IGroup.cs

// (C) 2012 Christian Schladetsch. See https://github.com/cschladetsch/Flow.

namespace Flow
{
    using System.Collections.Generic;

    public delegate void GroupHandler(IGroup node, ITransient child);

    /// <inheritdoc />
    /// <summary>
    /// A Group contains a collection of other Transients, and fires events when the
    /// contents of the group changes.
    ///
    /// <para>When a Group is stepped, nothing happens.</para>
    /// <para>When a Group is resumed, all child generators are also resumed.</para>
    /// <para>When a Group is suspended, all child generators are also suspended.</para>
    /// </summary>
    public interface IGroup
        : IGenerator
    {
        IList<ITransient> Contents { get; }
        IEnumerable<IGenerator> Generators { get; }

        bool Empty { get; }

        // Occurs when a transient is added to this group.
        event GroupHandler OnAdded;

        // Occurs when a transient is removed from this group.
        event GroupHandler OnRemoved;

        // Add the specified transient to this group iff it is not already a member
        // of this group.
        void Add(IEnumerable<ITransient> trans);
        void Add(params ITransient[] trans);

        // Remove the specified transient from this group.
        void Remove(ITransient trans);
    }
}