TaskManager.cs

/// TaskManager.cs
/// Copyright (c) 2011, Ken Rockot  <k-e-n-@-REMOVE-CAPS-AND-HYPHENS-oz.gs>.  All rights reserved.
/// Everyone is granted non-exclusive license to do anything at all with this code.
///
/// This is a new coroutine interface for Unity.
///
/// The motivation for this is twofold:
///
/// 1. The existing coroutine API provides no means of stopping specific
///    coroutines; StopCoroutine only takes a string argument, and it stops
///    all coroutines started with that same string; there is no way to stop
///    coroutines which were started directly from an enumerator.  This is
///    not robust enough and is also probably pretty inefficient.
///
/// 2. StartCoroutine and friends are MonoBehaviour methods.  This means
///    that in order to start a coroutine, a user typically must have some
///    component reference handy.  There are legitimate cases where such a
///    constraint is inconvenient.  This implementation hides that
///    constraint from the user.
///
/// Example usage:
///
/// ----------------------------------------------------------------------------
/// IEnumerator MyAwesomeTask()
/// {
///     while(true) {
///         Debug.Log("Logcat iz in ur consolez, spammin u wif messagez.");
///         yield return null;
////    }
/// }
///
/// IEnumerator TaskKiller(float delay, Task t)
/// {
///     yield return new WaitForSeconds(delay);
///     t.Stop();
/// }
///
/// void SomeCodeThatCouldBeAnywhereInTheUniverse()
/// {
///     Task spam = new Task(MyAwesomeTask());
///     new Task(TaskKiller(5, spam));
/// }
/// ----------------------------------------------------------------------------
///
/// When SomeCodeThatCouldBeAnywhereInTheUniverse is called, the debug console
/// will be spammed with annoying messages for 5 seconds.
///
/// Simple, really.  There is no need to initialize or even refer to TaskManager.
/// When the first Task is created in an application, a "TaskManager" GameObject
/// will automatically be added to the scene root with the TaskManager component
/// attached.  This component will be responsible for dispatching all coroutines
/// behind the scenes.
///
/// Task also provides an event that is triggered when the coroutine exits.

using UnityEngine;
using System.Collections;

/// A Task object represents a coroutine.  Tasks can be started, paused, and stopped.
/// It is an error to attempt to start a task that has been stopped or which has
/// naturally terminated.
public class Task
{
    /// Returns true if and only if the coroutine is running.  Paused tasks
    /// are considered to be running.
    public bool Running
    {
        get
        {
            return task.Running;
        }
    }

    /// Returns true if and only if the coroutine is currently paused.
    public bool Paused
    {
        get
        {
            return task.Paused;
        }
    }

    /// Delegate for termination subscribers.  manual is true if and only if
    /// the coroutine was stopped with an explicit call to Stop().
    public delegate void FinishedHandler(bool manual);

    /// Termination event.  Triggered when the coroutine completes execution.
    public event FinishedHandler Finished;

    /// Creates a new Task object for the given coroutine.
    ///
    /// If autoStart is true (default) the task is automatically started
    /// upon construction.
    public Task(IEnumerator c, bool autoStart = true)
    {
        task = TaskManager.CreateTask(c);
        task.Finished += TaskFinished;
        if (autoStart)
            Start();
    }

    /// Begins execution of the coroutine
    public void Start()
    {
        task.Start();
    }

    /// Discontinues execution of the coroutine at its next yield.
    public void Stop()
    {
        task.Stop();
    }

    public void Pause()
    {
        task.Pause();
    }

    public void Unpause()
    {
        task.Unpause();
    }

    void TaskFinished(bool manual)
    {
        FinishedHandler handler = Finished;
        if (handler != null)
            handler(manual);
    }

    TaskManager.TaskState task;
}

class TaskManager : MonoBehaviour
{
    public class TaskState
    {
        public bool Running
        {
            get
            {
                return running;
            }
        }

        public bool Paused
        {
            get
            {
                return paused;
            }
        }

        public delegate void FinishedHandler(bool manual);
        public event FinishedHandler Finished;

        IEnumerator coroutine;
        bool running;
        bool paused;
        bool stopped;

        public TaskState(IEnumerator c)
        {
            coroutine = c;
        }

        public void Pause()
        {
            paused = true;
        }

        public void Unpause()
        {
            paused = false;
        }

        public void Start()
        {
            running = true;
            singleton.StartCoroutine(CallWrapper());
        }

        public void Stop()
        {
            stopped = true;
            running = false;
        }

        IEnumerator CallWrapper()
        {
            yield return null;
            IEnumerator e = coroutine;
            while (running)
            {
                if (paused)
                    yield return null;
                else
                {
                    if (e != null && e.MoveNext())
                    {
                        yield return e.Current;
                    }
                    else
                    {
                        running = false;
                    }
                }
            }

            FinishedHandler handler = Finished;
            if (handler != null)
                handler(stopped);
        }
    }

    static TaskManager singleton;

    public static TaskState CreateTask(IEnumerator coroutine)
    {
        if (singleton == null)
        {
            GameObject go = new GameObject("TaskManager");
            singleton = go.AddComponent<TaskManager>();
        }
        return new TaskState(coroutine);
    }
}