Add type cast definitions for CPDF_Stream.

This Cl adds ToStream, CPDF_Object::AsStream and CPDF_Object::IsStream and
updates the src to use them as needed.

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

Review URL: https://codereview.chromium.org/1402413004 .

4 files changed, 71 insertions, 90 deletions

diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
index 2396261276..5333fe8087 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
@@ -338,8 +338,9 @@ FX_BOOL CPDF_Document::IsFormStream(FX_DWORD objnum, FX_BOOL& bForm) const {
   {
     CPDF_Object* pObj;
     if (m_IndirectObjs.Lookup((void*)(uintptr_t)objnum, (void*&)pObj)) {
-      bForm = pObj->GetType() == PDFOBJ_STREAM &&
-              ((CPDF_Stream*)pObj)->GetDict()->GetString(FX_BSTRC("Subtype")) ==
+      CPDF_Stream* pStream = pObj->AsStream();
+      bForm = pStream &&
+              pStream->GetDict()->GetString(FX_BSTRC("Subtype")) ==
                   FX_BSTRC("Form");
       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 6a090ce64d..fc473319fc 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
@@ -31,7 +31,7 @@ void CPDF_Object::Destroy() {
       delete AsDictionary();
       break;
     case PDFOBJ_STREAM:
-      delete (CPDF_Stream*)this;
+      delete AsStream();
       break;
     default:
       delete this;
@@ -144,7 +144,7 @@ CPDF_Dictionary* CPDF_Object::GetDict() const {
       // See bug #234.
       return const_cast<CPDF_Dictionary*>(AsDictionary());
     case PDFOBJ_STREAM:
-      return ((CPDF_Stream*)this)->GetDict();
+      return AsStream()->GetDict();
     case PDFOBJ_REFERENCE: {
       CPDF_Reference* pRef = (CPDF_Reference*)this;
       CPDF_IndirectObjects* pIndirect = pRef->GetObjList();
@@ -222,7 +222,7 @@ FX_BOOL CPDF_Object::IsIdentical(CPDF_Object* pOther) const {
     case PDFOBJ_NULL:
       return TRUE;
     case PDFOBJ_STREAM:
-      return (((CPDF_Stream*)this)->Identical((CPDF_Stream*)pOther));
+      return AsStream()->Identical(pOther->AsStream());
     case PDFOBJ_REFERENCE:
       return (((CPDF_Reference*)this)->Identical((CPDF_Reference*)pOther));
   }
@@ -284,7 +284,7 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
       return new CPDF_Null;
     }
     case PDFOBJ_STREAM: {
-      CPDF_Stream* pThis = (CPDF_Stream*)this;
+      const CPDF_Stream* pThis = AsStream();
       CPDF_StreamAcc acc;
       acc.LoadAllData(pThis, TRUE);
       FX_DWORD streamSize = acc.GetSize();
@@ -319,9 +319,9 @@ CFX_WideString CPDF_Object::GetUnicodeText(CFX_CharMap* pCharMap) const {
   if (const CPDF_String* pString = AsString())
     return PDF_DecodeText(pString->m_String, pCharMap);
 
-  if (m_Type == PDFOBJ_STREAM) {
+  if (const CPDF_Stream* pStream = AsStream()) {
     CPDF_StreamAcc stream;
-    stream.LoadAllData((CPDF_Stream*)this, FALSE);
+    stream.LoadAllData(pStream, FALSE);
     CFX_WideString result =
         PDF_DecodeText(stream.GetData(), stream.GetSize(), pCharMap);
     return result;
@@ -333,10 +333,10 @@ CFX_WideString CPDF_Object::GetUnicodeText(CFX_CharMap* pCharMap) const {
 void CPDF_Object::SetUnicodeText(const FX_WCHAR* pUnicodes, int len) {
   if (CPDF_String* pString = AsString()) {
     pString->m_String = PDF_EncodeText(pUnicodes, len);
-  } else if (m_Type == PDFOBJ_STREAM) {
+  } else if (CPDF_Stream* pStream = AsStream()) {
     CFX_ByteString result = PDF_EncodeText(pUnicodes, len);
-    ((CPDF_Stream*)this)
-        ->SetData((uint8_t*)result.c_str(), result.GetLength(), FALSE, FALSE);
+    pStream->SetData((uint8_t*)result.c_str(), result.GetLength(), FALSE,
+                     FALSE);
   }
 }
 
@@ -380,6 +380,14 @@ const CPDF_Number* CPDF_Object::AsNumber() const {
   return IsNumber() ? static_cast<const CPDF_Number*>(this) : nullptr;
 }
 
+CPDF_Stream* CPDF_Object::AsStream() {
+  return IsStream() ? static_cast<CPDF_Stream*>(this) : nullptr;
+}
+
+const CPDF_Stream* CPDF_Object::AsStream() const {
+  return IsStream() ? static_cast<const CPDF_Stream*>(this) : nullptr;
+}
+
 CPDF_String* CPDF_Object::AsString() {
   return IsString() ? static_cast<CPDF_String*>(this) : nullptr;
 }
@@ -487,23 +495,16 @@ FX_FLOAT CPDF_Array::GetNumber(FX_DWORD i) const {
 }
 CPDF_Dictionary* CPDF_Array::GetDict(FX_DWORD i) const {
   CPDF_Object* p = GetElementValue(i);
-  if (!p) {
+  if (!p)
     return NULL;
-  }
-  if (CPDF_Dictionary* pDict = p->AsDictionary()) {
+  if (CPDF_Dictionary* pDict = p->AsDictionary())
     return pDict;
-  }
-  if (p->GetType() == PDFOBJ_STREAM) {
-    return ((CPDF_Stream*)p)->GetDict();
-  }
+  if (CPDF_Stream* pStream = p->AsStream())
+    return pStream->GetDict();
   return NULL;
 }
 CPDF_Stream* CPDF_Array::GetStream(FX_DWORD i) const {
-  CPDF_Object* p = GetElementValue(i);
-  if (p == NULL || p->GetType() != PDFOBJ_STREAM) {
-    return NULL;
-  }
-  return (CPDF_Stream*)p;
+  return ToStream(GetElementValue(i));
 }
 CPDF_Array* CPDF_Array::GetArray(FX_DWORD i) const {
   return ToArray(GetElementValue(i));
@@ -703,26 +704,19 @@ FX_BOOL CPDF_Dictionary::GetBoolean(const CFX_ByteStringC& key,
 }
 CPDF_Dictionary* CPDF_Dictionary::GetDict(const CFX_ByteStringC& key) const {
   CPDF_Object* p = GetElementValue(key);
-  if (!p) {
+  if (!p)
     return nullptr;
-  }
-  if (CPDF_Dictionary* pDict = p->AsDictionary()) {
+  if (CPDF_Dictionary* pDict = p->AsDictionary())
     return pDict;
-  }
-  if (p->GetType() == PDFOBJ_STREAM) {
-    return ((CPDF_Stream*)p)->GetDict();
-  }
+  if (CPDF_Stream* pStream = p->AsStream())
+    return pStream->GetDict();
   return nullptr;
 }
 CPDF_Array* CPDF_Dictionary::GetArray(const CFX_ByteStringC& key) const {
   return ToArray(GetElementValue(key));
 }
 CPDF_Stream* CPDF_Dictionary::GetStream(const CFX_ByteStringC& key) const {
-  CPDF_Object* p = GetElementValue(key);
-  if (p == NULL || p->GetType() != PDFOBJ_STREAM) {
-    return NULL;
-  }
-  return (CPDF_Stream*)p;
+  return ToStream(GetElementValue(key));
 }
 CFX_FloatRect CPDF_Dictionary::GetRect(const CFX_ByteStringC& key) const {
   CFX_FloatRect rect;
@@ -1035,9 +1029,9 @@ void CPDF_StreamAcc::LoadAllData(const CPDF_Stream* pStream,
                                  FX_BOOL bRawAccess,
                                  FX_DWORD estimated_size,
                                  FX_BOOL bImageAcc) {
-  if (pStream == NULL || pStream->GetType() != PDFOBJ_STREAM) {
+  if (!pStream)
     return;
-  }
+
   m_pStream = pStream;
   if (pStream->IsMemoryBased() &&
       (!pStream->GetDict()->KeyExist(FX_BSTRC("Filter")) || bRawAccess)) {
@@ -1047,14 +1041,13 @@ void CPDF_StreamAcc::LoadAllData(const CPDF_Stream* pStream,
   }
   uint8_t* pSrcData;
   FX_DWORD dwSrcSize = pStream->m_dwSize;
-  if (dwSrcSize == 0) {
+  if (dwSrcSize == 0)
     return;
-  }
+
   if (!pStream->IsMemoryBased()) {
     pSrcData = m_pSrcData = FX_Alloc(uint8_t, dwSrcSize);
-    if (!pStream->ReadRawData(0, pSrcData, dwSrcSize)) {
+    if (!pStream->ReadRawData(0, pSrcData, dwSrcSize))
       return;
-    }
   } else {
     pSrcData = pStream->m_pDataBuf;
   }
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 8b822a8b9c..12e2a3946c 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -784,29 +784,20 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
                 FX_FILESIZE obj_end = 0;
                 CPDF_Object* pObject = ParseIndirectObjectAtByStrict(
                     m_pDocument, obj_pos, objnum, NULL, &obj_end);
-                if (pObject) {
-                  int iType = pObject->GetType();
-                  if (iType == PDFOBJ_STREAM) {
-                    CPDF_Stream* pStream = (CPDF_Stream*)pObject;
-                    CPDF_Dictionary* pDict = pStream->GetDict();
-                    if (pDict) {
-                      if (pDict->KeyExist(FX_BSTRC("Type"))) {
-                        CFX_ByteString bsValue =
-                            pDict->GetString(FX_BSTRC("Type"));
-                        if (bsValue == FX_BSTRC("XRef") &&
-                            pDict->KeyExist(FX_BSTRC("Size"))) {
-                          CPDF_Object* pRoot =
-                              pDict->GetElement(FX_BSTRC("Root"));
-                          if (pRoot && pRoot->GetDict() &&
-                              pRoot->GetDict()->GetElement(FX_BSTRC("Pages"))) {
-                            if (m_pTrailer) {
-                              m_pTrailer->Release();
-                            }
-                            m_pTrailer = ToDictionary(pDict->Clone());
-                          }
+                if (CPDF_Stream* pStream = ToStream(pObject)) {
+                  if (CPDF_Dictionary* pDict = pStream->GetDict()) {
+                    if ((pDict->KeyExist(FX_BSTRC("Type"))) &&
+                        (pDict->GetString(FX_BSTRC("Type")) ==
+                             FX_BSTRC("XRef") &&
+                         pDict->KeyExist(FX_BSTRC("Size")))) {
+                      CPDF_Object* pRoot = pDict->GetElement(FX_BSTRC("Root"));
+                      if (pRoot && pRoot->GetDict() &&
+                          pRoot->GetDict()->GetElement(FX_BSTRC("Pages"))) {
+                        if (m_pTrailer)
+                          m_pTrailer->Release();
+                        m_pTrailer = ToDictionary(pDict->Clone());
                         }
                       }
-                    }
                   }
                 }
                 FX_FILESIZE offset = 0;
@@ -855,16 +846,12 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
               m_Syntax.RestorePos(pos + i - m_Syntax.m_HeaderOffset);
               CPDF_Object* pObj = m_Syntax.GetObject(m_pDocument, 0, 0, 0);
               if (pObj) {
-                if (!pObj->IsDictionary() && pObj->GetType() != PDFOBJ_STREAM) {
+                if (!pObj->IsDictionary() && !pObj->AsStream()) {
                   pObj->Release();
                 } else {
-                  CPDF_Dictionary* pTrailer = NULL;
-                  if (pObj->GetType() == PDFOBJ_STREAM) {
-                    pTrailer = ((CPDF_Stream*)pObj)->GetDict();
-                  } else {
-                    pTrailer = pObj->AsDictionary();
-                  }
-                  if (pTrailer) {
+                  CPDF_Stream* pStream = pObj->AsStream();
+                  if (CPDF_Dictionary* pTrailer =
+                          pStream ? pStream->GetDict() : pObj->AsDictionary()) {
                     if (m_pTrailer) {
                       CPDF_Object* pRoot =
                           pTrailer->GetElement(FX_BSTRC("Root"));
@@ -886,7 +873,7 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
                         pObj->Release();
                       }
                     } else {
-                      if (pObj->GetType() == PDFOBJ_STREAM) {
+                      if (pObj->IsStream()) {
                         m_pTrailer = ToDictionary(pTrailer->Clone());
                         pObj->Release();
                       } else {
@@ -1005,25 +992,25 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
 FX_BOOL CPDF_Parser::LoadCrossRefV5(FX_FILESIZE pos,
                                     FX_FILESIZE& prev,
                                     FX_BOOL bMainXRef) {
-  CPDF_Stream* pStream =
-      (CPDF_Stream*)ParseIndirectObjectAt(m_pDocument, pos, 0, NULL);
-  if (!pStream) {
+  CPDF_Object* pObject = ParseIndirectObjectAt(m_pDocument, pos, 0, nullptr);
+  if (!pObject)
     return FALSE;
-  }
+
   if (m_pDocument) {
     CPDF_Dictionary* pDict = m_pDocument->GetRoot();
-    if (!pDict || pDict->GetObjNum() != pStream->m_ObjNum) {
-      m_pDocument->InsertIndirectObject(pStream->m_ObjNum, pStream);
+    if (!pDict || pDict->GetObjNum() != pObject->m_ObjNum) {
+      m_pDocument->InsertIndirectObject(pObject->m_ObjNum, pObject);
     } else {
-      if (pStream->GetType() == PDFOBJ_STREAM) {
-        pStream->Release();
-      }
+      if (pObject->IsStream())
+        pObject->Release();
       return FALSE;
     }
   }
-  if (pStream->GetType() != PDFOBJ_STREAM) {
+
+  CPDF_Stream* pStream = pObject->AsStream();
+  if (!pStream)
     return FALSE;
-  }
+
   prev = pStream->GetDict()->GetInteger(FX_BSTRC("Prev"));
   int32_t size = pStream->GetDict()->GetInteger(FX_BSTRC("Size"));
   if (size < 0) {
@@ -1245,15 +1232,15 @@ CPDF_Object* CPDF_Parser::ParseIndirectObject(CPDF_IndirectObjects* pObjList,
 }
 
 CPDF_StreamAcc* CPDF_Parser::GetObjectStream(FX_DWORD objnum) {
-  CPDF_StreamAcc* pStreamAcc = NULL;
-  if (m_ObjectStreamMap.Lookup((void*)(uintptr_t)objnum, (void*&)pStreamAcc)) {
+  CPDF_StreamAcc* pStreamAcc = nullptr;
+  if (m_ObjectStreamMap.Lookup((void*)(uintptr_t)objnum, (void*&)pStreamAcc))
     return pStreamAcc;
-  }
+
   const CPDF_Stream* pStream =
-      m_pDocument ? (CPDF_Stream*)m_pDocument->GetIndirectObject(objnum) : NULL;
-  if (pStream == NULL || pStream->GetType() != PDFOBJ_STREAM) {
-    return NULL;
-  }
+      ToStream(m_pDocument ? m_pDocument->GetIndirectObject(objnum) : nullptr);
+  if (!pStream)
+    return nullptr;
+
   pStreamAcc = new CPDF_StreamAcc;
   pStreamAcc->LoadAllData(pStream);
   m_ObjectStreamMap.SetAt((void*)(uintptr_t)objnum, pStreamAcc);
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
index a2d65fa4bd..606bd0f569 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
@@ -417,7 +417,7 @@ CFX_ByteTextBuf& operator<<(CFX_ByteTextBuf& buf, const CPDF_Object* pObj) {
       break;
     }
     case PDFOBJ_STREAM: {
-      CPDF_Stream* p = (CPDF_Stream*)pObj;
+      const CPDF_Stream* p = pObj->AsStream();
       buf << p->GetDict() << FX_BSTRC("stream\r\n");
       CPDF_StreamAcc acc;
       acc.LoadAllData(p, TRUE);