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, 13 insertions, 2 deletions

diff --git a/core/fxcrt/cfx_widestring.h b/core/fxcrt/cfx_widestring.h
index f9e800d0a2..a6d0eca044 100644
--- a/core/fxcrt/cfx_widestring.h
+++ b/core/fxcrt/cfx_widestring.h
@@ -15,6 +15,7 @@
 #include "core/fxcrt/cfx_string_data_template.h"
 #include "core/fxcrt/fx_memory.h"
 #include "core/fxcrt/fx_system.h"
+#include "third_party/base/optional.h"
 
 class CFX_ByteString;
 
@@ -142,8 +143,18 @@ class CFX_WideString {
   int GetInteger() const;
   float GetFloat() const;
 
-  FX_STRSIZE Find(const CFX_WideStringC& pSub, FX_STRSIZE start = 0) const;
-  FX_STRSIZE Find(wchar_t ch, FX_STRSIZE start = 0) const;
+  pdfium::Optional<FX_STRSIZE> Find(const CFX_WideStringC& pSub,
+                                    FX_STRSIZE start = 0) const;
+  pdfium::Optional<FX_STRSIZE> Find(wchar_t ch, FX_STRSIZE start = 0) const;
+
+  bool Contains(const CFX_WideStringC& lpszSub, FX_STRSIZE start = 0) const {
+    return Find(lpszSub, start).has_value();
+  }
+
+  bool Contains(char ch, FX_STRSIZE start = 0) const {
+    return Find(ch, start).has_value();
+  }
+
   FX_STRSIZE Replace(const CFX_WideStringC& pOld, const CFX_WideStringC& pNew);
   FX_STRSIZE Remove(wchar_t ch);