const_fmt/inc/format.h

158 lines
4.4 KiB
C++

#ifndef LOGGER_FORMAT_H
#define LOGGER_FORMAT_H
#include "parse.h"
#include "utility.h"
namespace detail {
template <fmt_node_t fmt_node, typename T>
constexpr void check_fmt_params() {
static_assert(fmt_node.length > fmt_node.precision + 1,
"Insufficient length for desired precision");
}
template <ConstString s>
constexpr int get_output_len() {
constexpr auto parse_result = parse_string<s>();
static_assert(parse_result.is_valid, "Syntax error in format string");
unsigned result = 0;
for (const auto& ast_node : parse_result.value) {
if (ast_node.is_char())
++result;
else
result += ast_node.get_node().length;
}
return result;
}
template <std::size_t len, bool zeroed>
constexpr std::array<char, len> get_init_array() {
if constexpr (zeroed) {
return {'0'};
} else {
return {' '};
}
}
// TODO: See if this is possible with charconv
template <fmt_node_t fmt_node, std::integral arg_t>
constexpr std::array<char, fmt_node.length> format_arg(arg_t arg) {
check_fmt_params<fmt_node, arg_t>();
std::array<char, fmt_node.length> result =
get_init_array<fmt_node.length, fmt_node.has_zero_padding>();
for (unsigned i = 1; (i <= result.size()) && arg > 0; ++i) {
result[result.size() - i] = arg % 10 + 48;
arg = arg / 10;
}
return result;
}
// TODO: See if this is possible with charconv
template <fmt_node_t fmt_node, std::floating_point arg_t>
constexpr std::array<char, fmt_node.length> format_arg(arg_t arg) {
check_fmt_params<fmt_node, arg_t>();
constexpr unsigned len_before_point =
fmt_node.length - fmt_node.precision - 1;
constexpr unsigned multiplier = const_pow(10, fmt_node.precision);
std::array<char, fmt_node.length> result =
get_init_array<fmt_node.length, fmt_node.has_zero_padding>();
result[len_before_point] = '.';
arg = arg * multiplier;
for (unsigned i = result.size() - 1; i > len_before_point; --i) {
result[i] = static_cast<int>(arg) % 10 + 48;
arg = arg / 10;
}
for (unsigned i = fmt_node.precision + 2; (i <= result.size()) && (arg >= 1); ++i) {
result[result.size() - i] = static_cast<int>(arg) % 10 + 48;
arg = arg / 10;
}
return result;
}
template <fmt_node_t fmt_node>
constexpr std::array<char, fmt_node.length> format_arg(const char* arg) {
check_fmt_params<fmt_node, const char*>();
std::array<char, fmt_node.length> result;
for (auto& c : result) {
if (*arg != '\0')
c = *(arg++);
else
c = ' ';
}
return result;
}
template <auto t_ast, unsigned t_ast_i = 0, unsigned t_result_i = 0,
typename char_array_t>
constexpr char_array_t format_args(char_array_t result) {
return result;
}
template <auto t_ast, unsigned t_ast_i = 0, unsigned t_result_i = 0,
typename char_array_t, typename first_arg_t, typename... other_args_t>
constexpr char_array_t format_args(char_array_t result, first_arg_t first_arg,
other_args_t... other_args) {
if constexpr (t_ast_i >= t_ast.size()) {
return result;
} else {
constexpr auto ast_node = t_ast[t_ast_i];
if (ast_node.is_char()) {
result[t_result_i] = ast_node.get_char();
return format_args<t_ast, t_ast_i + 1, t_result_i + 1>(
result, first_arg, other_args...);
} else {
constexpr auto fmt_node = ast_node.get_node();
const auto formatted_arg = format_arg<fmt_node>(first_arg);
std::copy(formatted_arg.begin(), formatted_arg.end(),
result.begin() + t_result_i);
return format_args<t_ast, t_ast_i + 1,
t_result_i + fmt_node.length>(result,
other_args...);
}
}
}
} // namespace detail
template <detail::ConstString s, typename... args_t>
constexpr std::array<char, detail::get_output_len<s>()> format(args_t... args) {
constexpr auto parse_result = detail::parse_string<s>();
static_assert(parse_result.is_valid, "Syntax error in format string");
std::array<char, detail::get_output_len<s>()> result;
return detail::format_args<parse_result.value>(result, args...);
}
#endif // LOGGER_FORMAT_H