Revert "Revert "Add type cast definitions for CPDF_Dictionary.""

core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp

Index: core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
index e1e821c4c5e3d1c0d22bc36cee94ff2f9c403106..1e6695ce2aff87cd402db03921d8b9d524d80354 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
@@ -28,7 +28,7 @@ void CPDF_Object::Destroy() {
       delete (CPDF_Array*)this;
       break;
     case PDFOBJ_DICTIONARY:
-      delete (CPDF_Dictionary*)this;
+      delete this->AsDictionary();
       break;
     case PDFOBJ_STREAM:
       delete (CPDF_Stream*)this;
@@ -138,7 +138,9 @@ int CPDF_Object::GetInteger() const {
 CPDF_Dictionary* CPDF_Object::GetDict() const {
   switch (m_Type) {
     case PDFOBJ_DICTIONARY:
-      return (CPDF_Dictionary*)this;
+      // The method should be made non-const if we want to not be const.
+      // See bug #234.
+      return const_cast<CPDF_Dictionary*>(this->AsDictionary());
     case PDFOBJ_STREAM:
       return ((CPDF_Stream*)this)->GetDict();
     case PDFOBJ_REFERENCE: {
@@ -215,7 +217,7 @@ FX_BOOL CPDF_Object::IsIdentical(CPDF_Object* pOther) const {
     case PDFOBJ_ARRAY:
       return (((CPDF_Array*)this)->Identical((CPDF_Array*)pOther));
     case PDFOBJ_DICTIONARY:
-      return (((CPDF_Dictionary*)this)->Identical((CPDF_Dictionary*)pOther));
+      return this->AsDictionary()->Identical(pOther->AsDictionary());
     case PDFOBJ_NULL:
       return TRUE;
     case PDFOBJ_STREAM:
@@ -264,7 +266,7 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
     }
     case PDFOBJ_DICTIONARY: {
       CPDF_Dictionary* pCopy = new CPDF_Dictionary();
-      CPDF_Dictionary* pThis = (CPDF_Dictionary*)this;
+      const CPDF_Dictionary* pThis = this->AsDictionary();
       FX_POSITION pos = pThis->m_Map.GetStartPosition();
       while (pos) {
         CFX_ByteString key;
@@ -283,9 +285,9 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
       acc.LoadAllData(pThis, TRUE);
       FX_DWORD streamSize = acc.GetSize();
       CPDF_Dictionary* pDict = pThis->GetDict();
-      if (pDict)
-        pDict = (CPDF_Dictionary*)((CPDF_Object*)pDict)
-                    ->CloneInternal(bDirect, visited);
+      if (pDict) {
+        pDict = ToDictionary(pDict->CloneInternal(bDirect, visited));
+      }
       return new CPDF_Stream(acc.DetachData(), streamSize, pDict);
     }
     case PDFOBJ_REFERENCE: {
@@ -335,6 +337,14 @@ void CPDF_Object::SetUnicodeText(const FX_WCHAR* pUnicodes, int len) {
   }
 }
 
+CPDF_Dictionary* CPDF_Object::AsDictionary() {
+  return IsDictionary() ? static_cast<CPDF_Dictionary*>(this) : nullptr;
+}
+
+const CPDF_Dictionary* CPDF_Object::AsDictionary() const {
+  return IsDictionary() ? static_cast<const CPDF_Dictionary*>(this) : nullptr;
+}
+
 CPDF_Number::CPDF_Number(int value)
     : CPDF_Object(PDFOBJ_NUMBER), m_bInteger(TRUE), m_Integer(value) {}
 
@@ -442,8 +452,8 @@ CPDF_Dictionary* CPDF_Array::GetDict(FX_DWORD i) const {
   if (!p) {
     return NULL;
   }
-  if (p->GetType() == PDFOBJ_DICTIONARY) {
-    return (CPDF_Dictionary*)p;
+  if (CPDF_Dictionary* pDict = p->AsDictionary()) {
+    return pDict;
   }
   if (p->GetType() == PDFOBJ_STREAM) {
     return ((CPDF_Stream*)p)->GetDict();
@@ -663,8 +673,8 @@ CPDF_Dictionary* CPDF_Dictionary::GetDict(const CFX_ByteStringC& key) const {
   if (!p) {
     return nullptr;
   }
-  if (p->GetType() == PDFOBJ_DICTIONARY) {
-    return (CPDF_Dictionary*)p;
+  if (CPDF_Dictionary* pDict = p->AsDictionary()) {
+    return pDict;
   }
   if (p->GetType() == PDFOBJ_STREAM) {
     return ((CPDF_Stream*)p)->GetDict();