Convert string Find methods to return an Optional

The Find and ReverseFind methods for WideString, WideStringC,
ByteString, and ByteStringC have been converted from returning a raw
FX_STRSIZE, to returning Optional<FX_STRSIZE>, so that success/failure
can be indicated without using FX_STRNPOS.

This allows for removing FX_STRNPOS and by association makes the
conversion of FX_STRSIZE to size_t easier, since it forces checking
the return value of Find to be explictly done as well as taking the
error value out of the range of FX_STRSIZE.

New Contains methods have been added for cases where the success or
failure is all the call site to Find cared about, and the actual
position was ignored.

BUG=pdfium:828


Change-Id: Id827e508c8660affa68cc08a13d96121369364b7
Reviewed-on: https://pdfium-review.googlesource.com/11350
Commit-Queue: Ryan Harrison <rharrison@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

7 files changed, 74 insertions, 69 deletions

diff --git a/xfa/fxfa/parser/cxfa_dataexporter.cpp b/xfa/fxfa/parser/cxfa_dataexporter.cpp
index b502bbdfa7..05586e12dd 100644
--- a/xfa/fxfa/parser/cxfa_dataexporter.cpp
+++ b/xfa/fxfa/parser/cxfa_dataexporter.cpp
@@ -226,14 +226,14 @@ void RegenerateFormFile_Changed(CXFA_Node* pNode,
 
         std::vector<CFX_WideString> wsSelTextArray;
         FX_STRSIZE iStart = 0;
-        FX_STRSIZE iEnd = wsRawValue.Find(L'\n', iStart);
-        iEnd = (iEnd == FX_STRNPOS) ? wsRawValue.GetLength() : iEnd;
-        while (iEnd != FX_STRNPOS && iEnd >= iStart) {
-          wsSelTextArray.push_back(wsRawValue.Mid(iStart, iEnd - iStart));
-          iStart = iEnd + 1;
+        auto iEnd = wsRawValue.Find(L'\n', iStart);
+        iEnd = !iEnd.has_value() ? wsRawValue.GetLength() : iEnd;
+        while (iEnd.has_value() && iEnd >= iStart) {
+          wsSelTextArray.push_back(
+              wsRawValue.Mid(iStart, iEnd.value() - iStart));
+          iStart = iEnd.value() + 1;
           if (iStart >= wsRawValue.GetLength())
             break;
-
           iEnd = wsRawValue.Find(L'\n', iStart);
         }
         CXFA_Node* pParentNode = pNode->GetNodeItem(XFA_NODEITEM_Parent);
diff --git a/xfa/fxfa/parser/cxfa_document.cpp b/xfa/fxfa/parser/cxfa_document.cpp
index f43deaf145..85d2758467 100644
--- a/xfa/fxfa/parser/cxfa_document.cpp
+++ b/xfa/fxfa/parser/cxfa_document.cpp
@@ -305,15 +305,17 @@ XFA_VERSION CXFA_Document::RecognizeXFAVersionNumber(
       wsTemplateURIPrefix) {
     return XFA_VERSION_UNKNOWN;
   }
-  FX_STRSIZE nDotPos = wsTemplateNS.Find('.', nPrefixLength);
-  if (nDotPos == FX_STRNPOS)
+  auto nDotPos = wsTemplateNS.Find('.', nPrefixLength);
+  if (!nDotPos.has_value())
     return XFA_VERSION_UNKNOWN;
 
   int8_t iMajor = FXSYS_wtoi(
-      wsTemplateNS.Mid(nPrefixLength, nDotPos - nPrefixLength).c_str());
-  int8_t iMinor = FXSYS_wtoi(
-      wsTemplateNS.Mid(nDotPos + 1, wsTemplateNS.GetLength() - nDotPos - 2)
-          .c_str());
+      wsTemplateNS.Mid(nPrefixLength, nDotPos.value() - nPrefixLength).c_str());
+  int8_t iMinor =
+      FXSYS_wtoi(wsTemplateNS
+                     .Mid(nDotPos.value() + 1,
+                          wsTemplateNS.GetLength() - nDotPos.value() - 2)
+                     .c_str());
   XFA_VERSION eVersion = (XFA_VERSION)((int32_t)iMajor * 100 + iMinor);
   if (eVersion < XFA_VERSION_MIN || eVersion > XFA_VERSION_MAX)
     return XFA_VERSION_UNKNOWN;
@@ -367,20 +369,21 @@ void CXFA_Document::DoProtoMerge() {
     CFX_WideStringC wsURI, wsID, wsSOM;
     if (pUseHrefNode->TryCData(XFA_ATTRIBUTE_Usehref, wsUseVal) &&
         !wsUseVal.IsEmpty()) {
-      FX_STRSIZE uSharpPos = wsUseVal.Find('#');
-      if (uSharpPos == FX_STRNPOS) {
+      auto uSharpPos = wsUseVal.Find('#');
+      if (!uSharpPos.has_value()) {
         wsURI = wsUseVal.AsStringC();
       } else {
-        wsURI = CFX_WideStringC(wsUseVal.c_str(), uSharpPos);
+        wsURI = CFX_WideStringC(wsUseVal.c_str(), uSharpPos.value());
         FX_STRSIZE uLen = wsUseVal.GetLength();
-        if (uLen >= uSharpPos + 5 &&
-            CFX_WideStringC(wsUseVal.c_str() + uSharpPos, 5) == L"#som(" &&
+        if (uLen >= uSharpPos.value() + 5 &&
+            CFX_WideStringC(wsUseVal.c_str() + uSharpPos.value(), 5) ==
+                L"#som(" &&
             wsUseVal[uLen - 1] == ')') {
-          wsSOM = CFX_WideStringC(wsUseVal.c_str() + uSharpPos + 5,
-                                  uLen - 1 - uSharpPos - 5);
+          wsSOM = CFX_WideStringC(wsUseVal.c_str() + uSharpPos.value() + 5,
+                                  uLen - 1 - uSharpPos.value() - 5);
         } else {
-          wsID = CFX_WideStringC(wsUseVal.c_str() + uSharpPos + 1,
-                                 uLen - uSharpPos - 1);
+          wsID = CFX_WideStringC(wsUseVal.c_str() + uSharpPos.value() + 1,
+                                 uLen - uSharpPos.value() - 1);
         }
       }
     } else if (pUseHrefNode->TryCData(XFA_ATTRIBUTE_Use, wsUseVal) &&
diff --git a/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp b/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
index e643bc502f..b02efbb45d 100644
--- a/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
+++ b/xfa/fxfa/parser/cxfa_layoutpagemgr.cpp
@@ -148,11 +148,13 @@ CXFA_Node* ResolveBreakTarget(CXFA_Node* pPageSetRoot,
   bool bTargetAllFind = true;
   while (iSplitIndex != -1) {
     CFX_WideString wsExpr;
-    FX_STRSIZE iSplitNextIndex = 0;
+    pdfium::Optional<FX_STRSIZE> iSplitNextIndex = 0;
     if (!bTargetAllFind) {
       iSplitNextIndex = wsTargetAll.Find(' ', iSplitIndex);
-      ASSERT(iSplitNextIndex != FX_STRNPOS);
-      wsExpr = wsTargetAll.Mid(iSplitIndex, iSplitNextIndex - iSplitIndex);
+      if (!iSplitNextIndex.has_value())
+        return nullptr;
+      wsExpr =
+          wsTargetAll.Mid(iSplitIndex, iSplitNextIndex.value() - iSplitIndex);
     } else {
       wsExpr = wsTargetAll;
     }
@@ -180,7 +182,7 @@ CXFA_Node* ResolveBreakTarget(CXFA_Node* pPageSetRoot,
       if (iCount > 0 && rs.objects.front()->IsNode())
         return rs.objects.front()->AsNode();
     }
-    iSplitIndex = iSplitNextIndex;
+    iSplitIndex = iSplitNextIndex.value();
   }
   return nullptr;
 }
diff --git a/xfa/fxfa/parser/cxfa_localevalue.cpp b/xfa/fxfa/parser/cxfa_localevalue.cpp
index aa0f74b170..dd56e6d7a1 100644
--- a/xfa/fxfa/parser/cxfa_localevalue.cpp
+++ b/xfa/fxfa/parser/cxfa_localevalue.cpp
@@ -49,14 +49,14 @@ bool ValueSplitDateTime(const CFX_WideString& wsDateTime,
   if (wsDateTime.IsEmpty())
     return false;
 
-  FX_STRSIZE nSplitIndex = wsDateTime.Find('T');
-  if (nSplitIndex == FX_STRNPOS)
+  auto nSplitIndex = wsDateTime.Find('T');
+  if (!nSplitIndex.has_value())
     nSplitIndex = wsDateTime.Find(' ');
-  if (nSplitIndex == FX_STRNPOS)
+  if (!nSplitIndex.has_value())
     return false;
 
-  wsDate = wsDateTime.Left(nSplitIndex);
-  wsTime = wsDateTime.Right(wsDateTime.GetLength() - nSplitIndex - 1);
+  wsDate = wsDateTime.Left(nSplitIndex.value());
+  wsTime = wsDateTime.Right(wsDateTime.GetLength() - nSplitIndex.value() - 1);
   return true;
 }
 
@@ -444,7 +444,7 @@ bool CXFA_LocaleValue::ValidateCanonicalDate(const CFX_WideString& wsDate,
   if (nLen < wCountY || nLen > wCountY + wCountM + wCountD + 2)
     return false;
 
-  const bool bSymbol = wsDate.Find(0x2D) != FX_STRNPOS;
+  const bool bSymbol = wsDate.Contains(0x2D);
   uint16_t wYear = 0;
   uint16_t wMonth = 0;
   uint16_t wDay = 0;
@@ -519,7 +519,7 @@ bool CXFA_LocaleValue::ValidateCanonicalTime(const CFX_WideString& wsTime) {
   const uint16_t wCountM = 2;
   const uint16_t wCountS = 2;
   const uint16_t wCountF = 3;
-  const bool bSymbol = wsTime.Find(':') != FX_STRNPOS;
+  const bool bSymbol = wsTime.Contains(':');
   uint16_t wHour = 0;
   uint16_t wMinute = 0;
   uint16_t wSecond = 0;
@@ -558,8 +558,8 @@ bool CXFA_LocaleValue::ValidateCanonicalTime(const CFX_WideString& wsTime) {
     wSecond = pTime[nIndex] - '0' + wSecond * 10;
     nIndex++;
   }
-  FX_STRSIZE ret = wsTime.Find('.');
-  if (ret && ret != FX_STRNPOS) {
+  auto pos = wsTime.Find('.');
+  if (pos.has_value() && pos.value() != 0) {
     if (pTime[nIndex] != '.')
       return false;
     nIndex++;
diff --git a/xfa/fxfa/parser/cxfa_node.cpp b/xfa/fxfa/parser/cxfa_node.cpp
index 2b4bdd22c0..eea7fb2489 100644
--- a/xfa/fxfa/parser/cxfa_node.cpp
+++ b/xfa/fxfa/parser/cxfa_node.cpp
@@ -4045,16 +4045,17 @@ bool CXFA_Node::SetScriptContent(const CFX_WideString& wsContent,
           if (!wsContent.IsEmpty()) {
             FX_STRSIZE iStart = 0;
             FX_STRSIZE iLength = wsContent.GetLength();
-            FX_STRSIZE iEnd = wsContent.Find(L'\n', iStart);
-            iEnd = (iEnd == FX_STRNPOS) ? iLength : iEnd;
-            while (iEnd >= iStart) {
-              wsSaveTextArray.push_back(wsContent.Mid(iStart, iEnd - iStart));
-              iStart = iEnd + 1;
+            auto iEnd = wsContent.Find(L'\n', iStart);
+            iEnd = !iEnd.has_value() ? iLength : iEnd;
+            while (iEnd.value() >= iStart) {
+              wsSaveTextArray.push_back(
+                  wsContent.Mid(iStart, iEnd.value() - iStart));
+              iStart = iEnd.value() + 1;
               if (iStart >= iLength) {
                 break;
               }
               iEnd = wsContent.Find(L'\n', iStart);
-              if (iEnd == FX_STRNPOS) {
+              if (!iEnd.has_value()) {
                 wsSaveTextArray.push_back(
                     wsContent.Mid(iStart, iLength - iStart));
               }
diff --git a/xfa/fxfa/parser/cxfa_simple_parser.cpp b/xfa/fxfa/parser/cxfa_simple_parser.cpp
index 39dc858b9e..ee2a2444fc 100644
--- a/xfa/fxfa/parser/cxfa_simple_parser.cpp
+++ b/xfa/fxfa/parser/cxfa_simple_parser.cpp
@@ -92,12 +92,12 @@ bool MatchNodeName(CFX_XMLNode* pNode,
 bool GetAttributeLocalName(const CFX_WideStringC& wsAttributeName,
                            CFX_WideString& wsLocalAttrName) {
   CFX_WideString wsAttrName(wsAttributeName);
-  FX_STRSIZE iFind = wsAttrName.Find(L':', 0);
-  if (iFind == FX_STRNPOS) {
+  auto pos = wsAttrName.Find(L':', 0);
+  if (!pos.has_value()) {
     wsLocalAttrName = wsAttrName;
     return false;
   }
-  wsLocalAttrName = wsAttrName.Right(wsAttrName.GetLength() - iFind - 1);
+  wsLocalAttrName = wsAttrName.Right(wsAttrName.GetLength() - pos.value() - 1);
   return true;
 }
 
@@ -133,17 +133,17 @@ bool FindAttributeWithNS(CFX_XMLElement* pElement,
 
   CFX_WideString wsAttrNS;
   for (auto it : pElement->GetAttributes()) {
-    FX_STRSIZE iFind = it.first.Find(L':', 0);
+    auto pos = it.first.Find(L':', 0);
     CFX_WideString wsNSPrefix;
-    if (iFind == FX_STRNPOS) {
+    if (!pos.has_value()) {
       if (wsLocalAttributeName != it.first)
         continue;
     } else {
       if (wsLocalAttributeName !=
-          it.first.Right(it.first.GetLength() - iFind - 1)) {
+          it.first.Right(it.first.GetLength() - pos.value() - 1)) {
         continue;
       }
-      wsNSPrefix = it.first.Left(iFind);
+      wsNSPrefix = it.first.Left(pos.value());
     }
 
     if (!XFA_FDEExtension_ResolveNamespaceQualifier(
diff --git a/xfa/fxfa/parser/cxfa_widgetdata.cpp b/xfa/fxfa/parser/cxfa_widgetdata.cpp
index 5b9f62c93f..2da8820b67 100644
--- a/xfa/fxfa/parser/cxfa_widgetdata.cpp
+++ b/xfa/fxfa/parser/cxfa_widgetdata.cpp
@@ -42,18 +42,18 @@ bool SplitDateTime(const CFX_WideString& wsDateTime,
   if (wsDateTime.IsEmpty())
     return false;
 
-  FX_STRSIZE nSplitIndex = wsDateTime.Find('T');
-  if (nSplitIndex == FX_STRNPOS)
+  auto nSplitIndex = wsDateTime.Find('T');
+  if (!nSplitIndex.has_value())
     nSplitIndex = wsDateTime.Find(' ');
-  if (nSplitIndex == FX_STRNPOS)
+  if (!nSplitIndex.has_value())
     return false;
 
-  wsDate = wsDateTime.Left(nSplitIndex);
+  wsDate = wsDateTime.Left(nSplitIndex.value());
   if (!wsDate.IsEmpty()) {
     if (!std::any_of(wsDate.begin(), wsDate.end(), std::iswdigit))
       return false;
   }
-  wsTime = wsDateTime.Right(wsDateTime.GetLength() - nSplitIndex - 1);
+  wsTime = wsDateTime.Right(wsDateTime.GetLength() - nSplitIndex.value() - 1);
   if (!wsTime.IsEmpty()) {
     if (!std::any_of(wsTime.begin(), wsTime.end(), std::iswdigit))
       return false;
@@ -849,15 +849,15 @@ std::vector<CFX_WideString> CXFA_WidgetData::GetSelectedItemsValue() {
     if (!wsValue.IsEmpty()) {
       FX_STRSIZE iStart = 0;
       FX_STRSIZE iLength = wsValue.GetLength();
-      FX_STRSIZE iEnd = wsValue.Find(L'\n', iStart);
-      iEnd = (iEnd == FX_STRNPOS) ? iLength : iEnd;
+      auto iEnd = wsValue.Find(L'\n', iStart);
+      iEnd = (!iEnd.has_value()) ? iLength : iEnd;
       while (iEnd >= iStart) {
-        wsSelTextArray.push_back(wsValue.Mid(iStart, iEnd - iStart));
-        iStart = iEnd + 1;
+        wsSelTextArray.push_back(wsValue.Mid(iStart, iEnd.value() - iStart));
+        iStart = iEnd.value() + 1;
         if (iStart >= iLength)
           break;
         iEnd = wsValue.Find(L'\n', iStart);
-        if (iEnd == FX_STRNPOS)
+        if (!iEnd.has_value())
           wsSelTextArray.push_back(wsValue.Mid(iStart, iLength - iStart));
       }
     }
@@ -1315,15 +1315,16 @@ bool CXFA_WidgetData::GetBarcodeAttribute_WideNarrowRatio(float* val) {
   CXFA_Node* pUIChild = GetUIChild();
   CFX_WideString wsWideNarrowRatio;
   if (pUIChild->TryCData(XFA_ATTRIBUTE_WideNarrowRatio, wsWideNarrowRatio)) {
-    FX_STRSIZE ptPos = wsWideNarrowRatio.Find(':');
+    auto ptPos = wsWideNarrowRatio.Find(':');
     float fRatio = 0;
-    if (ptPos != FX_STRNPOS) {
+    if (!ptPos.has_value()) {
       fRatio = (float)FXSYS_wtoi(wsWideNarrowRatio.c_str());
     } else {
       int32_t fA, fB;
-      fA = FXSYS_wtoi(wsWideNarrowRatio.Left(ptPos).c_str());
+      fA = FXSYS_wtoi(wsWideNarrowRatio.Left(ptPos.value()).c_str());
       fB = FXSYS_wtoi(
-          wsWideNarrowRatio.Right(wsWideNarrowRatio.GetLength() - (ptPos + 1))
+          wsWideNarrowRatio
+              .Right(wsWideNarrowRatio.GetLength() - (ptPos.value() + 1))
               .c_str());
       if (fB)
         fRatio = (float)fA / fB;
@@ -1742,9 +1743,8 @@ void CXFA_WidgetData::NormalizeNumStr(const CFX_WideString& wsValue,
 
   wsOutput = wsValue;
   wsOutput.TrimLeft('0');
-  FX_STRSIZE dot_index = wsOutput.Find('.');
   int32_t iFracDigits = 0;
-  if (!wsOutput.IsEmpty() && dot_index != FX_STRNPOS &&
+  if (!wsOutput.IsEmpty() && wsOutput.Contains('.') &&
       (!GetFracDigits(iFracDigits) || iFracDigits != -1)) {
     wsOutput.TrimRight(L"0");
     wsOutput.TrimRight(L".");
@@ -1768,13 +1768,12 @@ void CXFA_WidgetData::FormatNumStr(const CFX_WideString& wsValue,
     wsSrcNum.Delete(0, 1);
   }
   int32_t len = wsSrcNum.GetLength();
-  FX_STRSIZE dot_index = wsSrcNum.Find('.');
-  if (dot_index == FX_STRNPOS)
-    dot_index = len;
+  auto dot_index = wsSrcNum.Find('.');
+  dot_index = !dot_index.has_value() ? len : dot_index;
 
-  int32_t cc = dot_index - 1;
+  int32_t cc = dot_index.value() - 1;
   if (cc >= 0) {
-    int nPos = dot_index % 3;
+    int nPos = dot_index.value() % 3;
     wsOutput.clear();
     for (int32_t i = 0; i < dot_index; i++) {
       if (i % 3 == nPos && i != 0)
@@ -1784,7 +1783,7 @@ void CXFA_WidgetData::FormatNumStr(const CFX_WideString& wsValue,
     }
     if (dot_index < len) {
       wsOutput += pLocale->GetNumbericSymbol(FX_LOCALENUMSYMBOL_Decimal);
-      wsOutput += wsSrcNum.Right(len - dot_index - 1);
+      wsOutput += wsSrcNum.Right(len - dot_index.value() - 1);
     }
     if (bNeg) {
       wsOutput =