Add type cast definitions for CPDF_String.

This Cl adds ToString, CPDF_Object::AsString and CPDF_Object::IsString and
updates the src to use them as needed.

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

Review URL: https://codereview.chromium.org/1417933002 .

6 files changed, 39 insertions, 31 deletions

diff --git a/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp b/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
index 3d669a0410..b097389160 100644
--- a/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
+++ b/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
@@ -42,7 +42,7 @@ int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
       break;
     case PDFOBJ_STRING: {
       CFX_ByteString str = pObj->GetString();
-      FX_BOOL bHex = ((CPDF_String*)pObj)->IsHex();
+      FX_BOOL bHex = pObj->AsString()->IsHex();
       if ((len = pFile->AppendString(PDF_EncodeString(str, bHex))) < 0) {
         return -1;
       }
@@ -1116,7 +1116,7 @@ int32_t CPDF_Creator::WriteDirectObj(FX_DWORD objnum,
       break;
     case PDFOBJ_STRING: {
       CFX_ByteString str = pObj->GetString();
-      FX_BOOL bHex = ((CPDF_String*)pObj)->IsHex();
+      FX_BOOL bHex = pObj->AsString()->IsHex();
       if (m_pCryptoHandler == NULL || !bEncrypt) {
         CFX_ByteString content = PDF_EncodeString(str, bHex);
         if ((len = m_File.AppendString(content)) < 0) {
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
index 3f0de2d416..584f9c24d3 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
@@ -906,12 +906,13 @@ FX_BOOL CPDF_IndexedCS::v_Load(CPDF_Document* pDoc, CPDF_Array* pArray) {
     m_pCompMinMax[i * 2 + 1] -= m_pCompMinMax[i * 2];
   }
   m_MaxIndex = pArray->GetInteger(2);
+
   CPDF_Object* pTableObj = pArray->GetElementValue(3);
-  if (pTableObj == NULL) {
+  if (!pTableObj)
     return FALSE;
-  }
-  if (pTableObj->GetType() == PDFOBJ_STRING) {
-    m_Table = ((CPDF_String*)pTableObj)->GetString();
+
+  if (CPDF_String* pString = pTableObj->AsString()) {
+    m_Table = pString->GetString();
   } else if (pTableObj->GetType() == PDFOBJ_STREAM) {
     CPDF_StreamAcc acc;
     acc.LoadAllData((CPDF_Stream*)pTableObj, FALSE);
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index 1283a3a596..fbb364ee12 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -1359,10 +1359,8 @@ void CPDF_StreamContentParser::Handle_ShowText_Positioning() {
   }
   int n = pArray->GetCount(), nsegs = 0, i;
   for (i = 0; i < n; i++) {
-    CPDF_Object* pObj = pArray->GetElementValue(i);
-    if (pObj->GetType() == PDFOBJ_STRING) {
+    if (pArray->GetElementValue(i)->IsString())
       nsegs++;
-    }
   }
   if (nsegs == 0) {
     for (i = 0; i < n; i++) {
@@ -1379,7 +1377,7 @@ void CPDF_StreamContentParser::Handle_ShowText_Positioning() {
   FX_FLOAT fInitKerning = 0;
   for (i = 0; i < n; i++) {
     CPDF_Object* pObj = pArray->GetElementValue(i);
-    if (pObj->GetType() == PDFOBJ_STRING) {
+    if (pObj->IsString()) {
       CFX_ByteString str = pObj->GetString();
       if (str.IsEmpty()) {
         continue;
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_fdf.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_fdf.cpp
index 82bfbb56eb..c766dd397f 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_fdf.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_fdf.cpp
@@ -100,12 +100,10 @@ CFX_WideString CFDF_Document::GetWin32Path() const {
   CPDF_Dictionary* pDict =
       m_pRootDict ? m_pRootDict->GetDict(FX_BSTRC("FDF")) : NULL;
   CPDF_Object* pFileSpec = pDict ? pDict->GetElementValue(FX_BSTRC("F")) : NULL;
-  if (pFileSpec == NULL) {
+  if (!pFileSpec)
     return CFX_WideString();
-  }
-  if (pFileSpec->GetType() == PDFOBJ_STRING) {
+  if (pFileSpec->IsString())
     return FPDF_FileSpec_GetWin32Path(m_pRootDict->GetDict(FX_BSTRC("FDF")));
-  }
   return FPDF_FileSpec_GetWin32Path(pFileSpec);
 }
 static CFX_WideString ChangeSlash(const FX_WCHAR* str) {
@@ -138,7 +136,8 @@ void FPDF_FileSpec_SetWin32Path(CPDF_Object* pFileSpec,
   } else {
     result = ChangeSlash(filepath.c_str());
   }
-  if (pFileSpec->GetType() == PDFOBJ_STRING) {
+
+  if (pFileSpec->IsString()) {
     pFileSpec->SetString(CFX_ByteString::FromUnicode(result));
   } else if (CPDF_Dictionary* pFileDict = pFileSpec->AsDictionary()) {
     pFileDict->SetAtString(FX_BSTRC("F"), CFX_ByteString::FromUnicode(result));
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
index 59800dcd93..b2dc924322 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
@@ -19,7 +19,7 @@ void CPDF_Object::Release() {
 void CPDF_Object::Destroy() {
   switch (m_Type) {
     case PDFOBJ_STRING:
-      delete (CPDF_String*)this;
+      delete AsString();
       break;
     case PDFOBJ_NAME:
       delete (CPDF_Name*)this;
@@ -44,7 +44,7 @@ CFX_ByteString CPDF_Object::GetString() const {
     case PDFOBJ_NUMBER:
       return AsNumber()->GetString();
     case PDFOBJ_STRING:
-      return ((CPDF_String*)this)->m_String;
+      return AsString()->m_String;
     case PDFOBJ_NAME:
       return ((CPDF_Name*)this)->m_Name;
     case PDFOBJ_REFERENCE: {
@@ -64,9 +64,10 @@ CFX_ByteString CPDF_Object::GetString() const {
 }
 CFX_ByteStringC CPDF_Object::GetConstString() const {
   switch (m_Type) {
-    case PDFOBJ_STRING:
-      return CFX_ByteStringC((const uint8_t*)((CPDF_String*)this)->m_String,
-                             ((CPDF_String*)this)->m_String.GetLength());
+    case PDFOBJ_STRING: {
+      CFX_ByteString str = AsString()->m_String;
+      return CFX_ByteStringC((const uint8_t*)str, str.GetLength());
+    }
     case PDFOBJ_NAME:
       return CFX_ByteStringC((const uint8_t*)((CPDF_Name*)this)->m_Name,
                              ((CPDF_Name*)this)->m_Name.GetLength());
@@ -174,7 +175,7 @@ void CPDF_Object::SetString(const CFX_ByteString& str) {
       AsNumber()->SetString(str);
       return;
     case PDFOBJ_STRING:
-      ((CPDF_String*)this)->m_String = str;
+      AsString()->m_String = str;
       return;
     case PDFOBJ_NAME:
       ((CPDF_Name*)this)->m_Name = str;
@@ -211,7 +212,7 @@ FX_BOOL CPDF_Object::IsIdentical(CPDF_Object* pOther) const {
     case PDFOBJ_NUMBER:
       return AsNumber()->Identical(pOther->AsNumber());
     case PDFOBJ_STRING:
-      return (((CPDF_String*)this)->Identical((CPDF_String*)pOther));
+      return AsString()->Identical(pOther->AsString());
     case PDFOBJ_NAME:
       return (((CPDF_Name*)this)->Identical((CPDF_Name*)pOther));
     case PDFOBJ_ARRAY:
@@ -251,9 +252,10 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
       return new CPDF_Number(pThis->m_bInteger ? pThis->m_Integer
                                                : pThis->m_Float);
     }
-    case PDFOBJ_STRING:
-      return new CPDF_String(((CPDF_String*)this)->m_String,
-                             ((CPDF_String*)this)->IsHex());
+    case PDFOBJ_STRING: {
+      const CPDF_String* pString = AsString();
+      return new CPDF_String(pString->m_String, pString->IsHex());
+    }
     case PDFOBJ_NAME:
       return new CPDF_Name(((CPDF_Name*)this)->m_Name);
     case PDFOBJ_ARRAY: {
@@ -314,9 +316,9 @@ CPDF_Object* CPDF_Object::CloneRef(CPDF_IndirectObjects* pDoc) const {
   return Clone();
 }
 CFX_WideString CPDF_Object::GetUnicodeText(CFX_CharMap* pCharMap) const {
-  if (m_Type == PDFOBJ_STRING) {
-    return PDF_DecodeText(((CPDF_String*)this)->m_String, pCharMap);
-  }
+  if (const CPDF_String* pString = AsString())
+    return PDF_DecodeText(pString->m_String, pCharMap);
+
   if (m_Type == PDFOBJ_STREAM) {
     CPDF_StreamAcc stream;
     stream.LoadAllData((CPDF_Stream*)this, FALSE);
@@ -330,8 +332,8 @@ CFX_WideString CPDF_Object::GetUnicodeText(CFX_CharMap* pCharMap) const {
   return CFX_WideString();
 }
 void CPDF_Object::SetUnicodeText(const FX_WCHAR* pUnicodes, int len) {
-  if (m_Type == PDFOBJ_STRING) {
-    ((CPDF_String*)this)->m_String = PDF_EncodeText(pUnicodes, len);
+  if (CPDF_String* pString = AsString()) {
+    pString->m_String = PDF_EncodeText(pUnicodes, len);
   } else if (m_Type == PDFOBJ_STREAM) {
     CFX_ByteString result = PDF_EncodeText(pUnicodes, len);
     ((CPDF_Stream*)this)
@@ -363,6 +365,14 @@ const CPDF_Number* CPDF_Object::AsNumber() const {
   return IsNumber() ? static_cast<const CPDF_Number*>(this) : nullptr;
 }
 
+CPDF_String* CPDF_Object::AsString() {
+  return IsString() ? static_cast<CPDF_String*>(this) : nullptr;
+}
+
+const CPDF_String* CPDF_Object::AsString() const {
+  return IsString() ? static_cast<const CPDF_String*>(this) : nullptr;
+}
+
 CPDF_Number::CPDF_Number(int value)
     : CPDF_Object(PDFOBJ_NUMBER), m_bInteger(TRUE), m_Integer(value) {}
 
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
index c34d8122f8..84d1301c60 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
@@ -374,7 +374,7 @@ CFX_ByteTextBuf& operator<<(CFX_ByteTextBuf& buf, const CPDF_Object* pObj) {
       break;
     case PDFOBJ_STRING: {
       CFX_ByteString str = pObj->GetString();
-      FX_BOOL bHex = ((CPDF_String*)pObj)->IsHex();
+      FX_BOOL bHex = pObj->AsString()->IsHex();
       buf << PDF_EncodeString(str, bHex);
       break;
     }