Add type cast definitions for CPDF_String.

core/include/fpdfapi/fpdf_objects.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 CORE_INCLUDE_FPDFAPI_FPDF_OBJECTS_H_
 #define CORE_INCLUDE_FPDFAPI_FPDF_OBJECTS_H_
 
 #include "../fxcrt/fx_coordinates.h"
@@ skipping 63 matching lines @@
 
   void SetUnicodeText(const FX_WCHAR* pUnicodes, int len = -1);
 
   int GetDirectType() const;
 
   FX_BOOL IsModified() const { return FALSE; }
 
   bool IsBoolean() const { return m_Type == PDFOBJ_BOOLEAN; }
   bool IsDictionary() const { return m_Type == PDFOBJ_DICTIONARY; }
   bool IsNumber() const { return m_Type == PDFOBJ_NUMBER; }
+  bool IsString() const { return m_Type == PDFOBJ_STRING; }
 
   CPDF_Boolean* AsBoolean();
   const CPDF_Boolean* AsBoolean() const;
 
   CPDF_Dictionary* AsDictionary();
   const CPDF_Dictionary* AsDictionary() const;
 
   CPDF_Number* AsNumber();
   const CPDF_Number* AsNumber() const;
 
+  CPDF_String* AsString();
+  const CPDF_String* AsString() const;
+
  protected:
   CPDF_Object(FX_DWORD type) : m_Type(type), m_ObjNum(0), m_GenNum(0) {}
   ~CPDF_Object() {}
   void Destroy();
 
   static const int OBJECT_REF_MAX_DEPTH = 128;
   static int s_nCurRefDepth;
   FX_DWORD m_Type;
   FX_DWORD m_ObjNum;
   FX_DWORD m_GenNum;
@@ skipping 109 matching lines @@
   }
 
   FX_BOOL IsHex() const { return m_bHex; }
 
  protected:
   CFX_ByteString m_String;
 
   FX_BOOL m_bHex;
   friend class CPDF_Object;
 };
+inline CPDF_String* ToString(CPDF_Object* obj) {
+  return obj ? obj->AsString() : nullptr;
+}
+inline const CPDF_String* ToString(const CPDF_Object* obj) {
+  return obj ? obj->AsString() : nullptr;
+}
+
 class CPDF_Name : public CPDF_Object {
  public:
   static CPDF_Name* Create(const CFX_ByteString& str) {
     return new CPDF_Name(str);
   }
 
   static CPDF_Name* Create(const CFX_ByteStringC& str) {
     return new CPDF_Name(str);
   }
 
@@ skipping 353 matching lines @@
 
  protected:
   CFX_MapPtrToPtr m_IndirectObjs;
 
   CPDF_Parser* m_pParser;
 
   FX_DWORD m_LastObjNum;
 };
 
 #endif  // CORE_INCLUDE_FPDFAPI_FPDF_OBJECTS_H_