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//***************************************************************************
// Copyright © 2010 Microsoft Corporation. All Rights Reserved.
// This code released under the terms of the
// Microsoft Public License (MS-PL, http://opensource.org/licenses/ms-pl.html.)
//***************************************************************************
using System;
using System.Collections.Generic;
using System.Windows.Threading;
using Microsoft.VisualStudio.Text;
namespace DafnyLanguage
{
/// <summary>
/// Handy reusable utility to listen for change events on the associated buffer, but
/// only pass these along to a set of listeners when the user stops typing for a half second
/// </summary>
static class BufferIdleEventUtil
{
static object bufferListenersKey = new object();
static object bufferTimerKey = new object();
#region Public interface
public static bool AddBufferIdleEventListener(ITextBuffer buffer, EventHandler handler)
{
HashSet<EventHandler> listenersForBuffer;
if (!TryGetBufferListeners(buffer, out listenersForBuffer))
listenersForBuffer = ConnectToBuffer(buffer);
if (listenersForBuffer.Contains(handler))
return false;
listenersForBuffer.Add(handler);
return true;
}
public static bool RemoveBufferIdleEventListener(ITextBuffer buffer, EventHandler handler)
{
HashSet<EventHandler> listenersForBuffer;
if (!TryGetBufferListeners(buffer, out listenersForBuffer))
return false;
if (!listenersForBuffer.Contains(handler))
return false;
listenersForBuffer.Remove(handler);
if (listenersForBuffer.Count == 0)
DisconnectFromBuffer(buffer);
return true;
}
#endregion
#region Helpers
static bool TryGetBufferListeners(ITextBuffer buffer, out HashSet<EventHandler> listeners)
{
return buffer.Properties.TryGetProperty(bufferListenersKey, out listeners);
}
static void ClearBufferListeners(ITextBuffer buffer)
{
buffer.Properties.RemoveProperty(bufferListenersKey);
}
static bool TryGetBufferTimer(ITextBuffer buffer, out DispatcherTimer timer)
{
return buffer.Properties.TryGetProperty(bufferTimerKey, out timer);
}
static void ClearBufferTimer(ITextBuffer buffer)
{
DispatcherTimer timer;
if (TryGetBufferTimer(buffer, out timer))
{
if (timer != null)
timer.Stop();
buffer.Properties.RemoveProperty(bufferTimerKey);
}
}
static void DisconnectFromBuffer(ITextBuffer buffer)
{
buffer.Changed -= BufferChanged;
ClearBufferListeners(buffer);
ClearBufferTimer(buffer);
buffer.Properties.RemoveProperty(bufferListenersKey);
}
static HashSet<EventHandler> ConnectToBuffer(ITextBuffer buffer)
{
buffer.Changed += BufferChanged;
RestartTimerForBuffer(buffer);
HashSet<EventHandler> listenersForBuffer = new HashSet<EventHandler>();
buffer.Properties[bufferListenersKey] = listenersForBuffer;
return listenersForBuffer;
}
static void RestartTimerForBuffer(ITextBuffer buffer)
{
DispatcherTimer timer;
if (TryGetBufferTimer(buffer, out timer))
{
timer.Stop();
}
else
{
timer = new DispatcherTimer(DispatcherPriority.ApplicationIdle)
{
Interval = TimeSpan.FromMilliseconds(500)
};
timer.Tick += (s, e) =>
{
ClearBufferTimer(buffer);
HashSet<EventHandler> handlers;
if (TryGetBufferListeners(buffer, out handlers))
{
foreach (var handler in handlers)
{
handler(buffer, new EventArgs());
}
}
};
buffer.Properties[bufferTimerKey] = timer;
}
timer.Start();
}
static void BufferChanged(object sender, TextContentChangedEventArgs e)
{
ITextBuffer buffer = sender as ITextBuffer;
if (buffer == null)
return;
RestartTimerForBuffer(buffer);
}
#endregion
}
}
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