diff --git a/include/rapidjson/internal/strfunc.h b/include/rapidjson/internal/strfunc.h
index bbf444fe6df2e26d5ba438f2e827c3782c1af831..226439a767364577b3e8168104fb0d1575e4638a 100644
--- a/include/rapidjson/internal/strfunc.h
+++ b/include/rapidjson/internal/strfunc.h
@@ -1,24 +1,69 @@
+// Tencent is pleased to support the open source community by making RapidJSON available.
+// 
+// Copyright (C) 2015 THL A29 Limited, a Tencent company, and Milo Yip. All rights reserved.
+//
+// Licensed under the MIT License (the "License"); you may not use this file except
+// in compliance with the License. You may obtain a copy of the License at
+//
+// http://opensource.org/licenses/MIT
+//
+// Unless required by applicable law or agreed to in writing, software distributed 
+// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR 
+// CONDITIONS OF ANY KIND, either express or implied. See the License for the 
+// specific language governing permissions and limitations under the License.
+
 #ifndef RAPIDJSON_INTERNAL_STRFUNC_H_
 #define RAPIDJSON_INTERNAL_STRFUNC_H_
 
-namespace rapidjson {
+#include "../stream.h"
+#include <cwchar>
+
+RAPIDJSON_NAMESPACE_BEGIN
 namespace internal {
 
 //! Custom strlen() which works on different character types.
-/*!	\tparam Ch Character type (e.g. char, wchar_t, short)
-	\param s Null-terminated input string.
-	\return Number of characters in the string. 
-	\note This has the same semantics as strlen(), the return value is not number of Unicode codepoints.
+/*! \tparam Ch Character type (e.g. char, wchar_t, short)
+    \param s Null-terminated input string.
+    \return Number of characters in the string. 
+    \note This has the same semantics as strlen(), the return value is not number of Unicode codepoints.
 */
 template <typename Ch>
 inline SizeType StrLen(const Ch* s) {
-	const Ch* p = s;
-	while (*p != '\0')
-		++p;
-	return SizeType(p - s);
+    RAPIDJSON_ASSERT(s != 0);
+    const Ch* p = s;
+    while (*p) ++p;
+    return SizeType(p - s);
+}
+
+template <>
+inline SizeType StrLen(const char* s) {
+    return SizeType(std::strlen(s));
+}
+
+template <>
+inline SizeType StrLen(const wchar_t* s) {
+    return SizeType(std::wcslen(s));
+}
+
+//! Returns number of code points in a encoded string.
+template<typename Encoding>
+bool CountStringCodePoint(const typename Encoding::Ch* s, SizeType length, SizeType* outCount) {
+    RAPIDJSON_ASSERT(s != 0);
+    RAPIDJSON_ASSERT(outCount != 0);
+    GenericStringStream<Encoding> is(s);
+    const typename Encoding::Ch* end = s + length;
+    SizeType count = 0;
+    while (is.src_ < end) {
+        unsigned codepoint;
+        if (!Encoding::Decode(is, &codepoint))
+            return false;
+        count++;
+    }
+    *outCount = count;
+    return true;
 }
 
 } // namespace internal
-} // namespace rapidjson
+RAPIDJSON_NAMESPACE_END
 
 #endif // RAPIDJSON_INTERNAL_STRFUNC_H_