Using dynamic
You could leverage the dynamic
keyword to do this, but I think it might be too slow for you.
However, this is how you could do it. This will call a strongly-typed enumerate()
method for List<T>
and T[]
, or if the value is neither a List nor an array, it will call the overload of enumerate()
which just takes an object.
I'm not entire sure this is what you are after, but it does give you a strongly-typed enumeration for the lists and arrays in your KVP list.
Note that as per your specification, this ONLY considers List and Array types; other enumerable types (such as strings, HashSet and so on) are not considered:
using System;
using System.Collections.Generic;
namespace ConsoleApp1
{
sealed class Program
{
void test()
{
List<KeyValuePair<string, object>> lKVP = new List<KeyValuePair<string, object>>();
List<string> lS = new List<string> { "s1", "s2" };
string[] aS = {"a1", "a2"};
lKVP.Add(new KeyValuePair<string, object>("String", "E92D8719-38A6-0000-961F-0E66FCB0A363"));
lKVP.Add(new KeyValuePair<string, object>("Test", lS));
lKVP.Add(new KeyValuePair<string, object>("IntNotEnumerable", 12345));
lKVP.Add(new KeyValuePair<string, object>("Array", aS));
foreach (KeyValuePair<string,object> kvp in lKVP)
{
enumerate((dynamic) kvp.Value);
}
}
static void enumerate<T>(List<T> list)
{
Console.WriteLine("Enumerating list of " + typeof(T).FullName);
foreach (var item in list)
Console.WriteLine(item);
Console.WriteLine();
}
static void enumerate<T>(T[] array)
{
Console.WriteLine("Enumerating array of " + typeof(T).FullName);
foreach (var item in array)
Console.WriteLine(item);
Console.WriteLine();
}
static void enumerate(object obj)
{
Console.WriteLine("Not enumerating type " + obj.GetType().FullName + " with value " + obj);
Console.WriteLine();
}
static void Main(string[] args)
{
new Program().test();
}
}
}
Using explicit reflection
Here's a way of doing it using reflection that avoids using dynamic
, which means it's a lot faster - but as you can see it's significantly more fiddly!
using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
namespace ConsoleApp1
{
sealed class Program
{
void test()
{
List<KeyValuePair<string, object>> lKVP = new List<KeyValuePair<string, object>>();
List<string> lS = new List<string> { "s1", "s2" };
string[] aS = {"a1", "a2"};
lKVP.Add(new KeyValuePair<string, object>("String", "E92D8719-38A6-0000-961F-0E66FCB0A363"));
lKVP.Add(new KeyValuePair<string, object>("Test", lS));
lKVP.Add(new KeyValuePair<string, object>("IntNotEnumerable", 12345));
lKVP.Add(new KeyValuePair<string, object>("Array", aS));
var listEnumerator = this.GetType().GetMethod("enumerateList", BindingFlags.NonPublic | BindingFlags.Static);
var arrayEnumerator = this.GetType().GetMethod("enumerateArray", BindingFlags.NonPublic | BindingFlags.Static);
foreach (KeyValuePair<string, object> kvp in lKVP)
{
MethodInfo genericEnumerator = null;
var arrayElemType = arrayElementType(kvp.Value);
if (arrayElemType != null)
{
genericEnumerator = arrayEnumerator.MakeGenericMethod(arrayElemType);
}
else
{
var listElemType = listElementType(kvp.Value);
if (listElemType != null)
genericEnumerator = listEnumerator.MakeGenericMethod(listElemType);
}
if (genericEnumerator != null)
genericEnumerator.Invoke(null, new[] { kvp.Value });
else
Console.WriteLine("Not enumerating type: " + kvp.Value.GetType().FullName + "\n");
}
}
static Type arrayElementType(object sequence)
{
if (sequence is IEnumerable)
{
var type = sequence.GetType();
if (type.IsArray)
return type.GetElementType();
}
return null;
}
static Type listElementType(object sequence)
{
if (sequence is IEnumerable)
{
var type = sequence.GetType();
if (typeof(IList).IsAssignableFrom(type) && type.IsGenericType)
return type.GetProperty("Item").PropertyType;
}
return null;
}
static void enumerateList<T>(List<T> list)
{
Console.WriteLine("Enumerating list of " + typeof(T).FullName);
foreach (var item in list)
Console.WriteLine(item);
Console.WriteLine();
}
static void enumerateArray<T>(T[] array)
{
Console.WriteLine("Enumerating array of " + typeof(T).FullName);
foreach (var item in array)
Console.WriteLine(item);
Console.WriteLine();
}
static void Main(string[] args)
{
new Program().test();
}
}
}