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, 6 insertions, 6 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);