|
using System;
using System.Collections;
using System.Collections.Specialized;
using System.Collections.Generic;
using System.Diagnostics;
using System.Windows.Threading;
using MS.Internal;
using MS.Internal.AppModel;
using MS.Utility;
using System.ComponentModel;
namespace System.Windows.Navigation
{
/// <summary>
/// This is the base class for the JournalEntryBackStack and JournalEntryForwardStack
/// classes.
/// </summary>
internal abstract class JournalEntryStack : IEnumerable, INotifyCollectionChanged
{
internal JournalEntryStack(Journal journal)
{
_journal = journal;
}
internal void OnCollectionChanged()
{
if (CollectionChanged != null)
{
CollectionChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));
}
}
internal JournalEntryFilter Filter
{
get { return _filter; }
set { _filter = value; }
}
internal IEnumerable GetLimitedJournalEntryStackEnumerable()
{
if (_ljese == null)
{
_ljese = new LimitedJournalEntryStackEnumerable(this);
}
return _ljese;
}
LimitedJournalEntryStackEnumerable _ljese;
protected JournalEntryFilter _filter;
public event NotifyCollectionChangedEventHandler CollectionChanged;
public abstract IEnumerator GetEnumerator();
protected Journal _journal;
}
/// <summary>
/// This class exists to provide an IEnumerator over the BackStack.
/// </summary>
internal class JournalEntryBackStack : JournalEntryStack
{
public JournalEntryBackStack(Journal journal)
: base(journal)
{
}
public override IEnumerator GetEnumerator()
{
//Debug.WriteLine("Getting BackStack");
return new JournalEntryStackEnumerator(_journal, _journal.CurrentIndex - 1, -1, this.Filter);
}
}
/// <summary>
/// This class exists to provide an IEnumerator over the ForwardStack.
/// </summary>
internal class JournalEntryForwardStack : JournalEntryStack
{
public JournalEntryForwardStack(Journal journal)
: base(journal)
{
}
public override IEnumerator GetEnumerator()
{
//Debug.WriteLine("Getting ForwardStack");
return new JournalEntryStackEnumerator(_journal, _journal.CurrentIndex + 1, 1, this.Filter);
}
}
/// <summary>
/// This will enumerate over the navigable JournalEntries in the journal, starting at start,
/// going in the direction of delta, and returning no more than _viewLimit values.
/// This is used for display purposes.
/// </summary>
internal class JournalEntryStackEnumerator : IEnumerator
{
public JournalEntryStackEnumerator(Journal journal, int start, int delta, JournalEntryFilter filter)
{
_journal = journal;
_version = journal.Version;
_start = start;
_delta = delta;
_filter = filter;
this.Reset();
}
public void Reset()
{
_next = _start;
_current = null;
}
public bool MoveNext()
{
VerifyUnchanged();
while ((_next >= 0) && (_next < _journal.TotalCount))
{
_current = _journal[_next];
_next += _delta;
if ((_filter == null) || _filter(_current))
{
Debug.Assert(_current != null, "If we are returning true, our current cannot be null");
return true;
}
}
_current = null;
return false;
}
public object Current
{
get { return _current; }
}
/// <summary>
/// Verifies that the journal has not been changed since this enumerator was created
/// </summary>
protected void VerifyUnchanged()
{
if (_version != _journal.Version)
{
throw new InvalidOperationException(SR.Get(SRID.EnumeratorVersionChanged));
}
}
Journal _journal;
int _start;
int _delta;
int _next;
JournalEntry _current;
JournalEntryFilter _filter;
int _version;
}
internal class LimitedJournalEntryStackEnumerable : IEnumerable, INotifyCollectionChanged
{
internal LimitedJournalEntryStackEnumerable(IEnumerable ieble)
{
_ieble = ieble;
INotifyCollectionChanged ichildnotify = ieble as INotifyCollectionChanged;
if (ichildnotify != null)
{
ichildnotify.CollectionChanged += new NotifyCollectionChangedEventHandler(PropogateCollectionChanged);
}
}
public IEnumerator GetEnumerator()
{
return new LimitedJournalEntryStackEnumerator(_ieble, DefaultMaxMenuEntries);
}
internal void PropogateCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
if (CollectionChanged != null)
{
CollectionChanged(this, e);
}
}
private const uint DefaultMaxMenuEntries = 9; // the maximum number of items in the dropdown menus
public event NotifyCollectionChangedEventHandler CollectionChanged;
private IEnumerable _ieble;
}
internal class LimitedJournalEntryStackEnumerator : IEnumerator
{
internal LimitedJournalEntryStackEnumerator(IEnumerable ieble, uint viewLimit)
{
_ienum = ieble.GetEnumerator();
_viewLimit = viewLimit;
}
public void Reset()
{
_itemsReturned = 0;
_ienum.Reset();
}
public bool MoveNext()
{
bool success;
if (_itemsReturned == _viewLimit)
{
success = false;
}
else
{
success = _ienum.MoveNext();
if (success)
{
_itemsReturned++;
}
}
return success;
}
public object Current
{
get { return _ienum.Current; }
}
private uint _itemsReturned;
private uint _viewLimit;
private IEnumerator _ienum;
}
}
|