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>

1 files changed, 7 insertions, 7 deletions

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(