Traverse PDF page tree only once in CPDF_Document

core/fpdfapi/parser/cpdf_document.h

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef CORE_FPDFAPI_PARSER_CPDF_DOCUMENT_H_
 #define CORE_FPDFAPI_PARSER_CPDF_DOCUMENT_H_
 
 #include <functional>
 #include <memory>
+#include <stack>
 
 #include "core/fpdfapi/parser/cpdf_indirect_object_holder.h"
 #include "core/fpdfapi/parser/cpdf_object.h"
 #include "core/fpdfdoc/cpdf_linklist.h"
 #include "core/fxcrt/cfx_string_pool_template.h"
 #include "core/fxcrt/cfx_weak_ptr.h"
 #include "core/fxcrt/fx_basic.h"
 
 class CFX_Font;
 class CFX_Matrix;
@@ skipping 78 matching lines @@
   CPDF_Font* AddWindowsFont(LOGFONTW* pLogFont,
                             FX_BOOL bVert,
                             FX_BOOL bTranslateName = FALSE);
 #endif
 
  private:
   friend class CPDF_TestDocument;
 
   // Retrieve page count information by getting count value from the tree nodes
   int RetrievePageCount() const;
-  CPDF_Dictionary* FindPDFPage(CPDF_Dictionary* pPages,
-                               int iPage,
-                               int nPagesToGo,
-                               int level);
+  CPDF_Dictionary* TraversePDFPages(int iPage, int nPagesToGo);
   int FindPageIndex(CPDF_Dictionary* pNode,
                     uint32_t& skip_count,
                     uint32_t objnum,
                     int& index,
                     int level = 0);
   CPDF_Object* ParseIndirectObject(uint32_t objnum) override;
   void LoadDocInternal();
   size_t CalculateEncodingDict(int charset, CPDF_Dictionary* pBaseDict);
   CPDF_Dictionary* GetPagesDict() const;
   CPDF_Dictionary* ProcessbCJK(
       CPDF_Dictionary* pBaseDict,
       int charset,
       FX_BOOL bVert,
       CFX_ByteString basefont,
       std::function<void(FX_WCHAR, FX_WCHAR, CPDF_Array*)> Insert);
-
+  int InsertDeletePDFPage(CPDF_Dictionary* pPages,
+                          int nPagesToGo,
+                          CPDF_Dictionary* pPage,
+                          FX_BOOL bInsert,
+                          std::set<CPDF_Dictionary*>* pVisited);
+  int InsertNewPage(int iPage,
+                    CPDF_Dictionary* pPageDict,
+                    CFX_ArrayTemplate<uint32_t>& pageList);
   std::unique_ptr<CPDF_Parser> m_pParser;
   CPDF_Dictionary* m_pRootDict;
   CPDF_Dictionary* m_pInfoDict;
+  std::stack<std::pair<CPDF_Dictionary*, int>> m_pTreeTraversal;
+  int m_iLastPageTraversed;
   bool m_bLinearized;
   int m_iFirstPageNo;
   uint32_t m_dwFirstPageObjNum;
   // TODO(thestig): Figure out why this cannot be a std::unique_ptr.
   CPDF_DocPageData* m_pDocPage;
   std::unique_ptr<CPDF_DocRenderData> m_pDocRender;
   std::unique_ptr<JBig2_DocumentContext> m_pCodecContext;
   std::unique_ptr<CPDF_LinkList> m_pLinksContext;
   CFX_ArrayTemplate<uint32_t> m_PageList;
   CFX_WeakPtr<CFX_ByteStringPool> m_pByteStringPool;
 };
 
 #endif  // CORE_FPDFAPI_PARSER_CPDF_DOCUMENT_H_