Merge pull request #308 from fastfloat/turing_json_into_macro_parameter

turning json option into macro parameter

Author: lemire

benchmarks/benchmark.cpp

@@ -236,7 +236,7 @@ int main(int argc, char **argv) {
               << std::endl;
 #endif
   }
-  if(argc > 1) {
+  if (argc > 1) {
     fileload(argv[1]);
     return EXIT_SUCCESS;
   }

include/fast_float/ascii_number.h

@@ -279,7 +279,7 @@ report_parse_error(UC const *p, parse_error error) {
 
 // Assuming that you use no more than 19 digits, this will
 // parse an ASCII string.
-template <typename UC>
+template <bool basic_json_fmt, typename UC>
 fastfloat_really_inline FASTFLOAT_CONSTEXPR20 parsed_number_string_t<UC>
 parse_number_string(UC const *p, UC const *pend,
                     parse_options_t<UC> options) noexcept {
@@ -292,20 +292,20 @@ parse_number_string(UC const *p, UC const *pend,
   // assume p < pend, so dereference without checks;
   answer.negative = (*p == UC('-'));
   // C++17 20.19.3.(7.1) explicitly forbids '+' sign here
-  if ((*p == UC('-')) ||
-      (uint64_t(fmt & chars_format::allow_leading_plus) &&
-       !uint64_t(fmt & detail::basic_json_fmt) && *p == UC('+'))) {
+  if ((*p == UC('-')) || (uint64_t(fmt & chars_format::allow_leading_plus) &&
+                          !basic_json_fmt && *p == UC('+'))) {
     ++p;
     if (p == pend) {
       return report_parse_error<UC>(
           p, parse_error::missing_integer_or_dot_after_sign);
     }
-    if (uint64_t(fmt & detail::basic_json_fmt)) {
+    FASTFLOAT_IF_CONSTEXPR17(basic_json_fmt) {
       if (!is_integer(*p)) { // a sign must be followed by an integer
         return report_parse_error<UC>(p,
                                       parse_error::missing_integer_after_sign);
       }
-    } else {
+    }
+    else {
       if (!is_integer(*p) &&
           (*p !=
            decimal_point)) { // a sign must be followed by an integer or the dot
@@ -329,7 +329,7 @@ parse_number_string(UC const *p, UC const *pend,
   UC const *const end_of_integer_part = p;
   int64_t digit_count = int64_t(end_of_integer_part - start_digits);
   answer.integer = span<UC const>(start_digits, size_t(digit_count));
-  if (uint64_t(fmt & detail::basic_json_fmt)) {
+  FASTFLOAT_IF_CONSTEXPR17(basic_json_fmt) {
     // at least 1 digit in integer part, without leading zeros
     if (digit_count == 0) {
       return report_parse_error<UC>(p, parse_error::no_digits_in_integer_part);
@@ -358,14 +358,14 @@ parse_number_string(UC const *p, UC const *pend,
     answer.fraction = span<UC const>(before, size_t(p - before));
     digit_count -= exponent;
   }
-  if (uint64_t(fmt & detail::basic_json_fmt)) {
+  FASTFLOAT_IF_CONSTEXPR17(basic_json_fmt) {
     // at least 1 digit in fractional part
     if (has_decimal_point && exponent == 0) {
       return report_parse_error<UC>(p,
                                     parse_error::no_digits_in_fractional_part);
     }
-  } else if (digit_count ==
-             0) { // we must have encountered at least one integer!
+  }
+  else if (digit_count == 0) { // we must have encountered at least one integer!
     return report_parse_error<UC>(p, parse_error::no_digits_in_mantissa);
   }
   int64_t exp_number = 0; // explicit exponential part

include/fast_float/constexpr_feature_detect.h

@@ -27,6 +27,12 @@
 #define FASTFLOAT_HAS_IS_CONSTANT_EVALUATED 0
 #endif
 
+#if defined(__cpp_if_constexpr) && __cpp_if_constexpr >= 201606L
+#define FASTFLOAT_IF_CONSTEXPR17(x) if constexpr (x)
+#else
+#define FASTFLOAT_IF_CONSTEXPR17(x) if (x)
+#endif
+
 // Testing for relevant C++20 constexpr library features
 #if FASTFLOAT_HAS_IS_CONSTANT_EVALUATED && FASTFLOAT_HAS_BIT_CAST &&           \
     defined(__cpp_lib_constexpr_algorithms) &&                                 \

include/fast_float/parse_number.h

@@ -305,7 +305,9 @@ from_chars_float_advanced(UC const *first, UC const *last, T &value,
     return answer;
   }
   parsed_number_string_t<UC> pns =
-      parse_number_string<UC>(first, last, options);
+      uint64_t(fmt & detail::basic_json_fmt)
+          ? parse_number_string<true, UC>(first, last, options)
+          : parse_number_string<false, UC>(first, last, options);
   if (!pns.valid) {
     if (uint64_t(fmt & chars_format::no_infnan)) {
       answer.ec = std::errc::invalid_argument;

tests/json_fmt.cpp

@@ -131,7 +131,7 @@ int main() {
   for (std::size_t i = 0; i < reject.size(); ++i) {
     auto const &f = reject[i].input;
     auto const &expected_reason = reject[i].reason;
-    auto answer = fast_float::parse_number_string(
+    auto answer = fast_float::parse_number_string<true>(
         f.data(), f.data() + f.size(),
         fast_float::parse_options(
             fast_float::chars_format::json |