Add string_piece_util

Following functions are implemented for further performance
optimization.

* JoinStringPiece
* SplitStringPiece
* EqualsCaseInsensitiveASCII
* ToLowerASCII

To improve performance of CLParser, I will introduce above functions
into include_normalize-win32.cc.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/string_piece.h b/src/string_piece.h
index b1bf105..353b24e 100644
--- a/src/string_piece.h
+++ b/src/string_piece.h
@@ -25,6 +25,8 @@ using namespace std;
 /// externally.  It is useful for reducing the number of std::strings
 /// we need to allocate.
 struct StringPiece {
+  typedef const char* const_iterator;
+
   StringPiece() : str_(NULL), len_(0) {}
 
   /// The constructors intentionally allow for implicit conversions.
@@ -46,6 +48,14 @@ struct StringPiece {
     return len_ ? string(str_, len_) : string();
   }
 
+  const_iterator begin() const {
+    return str_;
+  }
+
+  const_iterator end() const {
+    return str_ + len_;
+  }
+
   const char* str_;
   size_t len_;
 };