Question

I have a need that is a bit similar to this question, except that it requires a deeper exploration of the source object.

Here is a code sample:

public class Target {};

public class Analyzed
{
    public Target EasyOne { get; set; }
    public IList<Target> ABitMoreTricky { get; set; }
    public IList<Tuple<string, Target>> Nightmare { get; set; }
}

From an instance of Analyzed, I want to extract all the Target instances.

In order to ease the exploration, we can assume the following:

1. Explore only properties.
2. There is no infinite reference loop.

For now, EasyOne is… easy, but I am looking for some strategy to get all the Target instances lost in more tricky structures.

Answer 1

How about something along these lines:

    public List<T> FindAllInstances<T>(object value) where T : class
    {

        HashSet<object> exploredObjects = new HashSet<object>();
        List<T> found = new List<T>();

        FindAllInstances(value, exploredObjects, found);

        return found;
    }

    private void FindAllInstances<T>(object value, HashSet<object> exploredObjects, List<T> found) where T : class
    {
        if (value == null)
            return;

        if (exploredObjects.Contains(value))
            return;

        exploredObjects.Add(value);

        IEnumerable enumerable = value as IEnumerable;

        if (enumerable != null)
        {
            foreach(object item in enumerable)
            {
                FindAllInstances<T>(item, exploredObjects, found);
            }
        }
        else
        {
            T possibleMatch = value as T;

            if (possibleMatch != null)
            {
                found.Add(possibleMatch);
            }

            Type type = value.GetType();

            PropertyInfo[] properties = type.GetProperties(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.GetProperty);

            foreach(PropertyInfo property in properties)
            {
                object propertyValue = property.GetValue(value, null);

                FindAllInstances<T>(propertyValue, exploredObjects, found);
            }

        }

    private void TestIt()
    {
        Analyzed analyzed = new Analyzed()
        {
            EasyOne = new Target(),
            ABitMoreTricky = new List<Target>() { new Target() },
            Nightmare = new List<Tuple<string, Target>>() { new Tuple<string, Target>("", new Target()) }
        };

        List<Target> found = FindAllInstances<Target>(analyzed);

        MessageBox.Show(found.Count.ToString());
    }