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, 6 deletions

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));
               }