The Service Tree Model

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Input;

namespace ServiceTreeSample
{
    /// <summary>
    /// An implementation of the <see cref="ICommand"/> interface
    /// that uses a delegate to execute the command.
    /// </summary>
    /// <typeparam name="TParameter">The type of the parameter.</typeparam>
    public class DelegateCommand<TParameter> : ICommand
    {
        Action<TParameter> execute;
        Func<TParameter, bool> canExecute;

        /// <summary>
        /// Initializes a new instance of the <see cref="DelegateCommand&lt;TParameter&gt;"/> class.
        /// </summary>
        /// <param name="execute">The execute.</param>
        /// <param name="canExecute">The can execute.</param>
        public DelegateCommand(Action<TParameter> execute, Func<TParameter, bool> canExecute)
        {
            this.execute = execute;
            this.canExecute = canExecute;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="DelegateCommand&lt;TParameter&gt;"/> class.
        /// </summary>
        /// <param name="execute">The execute.</param>
        public DelegateCommand(Action<TParameter> execute)
            : this(execute, null)
        {
        }

        /// <summary>
        /// Occurs when changes occur that affect whether or not the command should execute.
        /// </summary>
        public event EventHandler CanExecuteChanged;

        /// <summary>
        /// Defines the method that determines whether the command can execute in its current state.
        /// </summary>
        /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to null.</param>
        /// <returns>
        /// true if this command can be executed; otherwise, false.
        /// </returns>
        public bool CanExecute(object parameter)
        {
            if (canExecute == null)
                return true;
            if (parameter != null && !(parameter is TParameter))
                return false;
            return canExecute((TParameter)parameter);
        }

        /// <summary>
        /// Defines the method to be called when the command is invoked.
        /// </summary>
        /// <param name="parameter">Data used by the command.  If the command does not require data to be passed, this object can be set to null.</param>
        public void Execute(object parameter)
        {
            if (execute != null)
                execute((TParameter)parameter);
        }

        /// <summary>
        /// Raises the <see cref="CanExecuteChanged"/> event.
        /// </summary>
        public void RaiseCanExecuteChanged()
        {
            var handler = CanExecuteChanged;
            if (handler != null)
                handler(this, EventArgs.Empty);
        }
    }
}