Allow object lookup safety to be disabled

Use cmake -DSIMDJSON_API_USAGE_CHECKS=OFF ..

cmake/simdjson-flags.cmake

@@ -172,11 +172,11 @@ endif()
 #
 # Other optional flags
 #
-option(SIMDJSON_ONDEMAND_SAFETY_RAILS "Validate ondemand user code at runtime to ensure it is being used correctly. Defaults to ON for debug builds, OFF for release builds." $<IF:$<CONFIG:DEBUG>,ON,OFF>)
-if(SIMDJSON_ONDEMAND_SAFETY_RAILS)
-  message(STATUS "Ondemand safety rails enabled. Ondemand user code will be checked at runtime. This will be slower than normal!")
-  target_compile_definitions(simdjson-flags INTERFACE SIMDJSON_ONDEMAND_SAFETY_RAILS)
-endif(SIMDJSON_ONDEMAND_SAFETY_RAILS)
+option(SIMDJSON_API_USAGE_CHECKS "Validate ondemand user code at runtime to ensure it is being used correctly. Turning this off disables some checks that have a small performance impact. Defaults to ON." ON)
+if(SIMDJSON_API_USAGE_CHECKS)
+  message(STATUS "Ondemand safety rails enabled. Ondemand user code will be checked at runtime. Turn this on for production to get maximum performance!")
+  target_compile_definitions(simdjson-flags INTERFACE SIMDJSON_API_USAGE_CHECKS=1)
+endif(SIMDJSON_API_USAGE_CHECKS)
 
 option(SIMDJSON_BASH "Allow usage of bash within CMake" ON)
 

include/simdjson/generic/ondemand/json_iterator-inl.h

@@ -157,7 +157,9 @@ simdjson_really_inline void json_iterator::descend_to(depth_t child_depth) noexc
   SIMDJSON_ASSUME(child_depth >= 1 && child_depth < INT32_MAX);
   SIMDJSON_ASSUME(_depth == child_depth - 1);
   _depth = child_depth;
+#if SIMDJSON_API_USAGE_CHECKS
   parser->start_positions[_depth] = token.index;
+#endif
 }
 
 simdjson_really_inline depth_t json_iterator::depth() const noexcept {
@@ -181,11 +183,19 @@ simdjson_really_inline token_position json_iterator::position() const noexcept {
 simdjson_really_inline void json_iterator::reenter_child(token_position position, depth_t child_depth) noexcept {
   SIMDJSON_ASSUME(child_depth >= 1 && child_depth < INT32_MAX);
   SIMDJSON_ASSUME(_depth == child_depth - 1);
+#if SIMDJSON_API_USAGE_CHECKS
   SIMDJSON_ASSUME(position >= parser->start_positions[child_depth]);
+#endif
   token.set_position(position);
   _depth = child_depth;
 }
 
+#if SIMDJSON_API_USAGE_CHECKS
+simdjson_really_inline token_position json_iterator::start_position(depth_t depth) const noexcept {
+  return parser->start_positions[depth];
+}
+#endif
+
 
 simdjson_really_inline error_code json_iterator::optional_error(error_code _error, const char *message) noexcept {
   SIMDJSON_ASSUME(_error == INCORRECT_TYPE || _error == NO_SUCH_FIELD);

include/simdjson/generic/ondemand/json_iterator.h

@@ -181,6 +181,9 @@ public:
 
   simdjson_really_inline token_position position() const noexcept;
   simdjson_really_inline void reenter_child(token_position position, depth_t child_depth) noexcept;
+#if SIMDJSON_API_USAGE_CHECKS
+  simdjson_really_inline token_position start_position(depth_t depth) const noexcept;
+#endif
 
 protected:
   simdjson_really_inline json_iterator(const uint8_t *buf, ondemand::parser *parser) noexcept;

include/simdjson/generic/ondemand/parser-inl.h

@@ -8,7 +8,9 @@ simdjson_warn_unused simdjson_really_inline error_code parser::allocate(size_t n
   // string_capacity copied from document::allocate
   size_t string_capacity = SIMDJSON_ROUNDUP_N(5 * new_capacity / 3 + SIMDJSON_PADDING, 64);
   string_buf.reset(new (std::nothrow) uint8_t[string_capacity]);
+#if SIMDJSON_API_USAGE_CHECKS
   start_positions.reset(new (std::nothrow) token_position[new_max_depth]);
+#endif
   if (implementation) {
     SIMDJSON_TRY( implementation->set_capacity(new_capacity) );
     SIMDJSON_TRY( implementation->set_max_depth(new_max_depth) );

include/simdjson/generic/ondemand/parser.h

@@ -110,7 +110,9 @@ private:
   /** @private [for benchmarking access] The implementation to use */
   std::unique_ptr<internal::dom_parser_implementation> implementation{};
   std::unique_ptr<uint8_t[]> string_buf{};
+#if SIMDJSON_API_USAGE_CHECKS
   std::unique_ptr<token_position[]> start_positions{};
+#endif
 
   /**
    * Ensure this parser has enough memory to process JSON documents up to `capacity` bytes in length
@@ -123,7 +125,6 @@ private:
   simdjson_warn_unused error_code allocate(size_t capacity, size_t max_depth=DEFAULT_MAX_DEPTH) noexcept;
 
   friend class json_iterator;
-  friend class value_iterator;
 };
 
 } // namespace ondemand

include/simdjson/generic/ondemand/value_iterator-inl.h

@@ -94,7 +94,9 @@ simdjson_warn_unused simdjson_really_inline simdjson_result<bool> value_iterator
   } else {
     if ((error = skip_child() )) { abandon(); return error; }
     if ((error = has_next_field().get(has_value) )) { abandon(); return error; }
-    // if (_json_iter->parser->start_positions[_depth] != _start_position) { return OUT_OF_ORDER_ITERATION; }
+#if SIMDJSON_API_USAGE_CHECKS
+    if (_json_iter->start_position(_depth) != _start_position) { return OUT_OF_ORDER_ITERATION; }
+#endif
   }
   while (has_value) {
     // Get the key and colon, stopping at the value.
@@ -170,7 +172,9 @@ simdjson_warn_unused simdjson_really_inline simdjson_result<bool> value_iterator
     // Finish the previous value and see if , or } is next
     if ((error = skip_child() )) { abandon(); return error; }
     if ((error = has_next_field().get(has_value) )) { abandon(); return error; }
-    // if (_json_iter->parser->start_positions[_depth] != _start_position) { return OUT_OF_ORDER_ITERATION; }
+#if SIMDJSON_API_USAGE_CHECKS
+    if (_json_iter->start_position(_depth) != _start_position) { return OUT_OF_ORDER_ITERATION; }
+#endif
   }
 
   // After initial processing, we will be in one of two states: