26cdbe0564
* change parser template args order * amalgamate for previous commit * add newlines at end of file * incremental changes * incremental changes * incremental changes * incremental changes * incremental changes (code style) * incremental changes * incremental changes amalgamate * incremental changes (code style) * add missing include guards * incremental changes (code style) * incremental changes (code style) * incremental changes (amalgamate) * incremental changes * incremental changes * code style change * clean up includes * try using vector_of_uint8_t * add missing include * add missing include * add missing includes * add comment
286 lines
11 KiB
C++
286 lines
11 KiB
C++
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#pragma once
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#include <algorithm> // reverse, remove, fill, find, none_of
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#include <array> // array
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#include <clocale> // localeconv, lconv
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#include <cmath> // labs, isfinite, isnan, signbit
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#include <cstddef> // size_t, ptrdiff_t
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#include <cstdio> // snprintf
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#include <limits> // numeric_limits
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#include <string> // char_traits
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#include <nlohmann/detail/conversions/to_chars.hpp>
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#include <nlohmann/detail/macro_scope.hpp>
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#include <nlohmann/detail/meta/cpp_future.hpp>
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namespace nlohmann
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{
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namespace detail
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{
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struct denumerizer
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{
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using number_buffer_t = std::array<char, 64>;
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/*!
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@brief count digits
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Count the number of decimal (base 10) digits for an input unsigned integer.
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@param[in] x unsigned integer number to count its digits
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@return number of decimal digits
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*/
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template <typename number_unsigned_t>
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static unsigned int count_digits(number_unsigned_t x) noexcept
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{
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unsigned int n_digits = 1;
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for (;;)
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{
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if (x < 10)
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{
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return n_digits;
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}
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if (x < 100)
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{
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return n_digits + 1;
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}
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if (x < 1000)
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{
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return n_digits + 2;
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}
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if (x < 10000)
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{
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return n_digits + 3;
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}
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x = static_cast<number_unsigned_t>(x / 10000u);
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n_digits += 4;
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}
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}
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/*
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* Overload to make the compiler happy while it is instantiating
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* dump_integer for number_unsigned_t.
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* Must never be called.
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*/
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template <typename number_unsigned_t,
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detail::enable_if_t<
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std::is_unsigned<number_unsigned_t>::value, int> = 0>
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static number_unsigned_t remove_sign(number_unsigned_t x) noexcept
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{
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JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE
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return x; // LCOV_EXCL_LINE
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}
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/*
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* Helper function for dump_integer
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*
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* This function takes a negative signed integer and returns its absolute
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* value as unsigned integer. The plus/minus shuffling is necessary as we can
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* not directly remove the sign of an arbitrary signed integer as the
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* absolute values of INT_MIN and INT_MAX are usually not the same. See
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* #1708 for details.
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*/
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template <typename number_integer_t,
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detail::enable_if_t<
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std::is_signed<number_integer_t>::value, int> = 0,
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typename number_unsigned_t =
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typename std::make_unsigned<number_integer_t>::type>
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static number_unsigned_t remove_sign(number_integer_t x) noexcept
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{
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JSON_ASSERT(x < 0 && x < (std::numeric_limits<number_integer_t>::max)()); // NOLINT(misc-redundant-expression)
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return static_cast<number_unsigned_t>(-(x + 1)) + 1;
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}
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/*!
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@brief dump an integer
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Dump a given integer to output stream @a o.
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@param[in] x integer number (signed or unsigned) to dump
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*/
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template <typename OutputAdapterType, typename number_integral_t,
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typename number_unsigned_t = typename std::make_unsigned<
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number_integral_t>::type>
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static void dump_integer(OutputAdapterType& o, number_integral_t x)
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{
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static constexpr std::array<std::array<char, 2>, 100> digits_to_99
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{
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{
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{{'0', '0'}}, {{'0', '1'}}, {{'0', '2'}}, {{'0', '3'}}, {{'0', '4'}}, {{'0', '5'}}, {{'0', '6'}}, {{'0', '7'}}, {{'0', '8'}}, {{'0', '9'}},
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{{'1', '0'}}, {{'1', '1'}}, {{'1', '2'}}, {{'1', '3'}}, {{'1', '4'}}, {{'1', '5'}}, {{'1', '6'}}, {{'1', '7'}}, {{'1', '8'}}, {{'1', '9'}},
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{{'2', '0'}}, {{'2', '1'}}, {{'2', '2'}}, {{'2', '3'}}, {{'2', '4'}}, {{'2', '5'}}, {{'2', '6'}}, {{'2', '7'}}, {{'2', '8'}}, {{'2', '9'}},
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{{'3', '0'}}, {{'3', '1'}}, {{'3', '2'}}, {{'3', '3'}}, {{'3', '4'}}, {{'3', '5'}}, {{'3', '6'}}, {{'3', '7'}}, {{'3', '8'}}, {{'3', '9'}},
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{{'4', '0'}}, {{'4', '1'}}, {{'4', '2'}}, {{'4', '3'}}, {{'4', '4'}}, {{'4', '5'}}, {{'4', '6'}}, {{'4', '7'}}, {{'4', '8'}}, {{'4', '9'}},
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{{'5', '0'}}, {{'5', '1'}}, {{'5', '2'}}, {{'5', '3'}}, {{'5', '4'}}, {{'5', '5'}}, {{'5', '6'}}, {{'5', '7'}}, {{'5', '8'}}, {{'5', '9'}},
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{{'6', '0'}}, {{'6', '1'}}, {{'6', '2'}}, {{'6', '3'}}, {{'6', '4'}}, {{'6', '5'}}, {{'6', '6'}}, {{'6', '7'}}, {{'6', '8'}}, {{'6', '9'}},
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{{'7', '0'}}, {{'7', '1'}}, {{'7', '2'}}, {{'7', '3'}}, {{'7', '4'}}, {{'7', '5'}}, {{'7', '6'}}, {{'7', '7'}}, {{'7', '8'}}, {{'7', '9'}},
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{{'8', '0'}}, {{'8', '1'}}, {{'8', '2'}}, {{'8', '3'}}, {{'8', '4'}}, {{'8', '5'}}, {{'8', '6'}}, {{'8', '7'}}, {{'8', '8'}}, {{'8', '9'}},
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{{'9', '0'}}, {{'9', '1'}}, {{'9', '2'}}, {{'9', '3'}}, {{'9', '4'}}, {{'9', '5'}}, {{'9', '6'}}, {{'9', '7'}}, {{'9', '8'}}, {{'9', '9'}},
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}
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};
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// special case for "0"
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if (x == 0)
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{
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o->write_character('0');
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return;
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}
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number_buffer_t number_buffer{{}};
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// use a pointer to fill the buffer
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auto buffer_ptr = number_buffer.begin(); // NOLINT(llvm-qualified-auto,readability-qualified-auto,cppcoreguidelines-pro-type-vararg,hicpp-vararg)
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const bool is_negative = std::is_signed<number_integral_t>::value && !(x >= 0); // see issue #755
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number_unsigned_t abs_value;
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unsigned int n_chars{};
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if (is_negative)
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{
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*buffer_ptr = '-';
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abs_value = remove_sign(static_cast<number_integral_t>(x));
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// account one more byte for the minus sign
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n_chars = 1 + count_digits(abs_value);
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}
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else
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{
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abs_value = static_cast<number_unsigned_t>(x);
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n_chars = count_digits(abs_value);
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}
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// spare 1 byte for '\0'
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JSON_ASSERT(n_chars < number_buffer.size() - 1);
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// jump to the end to generate the string from backward
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// so we later avoid reversing the result
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buffer_ptr += n_chars;
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// Fast int2ascii implementation inspired by "Fastware" talk by Andrei Alexandrescu
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// See: https://www.youtube.com/watch?v=o4-CwDo2zpg
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while (abs_value >= 100)
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{
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const auto digits_index = static_cast<unsigned>((abs_value % 100));
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abs_value /= 100;
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*(--buffer_ptr) = digits_to_99[digits_index][1];
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*(--buffer_ptr) = digits_to_99[digits_index][0];
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}
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if (abs_value >= 10)
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{
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const auto digits_index = static_cast<unsigned>(abs_value);
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*(--buffer_ptr) = digits_to_99[digits_index][1];
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*(--buffer_ptr) = digits_to_99[digits_index][0];
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}
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else
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{
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*(--buffer_ptr) = static_cast<char>('0' + abs_value);
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}
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o->write_characters(number_buffer.data(), n_chars);
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}
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/*!
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@brief dump a floating-point number
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Dump a given floating-point number to output stream @a o.
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@param[in] x floating-point number to dump
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*/
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template <typename OutputAdapterType, typename number_float_t,
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detail::enable_if_t<
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std::is_floating_point<number_float_t>::value, int> = 0>
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static void dump_float(OutputAdapterType& o, number_float_t x)
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{
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// NaN / inf
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if (!std::isfinite(x))
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{
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o->write_characters("null", 4);
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return;
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}
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// If number_float_t is an IEEE-754 single or double precision number,
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// use the Grisu2 algorithm to produce short numbers which are
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// guaranteed to round-trip, using strtof and strtod, resp.
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//
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// NB: The test below works if <long double> == <double>.
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static constexpr bool is_ieee_single_or_double
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= (std::numeric_limits<number_float_t>::is_iec559 && std::numeric_limits<number_float_t>::digits == 24 && std::numeric_limits<number_float_t>::max_exponent == 128) ||
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(std::numeric_limits<number_float_t>::is_iec559 && std::numeric_limits<number_float_t>::digits == 53 && std::numeric_limits<number_float_t>::max_exponent == 1024);
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dump_float(o, x, std::integral_constant<bool, is_ieee_single_or_double>());
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}
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template <typename OutputAdapterType, typename number_float_t,
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detail::enable_if_t<
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std::is_floating_point<number_float_t>::value, int> = 0>
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static void dump_float(OutputAdapterType& o, number_float_t x, std::true_type /*is_ieee_single_or_double*/)
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{
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number_buffer_t number_buffer{{}};
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auto* begin = number_buffer.data();
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auto* end = ::nlohmann::detail::to_chars(begin, begin + number_buffer.size(), x);
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o->write_characters(begin, static_cast<size_t>(end - begin));
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}
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template <typename OutputAdapterType, typename number_float_t,
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detail::enable_if_t<
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std::is_floating_point<number_float_t>::value, int> = 0>
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static void dump_float(OutputAdapterType& o, number_float_t x, std::false_type /*is_ieee_single_or_double*/)
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{
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number_buffer_t number_buffer{{}};
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const std::lconv* loc(std::localeconv());
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const char thousands_sep(loc->thousands_sep == nullptr ? '\0' : std::char_traits<char>::to_char_type(* (loc->thousands_sep)));
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const char decimal_point(loc->decimal_point == nullptr ? '\0' : std::char_traits<char>::to_char_type(* (loc->decimal_point)));
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// get number of digits for a float -> text -> float round-trip
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static constexpr auto d = std::numeric_limits<number_float_t>::max_digits10;
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// the actual conversion
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// NOLINTNEXTLINE(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
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std::ptrdiff_t len = (std::snprintf)(number_buffer.data(), number_buffer.size(), "%.*g", d, x);
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// negative value indicates an error
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JSON_ASSERT(len > 0);
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// check if buffer was large enough
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JSON_ASSERT(static_cast<std::size_t>(len) < number_buffer.size());
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// erase thousands separator
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if (thousands_sep != '\0')
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{
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// NOLINTNEXTLINE(readability-qualified-auto,llvm-qualified-auto): std::remove returns an iterator, see https://github.com/nlohmann/json/issues/3081
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const auto end = std::remove(number_buffer.begin(), number_buffer.begin() + len, thousands_sep);
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std::fill(end, number_buffer.end(), '\0');
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JSON_ASSERT((end - number_buffer.begin()) <= len);
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len = (end - number_buffer.begin());
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}
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// convert decimal point to '.'
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if (decimal_point != '\0' && decimal_point != '.')
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{
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// NOLINTNEXTLINE(readability-qualified-auto,llvm-qualified-auto): std::find returns an iterator, see https://github.com/nlohmann/json/issues/3081
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const auto dec_pos = std::find(number_buffer.begin(), number_buffer.end(), decimal_point);
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if (dec_pos != number_buffer.end())
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{
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*dec_pos = '.';
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}
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}
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o->write_characters(number_buffer.data(), static_cast<std::size_t>(len));
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// determine if need to append ".0"
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const bool value_is_int_like =
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std::none_of(number_buffer.begin(), number_buffer.begin() + len + 1,
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[](char c)
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{
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return c == '.' || c == 'e';
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});
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if (value_is_int_like)
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{
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o->write_characters(".0", 2);
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}
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}
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};
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} // namespace detail
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} // namespace nlohmann
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