Use std::map as CPDF_Dictionary's underlying store.

Replaces CFX_CMapByteStringToPtr. XFA still uses CFX_CMapByteStringToPtr
so it's not completely removed just yet.

Adds begin()/end() to CPDF_Dictionary and removes the
GetStartPos()/GetNextElement() functions to traverse the dictionary.
Callers are changed accordingly. AddValue() is also removed.

R=tsepez@chromium.org, thestig@chromium.org

Review URL: https://codereview.chromium.org/1541703003 .

19 files changed, 175 insertions, 264 deletions

diff --git a/core/include/fpdfapi/fpdf_objects.h b/core/include/fpdfapi/fpdf_objects.h
index a9a27c74a1..5e17685e65 100644
--- a/core/include/fpdfapi/fpdf_objects.h
+++ b/core/include/fpdfapi/fpdf_objects.h
@@ -7,6 +7,7 @@
 #ifndef CORE_INCLUDE_FPDFAPI_FPDF_OBJECTS_H_
 #define CORE_INCLUDE_FPDFAPI_FPDF_OBJECTS_H_
 
+#include <map>
 #include <set>
 
 #include "core/include/fxcrt/fx_coordinates.h"
@@ -339,6 +340,9 @@ inline const CPDF_Array* ToArray(const CPDF_Object* obj) {
 
 class CPDF_Dictionary : public CPDF_Object {
  public:
+  using iterator = std::map<CFX_ByteString, CPDF_Object*>::iterator;
+  using const_iterator = std::map<CFX_ByteString, CPDF_Object*>::const_iterator;
+
   CPDF_Dictionary() : CPDF_Object(PDFOBJ_DICTIONARY) {}
 
   CPDF_Object* GetElement(const CFX_ByteStringC& key) const;
@@ -381,10 +385,6 @@ class CPDF_Dictionary : public CPDF_Object {
 
   FX_BOOL KeyExist(const CFX_ByteStringC& key) const;
 
-  FX_POSITION GetStartPos() const;
-
-  CPDF_Object* GetNextElement(FX_POSITION& pos, CFX_ByteString& key) const;
-
   void SetAt(const CFX_ByteStringC& key, CPDF_Object* pObj);
 
   void SetAtName(const CFX_ByteStringC& key, const CFX_ByteString& name);
@@ -421,14 +421,20 @@ class CPDF_Dictionary : public CPDF_Object {
 
   FX_BOOL Identical(CPDF_Dictionary* pDict) const;
 
-  int GetCount() const { return m_Map.GetCount(); }
+  size_t GetCount() const { return m_Map.size(); }
+
+  iterator begin() { return m_Map.begin(); }
+
+  iterator end() { return m_Map.end(); }
+
+  const_iterator begin() const { return m_Map.begin(); }
 
-  void AddValue(const CFX_ByteStringC& key, CPDF_Object* pObj);
+  const_iterator end() const { return m_Map.end(); }
 
  protected:
   ~CPDF_Dictionary();
 
-  CFX_CMapByteStringToPtr m_Map;
+  std::map<CFX_ByteString, CPDF_Object*> m_Map;
 
   friend class CPDF_Object;
 };
diff --git a/core/include/fpdfdoc/fpdf_doc.h b/core/include/fpdfdoc/fpdf_doc.h
index 09c93d6c3a..1027435400 100644
--- a/core/include/fpdfdoc/fpdf_doc.h
+++ b/core/include/fpdfdoc/fpdf_doc.h
@@ -298,10 +298,6 @@ class CPDF_AAction {
 
   CPDF_Action GetAction(AActionType eType) const;
 
-  FX_POSITION GetStartPos() const;
-
-  CPDF_Action GetNextAction(FX_POSITION& pos, AActionType& eType) const;
-
   CPDF_Dictionary* m_pDict;
 };
 class CPDF_DocJSActions {
diff --git a/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp b/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
index c1ef37dab6..65bb3d985e 100644
--- a/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
+++ b/core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp
@@ -15,6 +15,8 @@
 #define PDF_OBJECTSTREAM_MAXLENGTH (256 * 1024)
 #define PDF_XREFSTREAM_MAXSIZE 10000
 
+// TODO(ochang): Make helper for appending "objnum 0 R ".
+
 namespace {
 
 int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
@@ -112,10 +114,9 @@ int32_t PDF_CreatorAppendObject(const CPDF_Object* pObj,
       }
       offset += 2;
       const CPDF_Dictionary* p = pObj->AsDictionary();
-      FX_POSITION pos = p->GetStartPos();
-      while (pos) {
-        CFX_ByteString key;
-        CPDF_Object* pValue = p->GetNextElement(pos, key);
+      for (const auto& it : *p) {
+        const CFX_ByteString& key = it.first;
+        CPDF_Object* pValue = it.second;
         if (pFile->AppendString("/") < 0) {
           return -1;
         }
@@ -184,10 +185,9 @@ int32_t PDF_CreatorWriteTrailer(CPDF_Document* pDocument,
   CPDF_Parser* pParser = (CPDF_Parser*)pDocument->GetParser();
   if (pParser) {
     CPDF_Dictionary* p = pParser->GetTrailer();
-    FX_POSITION pos = p->GetStartPos();
-    while (pos) {
-      CFX_ByteString key;
-      CPDF_Object* pValue = p->GetNextElement(pos, key);
+    for (const auto& it : *p) {
+      const CFX_ByteString& key = it.first;
+      CPDF_Object* pValue = it.second;
       if (key == "Encrypt" || key == "Size" || key == "Filter" ||
           key == "Index" || key == "Length" || key == "Prev" || key == "W" ||
           key == "XRefStm" || key == "Type" || key == "ID") {
@@ -1238,11 +1238,10 @@ int32_t CPDF_Creator::WriteDirectObj(FX_DWORD objnum,
       m_Offset += 2;
       const CPDF_Dictionary* p = pObj->AsDictionary();
       bool bSignDict = IsSignatureDict(p);
-      FX_POSITION pos = p->GetStartPos();
-      while (pos) {
+      for (const auto& it : *p) {
         FX_BOOL bSignValue = FALSE;
-        CFX_ByteString key;
-        CPDF_Object* pValue = p->GetNextElement(pos, key);
+        const CFX_ByteString& key = it.first;
+        CPDF_Object* pValue = it.second;
         if (m_File.AppendString("/") < 0) {
           return -1;
         }
@@ -1773,10 +1772,11 @@ int32_t CPDF_Creator::WriteDoc_Stage4(IFX_Pause* pPause) {
     }
     if (m_pParser) {
       CPDF_Dictionary* p = m_pParser->m_pTrailer;
-      FX_POSITION pos = p->GetStartPos();
-      while (pos) {
-        CFX_ByteString key;
-        CPDF_Object* pValue = p->GetNextElement(pos, key);
+      for (const auto& it : *p) {
+        const CFX_ByteString& key = it.first;
+        CPDF_Object* pValue = it.second;
+        // TODO(ochang): Consolidate with similar check in
+        // PDF_CreatorWriteTrailer.
         if (key == "Encrypt" || key == "Size" || key == "Filter" ||
             key == "Index" || key == "Length" || key == "Prev" || key == "W" ||
             key == "XRefStm" || key == "ID") {
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
index be22344cd9..87b9e025bc 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_colors.cpp
@@ -1223,11 +1223,9 @@ CPDF_ColorSpace* CPDF_ColorSpace::Load(CPDF_Document* pDoc, CPDF_Object* pObj) {
     if (!pDict)
       return nullptr;
 
-    CPDF_ColorSpace* pRet = nullptr;
-    FX_POSITION pos = pDict->GetStartPos();
-    while (pos) {
-      CFX_ByteString bsKey;
-      CPDF_Object* pValue = pDict->GetNextElement(pos, bsKey);
+    for (const auto& it : *pDict) {
+      CPDF_ColorSpace* pRet = nullptr;
+      CPDF_Object* pValue = it.second;
       if (ToName(pValue))
         pRet = _CSFromName(pValue->GetString());
       if (pRet)
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_graph_state.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_graph_state.cpp
index d8f21c692d..dd16aa85ce 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_graph_state.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_graph_state.cpp
@@ -458,10 +458,9 @@ void CPDF_AllStates::SetLineDash(CPDF_Array* pArray,
 void CPDF_AllStates::ProcessExtGS(CPDF_Dictionary* pGS,
                                   CPDF_StreamContentParser* pParser) {
   CPDF_GeneralStateData* pGeneralState = m_GeneralState.GetModify();
-  FX_POSITION pos = pGS->GetStartPos();
-  while (pos) {
-    CFX_ByteString key_str;
-    CPDF_Object* pElement = pGS->GetNextElement(pos, key_str);
+  for (const auto& it : *pGS) {
+    const CFX_ByteString& key_str = it.first;
+    CPDF_Object* pElement = it.second;
     CPDF_Object* pObject = pElement ? pElement->GetDirect() : nullptr;
     if (!pObject)
       continue;
diff --git a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index d0cf9ed719..3fbd3e486e 100644
--- a/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/src/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -496,10 +496,9 @@ void PDF_ReplaceAbbr(CPDF_Object* pObj) {
   switch (pObj->GetType()) {
     case PDFOBJ_DICTIONARY: {
       CPDF_Dictionary* pDict = pObj->AsDictionary();
-      FX_POSITION pos = pDict->GetStartPos();
-      while (pos) {
-        CFX_ByteString key;
-        CPDF_Object* value = pDict->GetNextElement(pos, key);
+      for (const auto& it : *pDict) {
+        CFX_ByteString key = it.first;
+        CPDF_Object* value = it.second;
         CFX_ByteStringC fullname = PDF_FindFullName(
             PDF_InlineKeyAbbr, FX_ArraySize(PDF_InlineKeyAbbr), key);
         if (!fullname.IsEmpty()) {
@@ -544,10 +543,9 @@ void PDF_ReplaceFull(CPDF_Object* pObj) {
   switch (pObj->GetType()) {
     case PDFOBJ_DICTIONARY: {
       CPDF_Dictionary* pDict = pObj->AsDictionary();
-      FX_POSITION pos = pDict->GetStartPos();
-      while (pos) {
-        CFX_ByteString key;
-        CPDF_Object* value = pDict->GetNextElement(pos, key);
+      for (const auto& it : *pDict) {
+        CFX_ByteString key = it.first;
+        CPDF_Object* value = it.second;
         CFX_ByteStringC abbrName = PDF_FindAbbrName(
             PDF_InlineKeyAbbr, FX_ArraySize(PDF_InlineKeyAbbr), key);
         if (!abbrName.IsEmpty()) {
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
index 685becaf69..2cb81002fb 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_objects.cpp
@@ -267,12 +267,9 @@ CPDF_Object* CPDF_Object::CloneInternal(FX_BOOL bDirect,
     case PDFOBJ_DICTIONARY: {
       CPDF_Dictionary* pCopy = new CPDF_Dictionary();
       const CPDF_Dictionary* pThis = AsDictionary();
-      FX_POSITION pos = pThis->m_Map.GetStartPosition();
-      while (pos) {
-        CFX_ByteString key;
-        CPDF_Object* value;
-        pThis->m_Map.GetNextAssoc(pos, key, (void*&)value);
-        pCopy->m_Map.SetAt(key, value->CloneInternal(bDirect, visited));
+      for (const auto& it : *pThis) {
+        pCopy->m_Map.insert(std::make_pair(
+            it.first, it.second->CloneInternal(bDirect, visited)));
       }
       return pCopy;
     }
@@ -578,38 +575,23 @@ FX_BOOL CPDF_Array::Identical(CPDF_Array* pOther) const {
   return TRUE;
 }
 CPDF_Dictionary::~CPDF_Dictionary() {
-  FX_POSITION pos = m_Map.GetStartPosition();
-  while (pos) {
-    if (CPDF_Object* value = static_cast<CPDF_Object*>(m_Map.GetNextValue(pos)))
-      value->Release();
-  }
-}
-FX_POSITION CPDF_Dictionary::GetStartPos() const {
-  return m_Map.GetStartPosition();
-}
-CPDF_Object* CPDF_Dictionary::GetNextElement(FX_POSITION& pos,
-                                             CFX_ByteString& key) const {
-  if (!pos) {
-    return NULL;
+  for (const auto& it : m_Map) {
+    it.second->Release();
   }
-  CPDF_Object* p;
-  m_Map.GetNextAssoc(pos, key, (void*&)p);
-  return p;
 }
 CPDF_Object* CPDF_Dictionary::GetElement(const CFX_ByteStringC& key) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
-  return p;
+  auto it = m_Map.find(key);
+  if (it == m_Map.end())
+    return nullptr;
+  return it->second;
 }
 CPDF_Object* CPDF_Dictionary::GetElementValue(
     const CFX_ByteStringC& key) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
-  return p ? p->GetDirect() : NULL;
+  CPDF_Object* p = GetElement(key);
+  return p ? p->GetDirect() : nullptr;
 }
 CFX_ByteString CPDF_Dictionary::GetString(const CFX_ByteStringC& key) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (p) {
     return p->GetString();
   }
@@ -617,8 +599,7 @@ CFX_ByteString CPDF_Dictionary::GetString(const CFX_ByteStringC& key) const {
 }
 CFX_ByteStringC CPDF_Dictionary::GetConstString(
     const CFX_ByteStringC& key) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (p) {
     return p->GetConstString();
   }
@@ -626,16 +607,14 @@ CFX_ByteStringC CPDF_Dictionary::GetConstString(
 }
 CFX_WideString CPDF_Dictionary::GetUnicodeText(const CFX_ByteStringC& key,
                                                CFX_CharMap* pCharMap) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (CPDF_Reference* pRef = ToReference(p))
     p = pRef->GetDirect();
   return p ? p->GetUnicodeText(pCharMap) : CFX_WideString();
 }
 CFX_ByteString CPDF_Dictionary::GetString(const CFX_ByteStringC& key,
                                           const CFX_ByteStringC& def) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (p) {
     return p->GetString();
   }
@@ -644,32 +623,28 @@ CFX_ByteString CPDF_Dictionary::GetString(const CFX_ByteStringC& key,
 CFX_ByteStringC CPDF_Dictionary::GetConstString(
     const CFX_ByteStringC& key,
     const CFX_ByteStringC& def) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (p) {
     return p->GetConstString();
   }
   return CFX_ByteStringC(def);
 }
 int CPDF_Dictionary::GetInteger(const CFX_ByteStringC& key) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (p) {
     return p->GetInteger();
   }
   return 0;
 }
 int CPDF_Dictionary::GetInteger(const CFX_ByteStringC& key, int def) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (p) {
     return p->GetInteger();
   }
   return def;
 }
 FX_FLOAT CPDF_Dictionary::GetNumber(const CFX_ByteStringC& key) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (p) {
     return p->GetNumber();
   }
@@ -677,8 +652,7 @@ FX_FLOAT CPDF_Dictionary::GetNumber(const CFX_ByteStringC& key) const {
 }
 FX_BOOL CPDF_Dictionary::GetBoolean(const CFX_ByteStringC& key,
                                     FX_BOOL bDefault) const {
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
+  CPDF_Object* p = GetElement(key);
   if (ToBoolean(p))
     return p->GetInteger();
   return bDefault;
@@ -714,67 +688,67 @@ CFX_Matrix CPDF_Dictionary::GetMatrix(const CFX_ByteStringC& key) const {
   return matrix;
 }
 FX_BOOL CPDF_Dictionary::KeyExist(const CFX_ByteStringC& key) const {
-  void* value;
-  return m_Map.Lookup(key, value);
+  return pdfium::ContainsKey(m_Map, key);
 }
 
 void CPDF_Dictionary::SetAt(const CFX_ByteStringC& key, CPDF_Object* pObj) {
   ASSERT(IsDictionary());
-  void* pValue = nullptr;
-  m_Map.Lookup(key, pValue);
-  CPDF_Object* pExisting = static_cast<CPDF_Object*>(pValue);
-  if (pExisting == pObj)
+  // Avoid 2 constructions of CFX_ByteString.
+  CFX_ByteString key_bytestring = key;
+  auto it = m_Map.find(key_bytestring);
+  if (it == m_Map.end()) {
+    if (pObj) {
+      m_Map.insert(std::make_pair(key_bytestring, pObj));
+    }
     return;
+  }
 
-  if (pExisting)
-    pExisting->Release();
+  if (it->second == pObj)
+    return;
+  it->second->Release();
 
   if (pObj)
-    m_Map.SetAt(key, pObj);
+    it->second = pObj;
   else
-    m_Map.RemoveKey(key);
-}
-
-void CPDF_Dictionary::AddValue(const CFX_ByteStringC& key, CPDF_Object* pObj) {
-  ASSERT(m_Type == PDFOBJ_DICTIONARY);
-  m_Map.AddValue(key, pObj);
+    m_Map.erase(it);
 }
 void CPDF_Dictionary::RemoveAt(const CFX_ByteStringC& key) {
   ASSERT(m_Type == PDFOBJ_DICTIONARY);
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(key, (void*&)p);
-  if (!p) {
+  auto it = m_Map.find(key);
+  if (it == m_Map.end())
     return;
-  }
-  p->Release();
-  m_Map.RemoveKey(key);
+
+  it->second->Release();
+  m_Map.erase(it);
 }
 void CPDF_Dictionary::ReplaceKey(const CFX_ByteStringC& oldkey,
                                  const CFX_ByteStringC& newkey) {
   ASSERT(m_Type == PDFOBJ_DICTIONARY);
-  CPDF_Object* p = NULL;
-  m_Map.Lookup(oldkey, (void*&)p);
-  if (!p) {
+  auto old_it = m_Map.find(oldkey);
+  if (old_it == m_Map.end())
     return;
+
+  // Avoid 2 constructions of CFX_ByteString.
+  CFX_ByteString newkey_bytestring = newkey;
+  auto new_it = m_Map.find(newkey_bytestring);
+  if (new_it != m_Map.end()) {
+    new_it->second->Release();
+    new_it->second = old_it->second;
+  } else {
+    m_Map.insert(std::make_pair(newkey_bytestring, old_it->second));
   }
-  m_Map.RemoveKey(oldkey);
-  m_Map.SetAt(newkey, p);
+  m_Map.erase(old_it);
 }
 FX_BOOL CPDF_Dictionary::Identical(CPDF_Dictionary* pOther) const {
   if (!pOther) {
     return FALSE;
   }
-  if (m_Map.GetCount() != pOther->m_Map.GetCount()) {
+  if (m_Map.size() != pOther->m_Map.size()) {
     return FALSE;
   }
-  FX_POSITION pos = m_Map.GetStartPosition();
-  while (pos) {
-    CFX_ByteString key;
-    void* value;
-    m_Map.GetNextAssoc(pos, key, value);
-    if (!value)
-      return FALSE;
-    if (!static_cast<CPDF_Object*>(value)->IsIdentical(pOther->GetElement(key)))
+  for (const auto& it : m_Map) {
+    const CFX_ByteString& key = it.first;
+    if (!it.second->IsIdentical(pOther->GetElement(key)))
       return FALSE;
   }
   return TRUE;
@@ -798,7 +772,7 @@ void CPDF_Dictionary::SetAtReference(const CFX_ByteStringC& key,
 void CPDF_Dictionary::AddReference(const CFX_ByteStringC& key,
                                    CPDF_IndirectObjects* pDoc,
                                    FX_DWORD objnum) {
-  AddValue(key, new CPDF_Reference(pDoc, objnum));
+  SetAt(key, new CPDF_Reference(pDoc, objnum));
 }
 void CPDF_Dictionary::SetAtNumber(const CFX_ByteStringC& key, FX_FLOAT f) {
   CPDF_Number* pNumber = new CPDF_Number;
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
index 236ecaa837..3ab4423172 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_parser.cpp
@@ -869,11 +869,9 @@ FX_BOOL CPDF_Parser::RebuildCrossRef() {
                       if (!pRoot ||
                           (pRef && IsValidObjectNumber(pRef->GetRefObjNum()) &&
                            m_ObjectInfo[pRef->GetRefObjNum()].pos != 0)) {
-                        FX_POSITION trailer_pos = pTrailer->GetStartPos();
-                        while (trailer_pos) {
-                          CFX_ByteString key;
-                          CPDF_Object* pElement =
-                              pTrailer->GetNextElement(trailer_pos, key);
+                        for (const auto& it : *pTrailer) {
+                          const CFX_ByteString& key = it.first;
+                          CPDF_Object* pElement = it.second;
                           FX_DWORD dwObjNum =
                               pElement ? pElement->GetObjNum() : 0;
                           if (dwObjNum) {
@@ -2162,13 +2160,7 @@ CPDF_Object* CPDF_SyntaxParser::GetObject(CPDF_IndirectObjects* pObjList,
         continue;
 
       CFX_ByteStringC keyNoSlash(key.c_str() + 1, key.GetLength() - 1);
-      // TODO(thestig): Remove this conditional once CPDF_Dictionary has a
-      // better underlying map implementation.
-      if (nKeys < 32) {
-        pDict->SetAt(keyNoSlash, pObj);
-      } else {
-        pDict->AddValue(keyNoSlash, pObj);
-      }
+      pDict->SetAt(keyNoSlash, pObj);
     }
 
     if (IsSignatureDict(pDict.get())) {
@@ -2315,8 +2307,8 @@ CPDF_Object* CPDF_SyntaxParser::GetObjectByStrict(
         return nullptr;
       }
       if (key.GetLength() > 1) {
-        pDict->AddValue(CFX_ByteStringC(key.c_str() + 1, key.GetLength() - 1),
-                        obj.release());
+        pDict->SetAt(CFX_ByteStringC(key.c_str() + 1, key.GetLength() - 1),
+                     obj.release());
       }
     }
     if (pContext) {
@@ -3058,11 +3050,9 @@ FX_BOOL CPDF_DataAvail::IsObjectsAvail(
         if (pDict && pDict->GetString("Type") == "Page" && !bParsePage) {
           continue;
         }
-        FX_POSITION pos = pDict->GetStartPos();
-        while (pos) {
-          CPDF_Object* value;
-          CFX_ByteString key;
-          value = pDict->GetNextElement(pos, key);
+        for (const auto& it : *pDict) {
+          const CFX_ByteString& key = it.first;
+          CPDF_Object* value = it.second;
           if (key != "Parent") {
             new_obj_array.Add(value);
           }
diff --git a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
index ec155a8d02..1abf665d65 100644
--- a/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
+++ b/core/src/fpdfapi/fpdf_parser/fpdf_parser_utility.cpp
@@ -383,10 +383,9 @@ CFX_ByteTextBuf& operator<<(CFX_ByteTextBuf& buf, const CPDF_Object* pObj) {
     case PDFOBJ_DICTIONARY: {
       const CPDF_Dictionary* p = pObj->AsDictionary();
       buf << "<<";
-      FX_POSITION pos = p->GetStartPos();
-      while (pos) {
-        CFX_ByteString key;
-        CPDF_Object* pValue = p->GetNextElement(pos, key);
+      for (const auto& it : *p) {
+        const CFX_ByteString& key = it.first;
+        CPDF_Object* pValue = it.second;
         buf << "/" << PDF_NameEncode(key);
         if (pValue && pValue->GetObjNum()) {
           buf << " " << pValue->GetObjNum() << " 0 R ";
diff --git a/core/src/fpdfdoc/doc_action.cpp b/core/src/fpdfdoc/doc_action.cpp
index e68a8c8a06..28d17cd673 100644
--- a/core/src/fpdfdoc/doc_action.cpp
+++ b/core/src/fpdfdoc/doc_action.cpp
@@ -257,37 +257,6 @@ CPDF_Action CPDF_AAction::GetAction(AActionType eType) const {
   }
   return CPDF_Action(m_pDict->GetDict(g_sAATypes[(int)eType]));
 }
-FX_POSITION CPDF_AAction::GetStartPos() const {
-  if (!m_pDict) {
-    return NULL;
-  }
-  return m_pDict->GetStartPos();
-}
-CPDF_Action CPDF_AAction::GetNextAction(FX_POSITION& pos,
-                                        AActionType& eType) const {
-  if (!m_pDict) {
-    return CPDF_Action();
-  }
-  CFX_ByteString csKey;
-  CPDF_Object* pObj = m_pDict->GetNextElement(pos, csKey);
-  if (!pObj) {
-    return CPDF_Action();
-  }
-  CPDF_Object* pDirect = pObj->GetDirect();
-  CPDF_Dictionary* pDict = ToDictionary(pDirect);
-  if (!pDict)
-    return CPDF_Action();
-
-  int i = 0;
-  while (g_sAATypes[i][0] != '\0') {
-    if (csKey == g_sAATypes[i]) {
-      break;
-    }
-    i++;
-  }
-  eType = (AActionType)i;
-  return CPDF_Action(pDict);
-}
 
 CPDF_DocJSActions::CPDF_DocJSActions(CPDF_Document* pDoc) : m_pDocument(pDoc) {}
 
diff --git a/core/src/fpdfdoc/doc_formcontrol.cpp b/core/src/fpdfdoc/doc_formcontrol.cpp
index 29d3211f30..6c3d1ec9c4 100644
--- a/core/src/fpdfdoc/doc_formcontrol.cpp
+++ b/core/src/fpdfdoc/doc_formcontrol.cpp
@@ -29,11 +29,9 @@ CFX_ByteString CPDF_FormControl::GetOnStateName() {
   if (!pN) {
     return csOn;
   }
-  FX_POSITION pos = pN->GetStartPos();
-  while (pos) {
-    pN->GetNextElement(pos, csOn);
-    if (csOn != "Off") {
-      return csOn;
+  for (const auto& it : *pN) {
+    if (it.first != "Off") {
+      return it.first;
     }
   }
   return CFX_ByteString();
@@ -56,10 +54,8 @@ void CPDF_FormControl::SetOnStateName(const CFX_ByteString& csOn) {
   if (!pAP) {
     return;
   }
-  FX_POSITION pos1 = pAP->GetStartPos();
-  while (pos1) {
-    CFX_ByteString csKey1;
-    CPDF_Object* pObj1 = pAP->GetNextElement(pos1, csKey1);
+  for (const auto& it : *pAP) {
+    CPDF_Object* pObj1 = it.second;
     if (!pObj1) {
       continue;
     }
@@ -68,10 +64,9 @@ void CPDF_FormControl::SetOnStateName(const CFX_ByteString& csOn) {
     if (!pSubDict)
       continue;
 
-    FX_POSITION pos2 = pSubDict->GetStartPos();
-    while (pos2) {
-      CFX_ByteString csKey2;
-      CPDF_Object* pObj2 = pSubDict->GetNextElement(pos2, csKey2);
+    for (const auto& subdict_it : *pSubDict) {
+      const CFX_ByteString& csKey2 = subdict_it.first;
+      CPDF_Object* pObj2 = subdict_it.second;
       if (!pObj2) {
         continue;
       }
diff --git a/core/src/fpdfdoc/doc_utils.cpp b/core/src/fpdfdoc/doc_utils.cpp
index 0f54198c6f..4856cb51e5 100644
--- a/core/src/fpdfdoc/doc_utils.cpp
+++ b/core/src/fpdfdoc/doc_utils.cpp
@@ -281,11 +281,8 @@ FX_DWORD CountInterFormFonts(CPDF_Dictionary* pFormDict) {
     return 0;
   }
   FX_DWORD dwCount = 0;
-  FX_POSITION pos = pFonts->GetStartPos();
-  while (pos) {
-    CPDF_Object* pObj = NULL;
-    CFX_ByteString csKey;
-    pObj = pFonts->GetNextElement(pos, csKey);
+  for (const auto& it : *pFonts) {
+    CPDF_Object* pObj = it.second;
     if (!pObj) {
       continue;
     }
@@ -313,11 +310,9 @@ CPDF_Font* GetInterFormFont(CPDF_Dictionary* pFormDict,
     return NULL;
   }
   FX_DWORD dwCount = 0;
-  FX_POSITION pos = pFonts->GetStartPos();
-  while (pos) {
-    CPDF_Object* pObj = NULL;
-    CFX_ByteString csKey;
-    pObj = pFonts->GetNextElement(pos, csKey);
+  for (const auto& it : *pFonts) {
+    const CFX_ByteString& csKey = it.first;
+    CPDF_Object* pObj = it.second;
     if (!pObj) {
       continue;
     }
@@ -373,11 +368,9 @@ CPDF_Font* GetInterFormFont(CPDF_Dictionary* pFormDict,
   if (!pFonts) {
     return NULL;
   }
-  FX_POSITION pos = pFonts->GetStartPos();
-  while (pos) {
-    CPDF_Object* pObj = NULL;
-    CFX_ByteString csKey;
-    pObj = pFonts->GetNextElement(pos, csKey);
+  for (const auto& it : *pFonts) {
+    const CFX_ByteString& csKey = it.first;
+    CPDF_Object* pObj = it.second;
     if (!pObj) {
       continue;
     }
@@ -416,11 +409,9 @@ CPDF_Font* GetNativeInterFormFont(CPDF_Dictionary* pFormDict,
   if (!pFonts) {
     return NULL;
   }
-  FX_POSITION pos = pFonts->GetStartPos();
-  while (pos) {
-    CPDF_Object* pObj = NULL;
-    CFX_ByteString csKey;
-    pObj = pFonts->GetNextElement(pos, csKey);
+  for (const auto& it : *pFonts) {
+    const CFX_ByteString& csKey = it.first;
+    CPDF_Object* pObj = it.second;
     if (!pObj) {
       continue;
     }
@@ -474,11 +465,9 @@ FX_BOOL FindInterFormFont(CPDF_Dictionary* pFormDict,
   if (!pFonts) {
     return FALSE;
   }
-  FX_POSITION pos = pFonts->GetStartPos();
-  while (pos) {
-    CPDF_Object* pObj = NULL;
-    CFX_ByteString csKey;
-    pObj = pFonts->GetNextElement(pos, csKey);
+  for (const auto& it : *pFonts) {
+    const CFX_ByteString& csKey = it.first;
+    CPDF_Object* pObj = it.second;
     if (!pObj) {
       continue;
     }
@@ -514,11 +503,9 @@ FX_BOOL FindInterFormFont(CPDF_Dictionary* pFormDict,
   if (csFontName.GetLength() > 0) {
     csFontName.Remove(' ');
   }
-  FX_POSITION pos = pFonts->GetStartPos();
-  while (pos) {
-    CPDF_Object* pObj = NULL;
-    CFX_ByteString csKey, csTmp;
-    pObj = pFonts->GetNextElement(pos, csKey);
+  for (const auto& it : *pFonts) {
+    const CFX_ByteString& csKey = it.first;
+    CPDF_Object* pObj = it.second;
     if (!pObj) {
       continue;
     }
diff --git a/fpdfsdk/src/formfiller/FFL_CBA_Fontmap.cpp b/fpdfsdk/src/formfiller/FFL_CBA_Fontmap.cpp
index 1649eaf35d..9253563c38 100644
--- a/fpdfsdk/src/formfiller/FFL_CBA_Fontmap.cpp
+++ b/fpdfsdk/src/formfiller/FFL_CBA_Fontmap.cpp
@@ -118,11 +118,9 @@ CPDF_Font* CBA_FontMap::FindResFontSameCharset(CPDF_Dictionary* pResDict,
 
   CPDF_Font* pFind = NULL;
 
-  FX_POSITION pos = pFonts->GetStartPos();
-  while (pos) {
-    CPDF_Object* pObj = NULL;
-    CFX_ByteString csKey;
-    pObj = pFonts->GetNextElement(pos, csKey);
+  for (const auto& it : *pFonts) {
+    const CFX_ByteString& csKey = it.first;
+    CPDF_Object* pObj = it.second;
     if (!pObj)
       continue;
 
diff --git a/fpdfsdk/src/fpdf_flatten.cpp b/fpdfsdk/src/fpdf_flatten.cpp
index 5c30b662c4..50d5036724 100644
--- a/fpdfsdk/src/fpdf_flatten.cpp
+++ b/fpdfsdk/src/fpdf_flatten.cpp
@@ -442,10 +442,9 @@ DLLEXPORT int STDCALL FPDFPage_Flatten(FPDF_PAGE page, int nFlag) {
       if (!sAnnotState.IsEmpty()) {
         pAPStream = pAPDic->GetStream(sAnnotState);
       } else {
-        FX_POSITION pos = pAPDic->GetStartPos();
-        if (pos) {
-          CFX_ByteString sKey;
-          CPDF_Object* pFirstObj = pAPDic->GetNextElement(pos, sKey);
+        auto it = pAPDic->begin();
+        if (it != pAPDic->end()) {
+          CPDF_Object* pFirstObj = it->second;
           if (pFirstObj) {
             if (pFirstObj->IsReference())
               pFirstObj = pFirstObj->GetDirect();
diff --git a/fpdfsdk/src/fpdf_transformpage.cpp b/fpdfsdk/src/fpdf_transformpage.cpp
index 3f6ab972c8..3e2c7b1151 100644
--- a/fpdfsdk/src/fpdf_transformpage.cpp
+++ b/fpdfsdk/src/fpdf_transformpage.cpp
@@ -160,14 +160,12 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFPage_TransFormWithClip(FPDF_PAGE page,
   if (pRes) {
     CPDF_Dictionary* pPattenDict = pRes->GetDict("Pattern");
     if (pPattenDict) {
-      FX_POSITION pos = pPattenDict->GetStartPos();
-      while (pos) {
-        CPDF_Dictionary* pDict = nullptr;
-        CFX_ByteString key;
-        CPDF_Object* pObj = pPattenDict->GetNextElement(pos, key);
+      for (const auto& it : *pPattenDict) {
+        CPDF_Object* pObj = it.second;
         if (pObj->IsReference())
           pObj = pObj->GetDirect();
 
+        CPDF_Dictionary* pDict = nullptr;
         if (pObj->IsDictionary())
           pDict = pObj->AsDictionary();
         else if (CPDF_Stream* pStream = pObj->AsStream())
diff --git a/fpdfsdk/src/fpdfedit_embeddertest.cpp b/fpdfsdk/src/fpdfedit_embeddertest.cpp
index 1cd28cff45..480ef51dbd 100644
--- a/fpdfsdk/src/fpdfedit_embeddertest.cpp
+++ b/fpdfsdk/src/fpdfedit_embeddertest.cpp
@@ -22,20 +22,21 @@ TEST_F(FPDFEditEmbeddertest, EmptyCreation) {
                   "%PDF-1.7\r\n"
                   "%\xA1\xB3\xC5\xD7\r\n"
                   "1 0 obj\r\n"
-                  "<</Type/Catalog/Pages 2 0 R >>\r\n"
+                  "<</Pages 2 0 R /Type/Catalog>>\r\n"
                   "endobj\r\n"
                   "2 0 obj\r\n"
-                  "<</Type/Pages/Count 1/Kids\\[ 4 0 R \\]>>\r\n"
+                  "<</Count 1/Kids\\[ 4 0 R \\]/Type/Pages>>\r\n"
                   "endobj\r\n"
                   "3 0 obj\r\n"
                   "<</CreationDate\\(D:.*\\)/Creator\\(PDFium\\)>>\r\n"
                   "endobj\r\n"
                   "4 0 obj\r\n"
-                  "<</Type/Page/Parent 2 0 R /MediaBox\\[ 0 0 640 "
-                  "480\\]/Rotate 0/Resources<<>>/Contents 5 0 R >>\r\n"
+                  "<</Contents 5 0 R /MediaBox\\[ 0 0 640 480\\]"
+                  "/Parent 2 0 R /Resources<<>>/Rotate 0/Type/Page"
+                  ">>\r\n"
                   "endobj\r\n"
                   "5 0 obj\r\n"
-                  "<</Length 8/Filter/FlateDecode>>stream\r\n"
+                  "<</Filter/FlateDecode/Length 8>>stream\r\n"
                   "x\x9C\x3\0\0\0\0\x1\r\n"
                   "endstream\r\n"
                   "endobj\r\n"
diff --git a/fpdfsdk/src/fpdfppo.cpp b/fpdfsdk/src/fpdfppo.cpp
index 50ef262560..dac548131e 100644
--- a/fpdfsdk/src/fpdfppo.cpp
+++ b/fpdfsdk/src/fpdfppo.cpp
@@ -101,10 +101,9 @@ FX_BOOL CPDF_PageOrganizer::ExportPage(CPDF_Document* pSrcPDFDoc,
       return FALSE;
 
     // Clone the page dictionary
-    FX_POSITION SrcPos = pSrcPageDict->GetStartPos();
-    while (SrcPos) {
-      CFX_ByteString cbSrcKeyStr;
-      CPDF_Object* pObj = pSrcPageDict->GetNextElement(SrcPos, cbSrcKeyStr);
+    for (const auto& it : *pSrcPageDict) {
+      const CFX_ByteString& cbSrcKeyStr = it.first;
+      CPDF_Object* pObj = it.second;
       if (cbSrcKeyStr.Compare(("Type")) && cbSrcKeyStr.Compare(("Parent"))) {
         if (pCurPageDict->KeyExist(cbSrcKeyStr))
           pCurPageDict->RemoveAt(cbSrcKeyStr);
@@ -214,11 +213,9 @@ FX_BOOL CPDF_PageOrganizer::UpdateReference(CPDF_Object* pObj,
     }
     case PDFOBJ_DICTIONARY: {
       CPDF_Dictionary* pDict = pObj->AsDictionary();
-
-      FX_POSITION pos = pDict->GetStartPos();
-      while (pos) {
-        CFX_ByteString key("");
-        CPDF_Object* pNextObj = pDict->GetNextElement(pos, key);
+      for (const auto& it : *pDict) {
+        const CFX_ByteString& key = it.first;
+        CPDF_Object* pNextObj = it.second;
         if (!FXSYS_strcmp(key, "Parent") || !FXSYS_strcmp(key, "Prev") ||
             !FXSYS_strcmp(key, "First")) {
           continue;
diff --git a/fpdfsdk/src/fpdfview.cpp b/fpdfsdk/src/fpdfview.cpp
index 041adda21f..e59515a863 100644
--- a/fpdfsdk/src/fpdfview.cpp
+++ b/fpdfsdk/src/fpdfview.cpp
@@ -827,11 +827,15 @@ DLLEXPORT FPDF_DWORD STDCALL FPDF_CountNamedDests(FPDF_DOCUMENT document) {
     return 0;
 
   CPDF_NameTree nameTree(pDoc, "Dests");
-  int count = nameTree.GetCount();
+  pdfium::base::CheckedNumeric<FPDF_DWORD> count = nameTree.GetCount();
   CPDF_Dictionary* pDest = pRoot->GetDict("Dests");
   if (pDest)
     count += pDest->GetCount();
-  return count;
+
+  if (!count.IsValid())
+    return 0;
+
+  return count.ValueOrDie();
 }
 
 DLLEXPORT FPDF_DEST STDCALL FPDF_GetNamedDestByName(FPDF_DOCUMENT document,
@@ -865,21 +869,25 @@ DLLEXPORT FPDF_DEST STDCALL FPDF_GetNamedDest(FPDF_DOCUMENT document,
   if (!pRoot)
     return nullptr;
 
-  CPDF_Object* pDestObj = NULL;
+  CPDF_Object* pDestObj = nullptr;
   CFX_ByteString bsName;
   CPDF_NameTree nameTree(pDoc, "Dests");
   int count = nameTree.GetCount();
   if (index >= count) {
     CPDF_Dictionary* pDest = pRoot->GetDict("Dests");
     if (!pDest)
-      return NULL;
-    if (index >= count + pDest->GetCount())
-      return NULL;
+      return nullptr;
+
+    pdfium::base::CheckedNumeric<int> checked_count = count;
+    checked_count += pDest->GetCount();
+    if (!checked_count.IsValid() || index >= checked_count.ValueOrDie())
+      return nullptr;
+
     index -= count;
-    FX_POSITION pos = pDest->GetStartPos();
     int i = 0;
-    while (pos) {
-      pDestObj = pDest->GetNextElement(pos, bsName);
+    for (const auto& it : *pDest) {
+      bsName = it.first;
+      pDestObj = it.second;
       if (!pDestObj)
         continue;
       if (i == index)
diff --git a/fpdfsdk/src/javascript/Document.cpp b/fpdfsdk/src/javascript/Document.cpp
index db98fcc5e4..1040c34770 100644
--- a/fpdfsdk/src/javascript/Document.cpp
+++ b/fpdfsdk/src/javascript/Document.cpp
@@ -790,10 +790,9 @@ FX_BOOL Document::info(IJS_Context* cc,
     FXJS_PutObjectString(isolate, pObj, L"Trapped", cwTrapped.c_str());
 
     // It's to be compatible to non-standard info dictionary.
-    FX_POSITION pos = pDictionary->GetStartPos();
-    while (pos) {
-      CFX_ByteString bsKey;
-      CPDF_Object* pValueObj = pDictionary->GetNextElement(pos, bsKey);
+    for (const auto& it : *pDictionary) {
+      const CFX_ByteString& bsKey = it.first;
+      CPDF_Object* pValueObj = it.second;
       CFX_WideString wsKey = CFX_WideString::FromUTF8(bsKey, bsKey.GetLength());
 
       if (pValueObj->IsString() || pValueObj->IsName()) {