How to get a list of methods invoked by a method using reflection in C #

Question

How to get a list of methods called by a method using reflection in C # (DotNet) or How to check if Method1 is called from Method2 using reflection?

Answer 1

As others noted, this is almost impossible to do with reflection. You will need to analyze the bytecode of the IL method yourself to find the calls. Fortunately, there is a beautiful project called Mono Cecil (also available on nuget ) that does all the hard work for you. Here is a minimal example illustrating how your problem can be solved with Mono Cecil:

static class MethodDefinitionExtensions
{
    public static bool CallsMethod(this MethodDefinition caller, 
        MethodDefinition callee)
    {
        return caller.Body.Instructions.Any(x => 
            x.OpCode == OpCodes.Call && x.Operand == callee);
    }
}

class Program
{
    private static AssemblyDefinition _assembly = AssemblyDefinition.ReadAssembly(
        System.Reflection.Assembly.GetExecutingAssembly().Location);

    private static void Method1()
    {
        Method2();
    }

    private static void Method2()
    {
        Method1();
        Method3();
    }

    private static void Method3()
    {
        Method1();
    }

    private static IEnumerable<MethodDefinition> GetMethodsCalled(
        MethodDefinition caller)
    {
        return caller.Body.Instructions
            .Where(x => x.OpCode == OpCodes.Call)
            .Select(x => (MethodDefinition)x.Operand);
    }

    private static MethodDefinition GetMethod(string name)
    {
        TypeDefinition programType = _assembly.MainModule.Types
            .FirstOrDefault(x => x.Name == "Program");
        return programType.Methods.First(x => x.Name == name);
    }

    public static void Main(string[] args)
    {
        MethodDefinition method1 = GetMethod("Method1");
        MethodDefinition method2 = GetMethod("Method2");
        MethodDefinition method3 = GetMethod("Method3");

        Debug.Assert(method1.CallsMethod(method3) == false);
        Debug.Assert(method1.CallsMethod(method2) == true);
        Debug.Assert(method3.CallsMethod(method1) == true);

        Debug.Assert(GetMethodsCalled(method2).SequenceEqual(
            new List<MethodDefinition> { method1, method3 }));
    }
}