#region PDFsharp - A .NET library for processing PDF

//

// Authors:

// Stefan Lange

//

// Copyright (c) 2005-2016 empira Software GmbH, Cologne Area (Germany)

//

// http://www.PdfSharpCore.com

// http://sourceforge.net/projects/pdfsharp

//

// Permission is hereby granted, free of charge, to any person obtaining a

// copy of this software and associated documentation files (the "Software"),

// to deal in the Software without restriction, including without limitation

// the rights to use, copy, modify, merge, publish, distribute, sublicense,

// and/or sell copies of the Software, and to permit persons to whom the

// Software is furnished to do so, subject to the following conditions:

//

// The above copyright notice and this permission notice shall be included

// in all copies or substantial portions of the Software.

//

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

// DEALINGS IN THE SOFTWARE.

#endregion

using System;

using System.Collections.Generic;

using System.Diagnostics;

namespace PdfSharpCore.Pdf.IO

{

/// <summary>

/// Represents the stack for the shift-reduce parser. It seems that it is only needed for

/// reduction of indirect references.

/// </summary>

internal class ShiftStack

{

// TODO: make Lexer.PeekChars(20) and scan for 'R' to detect indirect references

public ShiftStack()

{

_items = new List<PdfItem>();

}

public PdfItem[] ToArray(int start, int length)

{

PdfItem[] items = new PdfItem[length];

for (int i = 0, j = start; i < length; i++, j++)

items[i] = _items[j];

return items;

}

/// <summary>

/// Gets the stack pointer index.

/// </summary>

// ReSharper disable InconsistentNaming

public int SP

// ReSharper restore InconsistentNaming

{

get { return _sp; }

}

/// <summary>

/// Gets the value at the specified index. Valid index is in range 0 up to sp-1.

/// </summary>

public PdfItem this[int index]

{

get

{

if (index >= _sp)

throw new ArgumentOutOfRangeException("index", index, "Value greater than stack index.");

return _items[index];

}

}

/// <summary>

/// Gets an item relative to the current stack pointer. The index must be a negative value (-1, -2, etc.).

/// </summary>

public PdfItem GetItem(int relativeIndex)

{

if (relativeIndex >= 0 || -relativeIndex > _sp)

throw new ArgumentOutOfRangeException("relativeIndex", relativeIndex, "Value out of stack range.");

return _items[_sp + relativeIndex];

}

/// <summary>

/// Gets an item relative to the current stack pointer. The index must be a negative value (-1, -2, etc.).

/// </summary>

public int GetInteger(int relativeIndex)

{

if (relativeIndex >= 0 || -relativeIndex > _sp)

throw new ArgumentOutOfRangeException("relativeIndex", relativeIndex, "Value out of stack range.");

return ((PdfInteger)_items[_sp + relativeIndex]).Value;

}

/// <summary>

/// Pushes the specified item onto the stack.

/// </summary>

public void Shift(PdfItem item)

{

Debug.Assert(item != null);

_items.Add(item);

_sp++;

}

/// <summary>

/// Replaces the last 'count' items with the specified item.

/// </summary>

public void Reduce(int count)

{

if (count > _sp)

throw new ArgumentException("count causes stack underflow.");

_items.RemoveRange(_sp - count, count);

_sp -= count;

}

/// <summary>

/// Replaces the last 'count' items with the specified item.

/// </summary>

public void Reduce(PdfItem item, int count)

{

Debug.Assert(item != null);

Reduce(count);

_items.Add(item);

_sp++;

}

/// <summary>

/// The stack pointer index. Points to the next free item.

/// </summary>

int _sp;

/// <summary>

/// An array representing the stack.

/// </summary>

readonly List<PdfItem> _items;

}

}