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>

4 files changed, 34 insertions, 33 deletions

diff --git a/fpdfsdk/fpdfedittext.cpp b/fpdfsdk/fpdfedittext.cpp
index 47facb4345..38f7cc2562 100644
--- a/fpdfsdk/fpdfedittext.cpp
+++ b/fpdfsdk/fpdfedittext.cpp
@@ -39,7 +39,7 @@ CPDF_Dictionary* LoadFontDesc(CPDF_Document* pDoc,
   int flags = 0;
   if (FXFT_Is_Face_fixedwidth(pFont->GetFace()))
     flags |= FXFONT_FIXED_PITCH;
-  if (font_name.Find("Serif") != FX_STRNPOS)
+  if (font_name.Contains("Serif"))
     flags |= FXFONT_SERIF;
   if (FXFT_Is_Face_Italic(pFont->GetFace()))
     flags |= FXFONT_ITALIC;
diff --git a/fpdfsdk/fpdfppo.cpp b/fpdfsdk/fpdfppo.cpp
index 905d53af48..861b15c259 100644
--- a/fpdfsdk/fpdfppo.cpp
+++ b/fpdfsdk/fpdfppo.cpp
@@ -80,35 +80,35 @@ bool ParserPageRangeString(CFX_ByteString rangstring,
   int nLength = rangstring.GetLength();
   CFX_ByteString cbCompareString("0123456789-,");
   for (int i = 0; i < nLength; ++i) {
-    if (cbCompareString.Find(rangstring[i]) == FX_STRNPOS)
+    if (!cbCompareString.Contains(rangstring[i]))
       return false;
   }
 
   CFX_ByteString cbMidRange;
   FX_STRSIZE nStringFrom = 0;
-  FX_STRSIZE nStringTo = 0;
+  pdfium::Optional<FX_STRSIZE> nStringTo = 0;
   while (nStringTo < nLength) {
     nStringTo = rangstring.Find(',', nStringFrom);
-    if (nStringTo == FX_STRNPOS)
+    if (!nStringTo.has_value())
       nStringTo = nLength;
-    cbMidRange = rangstring.Mid(nStringFrom, nStringTo - nStringFrom);
-    FX_STRSIZE nMid = cbMidRange.Find('-');
-    if (nMid == FX_STRNPOS) {
+    cbMidRange = rangstring.Mid(nStringFrom, nStringTo.value() - nStringFrom);
+    auto nMid = cbMidRange.Find('-');
+    if (!nMid.has_value()) {
       long lPageNum = atol(cbMidRange.c_str());
       if (lPageNum <= 0 || lPageNum > nCount)
         return false;
       pageArray->push_back((uint16_t)lPageNum);
     } else {
-      int nStartPageNum = atol(cbMidRange.Left(nMid).c_str());
+      int nStartPageNum = atol(cbMidRange.Left(nMid.value()).c_str());
       if (nStartPageNum == 0)
         return false;
 
-      ++nMid;
-      int nEnd = cbMidRange.GetLength() - nMid;
+      nMid = nMid.value() + 1;
+      int nEnd = cbMidRange.GetLength() - nMid.value();
       if (nEnd == 0)
         return false;
 
-      int nEndPageNum = atol(cbMidRange.Mid(nMid, nEnd).c_str());
+      int nEndPageNum = atol(cbMidRange.Mid(nMid.value(), nEnd).c_str());
       if (nStartPageNum < 0 || nStartPageNum > nEndPageNum ||
           nEndPageNum > nCount) {
         return false;
@@ -117,7 +117,7 @@ bool ParserPageRangeString(CFX_ByteString rangstring,
         pageArray->push_back(i);
       }
     }
-    nStringFrom = nStringTo + 1;
+    nStringFrom = nStringTo.value() + 1;
   }
   return true;
 }
diff --git a/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp b/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
index c12314f88d..c0c28db192 100644
--- a/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
+++ b/fpdfsdk/fpdfxfa/cpdfxfa_docenvironment.cpp
@@ -809,19 +809,19 @@ bool CPDFXFA_DocEnvironment::ExportSubmitFile(FPDF_FILEHANDLER* pFileHandler,
 
 void CPDFXFA_DocEnvironment::ToXFAContentFlags(CFX_WideString csSrcContent,
                                                FPDF_DWORD& flag) {
-  if (csSrcContent.Find(L" config ", 0) != FX_STRNPOS)
+  if (csSrcContent.Contains(L" config "))
     flag |= FXFA_CONFIG;
-  if (csSrcContent.Find(L" template ", 0) != FX_STRNPOS)
+  if (csSrcContent.Contains(L" template "))
     flag |= FXFA_TEMPLATE;
-  if (csSrcContent.Find(L" localeSet ", 0) != FX_STRNPOS)
+  if (csSrcContent.Contains(L" localeSet "))
     flag |= FXFA_LOCALESET;
-  if (csSrcContent.Find(L" datasets ", 0) != FX_STRNPOS)
+  if (csSrcContent.Contains(L" datasets "))
     flag |= FXFA_DATASETS;
-  if (csSrcContent.Find(L" xmpmeta ", 0) != FX_STRNPOS)
+  if (csSrcContent.Contains(L" xmpmeta "))
     flag |= FXFA_XMPMETA;
-  if (csSrcContent.Find(L" xfdf ", 0) != FX_STRNPOS)
+  if (csSrcContent.Contains(L" xfdf "))
     flag |= FXFA_XFDF;
-  if (csSrcContent.Find(L" form ", 0) != FX_STRNPOS)
+  if (csSrcContent.Contains(L" form "))
     flag |= FXFA_FORM;
   if (flag == 0) {
     flag = FXFA_CONFIG | FXFA_TEMPLATE | FXFA_LOCALESET | FXFA_DATASETS |
@@ -840,16 +840,16 @@ bool CPDFXFA_DocEnvironment::MailToInfo(CFX_WideString& csURL,
   if (srcURL.Left(7).CompareNoCase(L"mailto:") != 0)
     return false;
 
-  FX_STRSIZE pos = srcURL.Find(L'?', 0);
+  auto pos = srcURL.Find(L'?');
   CFX_WideString tmp;
-  if (pos == FX_STRNPOS) {
-    pos = srcURL.Find(L'@', 0);
-    if (pos == FX_STRNPOS)
+  if (!pos.has_value()) {
+    pos = srcURL.Find(L'@');
+    if (!pos.has_value())
       return false;
 
     tmp = srcURL.Right(csURL.GetLength() - 7);
   } else {
-    tmp = srcURL.Left(pos);
+    tmp = srcURL.Left(pos.value());
     tmp = tmp.Right(tmp.GetLength() - 7);
   }
   tmp.TrimLeft();
@@ -857,13 +857,13 @@ bool CPDFXFA_DocEnvironment::MailToInfo(CFX_WideString& csURL,
 
   csToAddress = tmp;
 
-  srcURL = srcURL.Right(srcURL.GetLength() - (pos + 1));
+  srcURL = srcURL.Right(srcURL.GetLength() - (pos.value() + 1));
   while (!srcURL.IsEmpty()) {
     srcURL.TrimLeft();
     srcURL.TrimRight();
-    pos = srcURL.Find(L'&', 0);
+    pos = srcURL.Find(L'&');
 
-    tmp = (pos == FX_STRNPOS) ? srcURL : srcURL.Left(pos);
+    tmp = (!pos.has_value()) ? srcURL : srcURL.Left(pos.value());
     tmp.TrimLeft();
     tmp.TrimRight();
     if (tmp.GetLength() >= 3 && tmp.Left(3).CompareNoCase(L"cc=") == 0) {
@@ -886,7 +886,9 @@ bool CPDFXFA_DocEnvironment::MailToInfo(CFX_WideString& csURL,
       tmp = tmp.Right(tmp.GetLength() - 5);
       csMsg += tmp;
     }
-    srcURL = (pos == -1) ? L"" : srcURL.Right(csURL.GetLength() - (pos + 1));
+    srcURL = !pos.has_value()
+                 ? L""
+                 : srcURL.Right(csURL.GetLength() - (pos.value() + 1));
   }
   csToAddress.Replace(L",", L";");
   csCCAddress.Replace(L",", L";");
diff --git a/fpdfsdk/javascript/PublicMethods.cpp b/fpdfsdk/javascript/PublicMethods.cpp
index 09815413ad..ff1d4fb7b7 100644
--- a/fpdfsdk/javascript/PublicMethods.cpp
+++ b/fpdfsdk/javascript/PublicMethods.cpp
@@ -527,7 +527,7 @@ double CJS_PublicMethods::MakeRegularDate(const CFX_WideString& value,
                 CFX_WideString sFullMonths = fullmonths[m];
                 sFullMonths.MakeLower();
 
-                if (sFullMonths.Find(sMonth.c_str(), 0) != FX_STRNPOS) {
+                if (sFullMonths.Contains(sMonth.c_str())) {
                   nMonth = m + 1;
                   i += 4;
                   j += nSkip;
@@ -933,8 +933,7 @@ bool CJS_PublicMethods::AFNumber_Keystroke(CJS_Runtime* pRuntime,
                                  pEvent->SelEnd() - pEvent->SelStart());
   }
 
-  bool bHasSign = wstrValue.Find(L'-') != FX_STRNPOS &&
-                  wstrSelected.Find(L'-') == FX_STRNPOS;
+  bool bHasSign = wstrValue.Contains(L'-') && !wstrSelected.Contains(L'-');
   if (bHasSign) {
     // can't insert "change" in front to sign postion.
     if (pEvent->SelStart() == 0) {
@@ -948,7 +947,7 @@ bool CJS_PublicMethods::AFNumber_Keystroke(CJS_Runtime* pRuntime,
     iSepStyle = 0;
   const wchar_t cSep = iSepStyle < 2 ? L'.' : L',';
 
-  bool bHasSep = wstrValue.Find(cSep) != FX_STRNPOS;
+  bool bHasSep = wstrValue.Contains(cSep);
   for (FX_STRSIZE i = 0; i < wstrChange.GetLength(); ++i) {
     if (wstrChange[i] == cSep) {
       if (bHasSep) {
@@ -1113,7 +1112,7 @@ bool CJS_PublicMethods::AFDate_FormatEx(CJS_Runtime* pRuntime,
   CFX_WideString sFormat = params[0].ToCFXWideString(pRuntime);
   double dDate = 0.0f;
 
-  if (strValue.Find(L"GMT") != FX_STRNPOS) {
+  if (strValue.Contains(L"GMT")) {
     // for GMT format time
     // such as "Tue Aug 11 14:24:16 GMT+08002009"
     dDate = MakeInterDate(strValue);