Remove CFX_PtrList from renderer main loop.

Exposes an iterator over the object list, but not the object
holder, since pages and forms inherit from object holder, and
we don't want to imply that there's only one thing that might
be iterated over for those classes.

R=thestig@chromium.org

Review URL: https://codereview.chromium.org/1700183002 .

10 files changed, 197 insertions, 237 deletions

diff --git a/core/src/fpdfapi/fpdf_edit/fpdf_edit_content.cpp b/core/src/fpdfapi/fpdf_edit/fpdf_edit_content.cpp
index 82ab370564..ef0344cda0 100644
--- a/core/src/fpdfapi/fpdf_edit/fpdf_edit_content.cpp
+++ b/core/src/fpdfapi/fpdf_edit/fpdf_edit_content.cpp
@@ -14,25 +14,18 @@ CFX_ByteTextBuf& operator<<(CFX_ByteTextBuf& ar, CFX_Matrix& matrix) {
      << matrix.e << " " << matrix.f;
   return ar;
 }
+
 CPDF_PageContentGenerator::CPDF_PageContentGenerator(CPDF_Page* pPage)
-    : m_pPage(pPage) {
-  m_pDocument = NULL;
-  if (m_pPage) {
-    m_pDocument = m_pPage->m_pDocument;
-  }
-  FX_POSITION pos = pPage->GetPageObjectList()->GetHeadPosition();
-  while (pos) {
-    InsertPageObject(pPage->GetPageObjectList()->GetNextObject(pos));
-  }
+    : m_pPage(pPage), m_pDocument(m_pPage->m_pDocument) {
+  for (const auto& pObj : *pPage->GetPageObjectList())
+    InsertPageObject(pObj.get());
 }
-CPDF_PageContentGenerator::~CPDF_PageContentGenerator() {}
+
 FX_BOOL CPDF_PageContentGenerator::InsertPageObject(
     CPDF_PageObject* pPageObject) {
-  if (!pPageObject) {
-    return FALSE;
-  }
-  return m_pageObjects.Add(pPageObject);
+  return pPageObject && m_pageObjects.Add(pPageObject);
 }
+
 void CPDF_PageContentGenerator::GenerateContent() {
   CFX_ByteTextBuf buf;
   CPDF_Dictionary* pPageDict = m_pPage->m_pFormDict;
diff --git a/core/src/fpdfapi/fpdf_font/fpdf_font.cpp b/core/src/fpdfapi/fpdf_font/fpdf_font.cpp
index 52b79b0c1a..540f9a0731 100644
--- a/core/src/fpdfapi/fpdf_font/fpdf_font.cpp
+++ b/core/src/fpdfapi/fpdf_font/fpdf_font.cpp
@@ -1706,7 +1706,7 @@ CPDF_Type3Char* CPDF_Type3Font::LoadChar(FX_DWORD charcode, int level) {
   ASSERT(!pdfium::ContainsKey(m_CacheMap, charcode));
   CPDF_Type3Char* pCachedChar = pNewChar.release();
   m_CacheMap[charcode] = pCachedChar;
-  if (pCachedChar->m_pForm->GetPageObjectList()->GetCount() == 0) {
+  if (pCachedChar->m_pForm->GetPageObjectList()->empty()) {
     delete pCachedChar->m_pForm;
     pCachedChar->m_pForm = nullptr;
   }
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page.cpp
index 4194ff75eb..b1de6d6de2 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page.cpp
@@ -6,8 +6,11 @@
 
 #include "core/src/fpdfapi/fpdf_page/pageint.h"
 
+#include <algorithm>
+
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfapi/fpdf_page.h"
+#include "third_party/base/stl_util.h"
 
 CPDF_PageObject* CPDF_PageObject::Create(int type) {
   switch (type) {
@@ -670,6 +673,19 @@ void CPDF_FormObject::CalcBoundingBox() {
   m_Right = form_rect.right;
   m_Top = form_rect.top;
 }
+
+CPDF_PageObject* CPDF_PageObjectList::GetPageObjectByIndex(int index) {
+  if (index < 0 || index >= pdfium::CollectionSize<int>(*this))
+    return nullptr;
+  int current = 0;
+  for (const auto& pObj : *this) {
+    if (index == current)
+      return pObj.get();
+    ++current;
+  }
+  return nullptr;
+}
+
 CPDF_PageObjectHolder::CPDF_PageObjectHolder()
     : m_pFormDict(nullptr),
       m_pFormStream(nullptr),
@@ -679,15 +695,8 @@ CPDF_PageObjectHolder::CPDF_PageObjectHolder()
       m_Transparency(0),
       m_bBackgroundAlphaNeeded(FALSE),
       m_bHasImageMask(FALSE),
-      m_ParseState(CONTENT_NOT_PARSED),
-      m_PageObjectList(128) {}
+      m_ParseState(CONTENT_NOT_PARSED) {}
 
-CPDF_PageObjectHolder::~CPDF_PageObjectHolder() {
-  FX_POSITION pos = m_PageObjectList.GetHeadPosition();
-  while (pos) {
-    delete m_PageObjectList.GetNextObject(pos);
-  }
-}
 void CPDF_PageObjectHolder::ContinueParse(IFX_Pause* pPause) {
   if (!m_pParser) {
     return;
@@ -698,48 +707,29 @@ void CPDF_PageObjectHolder::ContinueParse(IFX_Pause* pPause) {
     m_pParser.reset();
   }
 }
-FX_POSITION CPDF_PageObjectList::InsertObject(FX_POSITION posInsertAfter,
-                                              CPDF_PageObject* pNewObject) {
-  if (!posInsertAfter) {
-    return AddHead(pNewObject);
-  }
-  return InsertAfter(posInsertAfter, pNewObject);
-}
-CPDF_PageObject* CPDF_PageObjectList::GetObjectByIndex(int index) const {
-  FX_POSITION pos = FindIndex(index);
-  return pos ? GetObjectAt(pos) : nullptr;
-}
+
 void CPDF_PageObjectHolder::Transform(const CFX_Matrix& matrix) {
-  FX_POSITION pos = m_PageObjectList.GetHeadPosition();
-  while (pos) {
-    m_PageObjectList.GetNextObject(pos)->Transform(matrix);
-  }
+  for (auto& pObj : m_PageObjectList)
+    pObj->Transform(matrix);
 }
+
 CFX_FloatRect CPDF_PageObjectHolder::CalcBoundingBox() const {
-  if (m_PageObjectList.GetCount() == 0) {
+  if (m_PageObjectList.empty())
     return CFX_FloatRect(0, 0, 0, 0);
-  }
-  FX_FLOAT left, right, top, bottom;
-  left = bottom = 1000000 * 1.0f;
-  right = top = -1000000 * 1.0f;
-  FX_POSITION pos = m_PageObjectList.GetHeadPosition();
-  while (pos) {
-    CPDF_PageObject* pObj = (CPDF_PageObject*)m_PageObjectList.GetNext(pos);
-    if (left > pObj->m_Left) {
-      left = pObj->m_Left;
-    }
-    if (right < pObj->m_Right) {
-      right = pObj->m_Right;
-    }
-    if (top < pObj->m_Top) {
-      top = pObj->m_Top;
-    }
-    if (bottom > pObj->m_Bottom) {
-      bottom = pObj->m_Bottom;
-    }
+
+  FX_FLOAT left = 1000000.0f;
+  FX_FLOAT right = -1000000.0f;
+  FX_FLOAT bottom = 1000000.0f;
+  FX_FLOAT top = -1000000.0f;
+  for (const auto& pObj : m_PageObjectList) {
+    left = std::min(left, pObj->m_Left);
+    right = std::max(right, pObj->m_Right);
+    bottom = std::min(bottom, pObj->m_Bottom);
+    top = std::max(top, pObj->m_Top);
   }
   return CFX_FloatRect(left, bottom, right, top);
 }
+
 void CPDF_PageObjectHolder::LoadTransInfo() {
   if (!m_pFormDict) {
     return;
@@ -889,7 +879,9 @@ CPDF_Form::CPDF_Form(CPDF_Document* pDoc,
   m_Transparency = 0;
   LoadTransInfo();
 }
+
 CPDF_Form::~CPDF_Form() {}
+
 void CPDF_Form::StartParse(CPDF_AllStates* pGraphicStates,
                            CFX_Matrix* pParentMatrix,
                            CPDF_Type3Char* pType3Char,
@@ -903,6 +895,7 @@ void CPDF_Form::StartParse(CPDF_AllStates* pGraphicStates,
                    level);
   m_ParseState = CONTENT_PARSING;
 }
+
 void CPDF_Form::ParseContent(CPDF_AllStates* pGraphicStates,
                              CFX_Matrix* pParentMatrix,
                              CPDF_Type3Char* pType3Char,
@@ -911,16 +904,16 @@ void CPDF_Form::ParseContent(CPDF_AllStates* pGraphicStates,
   StartParse(pGraphicStates, pParentMatrix, pType3Char, pOptions, level);
   ContinueParse(NULL);
 }
+
 CPDF_Form* CPDF_Form::Clone() const {
-  CPDF_Form* pClone =
+  CPDF_Form* pCloneForm =
       new CPDF_Form(m_pDocument, m_pPageResources, m_pFormStream, m_pResources);
-  FX_POSITION pos = m_PageObjectList.GetHeadPosition();
-  while (pos) {
-    CPDF_PageObject* pObj = (CPDF_PageObject*)m_PageObjectList.GetNext(pos);
-    pClone->m_PageObjectList.AddTail(pObj->Clone());
-  }
-  return pClone;
+  for (const auto& pObj : m_PageObjectList)
+    pCloneForm->m_PageObjectList.emplace_back(pObj->Clone());
+
+  return pCloneForm;
 }
+
 void CPDF_Page::GetDisplayMatrix(CFX_Matrix& matrix,
                                  int xPos,
                                  int yPos,
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index 6e02cb11b4..d49186374f 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -780,7 +780,7 @@ void CPDF_StreamContentParser::AddForm(CPDF_Stream* pStream) {
     parser.Parse(stream.GetData(), stream.GetSize(), 0);
     return;
   }
-  CPDF_FormObject* pFormObj = new CPDF_FormObject;
+  std::unique_ptr<CPDF_FormObject> pFormObj(new CPDF_FormObject);
   pFormObj->m_pForm =
       new CPDF_Form(m_pDocument, m_pPageResources, pStream, m_pResources);
   pFormObj->m_FormMatrix = m_pCurStates->m_CTM;
@@ -796,8 +796,8 @@ void CPDF_StreamContentParser::AddForm(CPDF_Stream* pStream) {
     m_pObjectHolder->SetBackgroundAlphaNeeded(TRUE);
   }
   pFormObj->CalcBoundingBox();
-  SetGraphicStates(pFormObj, TRUE, TRUE, TRUE);
-  m_pObjectHolder->GetPageObjectList()->AddTail(pFormObj);
+  SetGraphicStates(pFormObj.get(), TRUE, TRUE, TRUE);
+  m_pObjectHolder->GetPageObjectList()->push_back(std::move(pFormObj));
 }
 
 CPDF_ImageObject* CPDF_StreamContentParser::AddImage(CPDF_Stream* pStream,
@@ -809,7 +809,8 @@ CPDF_ImageObject* CPDF_StreamContentParser::AddImage(CPDF_Stream* pStream,
   CFX_Matrix ImageMatrix;
   ImageMatrix.Copy(m_pCurStates->m_CTM);
   ImageMatrix.Concat(m_mtContentToUser);
-  CPDF_ImageObject* pImageObj = new CPDF_ImageObject;
+
+  std::unique_ptr<CPDF_ImageObject> pImageObj(new CPDF_ImageObject);
   if (pImage) {
     pImageObj->m_pImage =
         m_pDocument->GetPageData()->GetImage(pImage->GetStream());
@@ -819,11 +820,13 @@ CPDF_ImageObject* CPDF_StreamContentParser::AddImage(CPDF_Stream* pStream,
     pImageObj->m_pImage = new CPDF_Image(m_pDocument);
     pImageObj->m_pImage->LoadImageF(pStream, bInline);
   }
-  SetGraphicStates(pImageObj, pImageObj->m_pImage->IsMask(), FALSE, FALSE);
+  SetGraphicStates(pImageObj.get(), pImageObj->m_pImage->IsMask(), FALSE,
+                   FALSE);
   pImageObj->m_Matrix = ImageMatrix;
   pImageObj->CalcBoundingBox();
-  m_pObjectHolder->GetPageObjectList()->AddTail(pImageObj);
-  return pImageObj;
+  CPDF_ImageObject* pRet = pImageObj.get();
+  m_pObjectHolder->GetPageObjectList()->push_back(std::move(pImageObj));
+  return pRet;
 }
 
 void CPDF_StreamContentParser::Handle_MarkPlace_Dictionary() {}
@@ -1190,9 +1193,9 @@ void CPDF_StreamContentParser::Handle_ShadeFill() {
   if (!pShading->Load()) {
     return;
   }
-  CPDF_ShadingObject* pObj = new CPDF_ShadingObject;
+  std::unique_ptr<CPDF_ShadingObject> pObj(new CPDF_ShadingObject);
   pObj->m_pShading = pShading;
-  SetGraphicStates(pObj, FALSE, FALSE, FALSE);
+  SetGraphicStates(pObj.get(), FALSE, FALSE, FALSE);
   pObj->m_Matrix = m_pCurStates->m_CTM;
   pObj->m_Matrix.Concat(m_mtContentToUser);
   CFX_FloatRect bbox;
@@ -1211,7 +1214,7 @@ void CPDF_StreamContentParser::Handle_ShadeFill() {
   pObj->m_Right = bbox.right;
   pObj->m_Top = bbox.top;
   pObj->m_Bottom = bbox.bottom;
-  m_pObjectHolder->GetPageObjectList()->AddTail(pObj);
+  m_pObjectHolder->GetPageObjectList()->push_back(std::move(pObj));
 }
 
 void CPDF_StreamContentParser::Handle_SetCharSpace() {
@@ -1365,31 +1368,34 @@ void CPDF_StreamContentParser::AddTextObject(CFX_ByteString* pStrs,
   } else {
     textmode = m_pCurStates->m_TextState.GetObject()->m_TextMode;
   }
-  CPDF_TextObject* pText = new CPDF_TextObject;
-  m_pLastTextObject = pText;
-  SetGraphicStates(pText, TRUE, TRUE, TRUE);
-  if (textmode && textmode != 3 && textmode != 4 && textmode != 7) {
-    FX_FLOAT* pCTM = pText->m_TextState.GetModify()->m_CTM;
-    pCTM[0] = m_pCurStates->m_CTM.a;
-    pCTM[1] = m_pCurStates->m_CTM.c;
-    pCTM[2] = m_pCurStates->m_CTM.b;
-    pCTM[3] = m_pCurStates->m_CTM.d;
-  }
-  pText->SetSegments(pStrs, pKerning, nsegs);
-  pText->m_PosX = m_pCurStates->m_TextX;
-  pText->m_PosY = m_pCurStates->m_TextY + m_pCurStates->m_TextRise;
-  ConvertTextSpace(pText->m_PosX, pText->m_PosY);
-  FX_FLOAT x_advance, y_advance;
-  pText->CalcPositionData(&x_advance, &y_advance, m_pCurStates->m_TextHorzScale,
-                          m_Level);
-  m_pCurStates->m_TextX += x_advance;
-  m_pCurStates->m_TextY += y_advance;
-  if (textmode > 3) {
-    CPDF_TextObject* pCopy = new CPDF_TextObject;
-    pCopy->Copy(pText);
-    m_ClipTextList.Add(pCopy);
-  }
-  m_pObjectHolder->GetPageObjectList()->AddTail(pText);
+  {
+    std::unique_ptr<CPDF_TextObject> pText(new CPDF_TextObject);
+    m_pLastTextObject = pText.get();
+    SetGraphicStates(m_pLastTextObject, TRUE, TRUE, TRUE);
+    if (textmode && textmode != 3 && textmode != 4 && textmode != 7) {
+      FX_FLOAT* pCTM = pText->m_TextState.GetModify()->m_CTM;
+      pCTM[0] = m_pCurStates->m_CTM.a;
+      pCTM[1] = m_pCurStates->m_CTM.c;
+      pCTM[2] = m_pCurStates->m_CTM.b;
+      pCTM[3] = m_pCurStates->m_CTM.d;
+    }
+    pText->SetSegments(pStrs, pKerning, nsegs);
+    pText->m_PosX = m_pCurStates->m_TextX;
+    pText->m_PosY = m_pCurStates->m_TextY + m_pCurStates->m_TextRise;
+    ConvertTextSpace(pText->m_PosX, pText->m_PosY);
+    FX_FLOAT x_advance;
+    FX_FLOAT y_advance;
+    pText->CalcPositionData(&x_advance, &y_advance,
+                            m_pCurStates->m_TextHorzScale, m_Level);
+    m_pCurStates->m_TextX += x_advance;
+    m_pCurStates->m_TextY += y_advance;
+    if (textmode > 3) {
+      CPDF_TextObject* pCopy = new CPDF_TextObject;
+      pCopy->Copy(pText.get());
+      m_ClipTextList.Add(pCopy);
+    }
+    m_pObjectHolder->GetPageObjectList()->push_back(std::move(pText));
+  }
   if (pKerning && pKerning[nsegs - 1] != 0) {
     if (!pFont->IsVertWriting()) {
       m_pCurStates->m_TextX -=
@@ -1617,14 +1623,14 @@ void CPDF_StreamContentParser::AddPathObject(int FillType, FX_BOOL bStroke) {
   CFX_Matrix matrix = m_pCurStates->m_CTM;
   matrix.Concat(m_mtContentToUser);
   if (bStroke || FillType) {
-    CPDF_PathObject* pPathObj = new CPDF_PathObject;
+    std::unique_ptr<CPDF_PathObject> pPathObj(new CPDF_PathObject);
     pPathObj->m_bStroke = bStroke;
     pPathObj->m_FillType = FillType;
     pPathObj->m_Path = Path;
     pPathObj->m_Matrix = matrix;
-    SetGraphicStates(pPathObj, TRUE, FALSE, TRUE);
+    SetGraphicStates(pPathObj.get(), TRUE, FALSE, TRUE);
     pPathObj->CalcBoundingBox();
-    m_pObjectHolder->GetPageObjectList()->AddTail(pPathObj);
+    m_pObjectHolder->GetPageObjectList()->push_back(std::move(pPathObj));
   }
   if (PathClipType) {
     if (!matrix.IsIdentity()) {
@@ -1641,13 +1647,12 @@ FX_DWORD CPDF_StreamContentParser::Parse(const uint8_t* pData,
   if (m_Level > _FPDF_MAX_FORM_LEVEL_) {
     return dwSize;
   }
-  FX_DWORD InitObjCount = m_pObjectHolder->GetPageObjectList()->GetCount();
+  FX_DWORD InitObjCount = m_pObjectHolder->GetPageObjectList()->size();
   CPDF_StreamParser syntax(pData, dwSize);
   CPDF_StreamParserAutoClearer auto_clearer(&m_pSyntax, &syntax);
   m_CompatCount = 0;
   while (1) {
-    FX_DWORD cost =
-        m_pObjectHolder->GetPageObjectList()->GetCount() - InitObjCount;
+    FX_DWORD cost = m_pObjectHolder->GetPageObjectList()->size() - InitObjCount;
     if (max_cost && cost >= max_cost) {
       break;
     }
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
index 7fa3286e11..20f0c39c25 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
@@ -666,7 +666,7 @@ bool CPDF_StreamParser::PositionIsInBounds() const {
 CPDF_ContentParser::CPDF_ContentParser()
     : m_Status(Ready),
       m_InternalStage(STAGE_GETCONTENT),
-      m_pObjects(nullptr),
+      m_pObjectHolder(nullptr),
       m_bForm(false),
       m_pType3Char(nullptr),
       m_pData(nullptr),
@@ -684,7 +684,7 @@ void CPDF_ContentParser::Start(CPDF_Page* pPage, CPDF_ParseOptions* pOptions) {
     m_Status = Done;
     return;
   }
-  m_pObjects = pPage;
+  m_pObjectHolder = pPage;
   m_bForm = FALSE;
   if (pOptions) {
     m_Options = *pOptions;
@@ -720,7 +720,7 @@ void CPDF_ContentParser::Start(CPDF_Form* pForm,
                                CPDF_ParseOptions* pOptions,
                                int level) {
   m_pType3Char = pType3Char;
-  m_pObjects = pForm;
+  m_pObjectHolder = pForm;
   m_bForm = TRUE;
   CFX_Matrix form_matrix = pForm->m_pFormDict->GetMatrixBy("Matrix");
   if (pGraphicStates) {
@@ -803,7 +803,8 @@ void CPDF_ContentParser::Continue(IFX_Pause* pPause) {
         m_InternalStage = STAGE_PARSE;
         m_CurrentOffset = 0;
       } else {
-        CPDF_Array* pContent = m_pObjects->m_pFormDict->GetArrayBy("Contents");
+        CPDF_Array* pContent =
+            m_pObjectHolder->m_pFormDict->GetArrayBy("Contents");
         m_StreamArray[m_CurrentOffset].reset(new CPDF_StreamAcc);
         CPDF_Stream* pStreamObj = ToStream(
             pContent ? pContent->GetElementValue(m_CurrentOffset) : nullptr);
@@ -814,9 +815,9 @@ void CPDF_ContentParser::Continue(IFX_Pause* pPause) {
     if (m_InternalStage == STAGE_PARSE) {
       if (!m_pParser) {
         m_pParser.reset(new CPDF_StreamContentParser(
-            m_pObjects->m_pDocument, m_pObjects->m_pPageResources, nullptr,
-            nullptr, m_pObjects, m_pObjects->m_pResources, &m_pObjects->m_BBox,
-            &m_Options, nullptr, 0));
+            m_pObjectHolder->m_pDocument, m_pObjectHolder->m_pPageResources,
+            nullptr, nullptr, m_pObjectHolder, m_pObjectHolder->m_pResources,
+            &m_pObjectHolder->m_BBox, &m_Options, nullptr, 0));
         m_pParser->GetCurStates()->m_ColorState.GetModify()->Default();
       }
       if (m_CurrentOffset >= m_Size) {
@@ -841,10 +842,7 @@ void CPDF_ContentParser::Continue(IFX_Pause* pPause) {
         m_pType3Char->m_BBox.top =
             FXSYS_round(m_pParser->GetType3Data()[5] * 1000);
       }
-      FX_POSITION pos = m_pObjects->GetPageObjectList()->GetHeadPosition();
-      while (pos) {
-        CPDF_PageObject* pObj =
-            m_pObjects->GetPageObjectList()->GetNextObject(pos);
+      for (auto& pObj : *m_pObjectHolder->GetPageObjectList()) {
         if (pObj->m_ClipPath.IsNull()) {
           continue;
         }
diff --git a/core/src/fpdfapi/fpdf_page/pageint.h b/core/src/fpdfapi/fpdf_page/pageint.h
index 4df8d6aa9f..fb95b6b30d 100644
--- a/core/src/fpdfapi/fpdf_page/pageint.h
+++ b/core/src/fpdfapi/fpdf_page/pageint.h
@@ -94,7 +94,7 @@ class CPDF_StreamContentParser {
                            CPDF_Dictionary* pPageResources,
                            CPDF_Dictionary* pParentResources,
                            CFX_Matrix* pmtContentToUser,
-                           CPDF_PageObjectHolder* pObjHolder,
+                           CPDF_PageObjectHolder* pObjectHolder,
                            CPDF_Dictionary* pResources,
                            CFX_FloatRect* pBBox,
                            CPDF_ParseOptions* pOptions,
@@ -298,7 +298,7 @@ class CPDF_ContentParser {
 
   ParseStatus m_Status;
   InternalStage m_InternalStage;
-  CPDF_PageObjectHolder* m_pObjects;
+  CPDF_PageObjectHolder* m_pObjectHolder;
   FX_BOOL m_bForm;
   CPDF_ParseOptions m_Options;
   CPDF_Type3Char* m_pType3Char;
diff --git a/core/src/fpdfapi/fpdf_render/fpdf_render.cpp b/core/src/fpdfapi/fpdf_render/fpdf_render.cpp
index 0023ee92de..147de51f4d 100644
--- a/core/src/fpdfapi/fpdf_render/fpdf_render.cpp
+++ b/core/src/fpdfapi/fpdf_render/fpdf_render.cpp
@@ -244,29 +244,24 @@ void CPDF_RenderStatus::RenderObjectList(
   CFX_Matrix device2object;
   device2object.SetReverse(*pObj2Device);
   device2object.TransformRect(clip_rect);
-  int index = 0;
-  FX_POSITION pos = pObjectHolder->GetPageObjectList()->GetHeadPosition();
-  while (pos) {
-    index++;
-    CPDF_PageObject* pCurObj =
-        pObjectHolder->GetPageObjectList()->GetNextObject(pos);
-    if (pCurObj == m_pStopObj) {
+
+  for (const auto& pCurObj : *pObjectHolder->GetPageObjectList()) {
+    if (pCurObj.get() == m_pStopObj) {
       m_bStopped = TRUE;
       return;
     }
-    if (!pCurObj) {
+    if (!pCurObj)
       continue;
-    }
-    if (!pCurObj || pCurObj->m_Left > clip_rect.right ||
+
+    if (pCurObj->m_Left > clip_rect.right ||
         pCurObj->m_Right < clip_rect.left ||
         pCurObj->m_Bottom > clip_rect.top ||
         pCurObj->m_Top < clip_rect.bottom) {
       continue;
     }
-    RenderSingleObject(pCurObj, pObj2Device);
-    if (m_bStopped) {
+    RenderSingleObject(pCurObj.get(), pObj2Device);
+    if (m_bStopped)
       return;
-    }
   }
 }
 void CPDF_RenderStatus::RenderSingleObject(const CPDF_PageObject* pObj,
@@ -1037,8 +1032,7 @@ CPDF_ProgressiveRenderer::CPDF_ProgressiveRenderer(
       m_pDevice(pDevice),
       m_pOptions(pOptions),
       m_LayerIndex(0),
-      m_pCurrentLayer(nullptr),
-      m_LastObjectRendered(nullptr) {}
+      m_pCurrentLayer(nullptr) {}
 
 CPDF_ProgressiveRenderer::~CPDF_ProgressiveRenderer() {
   if (m_pRenderStatus)
@@ -1062,7 +1056,8 @@ void CPDF_ProgressiveRenderer::Continue(IFX_Pause* pPause) {
         return;
       }
       m_pCurrentLayer = m_pContext->GetLayer(m_LayerIndex);
-      m_LastObjectRendered = nullptr;
+      m_LastObjectRendered =
+          m_pCurrentLayer->m_pObjectHolder->GetPageObjectList()->end();
       m_pRenderStatus.reset(new CPDF_RenderStatus());
       m_pRenderStatus->Initialize(
           m_pContext, m_pDevice, NULL, NULL, NULL, NULL, m_pOptions,
@@ -1073,19 +1068,18 @@ void CPDF_ProgressiveRenderer::Continue(IFX_Pause* pPause) {
       device2object.SetReverse(m_pCurrentLayer->m_Matrix);
       device2object.TransformRect(m_ClipRect);
     }
-    FX_POSITION pos;
-    if (m_LastObjectRendered) {
-      pos = m_LastObjectRendered;
-      m_pCurrentLayer->m_pObjectHolder->GetPageObjectList()->GetNextObject(pos);
+    CPDF_PageObjectList::iterator iter;
+    CPDF_PageObjectList::iterator iterEnd =
+        m_pCurrentLayer->m_pObjectHolder->GetPageObjectList()->end();
+    if (m_LastObjectRendered != iterEnd) {
+      iter = m_LastObjectRendered;
+      ++iter;
     } else {
-      pos = m_pCurrentLayer->m_pObjectHolder->GetPageObjectList()
-                ->GetHeadPosition();
+      iter = m_pCurrentLayer->m_pObjectHolder->GetPageObjectList()->begin();
     }
     int nObjsToGo = kStepLimit;
-    while (pos) {
-      CPDF_PageObject* pCurObj =
-          m_pCurrentLayer->m_pObjectHolder->GetPageObjectList()->GetObjectAt(
-              pos);
+    while (iter != iterEnd) {
+      CPDF_PageObject* pCurObj = iter->get();
       if (pCurObj && pCurObj->m_Left <= m_ClipRect.right &&
           pCurObj->m_Right >= m_ClipRect.left &&
           pCurObj->m_Bottom <= m_ClipRect.top &&
@@ -1106,19 +1100,18 @@ void CPDF_ProgressiveRenderer::Continue(IFX_Pause* pPause) {
           --nObjsToGo;
         }
       }
-      m_LastObjectRendered = pos;
+      m_LastObjectRendered = iter;
       if (nObjsToGo == 0) {
         if (pPause && pPause->NeedToPauseNow())
           return;
         nObjsToGo = kStepLimit;
       }
-      m_pCurrentLayer->m_pObjectHolder->GetPageObjectList()->GetNextObject(pos);
+      ++iter;
     }
     if (m_pCurrentLayer->m_pObjectHolder->IsParsed()) {
       m_pRenderStatus.reset();
       m_pDevice->RestoreState();
       m_pCurrentLayer = nullptr;
-      m_LastObjectRendered = nullptr;
       m_LayerIndex++;
       if (pPause && pPause->NeedToPauseNow()) {
         return;
diff --git a/core/src/fpdfapi/fpdf_render/fpdf_render_text.cpp b/core/src/fpdfapi/fpdf_render/fpdf_render_text.cpp
index f19e6f8258..d2faac3b7e 100644
--- a/core/src/fpdfapi/fpdf_render/fpdf_render_text.cpp
+++ b/core/src/fpdfapi/fpdf_render/fpdf_render_text.cpp
@@ -316,11 +316,10 @@ FX_BOOL CPDF_Type3Char::LoadBitmap(CPDF_RenderContext* pContext) {
   if (m_pBitmap || !m_pForm) {
     return TRUE;
   }
-  if (m_pForm->GetPageObjectList()->GetCount() == 1 && !m_bColored) {
-    CPDF_PageObject* pPageObj = m_pForm->GetPageObjectList()->GetObjectAt(
-        m_pForm->GetPageObjectList()->GetHeadPosition());
+  if (m_pForm->GetPageObjectList()->size() == 1 && !m_bColored) {
+    auto& pPageObj = m_pForm->GetPageObjectList()->front();
     if (pPageObj->m_Type == CPDF_PageObject::IMAGE) {
-      CPDF_ImageObject* pImage = (CPDF_ImageObject*)pPageObj;
+      CPDF_ImageObject* pImage = static_cast<CPDF_ImageObject*>(pPageObj.get());
       m_ImageMatrix = pImage->m_Matrix;
       const CFX_DIBSource* pSource = pImage->m_pImage->LoadDIBSource();
       if (pSource) {
diff --git a/core/src/fpdftext/fpdf_text_int.cpp b/core/src/fpdftext/fpdf_text_int.cpp
index aa13acee8a..8972f84d7c 100644
--- a/core/src/fpdftext/fpdf_text_int.cpp
+++ b/core/src/fpdftext/fpdf_text_int.cpp
@@ -761,20 +761,13 @@ int32_t CPDF_TextPage::FindTextlineFlowDirection() {
   uint8_t* pDataV = nVerticalMask.data();
   int32_t index = 0;
   FX_FLOAT fLineHeight = 0.0f;
-  CPDF_PageObject* pPageObj = NULL;
-  FX_POSITION pos = NULL;
-  pos = m_pPage->GetPageObjectList()->GetHeadPosition();
-  if (!pos) {
+  if (m_pPage->GetPageObjectList()->empty())
     return -1;
-  }
-  while (pos) {
-    pPageObj = m_pPage->GetPageObjectList()->GetNextObject(pos);
-    if (!pPageObj) {
-      continue;
-    }
-    if (CPDF_PageObject::TEXT != pPageObj->m_Type) {
+
+  for (auto& pPageObj : *m_pPage->GetPageObjectList()) {
+    if (!pPageObj || pPageObj->m_Type != CPDF_PageObject::TEXT)
       continue;
-    }
+
     int32_t minH =
         (int32_t)pPageObj->m_Left < 0 ? 0 : (int32_t)pPageObj->m_Left;
     int32_t maxH = (int32_t)pPageObj->m_Right > nPageWidth
@@ -785,28 +778,26 @@ int32_t CPDF_TextPage::FindTextlineFlowDirection() {
     int32_t maxV = (int32_t)pPageObj->m_Top > nPageHeight
                        ? nPageHeight
                        : (int32_t)pPageObj->m_Top;
-    if (minH >= maxH || minV >= maxV) {
+    if (minH >= maxH || minV >= maxV)
       continue;
-    }
+
     FXSYS_memset(pDataH + minH, 1, maxH - minH);
     FXSYS_memset(pDataV + minV, 1, maxV - minV);
-    if (fLineHeight <= 0.0f) {
+    if (fLineHeight <= 0.0f)
       fLineHeight = pPageObj->m_Top - pPageObj->m_Bottom;
-    }
-    pPageObj = NULL;
   }
   int32_t nStartH = 0;
   int32_t nEndH = 0;
   FX_FLOAT nSumH = 0.0f;
-  for (index = 0; index < nPageWidth; index++)
-    if (1 == nHorizontalMask[index]) {
+  for (index = 0; index < nPageWidth; index++) {
+    if (1 == nHorizontalMask[index])
       break;
-    }
+  }
   nStartH = index;
-  for (index = nPageWidth; index > 0; index--)
-    if (1 == nHorizontalMask[index - 1]) {
+  for (index = nPageWidth; index > 0; index--) {
+    if (1 == nHorizontalMask[index - 1])
       break;
-    }
+  }
   nEndH = index;
   for (index = nStartH; index < nEndH; index++) {
     nSumH += nHorizontalMask[index];
@@ -815,15 +806,15 @@ int32_t CPDF_TextPage::FindTextlineFlowDirection() {
   int32_t nStartV = 0;
   int32_t nEndV = 0;
   FX_FLOAT nSumV = 0.0f;
-  for (index = 0; index < nPageHeight; index++)
-    if (1 == nVerticalMask[index]) {
+  for (index = 0; index < nPageHeight; index++) {
+    if (1 == nVerticalMask[index])
       break;
-    }
+  }
   nStartV = index;
-  for (index = nPageHeight; index > 0; index--)
-    if (1 == nVerticalMask[index - 1]) {
+  for (index = nPageHeight; index > 0; index--) {
+    if (1 == nVerticalMask[index - 1])
       break;
-    }
+  }
   nEndV = index;
   for (index = nStartV; index < nEndV; index++) {
     nSumV += nVerticalMask[index];
@@ -848,58 +839,50 @@ int32_t CPDF_TextPage::FindTextlineFlowDirection() {
 }
 
 void CPDF_TextPage::ProcessObject() {
-  FX_POSITION pos = m_pPage->GetPageObjectList()->GetHeadPosition();
-  if (!pos) {
+  if (m_pPage->GetPageObjectList()->empty())
     return;
-  }
+
   m_TextlineDir = FindTextlineFlowDirection();
-  int nCount = 0;
-  while (pos) {
-    CPDF_PageObject* pPageObj =
-        m_pPage->GetPageObjectList()->GetNextObject(pos);
-    if (pPageObj) {
-      if (pPageObj->m_Type == CPDF_PageObject::TEXT) {
+  const CPDF_PageObjectList* pObjList = m_pPage->GetPageObjectList();
+  for (auto it = pObjList->begin(); it != pObjList->end(); ++it) {
+    if (CPDF_PageObject* pObj = it->get()) {
+      if (pObj->m_Type == CPDF_PageObject::TEXT) {
         CFX_Matrix matrix;
-        ProcessTextObject((CPDF_TextObject*)pPageObj, matrix, pos);
-        nCount++;
-      } else if (pPageObj->m_Type == CPDF_PageObject::FORM) {
+        ProcessTextObject(static_cast<CPDF_TextObject*>(pObj), matrix, pObjList,
+                          it);
+      } else if (pObj->m_Type == CPDF_PageObject::FORM) {
         CFX_Matrix formMatrix(1, 0, 0, 1, 0, 0);
-        ProcessFormObject((CPDF_FormObject*)pPageObj, formMatrix);
+        ProcessFormObject(static_cast<CPDF_FormObject*>(pObj), formMatrix);
       }
     }
   }
-  int count = m_LineObj.GetSize();
-  for (int i = 0; i < count; i++) {
+  for (int i = 0; i < m_LineObj.GetSize(); i++)
     ProcessTextObject(m_LineObj.GetAt(i));
-  }
+
   m_LineObj.RemoveAll();
   CloseTempLine();
 }
 
 void CPDF_TextPage::ProcessFormObject(CPDF_FormObject* pFormObj,
                                       const CFX_Matrix& formMatrix) {
-  CPDF_PageObject* pPageObj = NULL;
-  FX_POSITION pos;
-  if (!pFormObj) {
+  CPDF_PageObjectList* pObjectList = pFormObj->m_pForm->GetPageObjectList();
+  if (pObjectList->empty())
     return;
-  }
-  pos = pFormObj->m_pForm->GetPageObjectList()->GetHeadPosition();
-  if (!pos) {
-    return;
-  }
+
   CFX_Matrix curFormMatrix;
   curFormMatrix.Copy(pFormObj->m_FormMatrix);
   curFormMatrix.Concat(formMatrix);
-  while (pos) {
-    pPageObj = pFormObj->m_pForm->GetPageObjectList()->GetNextObject(pos);
-    if (pPageObj) {
+
+  for (auto it = pObjectList->begin(); it != pObjectList->end(); ++it) {
+    if (CPDF_PageObject* pPageObj = it->get()) {
       if (pPageObj->m_Type == CPDF_PageObject::TEXT) {
-        ProcessTextObject((CPDF_TextObject*)pPageObj, curFormMatrix, pos);
+        ProcessTextObject(static_cast<CPDF_TextObject*>(pPageObj),
+                          curFormMatrix, pObjectList, it);
       } else if (pPageObj->m_Type == CPDF_PageObject::FORM) {
-        ProcessFormObject((CPDF_FormObject*)pPageObj, curFormMatrix);
+        ProcessFormObject(static_cast<CPDF_FormObject*>(pPageObj),
+                          curFormMatrix);
       }
     }
-    pPageObj = NULL;
   }
 }
 
@@ -1032,9 +1015,11 @@ void CPDF_TextPage::CloseTempLine() {
   m_TempTextBuf.Delete(0, m_TempTextBuf.GetLength());
 }
 
-void CPDF_TextPage::ProcessTextObject(CPDF_TextObject* pTextObj,
-                                      const CFX_Matrix& formMatrix,
-                                      FX_POSITION ObjPos) {
+void CPDF_TextPage::ProcessTextObject(
+    CPDF_TextObject* pTextObj,
+    const CFX_Matrix& formMatrix,
+    const CPDF_PageObjectList* pObjList,
+    CPDF_PageObjectList::const_iterator ObjPos) {
   CFX_FloatRect re(pTextObj->m_Left, pTextObj->m_Bottom, pTextObj->m_Right,
                    pTextObj->m_Top);
   if (FXSYS_fabs(pTextObj->m_Right - pTextObj->m_Left) < 0.01f) {
@@ -1048,7 +1033,7 @@ void CPDF_TextPage::ProcessTextObject(CPDF_TextObject* pTextObj,
     m_LineObj.Add(Obj);
     return;
   }
-  if (IsSameAsPreTextObject(pTextObj, ObjPos)) {
+  if (IsSameAsPreTextObject(pTextObj, pObjList, ObjPos)) {
     return;
   }
   PDFTEXT_Obj prev_Obj = m_LineObj.GetAt(count - 1);
@@ -1832,29 +1817,19 @@ FX_BOOL CPDF_TextPage::IsSameTextObject(CPDF_TextObject* pTextObj1,
   }
   return TRUE;
 }
-
-FX_BOOL CPDF_TextPage::IsSameAsPreTextObject(CPDF_TextObject* pTextObj,
-                                             FX_POSITION ObjPos) {
-  if (!pTextObj) {
-    return FALSE;
-  }
+FX_BOOL CPDF_TextPage::IsSameAsPreTextObject(
+    CPDF_TextObject* pTextObj,
+    const CPDF_PageObjectList* pObjList,
+    CPDF_PageObjectList::const_iterator iter) {
   int i = 0;
-  if (!ObjPos) {
-    ObjPos = m_pPage->GetPageObjectList()->GetTailPosition();
-  }
-  CPDF_PageObject* pObj = m_pPage->GetPageObjectList()->GetPrevObject(ObjPos);
-  while (i < 5 && ObjPos) {
-    pObj = m_pPage->GetPageObjectList()->GetPrevObject(ObjPos);
-    if (pObj == pTextObj) {
+  while (i < 5 && iter != pObjList->begin()) {
+    --iter;
+    CPDF_PageObject* pOtherObj = iter->get();
+    if (pOtherObj == pTextObj || pOtherObj->m_Type != CPDF_PageObject::TEXT)
       continue;
-    }
-    if (pObj->m_Type != CPDF_PageObject::TEXT) {
-      continue;
-    }
-    if (IsSameTextObject((CPDF_TextObject*)pObj, pTextObj)) {
+    if (IsSameTextObject(static_cast<CPDF_TextObject*>(pOtherObj), pTextObj))
       return TRUE;
-    }
-    i++;
+    ++i;
   }
   return FALSE;
 }
diff --git a/core/src/fpdftext/text_int.h b/core/src/fpdftext/text_int.h
index 9b7d654930..113e1d1ac8 100644
--- a/core/src/fpdftext/text_int.h
+++ b/core/src/fpdftext/text_int.h
@@ -10,6 +10,7 @@
 #include <deque>
 #include <vector>
 
+#include "core/include/fpdfapi/fpdf_page.h"
 #include "core/include/fpdftext/fpdf_text.h"
 #include "core/include/fxcrt/fx_basic.h"
 
@@ -107,11 +108,14 @@ class CPDF_TextPage : public IPDF_TextPage {
   void ProcessTextObject(PDFTEXT_Obj pObj);
   void ProcessTextObject(CPDF_TextObject* pTextObj,
                          const CFX_Matrix& formMatrix,
-                         FX_POSITION ObjPos);
+                         const CPDF_PageObjectList* pObjList,
+                         CPDF_PageObjectList::const_iterator ObjPos);
   int ProcessInsertObject(const CPDF_TextObject* pObj,
                           const CFX_Matrix& formMatrix);
   FX_BOOL GenerateCharInfo(FX_WCHAR unicode, PAGECHAR_INFO& info);
-  FX_BOOL IsSameAsPreTextObject(CPDF_TextObject* pTextObj, FX_POSITION ObjPos);
+  FX_BOOL IsSameAsPreTextObject(CPDF_TextObject* pTextObj,
+                                const CPDF_PageObjectList* pObjList,
+                                CPDF_PageObjectList::const_iterator ObjPos);
   FX_BOOL IsSameTextObject(CPDF_TextObject* pTextObj1,
                            CPDF_TextObject* pTextObj2);
   int GetCharWidth(FX_DWORD charCode, CPDF_Font* pFont) const;