Add CFX_ByteStringC::CharAt() to avoid c_str() and casts.

Most of the time, we want to operate on chars as if they
were unsigned, but there are a few places where we need
the default (questionably signed) values. Consolidate
the casting in a single place rather than forcing callers
to get a char* ptr.

BUG=pdfium:493

Review-Url: https://codereview.chromium.org/1972053003

1 files changed, 7 insertions, 13 deletions

diff --git a/core/fxcrt/fx_xml_composer.cpp b/core/fxcrt/fx_xml_composer.cpp
index 576ff95432..1bad069c34 100644
--- a/core/fxcrt/fx_xml_composer.cpp
+++ b/core/fxcrt/fx_xml_composer.cpp
@@ -11,24 +11,18 @@
 void FX_XML_SplitQualifiedName(const CFX_ByteStringC& bsFullName,
                                CFX_ByteStringC& bsSpace,
                                CFX_ByteStringC& bsName) {
-  if (bsFullName.IsEmpty()) {
+  if (bsFullName.IsEmpty())
     return;
-  }
-  int32_t iStart = 0;
-  for (; iStart < bsFullName.GetLength(); iStart++) {
-    if (bsFullName.GetAt(iStart) == ':') {
-      break;
-    }
-  }
-  if (iStart >= bsFullName.GetLength()) {
+
+  FX_STRSIZE iStart = bsFullName.Find(':');
+  if (iStart == -1) {
     bsName = bsFullName;
   } else {
-    bsSpace = CFX_ByteStringC(bsFullName.c_str(), iStart);
-    iStart++;
-    bsName = CFX_ByteStringC(bsFullName.c_str() + iStart,
-                             bsFullName.GetLength() - iStart);
+    bsSpace = bsFullName.Mid(0, iStart);
+    bsName = bsFullName.Mid(iStart + 1);
   }
 }
+
 void CXML_Element::SetTag(const CFX_ByteStringC& qSpace,
                           const CFX_ByteStringC& tagname) {
   m_QSpaceName = qSpace;