Add type cast definitions for CPDF_Array.

This Cl adds ToArray, CPDF_Object::AsArray and CPDF_Object::IsArray and
updates the src to use them as needed.

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

Review URL: https://codereview.chromium.org/1417893003 .

5 files changed, 51 insertions, 57 deletions

diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
index cbbfbd7197..1815d40194 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
@@ -331,31 +331,27 @@ FX_BOOL PDF_DataDecode(const uint8_t* src_buf,
 
 {
   CPDF_Object* pDecoder =
-      pDict ? pDict->GetElementValue(FX_BSTRC("Filter")) : NULL;
-  if (!pDecoder || (pDecoder->GetType() != PDFOBJ_ARRAY && !pDecoder->IsName()))
+      pDict ? pDict->GetElementValue(FX_BSTRC("Filter")) : nullptr;
+  if (!pDecoder || (!pDecoder->IsArray() && !pDecoder->IsName()))
     return FALSE;
 
   CPDF_Object* pParams =
-      pDict ? pDict->GetElementValue(FX_BSTRC("DecodeParms")) : NULL;
+      pDict ? pDict->GetElementValue(FX_BSTRC("DecodeParms")) : nullptr;
   CFX_ByteStringArray DecoderList;
   CFX_PtrArray ParamList;
-  if (pDecoder->GetType() == PDFOBJ_ARRAY) {
-    if (pParams && pParams->GetType() != PDFOBJ_ARRAY) {
-      pParams = NULL;
-    }
-    CPDF_Array* pDecoders = (CPDF_Array*)pDecoder;
+  if (CPDF_Array* pDecoders = pDecoder->AsArray()) {
+    CPDF_Array* pParamsArray = ToArray(pParams);
+    if (!pParamsArray)
+      pParams = nullptr;
+
     for (FX_DWORD i = 0; i < pDecoders->GetCount(); i++) {
       CFX_ByteStringC str = pDecoders->GetConstString(i);
       DecoderList.Add(str);
-      if (pParams) {
-        ParamList.Add(((CPDF_Array*)pParams)->GetDict(i));
-      } else {
-        ParamList.Add(NULL);
-      }
+      ParamList.Add(pParams ? pParamsArray->GetDict(i) : nullptr);
     }
   } else {
     DecoderList.Add(pDecoder->GetConstString());
-    ParamList.Add(pParams ? pParams->GetDict() : NULL);
+    ParamList.Add(pParams ? pParams->GetDict() : nullptr);
   }
   uint8_t* last_buf = (uint8_t*)src_buf;
   FX_DWORD last_size = src_size;
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
index 3d9900deac..2396261276 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_document.cpp
@@ -306,7 +306,7 @@ FX_BOOL CPDF_Document::IsContentUsedElsewhere(FX_DWORD objnum,
       continue;
     }
     if (pContents->GetDirectType() == PDFOBJ_ARRAY) {
-      CPDF_Array* pArray = (CPDF_Array*)pContents->GetDirect();
+      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) {
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
index e3d9cd7291..6a090ce64d 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
@@ -25,7 +25,7 @@ void CPDF_Object::Destroy() {
       delete AsName();
       break;
     case PDFOBJ_ARRAY:
-      delete (CPDF_Array*)this;
+      delete AsArray();
       break;
     case PDFOBJ_DICTIONARY:
       delete AsDictionary();
@@ -161,10 +161,9 @@ CPDF_Dictionary* CPDF_Object::GetDict() const {
 }
 
 CPDF_Array* CPDF_Object::GetArray() const {
-  if (m_Type == PDFOBJ_ARRAY)
-    return (CPDF_Array*)this;
-
-  return NULL;
+  // The method should be made non-const if we want to not be const.
+  // See bug #234.
+  return const_cast<CPDF_Array*>(AsArray());
 }
 void CPDF_Object::SetString(const CFX_ByteString& str) {
   ASSERT(this != NULL);
@@ -217,7 +216,7 @@ FX_BOOL CPDF_Object::IsIdentical(CPDF_Object* pOther) const {
     case PDFOBJ_NAME:
       return AsName()->Identical(pOther->AsName());
     case PDFOBJ_ARRAY:
-      return (((CPDF_Array*)this)->Identical((CPDF_Array*)pOther));
+      return AsArray()->Identical(pOther->AsArray());
     case PDFOBJ_DICTIONARY:
       return AsDictionary()->Identical(pOther->AsDictionary());
     case PDFOBJ_NULL:
@@ -261,7 +260,7 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
       return new CPDF_Name(AsName()->m_Name);
     case PDFOBJ_ARRAY: {
       CPDF_Array* pCopy = new CPDF_Array();
-      CPDF_Array* pThis = (CPDF_Array*)this;
+      const CPDF_Array* pThis = AsArray();
       int n = pThis->GetCount();
       for (int i = 0; i < n; i++) {
         CPDF_Object* value = (CPDF_Object*)pThis->m_Objects.GetAt(i);
@@ -341,6 +340,14 @@ void CPDF_Object::SetUnicodeText(const FX_WCHAR* pUnicodes, int len) {
   }
 }
 
+CPDF_Array* CPDF_Object::AsArray() {
+  return IsArray() ? static_cast<CPDF_Array*>(this) : nullptr;
+}
+
+const CPDF_Array* CPDF_Object::AsArray() const {
+  return IsArray() ? static_cast<const CPDF_Array*>(this) : nullptr;
+}
+
 CPDF_Boolean* CPDF_Object::AsBoolean() {
   return IsBoolean() ? static_cast<CPDF_Boolean*>(this) : nullptr;
 }
@@ -420,9 +427,9 @@ CPDF_Array::~CPDF_Array() {
 }
 CFX_FloatRect CPDF_Array::GetRect() {
   CFX_FloatRect rect;
-  if (m_Type != PDFOBJ_ARRAY || m_Objects.GetSize() != 4) {
+  if (!IsArray() || m_Objects.GetSize() != 4)
     return rect;
-  }
+
   rect.left = GetNumber(0);
   rect.bottom = GetNumber(1);
   rect.right = GetNumber(2);
@@ -431,9 +438,9 @@ CFX_FloatRect CPDF_Array::GetRect() {
 }
 CFX_AffineMatrix CPDF_Array::GetMatrix() {
   CFX_AffineMatrix matrix;
-  if (m_Type != PDFOBJ_ARRAY || m_Objects.GetSize() != 6) {
+  if (!IsArray() || m_Objects.GetSize() != 6)
     return matrix;
-  }
+
   matrix.Set(GetNumber(0), GetNumber(1), GetNumber(2), GetNumber(3),
              GetNumber(4), GetNumber(5));
   return matrix;
@@ -499,14 +506,10 @@ CPDF_Stream* CPDF_Array::GetStream(FX_DWORD i) const {
   return (CPDF_Stream*)p;
 }
 CPDF_Array* CPDF_Array::GetArray(FX_DWORD i) const {
-  CPDF_Object* p = GetElementValue(i);
-  if (p == NULL || p->GetType() != PDFOBJ_ARRAY) {
-    return NULL;
-  }
-  return (CPDF_Array*)p;
+  return ToArray(GetElementValue(i));
 }
 void CPDF_Array::RemoveAt(FX_DWORD i) {
-  ASSERT(m_Type == PDFOBJ_ARRAY);
+  ASSERT(IsArray());
   if (i >= (FX_DWORD)m_Objects.GetSize()) {
     return;
   }
@@ -518,7 +521,7 @@ void CPDF_Array::RemoveAt(FX_DWORD i) {
 void CPDF_Array::SetAt(FX_DWORD i,
                        CPDF_Object* pObj,
                        CPDF_IndirectObjects* pObjs) {
-  ASSERT(m_Type == PDFOBJ_ARRAY);
+  ASSERT(IsArray());
   ASSERT(i < (FX_DWORD)m_Objects.GetSize());
   if (i >= (FX_DWORD)m_Objects.GetSize()) {
     return;
@@ -551,25 +554,25 @@ void CPDF_Array::Add(CPDF_Object* pObj, CPDF_IndirectObjects* pObjs) {
   m_Objects.Add(pObj);
 }
 void CPDF_Array::AddName(const CFX_ByteString& str) {
-  ASSERT(m_Type == PDFOBJ_ARRAY);
+  ASSERT(IsArray());
   Add(new CPDF_Name(str));
 }
 void CPDF_Array::AddString(const CFX_ByteString& str) {
-  ASSERT(m_Type == PDFOBJ_ARRAY);
+  ASSERT(IsArray());
   Add(new CPDF_String(str));
 }
 void CPDF_Array::AddInteger(int i) {
-  ASSERT(m_Type == PDFOBJ_ARRAY);
+  ASSERT(IsArray());
   Add(new CPDF_Number(i));
 }
 void CPDF_Array::AddNumber(FX_FLOAT f) {
-  ASSERT(m_Type == PDFOBJ_ARRAY);
+  ASSERT(IsArray());
   CPDF_Number* pNumber = new CPDF_Number;
   pNumber->SetNumber(f);
   Add(pNumber);
 }
 void CPDF_Array::AddReference(CPDF_IndirectObjects* pDoc, FX_DWORD objnum) {
-  ASSERT(m_Type == PDFOBJ_ARRAY);
+  ASSERT(IsArray());
   Add(new CPDF_Reference(pDoc, objnum));
 }
 FX_BOOL CPDF_Array::Identical(CPDF_Array* pOther) const {
@@ -712,11 +715,7 @@ CPDF_Dictionary* CPDF_Dictionary::GetDict(const CFX_ByteStringC& key) const {
   return nullptr;
 }
 CPDF_Array* CPDF_Dictionary::GetArray(const CFX_ByteStringC& key) const {
-  CPDF_Object* p = GetElementValue(key);
-  if (p == NULL || p->GetType() != PDFOBJ_ARRAY) {
-    return NULL;
-  }
-  return (CPDF_Array*)p;
+  return ToArray(GetElementValue(key));
 }
 CPDF_Stream* CPDF_Dictionary::GetStream(const CFX_ByteStringC& key) const {
   CPDF_Object* p = GetElementValue(key);
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 514380eeab..8b822a8b9c 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -1154,17 +1154,14 @@ FX_BOOL CPDF_Parser::LoadCrossRefV5(FX_FILESIZE pos,
 }
 CPDF_Array* CPDF_Parser::GetIDArray() {
   CPDF_Object* pID = m_pTrailer ? m_pTrailer->GetElement(FX_BSTRC("ID")) : NULL;
-  if (pID == NULL) {
-    return NULL;
-  }
+  if (!pID)
+    return nullptr;
+
   if (pID->GetType() == PDFOBJ_REFERENCE) {
     pID = ParseIndirectObject(NULL, ((CPDF_Reference*)pID)->GetRefObjNum());
     m_pTrailer->SetAt(FX_BSTRC("ID"), pID);
   }
-  if (pID == NULL || pID->GetType() != PDFOBJ_ARRAY) {
-    return NULL;
-  }
-  return (CPDF_Array*)pID;
+  return ToArray(pID);
 }
 FX_DWORD CPDF_Parser::GetRootObjNum() {
   CPDF_Object* pRef =
@@ -3474,7 +3471,7 @@ FX_BOOL CPDF_DataAvail::CheckPage(IFX_DownloadHints* pHints) {
       }
       continue;
     }
-    if (pObj->GetType() == PDFOBJ_ARRAY) {
+    if (pObj->IsArray()) {
       CPDF_Array* pArray = pObj->GetArray();
       if (pArray) {
         int32_t iSize = pArray->GetCount();
@@ -3543,7 +3540,7 @@ FX_BOOL CPDF_DataAvail::GetPageKids(CPDF_Parser* pParser, CPDF_Object* pPages) {
       m_PageObjList.Add(pKid->GetRefObjNum());
     } break;
     case PDFOBJ_ARRAY: {
-      CPDF_Array* pKidsArray = (CPDF_Array*)pKids;
+      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) {
@@ -4116,13 +4113,15 @@ FX_BOOL CPDF_DataAvail::CheckArrayPageNode(FX_DWORD dwPageNo,
     }
     return FALSE;
   }
-  if (pPages->GetType() != PDFOBJ_ARRAY) {
+
+  CPDF_Array* pArray = pPages->AsArray();
+  if (!pArray) {
     pPages->Release();
     m_docStatus = PDF_DATAAVAIL_ERROR;
     return FALSE;
   }
+
   pPageNode->m_type = PDF_PAGENODE_PAGES;
-  CPDF_Array* pArray = (CPDF_Array*)pPages;
   for (FX_DWORD i = 0; i < pArray->GetCount(); ++i) {
     CPDF_Object* pKid = (CPDF_Object*)pArray->GetElement(i);
     if (!pKid || pKid->GetType() != PDFOBJ_REFERENCE) {
@@ -4151,7 +4150,7 @@ FX_BOOL CPDF_DataAvail::CheckUnkownPageNode(FX_DWORD dwPageNo,
     }
     return FALSE;
   }
-  if (pPage->GetType() == PDFOBJ_ARRAY) {
+  if (pPage->IsArray()) {
     pPageNode->m_dwPageNo = dwPageNo;
     pPageNode->m_type = PDF_PAGENODE_ARRAY;
     pPage->Release();
@@ -4180,7 +4179,7 @@ FX_BOOL CPDF_DataAvail::CheckUnkownPageNode(FX_DWORD dwPageNo,
         pNode->m_dwPageNo = pKid->GetRefObjNum();
       } break;
       case PDFOBJ_ARRAY: {
-        CPDF_Array* pKidsArray = (CPDF_Array*)pKids;
+        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) {
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
index 2c161a7dd4..a2d65fa4bd 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
@@ -386,7 +386,7 @@ CFX_ByteTextBuf& operator<<(CFX_ByteTextBuf& buf, const CPDF_Object* pObj) {
       break;
     }
     case PDFOBJ_ARRAY: {
-      CPDF_Array* p = (CPDF_Array*)pObj;
+      const CPDF_Array* p = pObj->AsArray();
       buf << FX_BSTRC("[");
       for (FX_DWORD i = 0; i < p->GetCount(); i++) {
         CPDF_Object* pElement = p->GetElement(i);