enum ExecutionState
{
    S_EVAL,
    S_CALL1,
    S_CALL2
};

enum NodeType
{
    AND_OPERATOR,
    OR_OPERATOR,
    VALUE
};

class LocalVars
{
    public IEnumerator<Node> Enumerator;
    public bool Result;
}

class Context
{
    public Node Node;
    public LocalVars LocalVariables;
    public ExecutionState State;

    public Context(Node node, ExecutionState state)
    {
        this.Node = node;
        this.State = state;
        this.LocalVariables = new LocalVars();
    }
};

class Node
{
    public bool Value;
    public NodeType Type;
    public List<Node> Childrens;
};

static bool EvaluateNode(Node node)
{
    Stack<Context> stack = new Stack<Context>();
    Context context = new Context(node, ExecutionState.S_EVAL);
    stack.Push(context);

    bool returnresult = false;
    while(stack.Any())
    {
        context = stack.Pop();
        switch(context.State)
        {
            case ExecutionState.S_EVAL:
                switch(context.Node.Type)
                {
                    case NodeType.AND_OPERATOR:
                        if(context.LocalVariables.Enumerator == null)
                        {
                            context.LocalVariables.Enumerator = context.Node.Childrens.GetEnumerator();
                            context.LocalVariables.Result = true;
                        }

                        if(context.LocalVariables.Enumerator.MoveNext())
                        {
                            context.State = ExecutionState.S_CALL1;
                            stack.Push(context);            // push resume with S_CALL1

                            Context call = new Context(context.LocalVariables.Enumerator.Current, ExecutionState.S_EVAL);
                            stack.Push(call);           // push call
                        }
                        else
                        {
                            returnresult = context.LocalVariables.Result;    // no push -> return
                        }
                        break;

                    case NodeType.OR_OPERATOR:
                        if(context.LocalVariables.Enumerator == null)
                        {
                            context.LocalVariables.Enumerator = context.Node.Childrens.GetEnumerator();
                            context.LocalVariables.Result = false;
                        }

                        if(context.LocalVariables.Enumerator.MoveNext())
                        {
                            context.State = ExecutionState.S_CALL2;
                            stack.Push(context);            // push resume with S_CALL2

                            Context call = new Context(context.LocalVariables.Enumerator.Current, ExecutionState.S_EVAL);
                            stack.Push(call);           // push call
                        }
                        else
                        {
                            returnresult = context.LocalVariables.Result;    // no push -> return
                        }
                        break;

                    case NodeType.VALUE:
                        returnresult = context.Node.Value;  // no push -> return
                        break;
                }
                break;

            case ExecutionState.S_CALL1:
                context.LocalVariables.Result = context.LocalVariables.Result && returnresult;
                context.State = ExecutionState.S_EVAL;
                stack.Push(context);                        // continue with S_EVAL
                break;

            case ExecutionState.S_CALL2:
                context.LocalVariables.Result = context.LocalVariables.Result || returnresult;
                context.State = ExecutionState.S_EVAL;
                stack.Push(context);                        // continue with S_EVAL
                break;
        }
    }

    return returnresult;
}