Remove GetAt from string classes

This method duplicates the behaviour of the const [] operator and
doesn't offer any additional safety. Folding them into one
implementation.

SetAt is retained, since implementing the non-const [] operator to
replace SetAt has potential performance concerns. Specifically many
non-obvious cases of reading an element using [] will cause a realloc
& copy.

BUG=pdfium:860

Change-Id: I3ef5e5e5a15376f040256b646eb0d90636e24b67
Reviewed-on: https://pdfium-review.googlesource.com/10870
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>

9 files changed, 21 insertions, 22 deletions

diff --git a/xfa/fxfa/parser/cxfa_dataexporter.cpp b/xfa/fxfa/parser/cxfa_dataexporter.cpp
index ff9e981e9f..b502bbdfa7 100644
--- a/xfa/fxfa/parser/cxfa_dataexporter.cpp
+++ b/xfa/fxfa/parser/cxfa_dataexporter.cpp
@@ -58,7 +58,7 @@ CFX_WideString ExportEncodeContent(const CFX_WideStringC& str) {
   CFX_WideTextBuf textBuf;
   int32_t iLen = str.GetLength();
   for (int32_t i = 0; i < iLen; i++) {
-    wchar_t ch = str.GetAt(i);
+    wchar_t ch = str[i];
     if (!IsXMLValidChar(ch))
       continue;
 
@@ -73,13 +73,13 @@ CFX_WideString ExportEncodeContent(const CFX_WideStringC& str) {
     } else if (ch == '\"') {
       textBuf << L"&quot;";
     } else if (ch == ' ') {
-      if (i && str.GetAt(i - 1) != ' ') {
+      if (i && str[i - 1] != ' ') {
         textBuf.AppendChar(' ');
       } else {
         textBuf << L"&#x20;";
       }
     } else {
-      textBuf.AppendChar(str.GetAt(i));
+      textBuf.AppendChar(str[i]);
     }
   }
   return textBuf.MakeString();
diff --git a/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp b/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
index 55851bb34a..e643bc502f 100644
--- a/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
+++ b/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
@@ -160,7 +160,7 @@ CXFA_Node* ResolveBreakTarget(CXFA_Node* pPageSetRoot,
       return nullptr;
 
     bTargetAllFind = false;
-    if (wsExpr.GetAt(0) == '#') {
+    if (wsExpr[0] == '#') {
       CXFA_Node* pNode = pDocument->GetNodeByID(
           ToNode(pDocument->GetXFAObject(XFA_HASHCODE_Template)),
           wsExpr.Right(wsExpr.GetLength() - 1).AsStringC());
diff --git a/xfa/fxfa/parser/cxfa_localemgr.cpp b/xfa/fxfa/parser/cxfa_localemgr.cpp
index 633f4b41fd..833f72c33f 100644
--- a/xfa/fxfa/parser/cxfa_localemgr.cpp
+++ b/xfa/fxfa/parser/cxfa_localemgr.cpp
@@ -1083,10 +1083,9 @@ static uint16_t XFA_GetLanguage(CFX_WideString wsLanguage) {
     return FX_LANG_en_US;
 
   wsLanguage.MakeLower();
-  uint32_t dwIDFirst = wsLanguage.GetAt(0) << 8 | wsLanguage.GetAt(1);
-  uint32_t dwIDSecond = wsLanguage.GetLength() >= 5
-                            ? wsLanguage.GetAt(3) << 8 | wsLanguage.GetAt(4)
-                            : 0;
+  uint32_t dwIDFirst = wsLanguage[0] << 8 | wsLanguage[1];
+  uint32_t dwIDSecond =
+      wsLanguage.GetLength() >= 5 ? wsLanguage[3] << 8 | wsLanguage[4] : 0;
   switch (dwIDFirst) {
     case FXBSTR_ID(0, 0, 'z', 'h'):
       if (dwIDSecond == FXBSTR_ID(0, 0, 'c', 'n'))
diff --git a/xfa/fxfa/parser/cxfa_measurement.cpp b/xfa/fxfa/parser/cxfa_measurement.cpp
index 66b715ec38..1c427209f9 100644
--- a/xfa/fxfa/parser/cxfa_measurement.cpp
+++ b/xfa/fxfa/parser/cxfa_measurement.cpp
@@ -37,7 +37,7 @@ void CXFA_Measurement::SetString(const CFX_WideStringC& wsMeasure) {
     return;
   }
   int32_t iUsedLen = 0;
-  int32_t iOffset = (wsMeasure.GetAt(0) == L'=') ? 1 : 0;
+  int32_t iOffset = (wsMeasure[0] == L'=') ? 1 : 0;
   float fValue = FXSYS_wcstof(wsMeasure.unterminated_c_str() + iOffset,
                               wsMeasure.GetLength() - iOffset, &iUsedLen);
   XFA_UNIT eUnit = GetUnitFromString(
diff --git a/xfa/fxfa/parser/cxfa_node.cpp b/xfa/fxfa/parser/cxfa_node.cpp
index 8497e60a74..2b4bdd22c0 100644
--- a/xfa/fxfa/parser/cxfa_node.cpp
+++ b/xfa/fxfa/parser/cxfa_node.cpp
@@ -76,7 +76,7 @@ int32_t GetCount(CXFA_Node* pInstMgrNode) {
     if (iCount == 0) {
       CFX_WideStringC wsName = pNode->GetCData(XFA_ATTRIBUTE_Name);
       CFX_WideStringC wsInstName = pInstMgrNode->GetCData(XFA_ATTRIBUTE_Name);
-      if (wsInstName.GetLength() < 1 || wsInstName.GetAt(0) != '_' ||
+      if (wsInstName.GetLength() < 1 || wsInstName[0] != '_' ||
           wsInstName.Right(wsInstName.GetLength() - 1) != wsName) {
         return iCount;
       }
@@ -197,7 +197,7 @@ CXFA_Node* GetItem(CXFA_Node* pInstMgrNode, int32_t iIndex) {
     if (iCount == 0) {
       CFX_WideStringC wsName = pNode->GetCData(XFA_ATTRIBUTE_Name);
       CFX_WideStringC wsInstName = pInstMgrNode->GetCData(XFA_ATTRIBUTE_Name);
-      if (wsInstName.GetLength() < 1 || wsInstName.GetAt(0) != '_' ||
+      if (wsInstName.GetLength() < 1 || wsInstName[0] != '_' ||
           wsInstName.Right(wsInstName.GetLength() - 1) != wsName) {
         return nullptr;
       }
@@ -406,7 +406,7 @@ void StrToRGB(const CFX_WideString& strRGB,
   int32_t iIndex = 0;
   int32_t iLen = strRGB.GetLength();
   for (int32_t i = 0; i < iLen; ++i) {
-    wchar_t ch = strRGB.GetAt(i);
+    wchar_t ch = strRGB[i];
     if (ch == L',')
       ++iIndex;
     if (iIndex > 2)
@@ -2736,7 +2736,7 @@ void CXFA_Node::Script_Subform_InstanceManager(CFXJSE_Value* pValue,
        pNode = pNode->GetNodeItem(XFA_NODEITEM_PrevSibling)) {
     if (pNode->GetElementType() == XFA_Element::InstanceManager) {
       CFX_WideStringC wsInstMgrName = pNode->GetCData(XFA_ATTRIBUTE_Name);
-      if (wsInstMgrName.GetLength() >= 1 && wsInstMgrName.GetAt(0) == '_' &&
+      if (wsInstMgrName.GetLength() >= 1 && wsInstMgrName[0] == '_' &&
           wsInstMgrName.Right(wsInstMgrName.GetLength() - 1) == wsName) {
         pInstanceMgr = pNode;
       }
@@ -4664,7 +4664,7 @@ CXFA_Node* CXFA_Node::GetInstanceMgrOfSubform() {
       if (eType == XFA_Element::InstanceManager) {
         CFX_WideStringC wsName = GetCData(XFA_ATTRIBUTE_Name);
         CFX_WideStringC wsInstName = pNode->GetCData(XFA_ATTRIBUTE_Name);
-        if (wsInstName.GetLength() > 0 && wsInstName.GetAt(0) == '_' &&
+        if (wsInstName.GetLength() > 0 && wsInstName[0] == '_' &&
             wsInstName.Right(wsInstName.GetLength() - 1) == wsName) {
           pInstanceMgr = pNode;
         }
diff --git a/xfa/fxfa/parser/cxfa_nodehelper.cpp b/xfa/fxfa/parser/cxfa_nodehelper.cpp
index 547831caca..4f1ed04fe3 100644
--- a/xfa/fxfa/parser/cxfa_nodehelper.cpp
+++ b/xfa/fxfa/parser/cxfa_nodehelper.cpp
@@ -283,7 +283,7 @@ bool CXFA_NodeHelper::CreateNode_ForCondition(CFX_WideString& wsCondition) {
     m_iCreateFlag = XFA_RESOLVENODE_RSTYPE_CreateNodeOne;
     return false;
   }
-  if (wsCondition.GetAt(0) == '[') {
+  if (wsCondition[0] == '[') {
     int32_t i = 1;
     for (; i < iLen; ++i) {
       wchar_t ch = wsCondition[i];
@@ -323,12 +323,12 @@ bool CXFA_NodeHelper::ResolveNodes_CreateNode(
   }
   bool bIsClassName = false;
   bool bResult = false;
-  if (wsName.GetAt(0) == '!') {
+  if (wsName[0] == '!') {
     wsName = wsName.Right(wsName.GetLength() - 1);
     m_pCreateParent = ToNode(
         pScriptContext->GetDocument()->GetXFAObject(XFA_HASHCODE_Datasets));
   }
-  if (wsName.GetAt(0) == '#') {
+  if (wsName[0] == '#') {
     bIsClassName = true;
     wsName = wsName.Right(wsName.GetLength() - 1);
   }
diff --git a/xfa/fxfa/parser/cxfa_resolveprocessor.cpp b/xfa/fxfa/parser/cxfa_resolveprocessor.cpp
index 93b2d86061..9edb3bce81 100644
--- a/xfa/fxfa/parser/cxfa_resolveprocessor.cpp
+++ b/xfa/fxfa/parser/cxfa_resolveprocessor.cpp
@@ -41,7 +41,7 @@ int32_t CXFA_ResolveProcessor::Resolve(CXFA_ResolveNodesData& rnd) {
   if (rnd.m_dwStyles & XFA_RESOLVENODE_AnyChild) {
     return ResolveAnyChild(rnd);
   }
-  wchar_t wch = rnd.m_wsName.GetAt(0);
+  wchar_t wch = rnd.m_wsName[0];
   switch (wch) {
     case '$':
       return ResolveDollar(rnd);
@@ -89,7 +89,7 @@ int32_t CXFA_ResolveProcessor::ResolveAnyChild(CXFA_ResolveNodesData& rnd) {
   CFX_WideString wsCondition = rnd.m_wsCondition;
   CXFA_Node* findNode = nullptr;
   bool bClassName = false;
-  if (wsName.GetAt(0) == '#') {
+  if (wsName[0] == '#') {
     bClassName = true;
     wsName = wsName.Right(wsName.GetLength() - 1);
   }
diff --git a/xfa/fxfa/parser/cxfa_scriptcontext.cpp b/xfa/fxfa/parser/cxfa_scriptcontext.cpp
index 115cd5651e..57caa9981b 100644
--- a/xfa/fxfa/parser/cxfa_scriptcontext.cpp
+++ b/xfa/fxfa/parser/cxfa_scriptcontext.cpp
@@ -340,7 +340,7 @@ void CXFA_ScriptContext::NormalPropertySetter(CFXJSE_Value* pOriginalValue,
         pReturnValue, true, (XFA_ATTRIBUTE)lpAttributeInfo->eAttribute);
   } else {
     if (pObject->IsNode()) {
-      if (wsPropName.GetAt(0) == '#') {
+      if (wsPropName[0] == '#') {
         wsPropName = wsPropName.Right(wsPropName.GetLength() - 1);
       }
       CXFA_Node* pNode = ToNode(pObject);
diff --git a/xfa/fxfa/parser/cxfa_widgetdata.cpp b/xfa/fxfa/parser/cxfa_widgetdata.cpp
index d68a907e18..5b9f62c93f 100644
--- a/xfa/fxfa/parser/cxfa_widgetdata.cpp
+++ b/xfa/fxfa/parser/cxfa_widgetdata.cpp
@@ -1215,7 +1215,7 @@ bool CXFA_WidgetData::GetBarcodeAttribute_StartChar(char* val) {
   CFX_WideStringC wsStartEndChar;
   if (pUIChild->TryCData(XFA_ATTRIBUTE_StartChar, wsStartEndChar)) {
     if (wsStartEndChar.GetLength()) {
-      *val = static_cast<char>(wsStartEndChar.GetAt(0));
+      *val = static_cast<char>(wsStartEndChar[0]);
       return true;
     }
   }
@@ -1227,7 +1227,7 @@ bool CXFA_WidgetData::GetBarcodeAttribute_EndChar(char* val) {
   CFX_WideStringC wsStartEndChar;
   if (pUIChild->TryCData(XFA_ATTRIBUTE_EndChar, wsStartEndChar)) {
     if (wsStartEndChar.GetLength()) {
-      *val = static_cast<char>(wsStartEndChar.GetAt(0));
+      *val = static_cast<char>(wsStartEndChar[0]);
       return true;
     }
   }