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replace float/double conversion with fast_float, update unit tests, update meson

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ado
2021-02-07 11:33:16 +01:00
parent a1ca012203
commit 9408c385d6
5 changed files with 25 additions and 107 deletions
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100
include/ss/extract.hpp
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@@ -2,6 +2,7 @@
#include "type_traits.hpp"
#include <cstring>
#include <fast_float/fast_float.h>
#include <functional>
#include <limits>
#include <optional>
@@ -14,104 +15,17 @@ namespace ss {
////////////////
// number converters
////////////////
template <typename T>
std::enable_if_t<std::is_floating_point_v<T>, T> pow10(int n) {
T ret = 1.0;
T r = 10.0;
if (n < 0) {
n = -n;
r = 0.1;
}
while (n) {
if (n & 1) {
ret *= r;
}
r *= r;
n >>= 1;
}
return ret;
}
// TODO not working with large number of digits
template <typename T>
std::enable_if_t<std::is_floating_point_v<T>, std::optional<T>> to_num(
const char* begin, const char* const end) {
if (begin == end) {
T ret;
auto answer = fast_float::from_chars(begin, end, ret);
if (answer.ec != std::errc() || answer.ptr != end) {
return std::nullopt;
}
int sign = 1;
T int_part = 0.0;
T frac_part = 0.0;
bool has_frac = false;
bool has_exp = false;
// +/- sign
if (*begin == '-') {
++begin;
sign = -1;
}
while (begin != end) {
if (*begin >= '0' && *begin <= '9') {
int_part = int_part * 10 + (*begin - '0');
} else if (*begin == '.') {
has_frac = true;
++begin;
break;
} else if (*begin == 'e') {
has_exp = true;
++begin;
break;
} else {
return std::nullopt;
}
++begin;
}
if (has_frac) {
T frac_exp = 0.1;
while (begin != end) {
if (*begin >= '0' && *begin <= '9') {
frac_part += frac_exp * (*begin - '0');
frac_exp *= 0.1;
} else if (*begin == 'e') {
has_exp = true;
++begin;
break;
} else {
return std::nullopt;
}
++begin;
}
}
// parsing exponent part
T exp_part = 1.0;
if (begin != end && has_exp) {
int exp_sign = 1;
if (*begin == '-') {
exp_sign = -1;
++begin;
} else if (*begin == '+') {
++begin;
}
int e = 0;
while (begin != end && *begin >= '0' && *begin <= '9') {
e = e * 10 + *begin - '0';
++begin;
}
exp_part = pow10<T>(exp_sign * e);
}
if (begin != end) {
return std::nullopt;
}
return sign * (int_part + frac_part) * exp_part;
return ret;
}
inline std::optional<short> from_char(char c) {
@@ -249,7 +163,7 @@ bool shift_and_add_overflow(T& value, T digit, F add_last_digit_owerflow) {
}
#else
#warning "use clang or gcc!!!"
#warning "Use clang or gcc if possible."
template <typename T, typename U>
bool shift_and_add_overflow(T& value, T digit, U is_negative) {
digit = (is_negative) ? -digit : digit;