Fix the utf8 convertor in VS2017

contributors.txt

@@ -144,3 +144,4 @@ YYYY/MM/DD, github id, Full name, email
 2017/03/15, robertvanderhulst, Robert van der Hulst, robert@xsharp.eu
 2017/03/28, cmd-johnson, Jonas Auer, jonas.auer.94@gmail.com
 2017/04/12, lys0716, Yishuang Lu, luyscmu@gmail.com
+2017/04/30, shravanrn, Shravan Narayan, shravanrn@gmail.com

runtime/Cpp/runtime/src/ANTLRInputStream.cpp

@@ -35,9 +35,9 @@ void ANTLRInputStream::load(const std::string &input) {
   // Remove the UTF-8 BOM if present.
   const char bom[4] = "\xef\xbb\xbf";
   if (input.compare(0, 3, bom, 3) == 0)
-    _data = antlrcpp::utfConverter.from_bytes(input.data() + 3, input.data() + input.size());
+    _data = antlrcpp::utf8_to_utf32(input.data() + 3, input.data() + input.size());
   else
-    _data = antlrcpp::utfConverter.from_bytes(input);
+    _data = antlrcpp::utf8_to_utf32(input.data(), input.data() + input.size());
   p = 0;
 }
 
@@ -136,7 +136,7 @@ std::string ANTLRInputStream::getText(const Interval &interval) {
     return "";
   }
 
-  return antlrcpp::utfConverter.to_bytes(_data.substr(start, count));
+  return antlrcpp::utf32_to_utf8(_data.substr(start, count));
 }
 
 std::string ANTLRInputStream::getSourceName() const {
@@ -147,7 +147,7 @@ std::string ANTLRInputStream::getSourceName() const {
 }
 
 std::string ANTLRInputStream::toString() const {
-  return antlrcpp::utfConverter.to_bytes(_data);
+  return antlrcpp::utf32_to_utf8(_data);
 }
 
 void ANTLRInputStream::InitializeInstanceFields() {

runtime/Cpp/runtime/src/UnbufferedCharStream.cpp

@@ -195,7 +195,7 @@ std::string UnbufferedCharStream::getText(const misc::Interval &interval) {
   }
   // convert from absolute to local index
   size_t i = interval.a - bufferStartIndex;
-  return utfConverter.to_bytes(_data.substr(i, interval.length()));
+  return utf32_to_utf8(_data.substr(i, interval.length()));
 }
 
 size_t UnbufferedCharStream::getBufferStartIndex() const {

runtime/Cpp/runtime/src/support/StringUtils.h

@@ -9,13 +9,36 @@
 
 namespace antlrcpp {
   // For all conversions utf8 <-> utf32.
-  // VS 2015 has a bug in std::codecvt_utf8<char32_t> (VS 2013 works fine).
+  // VS 2015 and VS 2017 have different bugs in std::codecvt_utf8<char32_t> (VS 2013 works fine).
-#if defined(_MSC_VER) && _MSC_VER == 1900
+#if defined(_MSC_VER) && _MSC_VER >= 1900 && _MSC_VER < 2000
   static std::wstring_convert<std::codecvt_utf8<__int32>, __int32> utfConverter;
 #else
   static std::wstring_convert<std::codecvt_utf8<char32_t>, char32_t> utfConverter;
 #endif
 
+  //the conversion functions fails in VS2017, so we explicitly use a workaround
+  template<typename T>
+  inline std::string utf32_to_utf8(T _data)
+  {
+    #if _MSC_VER > 1900 && _MSC_VER < 2000
+      auto p = reinterpret_cast<const int32_t *>(_data.data());
+      return antlrcpp::utfConverter.to_bytes(p, p + _data.size());
+    #else
+      return antlrcpp::utfConverter.to_bytes(_data);
+    #endif
+  }
+
+  inline auto utf8_to_utf32(const char* first, const char* last)
+  {
+    #if _MSC_VER > 1900 && _MSC_VER < 2000
+      auto r = antlrcpp::utfConverter.from_bytes(first, last);
+      std::u32string s = reinterpret_cast<const char32_t *>(r.data());
+      return s;
+    #else
+      return antlrcpp::utfConverter.from_bytes(first, last);
+    #endif
+  }
+
   void replaceAll(std::string& str, const std::string& from, const std::string& to);
 
   // string <-> wstring conversion (UTF-16), e.g. for use with Window's wide APIs.