
                        }
                    }
                }
                finally
                {
                    _busy = false;
                }
            }
        }

        private void ResetToStartingPoints()
        {
            _chain.Clear();
            _seen.Clear();
            foreach (var startingPoint in _startingPoints)
            {
                _chain.Add(startingPoint, new Stack<MethodReference>());
                _seen.Add(startingPoint);
            }
        }

        private static bool HasBody(MethodDefinition methodDefinition)
        {
            return !(methodDefinition.IsAbstract || methodDefinition.Body == null);
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }

    internal class CompareMembers<T> : IComparer<T>, IEqualityComparer<T>
        where T: class, IMemberReference
    {
        public int Compare(T x, T y)
        { return StringComparer.InvariantCultureIgnoreCase.Compare(KeyFor(x), KeyFor(y)); }

        public bool Equals(T x, T y)
        { return KeyFor(x).Equals(KeyFor(y)); }

        private static string KeyFor(T mr)
        { return null == mr ? "" : String.Format("{0}::{1}", mr.DeclaringType.FullName, mr.Name); }

        public int GetHashCode(T obj)
        { return KeyFor(obj).GetHashCode(); }
    }
}

注释

• 对 Resolve() 进行一些错误处理（我有一个扩展方法 TryResolve() 用于此目的），
• 可以选择在 a 中选择 MethodReferences 的用法仅调用操作（call、calli、callvirt ...）（参见 //TODO）

典型用法：

public static IEnumerable<T> SearchCallTree<T>(this TypeDefinition startingClass,
                                               Func<MethodReference, bool> methodSelect,
                                               Func<Instruction, Stack<MethodReference>, T> resultFunc,
                                               int maxdepth)
    where T : class
{
    return new CallTreeSearch<T>(startingClass.Methods.Cast<MethodDefinition>(), methodSelect, resultFunc, maxdepth);
}

public static IEnumerable<T> SearchCallTree<T>(this MethodDefinition startingMethod,
                                               Func<MethodReference, bool> methodSelect,
                                               Func<Instruction, Stack<MethodReference>, T> resultFunc,
                                               int maxdepth)
    where T : class
{
    return new CallTreeSearch<T>(new[] { startingMethod }, methodSelect, resultFunc, maxdepth); 
}

// Actual usage:
private static IEnumerable<TypeUsage> SearchMessages(TypeDefinition uiType, bool onlyConstructions)
{
    return uiType.SearchCallTree(IsBusinessCall,
           (instruction, stack) => DetectRequestUsage(instruction, stack, onlyConstructions));
}

注意函数的完成，例如检测请求使用情况满足您的需求完全取决于您（编辑：

Answer 2

在生成代码之前，必须检查它是否已经存在

。在某些情况下，捕获异常比阻止生成异常要便宜得多。这是一个很好的例子。您可以获得方法主体的 IL，但 Reflection 不是反汇编程序。反汇编程序也不是真正的解决方案，您可以反汇编整个调用树以实现您想要的行为。毕竟，主体中的方法调用本身可以调用方法等等。捕获编译 IL 时抖动抛出的异常要简单得多。

Answer 3

可以使用 StackTrace 类：

System.Diagnostics.StackTrace st = new System.Diagnostics.StackTrace();
System.Diagnostics.StackFrame sf = st.GetFrame(1); 
Console.Out.Write(sf.GetMethod().ReflectedType.Name + "." + sf.GetMethod().Name); 

可以调整 1 并确定您感兴趣的帧数。