//---------------------------------------------------------------------------
//
// File: RtfFormatStack.cs
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
// Description: Rtf format stack.
//
//---------------------------------------------------------------------------
using System.Collections;
using MS.Internal; // Invariant
namespace System.Windows.Documents
{
/// <summary>
/// RtfFormatStack
/// </summary>
internal class RtfFormatStack : ArrayList
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
internal RtfFormatStack() : base(20)
{
}
#endregion Constructors
//------------------------------------------------------
//
// Internal Methods
//
//------------------------------------------------------
#region Internal Methods
internal void Push()
{
FormatState previousFormatState = Top();
FormatState formatState;
formatState = previousFormatState != null ? new FormatState(previousFormatState) : new FormatState();
Add(formatState);
}
internal void Pop()
{
Invariant.Assert(Count != 0);
if (Count > 0)
{
RemoveAt(Count - 1);
}
}
internal FormatState Top()
{
return Count > 0 ? EntryAt(Count - 1) : null;
}
internal FormatState PrevTop(int fromTop)
{
int index = Count - 1 - fromTop;
if (index < 0 || index >= Count)
{
return null;
}
return EntryAt(index);
}
internal FormatState EntryAt(int index)
{
return (FormatState)this[index];
}
#endregion Internal Methods
}
}
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