Add type cast definitions for CPDF_Reference.

This Cl adds ToReference, CPDF_Object::AsReference and CPDF_Object::IsReference
and updates the src to use them as needed.

BUG=pdfium:201
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1420973002 .

9 files changed, 155 insertions, 224 deletions

diff --git a/core/include/fpdfapi/fpdf_objects.h b/core/include/fpdfapi/fpdf_objects.h
index 45ca665b99..419d5fc23e 100644
--- a/core/include/fpdfapi/fpdf_objects.h
+++ b/core/include/fpdfapi/fpdf_objects.h
@@ -84,6 +84,7 @@ class CPDF_Object {
   bool IsDictionary() const { return m_Type == PDFOBJ_DICTIONARY; }
   bool IsName() const { return m_Type == PDFOBJ_NAME; }
   bool IsNumber() const { return m_Type == PDFOBJ_NUMBER; }
+  bool IsReference() const { return m_Type == PDFOBJ_REFERENCE; }
   bool IsStream() const { return m_Type == PDFOBJ_STREAM; }
   bool IsString() const { return m_Type == PDFOBJ_STRING; }
 
@@ -102,6 +103,9 @@ class CPDF_Object {
   CPDF_Number* AsNumber();
   const CPDF_Number* AsNumber() const;
 
+  CPDF_Reference* AsReference();
+  const CPDF_Reference* AsReference() const;
+
   CPDF_Stream* AsStream();
   const CPDF_Stream* AsStream() const;
 
@@ -600,6 +604,13 @@ class CPDF_Reference : public CPDF_Object {
   FX_DWORD m_RefObjNum;
   friend class CPDF_Object;
 };
+inline CPDF_Reference* ToReference(CPDF_Object* obj) {
+  return obj ? obj->AsReference() : nullptr;
+}
+inline const CPDF_Reference* ToReference(const CPDF_Object* obj) {
+  return obj ? obj->AsReference() : nullptr;
+}
+
 class CPDF_IndirectObjects {
  public:
   CPDF_IndirectObjects(CPDF_Parser* pParser);
diff --git a/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp b/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
index 16124a3c38..fec4e4f8e1 100644
--- a/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
+++ b/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
@@ -61,16 +61,12 @@ int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
       break;
     }
     case PDFOBJ_REFERENCE: {
-      if (pFile->AppendString(FX_BSTRC(" ")) < 0) {
+      if (pFile->AppendString(FX_BSTRC(" ")) < 0)
         return -1;
-      }
-      CPDF_Reference* p = (CPDF_Reference*)pObj;
-      if ((len = pFile->AppendDWord(p->GetRefObjNum())) < 0) {
+      if ((len = pFile->AppendDWord(pObj->AsReference()->GetRefObjNum())) < 0)
         return -1;
-      }
-      if (pFile->AppendString(FX_BSTRC(" 0 R ")) < 0) {
+      if (pFile->AppendString(FX_BSTRC(" 0 R ")) < 0)
         return -1;
-      }
       offset += len + 6;
       break;
     }
@@ -1168,16 +1164,12 @@ int32_t CPDF_Creator::WriteDirectObj(FX_DWORD objnum,
       break;
     }
     case PDFOBJ_REFERENCE: {
-      if (m_File.AppendString(FX_BSTRC(" ")) < 0) {
+      if (m_File.AppendString(FX_BSTRC(" ")) < 0)
         return -1;
-      }
-      CPDF_Reference* p = (CPDF_Reference*)pObj;
-      if ((len = m_File.AppendDWord(p->GetRefObjNum())) < 0) {
+      if ((len = m_File.AppendDWord(pObj->AsReference()->GetRefObjNum())) < 0)
         return -1;
-      }
-      if (m_File.AppendString(FX_BSTRC(" 0 R")) < 0) {
+      if (m_File.AppendString(FX_BSTRC(" 0 R")) < 0)
         return -1;
-      }
       m_Offset += len + 5;
       break;
     }
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index 3295b7f9e0..b12a65a844 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -671,51 +671,28 @@ void CPDF_StreamContentParser::Handle_ExecuteXObject() {
   CFX_ByteString name = GetString(0);
   if (name == m_LastImageName && m_pLastImage && m_pLastImage->GetStream() &&
       m_pLastImage->GetStream()->GetObjNum()) {
-    AddImage(NULL, m_pLastImage, FALSE);
+    AddImage(nullptr, m_pLastImage, FALSE);
     return;
   }
+
   if (m_Options.m_bTextOnly) {
-    CPDF_Object* pRes = NULL;
-    if (m_pResources == NULL) {
+    if (!m_pResources)
       return;
-    }
-    if (m_pResources == m_pPageResources) {
-      CPDF_Dictionary* pList = m_pResources->GetDict(FX_BSTRC("XObject"));
-      if (pList == NULL) {
-        return;
-      }
-      pRes = pList->GetElement(name);
-      if (pRes == NULL || pRes->GetType() != PDFOBJ_REFERENCE) {
-        return;
-      }
-    } else {
-      CPDF_Dictionary* pList = m_pResources->GetDict(FX_BSTRC("XObject"));
-      if (pList == NULL) {
-        if (m_pPageResources == NULL) {
-          return;
-        }
-        CPDF_Dictionary* pList = m_pPageResources->GetDict(FX_BSTRC("XObject"));
-        if (pList == NULL) {
-          return;
-        }
-        pRes = pList->GetElement(name);
-        if (pRes == NULL || pRes->GetType() != PDFOBJ_REFERENCE) {
-          return;
-        }
-      } else {
-        pRes = pList->GetElement(name);
-        if (pRes == NULL || pRes->GetType() != PDFOBJ_REFERENCE) {
-          return;
-        }
-      }
-    }
+
+    CPDF_Dictionary* pList = m_pResources->GetDict(FX_BSTRC("XObject"));
+    if (!pList && m_pPageResources && m_pResources != m_pPageResources)
+      pList = m_pPageResources->GetDict(FX_BSTRC("XObject"));
+    if (!pList)
+      return;
+    CPDF_Reference* pRes = ToReference(pList->GetElement(name));
+    if (!pRes)
+      return;
+
     FX_BOOL bForm;
-    if (m_pDocument->IsFormStream(((CPDF_Reference*)pRes)->GetRefObjNum(),
-                                  bForm) &&
-        !bForm) {
+    if (m_pDocument->IsFormStream(pRes->GetRefObjNum(), bForm) && !bForm)
       return;
-    }
   }
+
   CPDF_Stream* pXObject = ToStream(FindResourceObj(FX_BSTRC("XObject"), name));
   if (!pXObject) {
     m_bResourceMissing = TRUE;
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
index 5333fe8087..67c18f8ae0 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
@@ -190,9 +190,8 @@ int CPDF_Document::_FindPageIndex(CPDF_Dictionary* pNode,
     }
     if (count && count == pKidList->GetCount()) {
       for (FX_DWORD i = 0; i < count; i++) {
-        CPDF_Object* pKid = pKidList->GetElement(i);
-        if (pKid && pKid->GetType() == PDFOBJ_REFERENCE) {
-          if (((CPDF_Reference*)pKid)->GetRefObjNum() == objnum) {
+        if (CPDF_Reference* pKid = ToReference(pKidList->GetElement(i))) {
+          if (pKid->GetRefObjNum() == objnum) {
             m_PageList.SetAt(index + i, objnum);
             return index + i;
           }
@@ -308,13 +307,9 @@ FX_BOOL CPDF_Document::IsContentUsedElsewhere(FX_DWORD objnum,
     if (pContents->GetDirectType() == PDFOBJ_ARRAY) {
       CPDF_Array* pArray = pContents->GetDirect()->AsArray();
       for (FX_DWORD j = 0; j < pArray->GetCount(); j++) {
-        CPDF_Object* pRef = pArray->GetElement(j);
-        if (pRef == NULL || pRef->GetType() != PDFOBJ_REFERENCE) {
-          continue;
-        }
-        if (((CPDF_Reference*)pRef)->GetRefObjNum() == objnum) {
+        CPDF_Reference* pRef = ToReference(pArray->GetElement(j));
+        if (pRef && pRef->GetRefObjNum() == objnum)
           return TRUE;
-        }
       }
     } else if (pContents->GetObjNum() == objnum) {
       return TRUE;
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
index fc473319fc..07b1a208d7 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
@@ -48,16 +48,13 @@ CFX_ByteString CPDF_Object::GetString() const {
     case PDFOBJ_NAME:
       return AsName()->m_Name;
     case PDFOBJ_REFERENCE: {
-      CPDF_Reference* pRef = (CPDF_Reference*)(void*)this;
-      if (pRef->m_pObjList == NULL) {
+      const CPDF_Reference* pRef = AsReference();
+      if (!pRef->m_pObjList)
         break;
-      }
+
       CPDF_Object* pObj =
           pRef->m_pObjList->GetIndirectObject(pRef->GetRefObjNum());
-      if (pObj == NULL) {
-        return CFX_ByteString();
-      }
-      return pObj->GetString();
+      return pObj ? pObj->GetString() : CFX_ByteString();
     }
   }
   return CFX_ByteString();
@@ -73,16 +70,13 @@ CFX_ByteStringC CPDF_Object::GetConstString() const {
       return CFX_ByteStringC((const uint8_t*)name, name.GetLength());
     }
     case PDFOBJ_REFERENCE: {
-      CPDF_Reference* pRef = (CPDF_Reference*)(void*)this;
-      if (pRef->m_pObjList == NULL) {
+      const CPDF_Reference* pRef = AsReference();
+      if (!pRef->m_pObjList)
         break;
-      }
+
       CPDF_Object* pObj =
           pRef->m_pObjList->GetIndirectObject(pRef->GetRefObjNum());
-      if (pObj == NULL) {
-        return CFX_ByteStringC();
-      }
-      return pObj->GetConstString();
+      return pObj ? pObj->GetConstString() : CFX_ByteStringC();
     }
   }
   return CFX_ByteStringC();
@@ -92,16 +86,13 @@ FX_FLOAT CPDF_Object::GetNumber() const {
     case PDFOBJ_NUMBER:
       return AsNumber()->GetNumber();
     case PDFOBJ_REFERENCE: {
-      CPDF_Reference* pRef = (CPDF_Reference*)(void*)this;
-      if (pRef->m_pObjList == NULL) {
+      const CPDF_Reference* pRef = AsReference();
+      if (!pRef->m_pObjList)
         break;
-      }
+
       CPDF_Object* pObj =
           pRef->m_pObjList->GetIndirectObject(pRef->GetRefObjNum());
-      if (pObj == NULL) {
-        return 0;
-      }
-      return pObj->GetNumber();
+      return pObj ? pObj->GetNumber() : 0;
     }
   }
   return 0;
@@ -120,18 +111,15 @@ int CPDF_Object::GetInteger() const {
     case PDFOBJ_NUMBER:
       return AsNumber()->GetInteger();
     case PDFOBJ_REFERENCE: {
-      CPDF_Reference* pRef = (CPDF_Reference*)(void*)this;
+      const CPDF_Reference* pRef = AsReference();
       PARSE_CONTEXT context;
       FXSYS_memset(&context, 0, sizeof(PARSE_CONTEXT));
-      if (pRef->m_pObjList == NULL) {
+      if (!pRef->m_pObjList)
         return 0;
-      }
+
       CPDF_Object* pObj =
           pRef->m_pObjList->GetIndirectObject(pRef->GetRefObjNum(), &context);
-      if (pObj == NULL) {
-        return 0;
-      }
-      return pObj->GetInteger();
+      return pObj ? pObj->GetInteger() : 0;
     }
   }
   return 0;
@@ -146,7 +134,7 @@ CPDF_Dictionary* CPDF_Object::GetDict() const {
     case PDFOBJ_STREAM:
       return AsStream()->GetDict();
     case PDFOBJ_REFERENCE: {
-      CPDF_Reference* pRef = (CPDF_Reference*)this;
+      const CPDF_Reference* pRef = AsReference();
       CPDF_IndirectObjects* pIndirect = pRef->GetObjList();
       if (!pIndirect)
         return nullptr;
@@ -184,26 +172,21 @@ void CPDF_Object::SetString(const CFX_ByteString& str) {
   ASSERT(FALSE);
 }
 int CPDF_Object::GetDirectType() const {
-  if (m_Type != PDFOBJ_REFERENCE) {
+  const CPDF_Reference* pRef = AsReference();
+  if (!pRef)
     return m_Type;
-  }
-  CPDF_Reference* pRef = (CPDF_Reference*)this;
   return pRef->m_pObjList->GetIndirectType(pRef->GetRefObjNum());
 }
 FX_BOOL CPDF_Object::IsIdentical(CPDF_Object* pOther) const {
-  if (this == pOther) {
+  if (this == pOther)
     return TRUE;
-  }
-  if (pOther == NULL) {
+  if (!pOther)
     return FALSE;
-  }
   if (pOther->m_Type != m_Type) {
-    if (m_Type == PDFOBJ_REFERENCE && GetDirect()) {
+    if (IsReference() && GetDirect())
       return GetDirect()->IsIdentical(pOther);
-    }
-    if (pOther->m_Type == PDFOBJ_REFERENCE) {
+    if (pOther->IsReference())
       return IsIdentical(pOther->GetDirect());
-    }
     return FALSE;
   }
   switch (m_Type) {
@@ -224,18 +207,16 @@ FX_BOOL CPDF_Object::IsIdentical(CPDF_Object* pOther) const {
     case PDFOBJ_STREAM:
       return AsStream()->Identical(pOther->AsStream());
     case PDFOBJ_REFERENCE:
-      return (((CPDF_Reference*)this)->Identical((CPDF_Reference*)pOther));
+      return AsReference()->Identical(pOther->AsReference());
   }
   return FALSE;
 }
 CPDF_Object* CPDF_Object::GetDirect() const {
-  if (m_Type != PDFOBJ_REFERENCE) {
-    return (CPDF_Object*)this;
-  }
-  CPDF_Reference* pRef = (CPDF_Reference*)(void*)this;
-  if (pRef->m_pObjList == NULL) {
-    return NULL;
-  }
+  const CPDF_Reference* pRef = AsReference();
+  if (!pRef)
+    return const_cast<CPDF_Object*>(this);
+  if (!pRef->m_pObjList)
+    return nullptr;
   return pRef->m_pObjList->GetIndirectObject(pRef->GetRefObjNum());
 }
 CPDF_Object* CPDF_Object::Clone(FX_BOOL bDirect) const {
@@ -295,7 +276,7 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
       return new CPDF_Stream(acc.DetachData(), streamSize, pDict);
     }
     case PDFOBJ_REFERENCE: {
-      CPDF_Reference* pRef = (CPDF_Reference*)this;
+      const CPDF_Reference* pRef = AsReference();
       FX_DWORD obj_num = pRef->GetRefObjNum();
       if (bDirect && !visited->GetValueAt((void*)(uintptr_t)obj_num)) {
         visited->SetAt((void*)(uintptr_t)obj_num, (void*)1);
@@ -380,6 +361,14 @@ const CPDF_Number* CPDF_Object::AsNumber() const {
   return IsNumber() ? static_cast<const CPDF_Number*>(this) : nullptr;
 }
 
+CPDF_Reference* CPDF_Object::AsReference() {
+  return IsReference() ? static_cast<CPDF_Reference*>(this) : nullptr;
+}
+
+const CPDF_Reference* CPDF_Object::AsReference() const {
+  return IsReference() ? static_cast<const CPDF_Reference*>(this) : nullptr;
+}
+
 CPDF_Stream* CPDF_Object::AsStream() {
   return IsStream() ? static_cast<CPDF_Stream*>(this) : nullptr;
 }
@@ -639,17 +628,9 @@ CFX_WideString CPDF_Dictionary::GetUnicodeText(const CFX_ByteStringC& key,
                                                CFX_CharMap* pCharMap) const {
   CPDF_Object* p = NULL;
   m_Map.Lookup(key, (void*&)p);
-  if (p) {
-    if (p->GetType() == PDFOBJ_REFERENCE) {
-      p = ((CPDF_Reference*)p)->GetDirect();
-      if (p) {
-        return p->GetUnicodeText(pCharMap);
-      }
-    } else {
-      return p->GetUnicodeText(pCharMap);
-    }
-  }
-  return CFX_WideString();
+  if (CPDF_Reference* pRef = ToReference(p))
+    p = pRef->GetDirect();
+  return p ? p->GetUnicodeText(pCharMap) : CFX_WideString();
 }
 CFX_ByteString CPDF_Dictionary::GetString(const CFX_ByteStringC& key,
                                           const CFX_ByteStringC& def) const {
@@ -721,17 +702,15 @@ CPDF_Stream* CPDF_Dictionary::GetStream(const CFX_ByteStringC& key) const {
 CFX_FloatRect CPDF_Dictionary::GetRect(const CFX_ByteStringC& key) const {
   CFX_FloatRect rect;
   CPDF_Array* pArray = GetArray(key);
-  if (pArray) {
+  if (pArray)
     rect = pArray->GetRect();
-  }
   return rect;
 }
 CFX_AffineMatrix CPDF_Dictionary::GetMatrix(const CFX_ByteStringC& key) const {
   CFX_AffineMatrix matrix;
   CPDF_Array* pArray = GetArray(key);
-  if (pArray) {
+  if (pArray)
     matrix = pArray->GetMatrix();
-  }
   return matrix;
 }
 FX_BOOL CPDF_Dictionary::KeyExist(const CFX_ByteStringC& key) const {
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index b2f7eb6d7e..71cd8443d5 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -258,11 +258,9 @@ FX_DWORD CPDF_Parser::StartParse(IFX_FileRead* pFileAccess,
   }
   if (m_pSecurityHandler && !m_pSecurityHandler->IsMetadataEncrypted()) {
     CPDF_Reference* pMetadata =
-        (CPDF_Reference*)m_pDocument->GetRoot()->GetElement(
-            FX_BSTRC("Metadata"));
-    if (pMetadata && pMetadata->GetType() == PDFOBJ_REFERENCE) {
+        ToReference(m_pDocument->GetRoot()->GetElement(FX_BSTRC("Metadata")));
+    if (pMetadata)
       m_Syntax.m_MetadataObjnum = pMetadata->GetRefObjNum();
-    }
   }
   return PDFPARSE_ERROR_SUCCESS;
 }
@@ -276,12 +274,10 @@ FX_DWORD CPDF_Parser::SetEncryptHandler() {
   if (pEncryptObj) {
     if (CPDF_Dictionary* pEncryptDict = pEncryptObj->AsDictionary()) {
       SetEncryptDictionary(pEncryptDict);
-    } else if (pEncryptObj->GetType() == PDFOBJ_REFERENCE) {
-      pEncryptObj = m_pDocument->GetIndirectObject(
-          ((CPDF_Reference*)pEncryptObj)->GetRefObjNum());
-      if (pEncryptObj) {
+    } else if (CPDF_Reference* pRef = pEncryptObj->AsReference()) {
+      pEncryptObj = m_pDocument->GetIndirectObject(pRef->GetRefObjNum());
+      if (pEncryptObj)
         SetEncryptDictionary(pEncryptObj->GetDict());
-      }
     }
   }
   if (m_bForceUseSecurityHandler) {
@@ -840,12 +836,12 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
                     if (m_pTrailer) {
                       CPDF_Object* pRoot =
                           pTrailer->GetElement(FX_BSTRC("Root"));
-                      if (pRoot == NULL ||
-                          (pRoot->GetType() == PDFOBJ_REFERENCE &&
+                      CPDF_Reference* pRef = ToReference(pRoot);
+                      if (!pRoot ||
+                          (pRef &&
                            (FX_DWORD)m_CrossRef.GetSize() >
-                               ((CPDF_Reference*)pRoot)->GetRefObjNum() &&
-                           m_CrossRef.GetAt(((CPDF_Reference*)pRoot)
-                                                ->GetRefObjNum()) != 0)) {
+                               pRef->GetRefObjNum() &&
+                           m_CrossRef.GetAt(pRef->GetRefObjNum()) != 0)) {
                         FX_POSITION pos = pTrailer->GetStartPos();
                         while (pos) {
                           CFX_ByteString key;
@@ -1129,27 +1125,21 @@ CPDF_Array* CPDF_Parser::GetIDArray() {
   if (!pID)
     return nullptr;
 
-  if (pID->GetType() == PDFOBJ_REFERENCE) {
-    pID = ParseIndirectObject(NULL, ((CPDF_Reference*)pID)->GetRefObjNum());
+  if (CPDF_Reference* pRef = pID->AsReference()) {
+    pID = ParseIndirectObject(nullptr, pRef->GetRefObjNum());
     m_pTrailer->SetAt(FX_BSTRC("ID"), pID);
   }
   return ToArray(pID);
 }
 FX_DWORD CPDF_Parser::GetRootObjNum() {
-  CPDF_Object* pRef =
-      m_pTrailer ? m_pTrailer->GetElement(FX_BSTRC("Root")) : NULL;
-  if (pRef == NULL || pRef->GetType() != PDFOBJ_REFERENCE) {
-    return 0;
-  }
-  return ((CPDF_Reference*)pRef)->GetRefObjNum();
+  CPDF_Reference* pRef = ToReference(
+      m_pTrailer ? m_pTrailer->GetElement(FX_BSTRC("Root")) : nullptr);
+  return pRef ? pRef->GetRefObjNum() : 0;
 }
 FX_DWORD CPDF_Parser::GetInfoObjNum() {
-  CPDF_Object* pRef =
-      m_pTrailer ? m_pTrailer->GetElement(FX_BSTRC("Info")) : NULL;
-  if (pRef == NULL || pRef->GetType() != PDFOBJ_REFERENCE) {
-    return 0;
-  }
-  return ((CPDF_Reference*)pRef)->GetRefObjNum();
+  CPDF_Reference* pRef = ToReference(
+      m_pTrailer ? m_pTrailer->GetElement(FX_BSTRC("Info")) : nullptr);
+  return pRef ? pRef->GetRefObjNum() : 0;
 }
 FX_BOOL CPDF_Parser::IsFormStream(FX_DWORD objnum, FX_BOOL& bForm) {
   bForm = FALSE;
@@ -1617,11 +1607,9 @@ FX_DWORD CPDF_Parser::StartAsynParse(IFX_FileRead* pFileAccess,
     }
   }
   if (m_pSecurityHandler && m_pSecurityHandler->IsMetadataEncrypted()) {
-    CPDF_Object* pMetadata =
-        m_pDocument->GetRoot()->GetElement(FX_BSTRC("Metadata"));
-    if (pMetadata && pMetadata->GetType() == PDFOBJ_REFERENCE) {
-      m_Syntax.m_MetadataObjnum = ((CPDF_Reference*)pMetadata)->GetRefObjNum();
-    }
+    if (CPDF_Reference* pMetadata = ToReference(
+            m_pDocument->GetRoot()->GetElement(FX_BSTRC("Metadata"))))
+      m_Syntax.m_MetadataObjnum = pMetadata->GetRefObjNum();
   }
   return PDFPARSE_ERROR_SUCCESS;
 }
@@ -2374,11 +2362,13 @@ CPDF_Stream* CPDF_SyntaxParser::ReadStream(CPDF_Dictionary* pDict,
                                            FX_DWORD gennum) {
   CPDF_Object* pLenObj = pDict->GetElement(FX_BSTRC("Length"));
   FX_FILESIZE len = -1;
-  if (pLenObj && ((pLenObj->GetType() != PDFOBJ_REFERENCE) ||
-                  ((((CPDF_Reference*)pLenObj)->GetObjList()) &&
-                   ((CPDF_Reference*)pLenObj)->GetRefObjNum() != objnum))) {
+  CPDF_Reference* pLenObjRef = ToReference(pLenObj);
+
+  bool differingObjNum = pLenObjRef && pLenObjRef->GetObjList() &&
+                         pLenObjRef->GetRefObjNum() != objnum;
+  if (pLenObj && differingObjNum)
     len = pLenObj->GetInteger();
-  }
+
   // Locate the start of stream.
   ToNextLine();
   FX_FILESIZE streamStartPos = m_Pos;
@@ -3064,7 +3054,7 @@ FX_BOOL CPDF_DataAvail::IsObjectsAvail(CFX_PtrArray& obj_array,
         }
       } break;
       case PDFOBJ_REFERENCE: {
-        CPDF_Reference* pRef = (CPDF_Reference*)pObj;
+        CPDF_Reference* pRef = pObj->AsReference();
         FX_DWORD dwNum = pRef->GetRefObjNum();
         FX_FILESIZE offset;
         FX_DWORD original_size = GetObjectSize(dwNum, offset);
@@ -3106,13 +3096,10 @@ FX_BOOL CPDF_DataAvail::IsObjectsAvail(CFX_PtrArray& obj_array,
     int32_t iSize = new_obj_array.GetSize();
     for (i = 0; i < iSize; ++i) {
       CPDF_Object* pObj = (CPDF_Object*)new_obj_array[i];
-      int32_t type = pObj->GetType();
-      if (type == PDFOBJ_REFERENCE) {
-        CPDF_Reference* pRef = (CPDF_Reference*)pObj;
+      if (CPDF_Reference* pRef = pObj->AsReference()) {
         FX_DWORD dwNum = pRef->GetRefObjNum();
-        if (!m_objnum_array.Find(dwNum)) {
+        if (!m_objnum_array.Find(dwNum))
           ret_array.Add(pObj);
-        }
       } else {
         ret_array.Add(pObj);
       }
@@ -3380,37 +3367,37 @@ FX_BOOL CPDF_DataAvail::CheckRoot(IFX_DownloadHints* pHints) {
     m_docStatus = PDF_DATAAVAIL_ERROR;
     return FALSE;
   }
-  CPDF_Reference* pRef = (CPDF_Reference*)pDict->GetElement(FX_BSTRC("Pages"));
-  if (pRef == NULL || pRef->GetType() != PDFOBJ_REFERENCE) {
+  CPDF_Reference* pRef = ToReference(pDict->GetElement(FX_BSTRC("Pages")));
+  if (!pRef) {
     m_docStatus = PDF_DATAAVAIL_ERROR;
     return FALSE;
   }
+
   m_PagesObjNum = pRef->GetRefObjNum();
   CPDF_Reference* pAcroFormRef =
-      (CPDF_Reference*)m_pRoot->GetDict()->GetElement(FX_BSTRC("AcroForm"));
-  if (pAcroFormRef && pAcroFormRef->GetType() == PDFOBJ_REFERENCE) {
+      ToReference(m_pRoot->GetDict()->GetElement(FX_BSTRC("AcroForm")));
+  if (pAcroFormRef) {
     m_bHaveAcroForm = TRUE;
     m_dwAcroFormObjNum = pAcroFormRef->GetRefObjNum();
   }
+
   if (m_dwInfoObjNum) {
     m_docStatus = PDF_DATAAVAIL_INFO;
   } else {
-    if (m_bHaveAcroForm) {
-      m_docStatus = PDF_DATAAVAIL_ACROFORM;
-    } else {
-      m_docStatus = PDF_DATAAVAIL_PAGETREE;
-    }
+    m_docStatus =
+        m_bHaveAcroForm ? PDF_DATAAVAIL_ACROFORM : PDF_DATAAVAIL_PAGETREE;
   }
   return TRUE;
 }
 FX_BOOL CPDF_DataAvail::PreparePageItem() {
   CPDF_Dictionary* pRoot = m_pDocument->GetRoot();
   CPDF_Reference* pRef =
-      pRoot ? (CPDF_Reference*)pRoot->GetElement(FX_BSTRC("Pages")) : NULL;
-  if (pRef == NULL || pRef->GetType() != PDFOBJ_REFERENCE) {
+      ToReference(pRoot ? pRoot->GetElement(FX_BSTRC("Pages")) : nullptr);
+  if (!pRef) {
     m_docStatus = PDF_DATAAVAIL_ERROR;
     return FALSE;
   }
+
   m_PagesObjNum = pRef->GetRefObjNum();
   m_pCurrentParser = (CPDF_Parser*)m_pDocument->GetParser();
   m_docStatus = PDF_DATAAVAIL_PAGETREE;
@@ -3443,12 +3430,9 @@ FX_BOOL CPDF_DataAvail::CheckPage(IFX_DownloadHints* pHints) {
       CPDF_Array* pArray = pObj->GetArray();
       if (pArray) {
         int32_t iSize = pArray->GetCount();
-        CPDF_Object* pItem = NULL;
         for (int32_t j = 0; j < iSize; ++j) {
-          pItem = pArray->GetElement(j);
-          if (pItem && pItem->GetType() == PDFOBJ_REFERENCE) {
-            UnavailObjList.Add(((CPDF_Reference*)pItem)->GetRefObjNum());
-          }
+          if (CPDF_Reference* pRef = ToReference(pArray->GetElement(j)))
+            UnavailObjList.Add(pRef->GetRefObjNum());
         }
       }
     }
@@ -3503,17 +3487,14 @@ FX_BOOL CPDF_DataAvail::GetPageKids(CPDF_Parser* pParser, CPDF_Object* pPages) {
     return TRUE;
   }
   switch (pKids->GetType()) {
-    case PDFOBJ_REFERENCE: {
-      CPDF_Reference* pKid = (CPDF_Reference*)pKids;
-      m_PageObjList.Add(pKid->GetRefObjNum());
-    } break;
+    case PDFOBJ_REFERENCE:
+      m_PageObjList.Add(pKids->AsReference()->GetRefObjNum());
+      break;
     case PDFOBJ_ARRAY: {
       CPDF_Array* pKidsArray = pKids->AsArray();
       for (FX_DWORD i = 0; i < pKidsArray->GetCount(); ++i) {
-        CPDF_Object* pKid = (CPDF_Object*)pKidsArray->GetElement(i);
-        if (pKid && pKid->GetType() == PDFOBJ_REFERENCE) {
-          m_PageObjList.Add(((CPDF_Reference*)pKid)->GetRefObjNum());
-        }
+        if (CPDF_Reference* pRef = ToReference(pKidsArray->GetElement(i)))
+          m_PageObjList.Add(pRef->GetRefObjNum());
       }
     } break;
     default:
@@ -4012,7 +3993,7 @@ FX_BOOL CPDF_DataAvail::CheckTrailer(IFX_DownloadHints* pHints) {
 
     CPDF_Dictionary* pTrailerDict = pTrailer->GetDict();
     CPDF_Object* pEncrypt = pTrailerDict->GetElement("Encrypt");
-    if (pEncrypt && pEncrypt->GetType() == PDFOBJ_REFERENCE) {
+    if (ToReference(pEncrypt)) {
       m_docStatus = PDF_DATAAVAIL_LOADALLFILE;
       return TRUE;
     }
@@ -4091,13 +4072,13 @@ FX_BOOL CPDF_DataAvail::CheckArrayPageNode(FX_DWORD dwPageNo,
 
   pPageNode->m_type = PDF_PAGENODE_PAGES;
   for (FX_DWORD i = 0; i < pArray->GetCount(); ++i) {
-    CPDF_Object* pKid = (CPDF_Object*)pArray->GetElement(i);
-    if (!pKid || pKid->GetType() != PDFOBJ_REFERENCE) {
+    CPDF_Reference* pKid = ToReference(pArray->GetElement(i));
+    if (!pKid)
       continue;
-    }
+
     CPDF_PageNode* pNode = new CPDF_PageNode();
     pPageNode->m_childNode.Add(pNode);
-    pNode->m_dwPageNo = ((CPDF_Reference*)pKid)->GetRefObjNum();
+    pNode->m_dwPageNo = pKid->GetRefObjNum();
   }
   pPages->Release();
   return TRUE;
@@ -4141,7 +4122,7 @@ FX_BOOL CPDF_DataAvail::CheckUnkownPageNode(FX_DWORD dwPageNo,
     }
     switch (pKids->GetType()) {
       case PDFOBJ_REFERENCE: {
-        CPDF_Reference* pKid = (CPDF_Reference*)pKids;
+        CPDF_Reference* pKid = pKids->AsReference();
         CPDF_PageNode* pNode = new CPDF_PageNode();
         pPageNode->m_childNode.Add(pNode);
         pNode->m_dwPageNo = pKid->GetRefObjNum();
@@ -4149,13 +4130,13 @@ FX_BOOL CPDF_DataAvail::CheckUnkownPageNode(FX_DWORD dwPageNo,
       case PDFOBJ_ARRAY: {
         CPDF_Array* pKidsArray = pKids->AsArray();
         for (FX_DWORD i = 0; i < pKidsArray->GetCount(); ++i) {
-          CPDF_Object* pKid = (CPDF_Object*)pKidsArray->GetElement(i);
-          if (!pKid || pKid->GetType() != PDFOBJ_REFERENCE) {
+          CPDF_Reference* pKid = ToReference(pKidsArray->GetElement(i));
+          if (!pKid)
             continue;
-          }
+
           CPDF_PageNode* pNode = new CPDF_PageNode();
           pPageNode->m_childNode.Add(pNode);
-          pNode->m_dwPageNo = ((CPDF_Reference*)pKid)->GetRefObjNum();
+          pNode->m_dwPageNo = pKid->GetRefObjNum();
         }
       } break;
       default:
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
index 606bd0f569..e1e60ecae3 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
@@ -381,8 +381,7 @@ CFX_ByteTextBuf& operator<<(CFX_ByteTextBuf& buf, const CPDF_Object* pObj) {
       break;
     }
     case PDFOBJ_REFERENCE: {
-      CPDF_Reference* p = (CPDF_Reference*)pObj;
-      buf << " " << p->GetRefObjNum() << FX_BSTRC(" 0 R ");
+      buf << " " << pObj->AsReference()->GetRefObjNum() << FX_BSTRC(" 0 R ");
       break;
     }
     case PDFOBJ_ARRAY: {
diff --git a/core/src/fpdfdoc/doc_form.cpp b/core/src/fpdfdoc/doc_form.cpp
index 8078608883..3192445d90 100644
--- a/core/src/fpdfdoc/doc_form.cpp
+++ b/core/src/fpdfdoc/doc_form.cpp
@@ -1086,13 +1086,12 @@ CPDF_FormField* CPDF_InterForm::AddTerminalField(CPDF_Dictionary* pFieldDict) {
     }
     pField = new CPDF_FormField(this, pParent);
     CPDF_Object* pTObj = pDict->GetElement("T");
-    if (pTObj && pTObj->GetType() == PDFOBJ_REFERENCE) {
+    if (ToReference(pTObj)) {
       CPDF_Object* pClone = pTObj->Clone(TRUE);
-      if (pClone) {
+      if (pClone)
         pDict->SetAt("T", pClone);
-      } else {
+      else
         pDict->SetAtName("T", "");
-      }
     }
     m_pFieldTree->SetField(csWName, pField);
   }
diff --git a/core/src/fpdfdoc/doc_tagged.cpp b/core/src/fpdfdoc/doc_tagged.cpp
index f74aa7f6f5..f1877c6573 100644
--- a/core/src/fpdfdoc/doc_tagged.cpp
+++ b/core/src/fpdfdoc/doc_tagged.cpp
@@ -173,10 +173,10 @@ FX_BOOL CPDF_StructTreeImpl::AddTopLevelNode(CPDF_Dictionary* pDict,
     FX_DWORD i;
     FX_BOOL bSave = FALSE;
     for (i = 0; i < pTopKids->GetCount(); i++) {
-      CPDF_Object* pKidRef = pTopKids->GetElement(i);
-      if (!pKidRef || pKidRef->GetType() != PDFOBJ_REFERENCE)
+      CPDF_Reference* pKidRef = ToReference(pTopKids->GetElement(i));
+      if (!pKidRef)
         continue;
-      if (((CPDF_Reference*)pKidRef)->GetRefObjNum() != pDict->GetObjNum())
+      if (pKidRef->GetRefObjNum() != pDict->GetObjNum())
         continue;
 
       if (m_Kids[i])
@@ -225,8 +225,8 @@ void CPDF_StructElementImpl::Release() {
 void CPDF_StructElementImpl::LoadKids(CPDF_Dictionary* pDict) {
   CPDF_Object* pObj = pDict->GetElement(FX_BSTRC("Pg"));
   FX_DWORD PageObjNum = 0;
-  if (pObj && pObj->GetType() == PDFOBJ_REFERENCE)
-    PageObjNum = ((CPDF_Reference*)pObj)->GetRefObjNum();
+  if (CPDF_Reference* pRef = ToReference(pObj))
+    PageObjNum = pRef->GetRefObjNum();
 
   CPDF_Object* pKids = pDict->GetElementValue(FX_BSTRC("K"));
   if (!pKids)
@@ -264,20 +264,18 @@ void CPDF_StructElementImpl::LoadKid(FX_DWORD PageObjNum,
   if (!pKidDict)
     return;
 
-  CPDF_Object* pPageObj = pKidDict->GetElement(FX_BSTRC("Pg"));
-  if (pPageObj && pPageObj->GetType() == PDFOBJ_REFERENCE) {
-    PageObjNum = ((CPDF_Reference*)pPageObj)->GetRefObjNum();
-  }
+  if (CPDF_Reference* pRef = ToReference(pKidDict->GetElement(FX_BSTRC("Pg"))))
+    PageObjNum = pRef->GetRefObjNum();
+
   CFX_ByteString type = pKidDict->GetString(FX_BSTRC("Type"));
   if (type == FX_BSTRC("MCR")) {
     if (m_pTree->m_pPage && m_pTree->m_pPage->GetObjNum() != PageObjNum) {
       return;
     }
     pKid->m_Type = CPDF_StructKid::StreamContent;
-    CPDF_Object* pStreamObj = pKidDict->GetElement(FX_BSTRC("Stm"));
-    if (pStreamObj && pStreamObj->GetType() == PDFOBJ_REFERENCE) {
-      pKid->m_StreamContent.m_RefObjNum =
-          ((CPDF_Reference*)pStreamObj)->GetRefObjNum();
+    if (CPDF_Reference* pRef =
+            ToReference(pKidDict->GetElement(FX_BSTRC("Stm")))) {
+      pKid->m_StreamContent.m_RefObjNum = pRef->GetRefObjNum();
     } else {
       pKid->m_StreamContent.m_RefObjNum = 0;
     }
@@ -288,9 +286,9 @@ void CPDF_StructElementImpl::LoadKid(FX_DWORD PageObjNum,
       return;
     }
     pKid->m_Type = CPDF_StructKid::Object;
-    CPDF_Object* pObj = pKidDict->GetElement(FX_BSTRC("Obj"));
-    if (pObj && pObj->GetType() == PDFOBJ_REFERENCE) {
-      pKid->m_Object.m_RefObjNum = ((CPDF_Reference*)pObj)->GetRefObjNum();
+    if (CPDF_Reference* pObj =
+            ToReference(pKidDict->GetElement(FX_BSTRC("Obj")))) {
+      pKid->m_Object.m_RefObjNum = pObj->GetRefObjNum();
     } else {
       pKid->m_Object.m_RefObjNum = 0;
     }