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Implemented format_float in terms of format_int

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This commit is contained in:
Andreas Tsouchlos 2022-02-13 23:12:25 +01:00
parent 4666b4e737
commit 9bf3e63058
3 changed files with 48 additions and 6 deletions
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2
const_fmt/format.h
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@ -47,7 +47,7 @@ constexpr inline void format_arg(char* dest, arg_t arg) {
template <fmt_data_t fmt_data, std::floating_point arg_t>
constexpr inline void format_arg(char* dest, arg_t arg){
// const_fmt_detail::format_float<arg_t, fmt_data>(dest, arg);
const_fmt_detail::format_float<arg_t, fmt_data>(dest, arg);
};
// TODO: Error handling

50
const_fmt/format_impl.h
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@ -112,6 +112,25 @@ constexpr inline void format_decimal(char* out, uint_t value, int n_digits,
copy2(out, digits2(static_cast<size_t>(value)));
}
// returns {abs_value, was_negative}
template <std::signed_integral int_t>
constexpr std::pair<typename std::make_unsigned<int_t>::type, bool>
get_abs_value(int_t value) {
using uint_t = typename std::make_unsigned<int_t>::type;
uint_t abs_value = static_cast<uint_t>(value);
const bool negative = value < 0;
if (negative) abs_value = 0 - abs_value;
return {abs_value, negative};
}
template <std::unsigned_integral int_t>
constexpr std::pair<int_t, bool> get_abs_value(int_t value) {
return {value, false};
}
/*
*
@ -127,9 +146,7 @@ constexpr inline void format_int(char* out, uint_t value) {
template <std::signed_integral int_t, fmt_data_t t_fmt_node>
constexpr inline void format_int(char* out, int_t value) {
uint64_t abs_value = static_cast<uint64_t>(value);
const bool negative = value < 0;
if (negative) abs_value = 0 - abs_value;
const auto [abs_value, negative] = get_abs_value(value);
const int n_digits = count_digits(abs_value);
@ -153,9 +170,34 @@ constexpr inline void format_int(char* out, int_t value) {
template <std::floating_point float_t, fmt_data_t t_fmt_node>
constexpr inline void format_float(char* out, float_t value) {
// clang-format off
constexpr fmt_data_t fmt_node_integral = {
t_fmt_node.has_zero_padding, // has_zero_padding
t_fmt_node.length - t_fmt_node.precision - 1, // length
t_fmt_node.precision, // ignored
t_fmt_node.type, // ignored
t_fmt_node.position // ignored
};
constexpr fmt_data_t fmt_node_fractional = {
true, // has_zero_padding
t_fmt_node.precision, // length
t_fmt_node.precision, // ignored
t_fmt_node.type, // ignored
t_fmt_node.position // ignored
};
// clang-format on
*(out) = 'f';
*(out + t_fmt_node.length - t_fmt_node.precision - 1) = '.';
const int integral = static_cast<int>(value);
constexpr std::size_t factor = const_pow(10, t_fmt_node.precision);
const int fractional = static_cast<int>((value - integral) * factor);
const auto [fractional_abs, fractional_negative] = get_abs_value(fractional);
format_int<int, fmt_node_integral>(out, integral);
format_int<uint16_t, fmt_node_fractional>(out + t_fmt_node.length - t_fmt_node.precision, fractional_abs);
}

2
examples/src/examples.cpp
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@ -5,7 +5,7 @@
using namespace const_fmt;
int main() {
constexpr auto s = "abcdef {:04}"_const_fmt(123);
constexpr auto s = "abcdef {:9.3}"_const_fmt(-876.3);
// Convert s (with a type of 'std::array<char, N>') into something
// writable to std::cout