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, 15 insertions, 11 deletions

diff --git a/core/fpdfapi/edit/cpdf_pagecontentgenerator_unittest.cpp b/core/fpdfapi/edit/cpdf_pagecontentgenerator_unittest.cpp
index 1f4d821dae..c7a98c9493 100644
--- a/core/fpdfapi/edit/cpdf_pagecontentgenerator_unittest.cpp
+++ b/core/fpdfapi/edit/cpdf_pagecontentgenerator_unittest.cpp
@@ -186,15 +186,18 @@ TEST_F(CPDF_PageContentGeneratorTest, ProcessStandardText) {
   std::ostringstream buf;
   TestProcessText(&generator, &buf, pTextObj.get());
   CFX_ByteString textString(buf);
-  FX_STRSIZE firstResourceAt = textString.Find('/') + 1;
-  FX_STRSIZE secondResourceAt = textString.ReverseFind('/') + 1;
-  EXPECT_NE(FX_STRNPOS, firstResourceAt);
-  EXPECT_NE(FX_STRNPOS, secondResourceAt);
-  CFX_ByteString firstString = textString.Left(firstResourceAt);
+  auto firstResourceAt = textString.Find('/');
+  ASSERT_TRUE(firstResourceAt.has_value());
+  firstResourceAt = firstResourceAt.value() + 1;
+  auto secondResourceAt = textString.ReverseFind('/');
+  ASSERT_TRUE(secondResourceAt.has_value());
+  secondResourceAt = secondResourceAt.value() + 1;
+  CFX_ByteString firstString = textString.Left(firstResourceAt.value());
   CFX_ByteString midString =
-      textString.Mid(firstResourceAt, secondResourceAt - firstResourceAt);
+      textString.Mid(firstResourceAt.value(),
+                     secondResourceAt.value() - firstResourceAt.value());
   CFX_ByteString lastString =
-      textString.Right(textString.GetLength() - secondResourceAt);
+      textString.Right(textString.GetLength() - secondResourceAt.value());
   // q and Q must be outside the BT .. ET operations
   CFX_ByteString compareString1 =
       "q 0.501961 0.701961 0.34902 rg 1 0.901961 0 RG /";
@@ -255,11 +258,12 @@ TEST_F(CPDF_PageContentGeneratorTest, ProcessText) {
   }
 
   CFX_ByteString textString(buf);
-  FX_STRSIZE firstResourceAt = textString.Find('/') + 1;
-  EXPECT_NE(FX_STRNPOS, firstResourceAt);
-  CFX_ByteString firstString = textString.Left(firstResourceAt);
+  auto firstResourceAt = textString.Find('/');
+  ASSERT_TRUE(firstResourceAt.has_value());
+  firstResourceAt = firstResourceAt.value() + 1;
+  CFX_ByteString firstString = textString.Left(firstResourceAt.value());
   CFX_ByteString lastString =
-      textString.Right(textString.GetLength() - firstResourceAt);
+      textString.Right(textString.GetLength() - firstResourceAt.value());
   // q and Q must be outside the BT .. ET operations
   CFX_ByteString compareString1 = "q BT 1 0 0 1 0 0 Tm /";
   CFX_ByteString compareString2 =