Switch CFX_SAXReader to use std::stack.

xfa/fde/xml/cfx_saxreader.h

 // Copyright 2014 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 XFA_FDE_XML_CFX_SAXREADER_H_
 #define XFA_FDE_XML_CFX_SAXREADER_H_
 
+#include <memory>
+#include <stack>
+
 #include "core/fxcrt/include/fx_basic.h"
 
 class CXFA_SAXContext;
 
 class CFX_SAXItem {
  public:
   enum class Type {
     Unknown = 0,
     Instruction,
     Declaration,
     Comment,
     Tag,
     Text,
     CharData,
   };
 
-  CFX_SAXItem()
-      : m_pNode(nullptr),
-        m_eNode(Type::Unknown),
-        m_dwID(0),
-        m_bSkip(FALSE),
-        m_pPrev(nullptr),
-        m_pNext(nullptr) {}
+  explicit CFX_SAXItem(uint32_t id)
+      : m_pNode(nullptr), m_eNode(Type::Unknown), m_dwID(id), m_bSkip(FALSE) {}
 
   CXFA_SAXContext* m_pNode;
   Type m_eNode;
-  uint32_t m_dwID;
+  const uint32_t m_dwID;
   FX_BOOL m_bSkip;
-  CFX_SAXItem* m_pPrev;
-  CFX_SAXItem* m_pNext;
 };
 
 class CFX_SAXFile {
  public:
   CFX_SAXFile();
   FX_BOOL StartFile(IFX_FileRead* pFile, uint32_t dwStart, uint32_t dwLen);
   FX_BOOL ReadNextBlock();
   void Reset();
   IFX_FileRead* m_pFile;
   uint32_t m_dwStart;
@@ skipping 46 matching lines @@
   void ParseTagAttributeValue();
   void ParseMaybeClose();
   void ParseTagClose();
   void ParseTagEnd();
   void ParseTargetData();
 
  private:
   void Reset();
   void Push();
   void Pop();
+  CFX_SAXItem* GetCurrentItem() const;
   FX_BOOL SkipSpace(uint8_t ch);
   void SkipNode();
   void NotifyData();
   void NotifyEnter();
   void NotifyAttribute();
   void NotifyBreak();
   void NotifyClose();
   void NotifyEnd();
   void NotifyTargetData();
   void ReallocDataBuffer();
   void ReallocNameBuffer();
   void ParseChar(uint8_t ch);
 
   CFX_SAXFile m_File;
   CXFA_SAXReaderHandler* m_pHandler;
   int32_t m_iState;
-  CFX_SAXItem* m_pRoot;
-  CFX_SAXItem* m_pCurItem;
+  std::stack<std::unique_ptr<CFX_SAXItem>> m_Stack;
   uint32_t m_dwItemID;
   CFX_SaxMode m_eMode;
   CFX_SaxMode m_ePrevMode;
   FX_BOOL m_bCharData;
   uint8_t m_CurByte;
   uint32_t m_dwDataOffset;
   CFX_ByteArray m_SkipStack;
   uint8_t m_SkipChar;
   uint32_t m_dwNodePos;
   uint8_t* m_pszData;
   int32_t m_iDataSize;
   int32_t m_iDataLength;
   int32_t m_iEntityStart;
   int32_t m_iDataPos;
   uint8_t* m_pszName;
   int32_t m_iNameSize;
   int32_t m_iNameLength;
   uint32_t m_dwParseMode;
   CFX_SAXCommentContext* m_pCommentContext;
 };
 
 #endif  // XFA_FDE_XML_CFX_SAXREADER_H_