changes to address #295

src/json.hpp

@@ -8892,7 +8892,8 @@ basic_json_parser_63:
             {
                 case lexer::token_type::begin_object:
                 {
-                    if (keep and (not callback or (keep = callback(depth++, parse_event_t::object_start, result))))
+                    if (keep and (not callback
+                                  or ((keep = callback(depth++, parse_event_t::object_start, result)) != 0)))
                     {
                         // explicitly set result to object to cope with {}
                         result.m_type = value_t::object;
@@ -8970,7 +8971,8 @@ basic_json_parser_63:
 
                 case lexer::token_type::begin_array:
                 {
-                    if (keep and (not callback or (keep = callback(depth++, parse_event_t::array_start, result))))
+                    if (keep and (not callback
+                                  or ((keep = callback(depth++, parse_event_t::array_start, result)) != 0)))
                     {
                         // explicitly set result to object to cope with []
                         result.m_type = value_t::array;

src/json.hpp.re2c

@@ -8189,7 +8189,8 @@ class basic_json
             {
                 case lexer::token_type::begin_object:
                 {
-                    if (keep and (not callback or (keep = callback(depth++, parse_event_t::object_start, result))))
+                    if (keep and (not callback
+                                  or ((keep = callback(depth++, parse_event_t::object_start, result)) != 0)))
                     {
                         // explicitly set result to object to cope with {}
                         result.m_type = value_t::object;
@@ -8267,7 +8268,8 @@ class basic_json
 
                 case lexer::token_type::begin_array:
                 {
-                    if (keep and (not callback or (keep = callback(depth++, parse_event_t::array_start, result))))
+                    if (keep and (not callback
+                                  or ((keep = callback(depth++, parse_event_t::array_start, result)) != 0)))
                     {
                         // explicitly set result to object to cope with []
                         result.m_type = value_t::array;