fix generic_json usage across grammars

include/mapnik/json/extract_bounding_box_grammar_impl.hpp

@@ -154,7 +154,7 @@ extract_bounding_box_grammar<Iterator, Boxes, ErrorHandler>::extract_bounding_bo
     json.key_value = (json.string_ >> lit(':') >> json.value)
         ;
 
-    json.object = lit('{') >> *json.pairs >> lit('}')
+    json.object = lit('{') >> json.pairs >> lit('}')
         ;
 
     json.array = lit('[')

include/mapnik/json/geometry_grammar_impl.hpp

@@ -65,7 +65,7 @@ geometry_grammar<Iterator, ErrorHandler>::geometry_grammar()
         ;
 
     json_.object = lit('{')
-        > *json_.pairs
+        > json_.pairs
         > lit('}')
         ;
     json_.array = lit('[')

include/mapnik/json/topojson_grammar_impl.hpp

@@ -139,7 +139,7 @@ topojson_grammar<Iterator, ErrorHandler>::topojson_grammar()
     json.key_value = (json.string_ >> lit(':') >> json.value)
         ;
 
-    json.object = lit('{') >> *json.pairs >> lit('}')
+    json.object = lit('{') >> json.pairs >> lit('}')
         ;
 
     json.array = lit('[')

include/mapnik/json/topojson_utils.hpp

@@ -257,7 +257,14 @@ public:
     {
         return mapnik::value(tr_.transcode(val.c_str()));
     }
-
+    mapnik::value operator()(std::vector<mapnik::json::json_value> const& arr) const
+    {
+        return mapnik::value(tr_.transcode("FAIL ARRAY"));
+    }
+    mapnik::value operator()(std::unordered_map<std::string, mapnik::json::json_value> const& obj) const
+    {
+        return mapnik::value(tr_.transcode("FAIL OBJECT"));
+    }
     template <typename T>
     mapnik::value operator()(T const& val) const
     {

plugins/input/topojson/topojson_datasource.cpp

@@ -67,17 +67,9 @@ struct attr_value_converter
         return mapnik::Boolean;
     }
 
-    mapnik::eAttributeType operator() (std::string const& /*val*/) const
-    {
-        return mapnik::String;
-    }
-
-    mapnik::eAttributeType operator() (mapnik::value_unicode_string const& /*val*/) const
-    {
-        return mapnik::String;
-    }
-
-    mapnik::eAttributeType operator() (mapnik::value_null const& /*val*/) const
+    // string, object, array
+    template <typename T>
+    mapnik::eAttributeType operator() (T const& /*val*/) const
     {
         return mapnik::String;
     }