143 lines
4.7 KiB
C#
143 lines
4.7 KiB
C#
#region PDFsharp - A .NET library for processing PDF
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//
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// Authors:
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// Stefan Lange
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//
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// Copyright (c) 2005-2017 empira Software GmbH, Cologne Area (Germany)
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//
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// http://www.pdfsharp.com
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// http://sourceforge.net/projects/pdfsharp
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and associated documentation files (the "Software"),
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// to deal in the Software without restriction, including without limitation
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// the rights to use, copy, modify, merge, publish, distribute, sublicense,
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// and/or sell copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included
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// in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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#endregion
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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namespace PdfSharp.Pdf.IO
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{
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/// <summary>
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/// Represents the stack for the shift-reduce parser. It seems that it is only needed for
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/// reduction of indirect references.
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/// </summary>
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internal class ShiftStack
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{
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// TODO: make Lexer.PeekChars(20) and scan for 'R' to detect indirect references
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public ShiftStack()
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{
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_items = new List<PdfItem>();
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}
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public PdfItem[] ToArray(int start, int length)
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{
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PdfItem[] items = new PdfItem[length];
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for (int i = 0, j = start; i < length; i++, j++)
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items[i] = _items[j];
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return items;
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}
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/// <summary>
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/// Gets the stack pointer index.
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/// </summary>
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// ReSharper disable InconsistentNaming
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public int SP
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// ReSharper restore InconsistentNaming
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{
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get { return _sp; }
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}
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/// <summary>
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/// Gets the value at the specified index. Valid index is in range 0 up to sp-1.
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/// </summary>
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public PdfItem this[int index]
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{
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get
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{
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if (index >= _sp)
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throw new ArgumentOutOfRangeException("index", index, "Value greater than stack index.");
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return _items[index];
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}
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}
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/// <summary>
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/// Gets an item relative to the current stack pointer. The index must be a negative value (-1, -2, etc.).
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/// </summary>
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public PdfItem GetItem(int relativeIndex)
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{
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if (relativeIndex >= 0 || -relativeIndex > _sp)
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throw new ArgumentOutOfRangeException("relativeIndex", relativeIndex, "Value out of stack range.");
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return _items[_sp + relativeIndex];
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}
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/// <summary>
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/// Gets an item relative to the current stack pointer. The index must be a negative value (-1, -2, etc.).
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/// </summary>
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public int GetInteger(int relativeIndex)
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{
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if (relativeIndex >= 0 || -relativeIndex > _sp)
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throw new ArgumentOutOfRangeException("relativeIndex", relativeIndex, "Value out of stack range.");
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return ((PdfInteger)_items[_sp + relativeIndex]).Value;
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}
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/// <summary>
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/// Pushes the specified item onto the stack.
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/// </summary>
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public void Shift(PdfItem item)
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{
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Debug.Assert(item != null);
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_items.Add(item);
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_sp++;
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}
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/// <summary>
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/// Replaces the last 'count' items with the specified item.
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/// </summary>
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public void Reduce(int count)
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{
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if (count > _sp)
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throw new ArgumentException("count causes stack underflow.");
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_items.RemoveRange(_sp - count, count);
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_sp -= count;
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}
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/// <summary>
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/// Replaces the last 'count' items with the specified item.
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/// </summary>
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public void Reduce(PdfItem item, int count)
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{
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Debug.Assert(item != null);
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Reduce(count);
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_items.Add(item);
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_sp++;
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}
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/// <summary>
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/// The stack pointer index. Points to the next free item.
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/// </summary>
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int _sp;
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/// <summary>
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/// An array representing the stack.
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/// </summary>
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readonly List<PdfItem> _items;
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}
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}
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