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// Copyright 2017 Elias Kosunen
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// This file is a part of scnlib:
// https://github.com/eliaskosunen/scnlib
#ifndef SCN_READER_FLOAT_H
#define SCN_READER_FLOAT_H
#include "../util/small_vector.h"
#include "common.h"
namespace scn {
SCN_BEGIN_NAMESPACE
namespace detail {
template <typename T>
struct float_scanner_access;
template <typename T>
struct float_scanner : common_parser {
static_assert(std::is_floating_point<T>::value,
"float_scanner requires a floating point type");
friend struct float_scanner_access<T>;
template <typename ParseCtx>
error parse(ParseCtx& pctx)
{
using char_type = typename ParseCtx::char_type;
array<char_type, 10> options{
{// hex
ascii_widen<char_type>('a'), ascii_widen<char_type>('A'),
// scientific
ascii_widen<char_type>('e'), ascii_widen<char_type>('E'),
// fixed
ascii_widen<char_type>('f'), ascii_widen<char_type>('F'),
// general
ascii_widen<char_type>('g'), ascii_widen<char_type>('G'),
// localized digits
ascii_widen<char_type>('n'),
// thsep
ascii_widen<char_type>('\'')}};
bool flags[10] = {false};
auto e = parse_common(
pctx, span<const char_type>{options.begin(), options.end()},
span<bool>{flags, 10}, null_type_cb<ParseCtx>);
if (!e) {
return e;
}
if (flags[0] && flags[1]) {
return {error::invalid_format_string,
"Can't have both 'a' and 'A' flags with floats"};
}
if (flags[2] && flags[3]) {
return {error::invalid_format_string,
"Can't have both 'e' and 'E' flags with floats"};
}
if (flags[4] && flags[5]) {
return {error::invalid_format_string,
"Can't have both 'f' and 'F' flags with floats"};
}
if (flags[6] && flags[7]) {
return {error::invalid_format_string,
"Can't have both 'g' and 'G' flags with floats"};
}
bool set_hex = flags[0] || flags[1];
bool set_scientific = flags[2] || flags[3];
bool set_fixed = flags[4] || flags[5];
bool set_general = flags[6] || flags[7];
if (set_general && set_fixed) {
return {error::invalid_format_string,
"General float already implies fixed"};
}
if (set_general && set_scientific) {
return {error::invalid_format_string,
"General float already implies scientific"};
}
format_options = 0;
if (set_hex) {
format_options |= allow_hex;
}
if (set_scientific) {
format_options |= allow_scientific;
}
if (set_fixed) {
format_options |= allow_fixed;
}
if (set_general) {
format_options |= allow_fixed | allow_scientific;
}
if (format_options == 0) {
format_options |=
allow_fixed | allow_scientific | allow_hex;
}
// 'n'
if (flags[8]) {
common_options |= localized;
format_options |= localized_digits;
}
// thsep
if (flags[9]) {
format_options |= allow_thsep;
}
return {};
}
template <typename Context>
error scan(T& val, Context& ctx)
{
using char_type = typename Context::char_type;
auto do_parse_float = [&](span<const char_type> s) -> error {
T tmp = 0;
expected<std::ptrdiff_t> ret{0};
if (SCN_UNLIKELY((format_options & localized_digits) != 0 ||
((common_options & localized) != 0 &&
(format_options & allow_hex) != 0))) {
// 'n' OR ('L' AND 'a')
// because none of our parsers support BOTH hexfloats
// and custom (localized) decimal points,
// so we have to fall back on iostreams
SCN_CLANG_PUSH_IGNORE_UNDEFINED_TEMPLATE
std::basic_string<char_type> str(s.data(), s.size());
ret =
ctx.locale().get_localized().read_num(tmp, str, 0);
SCN_CLANG_POP_IGNORE_UNDEFINED_TEMPLATE
}
else {
ret = _read_float(
tmp, s,
ctx.locale()
.get((common_options & localized) != 0)
.decimal_point());
}
if (!ret) {
return ret.error();
}
if (ret.value() != s.ssize()) {
auto pb =
putback_n(ctx.range(), s.ssize() - ret.value());
if (!pb) {
return pb;
}
}
val = tmp;
return {};
};
auto is_space_pred = make_is_space_predicate(
ctx.locale(), (common_options & localized) != 0,
field_width);
if (Context::range_type::is_contiguous) {
auto s = read_until_space_zero_copy(ctx.range(),
is_space_pred, false);
if (!s) {
return s.error();
}
return do_parse_float(s.value());
}
small_vector<char_type, 32> buf;
auto outputit = std::back_inserter(buf);
auto e = read_until_space(ctx.range(), outputit, is_space_pred,
false);
if (!e && buf.empty()) {
return e;
}
return do_parse_float(make_span(buf));
}
enum format_options_type {
allow_hex = 1,
allow_scientific = 2,
allow_fixed = 4,
localized_digits = 8,
allow_thsep = 16
};
uint8_t format_options{allow_hex | allow_scientific | allow_fixed};
private:
template <typename CharT>
expected<std::ptrdiff_t> _read_float(T& val,
span<const CharT> s,
CharT locale_decimal_point)
{
size_t chars{};
std::basic_string<CharT> str(s.data(), s.size());
SCN_CLANG_PUSH_IGNORE_UNDEFINED_TEMPLATE
auto ret =
_read_float_impl(str.data(), chars, locale_decimal_point);
SCN_CLANG_POP_IGNORE_UNDEFINED_TEMPLATE
if (!ret) {
return ret.error();
}
val = ret.value();
return static_cast<std::ptrdiff_t>(chars);
}
template <typename CharT>
expected<T> _read_float_impl(const CharT* str,
size_t& chars,
CharT locale_decimal_point);
};
// instantiate
template struct float_scanner<float>;
template struct float_scanner<double>;
template struct float_scanner<long double>;
template <typename T>
struct float_scanner_access : public float_scanner<T> {
using float_scanner<T>::_read_float;
using float_scanner<T>::_read_float_impl;
};
} // namespace detail
SCN_END_NAMESPACE
} // namespace scn
#if defined(SCN_HEADER_ONLY) && SCN_HEADER_ONLY && \
!defined(SCN_READER_FLOAT_CPP)
#include "reader_float.cpp"
#endif
#endif
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