[c++] Address failure in JSON Unicode conversion

Throw a bond::CoreException insteand of a Boost exception when Unicode
conversion fails during JSON deserialization to wstring.

CHANGELOG.md

@@ -15,14 +15,18 @@ different versioning scheme, following the Haskell community's
 * `gbc` & compiler library: TBD
 * IDL core version: TBD
 * IDL comm version: TBD
-* C++ version: TBD
+* C++ version: TBD (bug fix bump needed)
 * C# NuGet version: TBD  (bug fix bump needed)
 * C# Comm NuGet version: TBD
 
+### C++ ###
+
+* When Unicode conversion fails during JSON deserialization to wstring, a
+  bond::CoreException is now thrown instead of a Boost exception.
+
 ### C# ###
 
-* Reflection.IsBonded now recognizes custom IBonded
-implementations.
+* Reflection.IsBonded now recognizes custom IBonded implementations.
 
 ## 6.0.0: 2017-06-29  ##
 * `gbc` & compiler library: 0.10.0.0

cpp/inc/bond/core/exception.h

@@ -105,7 +105,14 @@ BOND_NORETURN inline void RapidJsonException(const char* error, size_t offset)
         "JSON parser error: " << error << " at offset " << offset);
 }
 
- 
+
+BOND_NORETURN inline void UnicodeConversionException(void)
+{
+    BOND_THROW(CoreException,
+        "Unicode conversion exception");
+}
+
+
 struct StreamException
     : Exception
 {

cpp/inc/bond/protocol/detail/rapidjson_helper.h

@@ -279,19 +279,26 @@ template <typename T>
 typename boost::enable_if<is_wstring<T> >::type
 Read(const rapidjson::Value& value, T& var)
 {
-    const std::basic_string<uint16_t> str =
-        boost::locale::conv::utf_to_utf<uint16_t>(
-            value.GetString(),
-            value.GetString() + value.GetStringLength(),
-            boost::locale::conv::stop);
+    try
+    {
+        const std::basic_string<uint16_t> str =
+            boost::locale::conv::utf_to_utf<uint16_t>(
+                value.GetString(),
+                value.GetString() + value.GetStringLength(),
+                boost::locale::conv::stop);
 
-    const size_t length = str.size();
-    resize_string(var, static_cast<uint32_t>(length));
+        const size_t length = str.size();
+        resize_string(var, static_cast<uint32_t>(length));
 
-    std::copy(
-        str.begin(),
-        str.end(),
-        make_checked_array_iterator(string_data(var), length));
+        std::copy(
+            str.begin(),
+            str.end(),
+            make_checked_array_iterator(string_data(var), length));
+    }
+    catch (const boost::locale::conv::conversion_error &)
+    {
+        UnicodeConversionException();
+    }
 }