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llvm / llvm-project / libcxx / refs/heads/main / . / include / __format / parser_std_format_spec.h
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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___FORMAT_PARSER_STD_FORMAT_SPEC_H
#define _LIBCPP___FORMAT_PARSER_STD_FORMAT_SPEC_H
/// \file Contains the std-format-spec parser.
///
/// Most of the code can be reused in the chrono-format-spec.
/// This header has some support for the chrono-format-spec since it doesn't
/// affect the std-format-spec.
#include <__algorithm/copy_n.h>
#include <__algorithm/min.h>
#include <__assert>
#include <__concepts/arithmetic.h>
#include <__concepts/same_as.h>
#include <__config>
#include <__format/format_arg.h>
#include <__format/format_error.h>
#include <__format/format_parse_context.h>
#include <__format/format_string.h>
#include <__format/unicode.h>
#include <__format/width_estimation_table.h>
#include <__iterator/concepts.h>
#include <__iterator/iterator_traits.h> // iter_value_t
#include <__memory/addressof.h>
#include <__type_traits/common_type.h>
#include <__type_traits/is_constant_evaluated.h>
#include <__type_traits/is_trivially_copyable.h>
#include <__variant/monostate.h>
#include <cstdint>
#include <string>
#include <string_view>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 20
namespace __format_spec {
_LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI inline void
__throw_invalid_option_format_error(const char* __id, const char* __option) {
std::__throw_format_error(
(string("The format specifier for ") + __id + " does not allow the " + __option + " option").c_str());
}
_LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI inline void __throw_invalid_type_format_error(const char* __id) {
std::__throw_format_error(
(string("The type option contains an invalid value for ") + __id + " formatting argument").c_str());
}
template <contiguous_iterator _Iterator, class _ParseContext>
_LIBCPP_HIDE_FROM_ABI constexpr __format::__parse_number_result<_Iterator>
__parse_arg_id(_Iterator __begin, _Iterator __end, _ParseContext& __ctx) {
using _CharT = iter_value_t<_Iterator>;
// This function is a wrapper to call the real parser. But it does the
// validation for the pre-conditions and post-conditions.
if (__begin == __end)
std::__throw_format_error("End of input while parsing an argument index");
__format::__parse_number_result __r = __format::__parse_arg_id(__begin, __end, __ctx);
if (__r.__last == __end || *__r.__last != _CharT('}'))
std::__throw_format_error("The argument index is invalid");
++__r.__last;
return __r;
}
template <class _Context>
_LIBCPP_HIDE_FROM_ABI constexpr uint32_t __substitute_arg_id(basic_format_arg<_Context> __format_arg) {
// [format.string.std]/8
// If the corresponding formatting argument is not of integral type...
// This wording allows char and bool too. LWG-3720 changes the wording to
// If the corresponding formatting argument is not of standard signed or
// unsigned integer type,
// This means the 128-bit will not be valid anymore.
// TODO FMT Verify this resolution is accepted and add a test to verify
// 128-bit integrals fail and switch to visit_format_arg.
return std::__visit_format_arg(
[](auto __arg) -> uint32_t {
using _Type = decltype(__arg);
if constexpr (same_as<_Type, monostate>)
std::__throw_format_error("The argument index value is too large for the number of arguments supplied");
// [format.string.std]/8
// If { arg-idopt } is used in a width or precision, the value of the
// corresponding formatting argument is used in its place. If the
// corresponding formatting argument is not of standard signed or unsigned
// integer type, or its value is negative for precision or non-positive for
// width, an exception of type format_error is thrown.
//
// When an integral is used in a format function, it is stored as one of
// the types checked below. Other integral types are promoted. For example,
// a signed char is stored as an int.
if constexpr (same_as<_Type, int> || same_as<_Type, unsigned int> || //
same_as<_Type, long long> || same_as<_Type, unsigned long long>) {
if constexpr (signed_integral<_Type>) {
if (__arg < 0)
std::__throw_format_error("An argument index may not have a negative value");
}
using _CT = common_type_t<_Type, decltype(__format::__number_max)>;
if (static_cast<_CT>(__arg) > static_cast<_CT>(__format::__number_max))
std::__throw_format_error("The value of the argument index exceeds its maximum value");
return __arg;
} else
std::__throw_format_error("Replacement argument isn't a standard signed or unsigned integer type");
},
__format_arg);
}
/// These fields are a filter for which elements to parse.
///
/// They default to false so when a new field is added it needs to be opted in
/// explicitly.
struct _LIBCPP_HIDE_FROM_ABI __fields {
uint16_t __sign_ : 1 {false};
uint16_t __alternate_form_ : 1 {false};
uint16_t __zero_padding_ : 1 {false};
uint16_t __precision_ : 1 {false};
uint16_t __locale_specific_form_ : 1 {false};
uint16_t __type_ : 1 {false};
// Determines the valid values for fill.
//
// Originally the fill could be any character except { and }. Range-based
// formatters use the colon to mark the beginning of the
// underlying-format-spec. To avoid parsing ambiguities these formatter
// specializations prohibit the use of the colon as a fill character.
uint16_t __use_range_fill_ : 1 {false};
uint16_t __clear_brackets_ : 1 {false};
uint16_t __consume_all_ : 1 {false};
};
// By not placing this constant in the formatter class it's not duplicated for
// char and wchar_t.
inline constexpr __fields __fields_bool{.__locale_specific_form_ = true, .__type_ = true, .__consume_all_ = true};
inline constexpr __fields __fields_integral{
.__sign_ = true,
.__alternate_form_ = true,
.__zero_padding_ = true,
.__locale_specific_form_ = true,
.__type_ = true,
.__consume_all_ = true};
inline constexpr __fields __fields_floating_point{
.__sign_ = true,
.__alternate_form_ = true,
.__zero_padding_ = true,
.__precision_ = true,
.__locale_specific_form_ = true,
.__type_ = true,
.__consume_all_ = true};
inline constexpr __fields __fields_string{.__precision_ = true, .__type_ = true, .__consume_all_ = true};
inline constexpr __fields __fields_pointer{.__zero_padding_ = true, .__type_ = true, .__consume_all_ = true};
# if _LIBCPP_STD_VER >= 23
inline constexpr __fields __fields_tuple{.__use_range_fill_ = true, .__clear_brackets_ = true};
inline constexpr __fields __fields_range{.__use_range_fill_ = true, .__clear_brackets_ = true};
inline constexpr __fields __fields_fill_align_width{};
# endif
enum class __alignment : uint8_t {
/// No alignment is set in the format string.
__default,
__left,
__center,
__right,
__zero_padding
};
enum class __sign : uint8_t {
/// No sign is set in the format string.
///
/// The sign isn't allowed for certain format-types. By using this value
/// it's possible to detect whether or not the user explicitly set the sign
/// flag. For formatting purposes it behaves the same as \ref __minus.
__default,
__minus,
__plus,
__space
};
enum class __type : uint8_t {
__default = 0,
__string,
__binary_lower_case,
__binary_upper_case,
__octal,
__decimal,
__hexadecimal_lower_case,
__hexadecimal_upper_case,
__pointer_lower_case,
__pointer_upper_case,
__char,
__hexfloat_lower_case,
__hexfloat_upper_case,
__scientific_lower_case,
__scientific_upper_case,
__fixed_lower_case,
__fixed_upper_case,
__general_lower_case,
__general_upper_case,
__debug
};
_LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __create_type_mask(__type __t) {
uint32_t __shift = static_cast<uint32_t>(__t);
if (__shift == 0)
return 1;
if (__shift > 31)
std::__throw_format_error("The type does not fit in the mask");
return 1 << __shift;
}
inline constexpr uint32_t __type_mask_integer =
__create_type_mask(__type::__binary_lower_case) | //
__create_type_mask(__type::__binary_upper_case) | //
__create_type_mask(__type::__decimal) | //
__create_type_mask(__type::__octal) | //
__create_type_mask(__type::__hexadecimal_lower_case) | //
__create_type_mask(__type::__hexadecimal_upper_case);
struct __std {
__alignment __alignment_ : 3;
__sign __sign_ : 2;
bool __alternate_form_ : 1;
bool __locale_specific_form_ : 1;
__type __type_;
};
struct __chrono {
__alignment __alignment_ : 3;
bool __locale_specific_form_ : 1;
bool __hour_ : 1;
bool __weekday_name_ : 1;
bool __weekday_ : 1;
bool __day_of_year_ : 1;
bool __week_of_year_ : 1;
bool __month_name_ : 1;
};
// The fill UCS scalar value.
//
// This is always an array, with 1, 2, or 4 elements.
// The size of the data structure is always 32-bits.
template <class _CharT>
struct __code_point;
template <>
struct __code_point<char> {
char __data[4] = {' '};
};
# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <>
struct __code_point<wchar_t> {
wchar_t __data[4 / sizeof(wchar_t)] = {L' '};
};
# endif
/// Contains the parsed formatting specifications.
///
/// This contains information for both the std-format-spec and the
/// chrono-format-spec. This results in some unused members for both
/// specifications. However these unused members don't increase the size
/// of the structure.
///
/// This struct doesn't cross ABI boundaries so its layout doesn't need to be
/// kept stable.
template <class _CharT>
struct __parsed_specifications {
union {
// The field __alignment_ is the first element in __std_ and __chrono_.
// This allows the code to always inspect this value regards which member
// of the union is the active member [class.union.general]/2.
//
// This is needed since the generic output routines handle the alignment of
// the output.
__alignment __alignment_ : 3;
__std __std_;
__chrono __chrono_;
};
/// The requested width.
///
/// When the format-spec used an arg-id for this field it has already been
/// replaced with the value of that arg-id.
int32_t __width_;
/// The requested precision.
///
/// When the format-spec used an arg-id for this field it has already been
/// replaced with the value of that arg-id.
int32_t __precision_;
__code_point<_CharT> __fill_;
_LIBCPP_HIDE_FROM_ABI constexpr bool __has_width() const { return __width_ > 0; }
_LIBCPP_HIDE_FROM_ABI constexpr bool __has_precision() const { return __precision_ >= 0; }
};
// Validate the struct is small and cheap to copy since the struct is passed by
// value in formatting functions.
static_assert(sizeof(__parsed_specifications<char>) == 16);
static_assert(is_trivially_copyable_v<__parsed_specifications<char>>);
# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
static_assert(sizeof(__parsed_specifications<wchar_t>) == 16);
static_assert(is_trivially_copyable_v<__parsed_specifications<wchar_t>>);
# endif
/// The parser for the std-format-spec.
///
/// Note this class is a member of std::formatter specializations. It's
/// expected developers will create their own formatter specializations that
/// inherit from the std::formatter specializations. This means this class
/// must be ABI stable. To aid the stability the unused bits in the class are
/// set to zero. That way they can be repurposed if a future revision of the
/// Standards adds new fields to std-format-spec.
template <class _CharT>
class _LIBCPP_TEMPLATE_VIS __parser {
public:
// Parses the format specification.
//
// Depending on whether the parsing is done compile-time or run-time
// the method slightly differs.
// - Only parses a field when it is in the __fields. Accepting all
// fields and then validating the valid ones has a performance impact.
// This is faster but gives slighly worse error messages.
// - At compile-time when a field is not accepted the parser will still
// parse it and give an error when it's present. This gives a more
// accurate error.
// The idea is that most times the format instead of the vformat
// functions are used. In that case the error will be detected during
// compilation and there is no need to pay for the run-time overhead.
template <class _ParseContext>
_LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator __parse(_ParseContext& __ctx, __fields __fields) {
auto __begin = __ctx.begin();
auto __end = __ctx.end();
if (__begin == __end || *__begin == _CharT('}') || (__fields.__use_range_fill_ && *__begin == _CharT(':')))
return __begin;
if (__parse_fill_align(__begin, __end) && __begin == __end)
return __begin;
if (__fields.__sign_) {
if (__parse_sign(__begin) && __begin == __end)
return __begin;
} else if (std::is_constant_evaluated() && __parse_sign(__begin)) {
std::__throw_format_error("The format specification does not allow the sign option");
}
if (__fields.__alternate_form_) {
if (__parse_alternate_form(__begin) && __begin == __end)
return __begin;
} else if (std::is_constant_evaluated() && __parse_alternate_form(__begin)) {
std::__throw_format_error("The format specifier does not allow the alternate form option");
}
if (__fields.__zero_padding_) {
if (__parse_zero_padding(__begin) && __begin == __end)
return __begin;
} else if (std::is_constant_evaluated() && __parse_zero_padding(__begin)) {
std::__throw_format_error("The format specifier does not allow the zero-padding option");
}
if (__parse_width(__begin, __end, __ctx) && __begin == __end)
return __begin;
if (__fields.__precision_) {
if (__parse_precision(__begin, __end, __ctx) && __begin == __end)
return __begin;
} else if (std::is_constant_evaluated() && __parse_precision(__begin, __end, __ctx)) {
std::__throw_format_error("The format specifier does not allow the precision option");
}
if (__fields.__locale_specific_form_) {
if (__parse_locale_specific_form(__begin) && __begin == __end)
return __begin;
} else if (std::is_constant_evaluated() && __parse_locale_specific_form(__begin)) {
std::__throw_format_error("The format specifier does not allow the locale-specific form option");
}
if (__fields.__clear_brackets_) {
if (__parse_clear_brackets(__begin) && __begin == __end)
return __begin;
} else if (std::is_constant_evaluated() && __parse_clear_brackets(__begin)) {
std::__throw_format_error("The format specifier does not allow the n option");
}
if (__fields.__type_)
__parse_type(__begin);
if (!__fields.__consume_all_)
return __begin;
if (__begin != __end && *__begin != _CharT('}'))
std::__throw_format_error("The format specifier should consume the input or end with a '}'");
return __begin;
}
// Validates the selected the parsed data.
//
// The valid fields in the parser may depend on the display type
// selected. But the type is the last optional field, so by the time
// it's known an option can't be used, it already has been parsed.
// This does the validation again.
//
// For example an integral may have a sign, zero-padding, or alternate
// form when the type option is not 'c'. So the generic approach is:
//
// typename _ParseContext::iterator __result = __parser_.__parse(__ctx, __format_spec::__fields_integral);
// if (__parser.__type_ == __format_spec::__type::__char) {
// __parser.__validate((__format_spec::__fields_bool, "an integer");
// ... // more char adjustments
// } else {
// ... // validate an integral type.
// }
//
// For some types all valid options need a second validation run, like
// boolean types.
//
// Depending on whether the validation is done at compile-time or
// run-time the error differs
// - run-time the exception is thrown and contains the type of field
// being validated.
// - at compile-time the line with `std::__throw_format_error` is shown
// in the output. In that case it's important for the error to be on one
// line.
// Note future versions of C++ may allow better compile-time error
// reporting.
_LIBCPP_HIDE_FROM_ABI constexpr void
__validate(__fields __fields, const char* __id, uint32_t __type_mask = -1) const {
if (!__fields.__sign_ && __sign_ != __sign::__default) {
if (std::is_constant_evaluated())
std::__throw_format_error("The format specifier does not allow the sign option");
else
__format_spec::__throw_invalid_option_format_error(__id, "sign");
}
if (!__fields.__alternate_form_ && __alternate_form_) {
if (std::is_constant_evaluated())
std::__throw_format_error("The format specifier does not allow the alternate form option");
else
__format_spec::__throw_invalid_option_format_error(__id, "alternate form");
}
if (!__fields.__zero_padding_ && __alignment_ == __alignment::__zero_padding) {
if (std::is_constant_evaluated())
std::__throw_format_error("The format specifier does not allow the zero-padding option");
else
__format_spec::__throw_invalid_option_format_error(__id, "zero-padding");
}
if (!__fields.__precision_ && __precision_ != -1) { // Works both when the precision has a value or an arg-id.
if (std::is_constant_evaluated())
std::__throw_format_error("The format specifier does not allow the precision option");
else
__format_spec::__throw_invalid_option_format_error(__id, "precision");
}
if (!__fields.__locale_specific_form_ && __locale_specific_form_) {
if (std::is_constant_evaluated())
std::__throw_format_error("The format specifier does not allow the locale-specific form option");
else
__format_spec::__throw_invalid_option_format_error(__id, "locale-specific form");
}
if ((__create_type_mask(__type_) & __type_mask) == 0) {
if (std::is_constant_evaluated())
std::__throw_format_error("The format specifier uses an invalid value for the type option");
else
__format_spec::__throw_invalid_type_format_error(__id);
}
}
/// \returns the `__parsed_specifications` with the resolved dynamic sizes..
_LIBCPP_HIDE_FROM_ABI __parsed_specifications<_CharT> __get_parsed_std_specifications(auto& __ctx) const {
return __parsed_specifications<_CharT>{
.__std_ = __std{.__alignment_ = __alignment_,
.__sign_ = __sign_,
.__alternate_form_ = __alternate_form_,
.__locale_specific_form_ = __locale_specific_form_,
.__type_ = __type_},
.__width_{__get_width(__ctx)},
.__precision_{__get_precision(__ctx)},
.__fill_{__fill_}};
}
_LIBCPP_HIDE_FROM_ABI __parsed_specifications<_CharT> __get_parsed_chrono_specifications(auto& __ctx) const {
return __parsed_specifications<_CharT>{
.__chrono_ =
__chrono{.__alignment_ = __alignment_,
.__locale_specific_form_ = __locale_specific_form_,
.__hour_ = __hour_,
.__weekday_name_ = __weekday_name_,
.__weekday_ = __weekday_,
.__day_of_year_ = __day_of_year_,
.__week_of_year_ = __week_of_year_,
.__month_name_ = __month_name_},
.__width_{__get_width(__ctx)},
.__precision_{__get_precision(__ctx)},
.__fill_{__fill_}};
}
__alignment __alignment_ : 3 {__alignment::__default};
__sign __sign_ : 2 {__sign::__default};
bool __alternate_form_ : 1 {false};
bool __locale_specific_form_ : 1 {false};
bool __clear_brackets_ : 1 {false};
__type __type_{__type::__default};
// These flags are only used for formatting chrono. Since the struct has
// padding space left it's added to this structure.
bool __hour_ : 1 {false};
bool __weekday_name_ : 1 {false};
bool __weekday_ : 1 {false};
bool __day_of_year_ : 1 {false};
bool __week_of_year_ : 1 {false};
bool __month_name_ : 1 {false};
uint8_t __reserved_0_ : 2 {0};
uint8_t __reserved_1_ : 6 {0};
// These two flags are only used internally and not part of the
// __parsed_specifications. Therefore put them at the end.
bool __width_as_arg_ : 1 {false};
bool __precision_as_arg_ : 1 {false};
/// The requested width, either the value or the arg-id.
int32_t __width_{0};
/// The requested precision, either the value or the arg-id.
int32_t __precision_{-1};
__code_point<_CharT> __fill_{};
private:
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_alignment(_CharT __c) {
switch (__c) {
case _CharT('<'):
__alignment_ = __alignment::__left;
return true;
case _CharT('^'):
__alignment_ = __alignment::__center;
return true;
case _CharT('>'):
__alignment_ = __alignment::__right;
return true;
}
return false;
}
_LIBCPP_HIDE_FROM_ABI constexpr void __validate_fill_character(_CharT __fill) {
// The forbidden fill characters all code points formed from a single code unit, thus the
// check can be omitted when more code units are used.
if (__fill == _CharT('{'))
std::__throw_format_error("The fill option contains an invalid value");
}
# ifndef _LIBCPP_HAS_NO_UNICODE
// range-fill and tuple-fill are identical
template <contiguous_iterator _Iterator>
requires same_as<_CharT, char>
# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
|| (same_as<_CharT, wchar_t> && sizeof(wchar_t) == 2)
# endif
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end) {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__begin != __end,
"when called with an empty input the function will cause "
"undefined behavior by evaluating data not in the input");
__unicode::__code_point_view<_CharT> __view{__begin, __end};
__unicode::__consume_result __consumed = __view.__consume();
if (__consumed.__status != __unicode::__consume_result::__ok)
std::__throw_format_error("The format specifier contains malformed Unicode characters");
if (__view.__position() < __end && __parse_alignment(*__view.__position())) {
ptrdiff_t __code_units = __view.__position() - __begin;
if (__code_units == 1)
// The forbidden fill characters all are code points encoded
// in one code unit, thus the check can be omitted when more
// code units are used.
__validate_fill_character(*__begin);
std::copy_n(__begin, __code_units, std::addressof(__fill_.__data[0]));
__begin += __code_units + 1;
return true;
}
if (!__parse_alignment(*__begin))
return false;
++__begin;
return true;
}
# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <contiguous_iterator _Iterator>
requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 4)
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end) {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__begin != __end,
"when called with an empty input the function will cause "
"undefined behavior by evaluating data not in the input");
if (__begin + 1 != __end && __parse_alignment(*(__begin + 1))) {
if (!__unicode::__is_scalar_value(*__begin))
std::__throw_format_error("The fill option contains an invalid value");
__validate_fill_character(*__begin);
__fill_.__data[0] = *__begin;
__begin += 2;
return true;
}
if (!__parse_alignment(*__begin))
return false;
++__begin;
return true;
}
# endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
# else // _LIBCPP_HAS_NO_UNICODE
// range-fill and tuple-fill are identical
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end) {
_LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
__begin != __end,
"when called with an empty input the function will cause "
"undefined behavior by evaluating data not in the input");
if (__begin + 1 != __end) {
if (__parse_alignment(*(__begin + 1))) {
__validate_fill_character(*__begin);
__fill_.__data[0] = *__begin;
__begin += 2;
return true;
}
}
if (!__parse_alignment(*__begin))
return false;
++__begin;
return true;
}
# endif // _LIBCPP_HAS_NO_UNICODE
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_sign(_Iterator& __begin) {
switch (*__begin) {
case _CharT('-'):
__sign_ = __sign::__minus;
break;
case _CharT('+'):
__sign_ = __sign::__plus;
break;
case _CharT(' '):
__sign_ = __sign::__space;
break;
default:
return false;
}
++__begin;
return true;
}
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_alternate_form(_Iterator& __begin) {
if (*__begin != _CharT('#'))
return false;
__alternate_form_ = true;
++__begin;
return true;
}
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_zero_padding(_Iterator& __begin) {
if (*__begin != _CharT('0'))
return false;
if (__alignment_ == __alignment::__default)
__alignment_ = __alignment::__zero_padding;
++__begin;
return true;
}
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_width(_Iterator& __begin, _Iterator __end, auto& __ctx) {
if (*__begin == _CharT('0'))
std::__throw_format_error("The width option should not have a leading zero");
if (*__begin == _CharT('{')) {
__format::__parse_number_result __r = __format_spec::__parse_arg_id(++__begin, __end, __ctx);
__width_as_arg_ = true;
__width_ = __r.__value;
__begin = __r.__last;
return true;
}
if (*__begin < _CharT('0') || *__begin > _CharT('9'))
return false;
__format::__parse_number_result __r = __format::__parse_number(__begin, __end);
__width_ = __r.__value;
_LIBCPP_ASSERT_INTERNAL(__width_ != 0,
"A zero value isn't allowed and should be impossible, "
"due to validations in this function");
__begin = __r.__last;
return true;
}
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_precision(_Iterator& __begin, _Iterator __end, auto& __ctx) {
if (*__begin != _CharT('.'))
return false;
++__begin;
if (__begin == __end)
std::__throw_format_error("End of input while parsing format specifier precision");
if (*__begin == _CharT('{')) {
__format::__parse_number_result __arg_id = __format_spec::__parse_arg_id(++__begin, __end, __ctx);
__precision_as_arg_ = true;
__precision_ = __arg_id.__value;
__begin = __arg_id.__last;
return true;
}
if (*__begin < _CharT('0') || *__begin > _CharT('9'))
std::__throw_format_error("The precision option does not contain a value or an argument index");
__format::__parse_number_result __r = __format::__parse_number(__begin, __end);
__precision_ = __r.__value;
__precision_as_arg_ = false;
__begin = __r.__last;
return true;
}
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_locale_specific_form(_Iterator& __begin) {
if (*__begin != _CharT('L'))
return false;
__locale_specific_form_ = true;
++__begin;
return true;
}
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr bool __parse_clear_brackets(_Iterator& __begin) {
if (*__begin != _CharT('n'))
return false;
__clear_brackets_ = true;
++__begin;
return true;
}
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr void __parse_type(_Iterator& __begin) {
// Determines the type. It does not validate whether the selected type is
// valid. Most formatters have optional fields that are only allowed for
// certain types. These parsers need to do validation after the type has
// been parsed. So its easier to implement the validation for all types in
// the specific parse function.
switch (*__begin) {
case 'A':
__type_ = __type::__hexfloat_upper_case;
break;
case 'B':
__type_ = __type::__binary_upper_case;
break;
case 'E':
__type_ = __type::__scientific_upper_case;
break;
case 'F':
__type_ = __type::__fixed_upper_case;
break;
case 'G':
__type_ = __type::__general_upper_case;
break;
case 'X':
__type_ = __type::__hexadecimal_upper_case;
break;
case 'a':
__type_ = __type::__hexfloat_lower_case;
break;
case 'b':
__type_ = __type::__binary_lower_case;
break;
case 'c':
__type_ = __type::__char;
break;
case 'd':
__type_ = __type::__decimal;
break;
case 'e':
__type_ = __type::__scientific_lower_case;
break;
case 'f':
__type_ = __type::__fixed_lower_case;
break;
case 'g':
__type_ = __type::__general_lower_case;
break;
case 'o':
__type_ = __type::__octal;
break;
case 'p':
__type_ = __type::__pointer_lower_case;
break;
case 'P':
__type_ = __type::__pointer_upper_case;
break;
case 's':
__type_ = __type::__string;
break;
case 'x':
__type_ = __type::__hexadecimal_lower_case;
break;
# if _LIBCPP_STD_VER >= 23
case '?':
__type_ = __type::__debug;
break;
# endif
default:
return;
}
++__begin;
}
_LIBCPP_HIDE_FROM_ABI int32_t __get_width(auto& __ctx) const {
if (!__width_as_arg_)
return __width_;
return __format_spec::__substitute_arg_id(__ctx.arg(__width_));
}
_LIBCPP_HIDE_FROM_ABI int32_t __get_precision(auto& __ctx) const {
if (!__precision_as_arg_)
return __precision_;
return __format_spec::__substitute_arg_id(__ctx.arg(__precision_));
}
};
// Validates whether the reserved bitfields don't change the size.
static_assert(sizeof(__parser<char>) == 16);
# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
static_assert(sizeof(__parser<wchar_t>) == 16);
# endif
_LIBCPP_HIDE_FROM_ABI constexpr void __process_display_type_string(__format_spec::__type __type) {
switch (__type) {
case __format_spec::__type::__default:
case __format_spec::__type::__string:
case __format_spec::__type::__debug:
break;
default:
std::__throw_format_error("The type option contains an invalid value for a string formatting argument");
}
}
template <class _CharT>
_LIBCPP_HIDE_FROM_ABI constexpr void __process_display_type_bool_string(__parser<_CharT>& __parser, const char* __id) {
__parser.__validate(__format_spec::__fields_bool, __id);
if (__parser.__alignment_ == __alignment::__default)
__parser.__alignment_ = __alignment::__left;
}
template <class _CharT>
_LIBCPP_HIDE_FROM_ABI constexpr void __process_display_type_char(__parser<_CharT>& __parser, const char* __id) {
__format_spec::__process_display_type_bool_string(__parser, __id);
}
template <class _CharT>
_LIBCPP_HIDE_FROM_ABI constexpr void __process_parsed_bool(__parser<_CharT>& __parser, const char* __id) {
switch (__parser.__type_) {
case __format_spec::__type::__default:
case __format_spec::__type::__string:
__format_spec::__process_display_type_bool_string(__parser, __id);
break;
case __format_spec::__type::__binary_lower_case:
case __format_spec::__type::__binary_upper_case:
case __format_spec::__type::__octal:
case __format_spec::__type::__decimal:
case __format_spec::__type::__hexadecimal_lower_case:
case __format_spec::__type::__hexadecimal_upper_case:
break;
default:
__format_spec::__throw_invalid_type_format_error(__id);
}
}
template <class _CharT>
_LIBCPP_HIDE_FROM_ABI constexpr void __process_parsed_char(__parser<_CharT>& __parser, const char* __id) {
switch (__parser.__type_) {
case __format_spec::__type::__default:
case __format_spec::__type::__char:
case __format_spec::__type::__debug:
__format_spec::__process_display_type_char(__parser, __id);
break;
case __format_spec::__type::__binary_lower_case:
case __format_spec::__type::__binary_upper_case:
case __format_spec::__type::__octal:
case __format_spec::__type::__decimal:
case __format_spec::__type::__hexadecimal_lower_case:
case __format_spec::__type::__hexadecimal_upper_case:
break;
default:
__format_spec::__throw_invalid_type_format_error(__id);
}
}
template <class _CharT>
_LIBCPP_HIDE_FROM_ABI constexpr void __process_parsed_integer(__parser<_CharT>& __parser, const char* __id) {
switch (__parser.__type_) {
case __format_spec::__type::__default:
case __format_spec::__type::__binary_lower_case:
case __format_spec::__type::__binary_upper_case:
case __format_spec::__type::__octal:
case __format_spec::__type::__decimal:
case __format_spec::__type::__hexadecimal_lower_case:
case __format_spec::__type::__hexadecimal_upper_case:
break;
case __format_spec::__type::__char:
__format_spec::__process_display_type_char(__parser, __id);
break;
default:
__format_spec::__throw_invalid_type_format_error(__id);
}
}
template <class _CharT>
_LIBCPP_HIDE_FROM_ABI constexpr void __process_parsed_floating_point(__parser<_CharT>& __parser, const char* __id) {
switch (__parser.__type_) {
case __format_spec::__type::__default:
case __format_spec::__type::__hexfloat_lower_case:
case __format_spec::__type::__hexfloat_upper_case:
// Precision specific behavior will be handled later.
break;
case __format_spec::__type::__scientific_lower_case:
case __format_spec::__type::__scientific_upper_case:
case __format_spec::__type::__fixed_lower_case:
case __format_spec::__type::__fixed_upper_case:
case __format_spec::__type::__general_lower_case:
case __format_spec::__type::__general_upper_case:
if (!__parser.__precision_as_arg_ && __parser.__precision_ == -1)
// Set the default precision for the call to to_chars.
__parser.__precision_ = 6;
break;
default:
__format_spec::__throw_invalid_type_format_error(__id);
}
}
_LIBCPP_HIDE_FROM_ABI constexpr void __process_display_type_pointer(__format_spec::__type __type, const char* __id) {
switch (__type) {
case __format_spec::__type::__default:
case __format_spec::__type::__pointer_lower_case:
case __format_spec::__type::__pointer_upper_case:
break;
default:
__format_spec::__throw_invalid_type_format_error(__id);
}
}
template <contiguous_iterator _Iterator>
struct __column_width_result {
/// The number of output columns.
size_t __width_;
/// One beyond the last code unit used in the estimation.
///
/// This limits the original output to fit in the wanted number of columns.
_Iterator __last_;
};
template <contiguous_iterator _Iterator>
__column_width_result(size_t, _Iterator) -> __column_width_result<_Iterator>;
/// Since a column width can be two it's possible that the requested column
/// width can't be achieved. Depending on the intended usage the policy can be
/// selected.
/// - When used as precision the maximum width may not be exceeded and the
/// result should be "rounded down" to the previous boundary.
/// - When used as a width we're done once the minimum is reached, but
/// exceeding is not an issue. Rounding down is an issue since that will
/// result in writing fill characters. Therefore the result needs to be
/// "rounded up".
enum class __column_width_rounding { __down, __up };
# ifndef _LIBCPP_HAS_NO_UNICODE
namespace __detail {
template <contiguous_iterator _Iterator>
_LIBCPP_HIDE_FROM_ABI constexpr __column_width_result<_Iterator> __estimate_column_width_grapheme_clustering(
_Iterator __first, _Iterator __last, size_t __maximum, __column_width_rounding __rounding) noexcept {
using _CharT = iter_value_t<_Iterator>;
__unicode::__extended_grapheme_cluster_view<_CharT> __view{__first, __last};
__column_width_result<_Iterator> __result{0, __first};
while (__result.__last_ != __last && __result.__width_ <= __maximum) {
typename __unicode::__extended_grapheme_cluster_view<_CharT>::__cluster __cluster = __view.__consume();
int __width = __width_estimation_table::__estimated_width(__cluster.__code_point_);
// When the next entry would exceed the maximum width the previous width
// might be returned. For example when a width of 100 is requested the
// returned width might be 99, since the next code point has an estimated
// column width of 2. This depends on the rounding flag.
// When the maximum is exceeded the loop will abort the next iteration.
if (__rounding == __column_width_rounding::__down && __result.__width_ + __width > __maximum)
return __result;
__result.__width_ += __width;
__result.__last_ = __cluster.__last_;
}
return __result;
}
} // namespace __detail
// Unicode can be stored in several formats: UTF-8, UTF-16, and UTF-32.
// Depending on format the relation between the number of code units stored and
// the number of output columns differs. The first relation is the number of
// code units forming a code point. (The text assumes the code units are
// unsigned.)
// - UTF-8 The number of code units is between one and four. The first 127
// Unicode code points match the ASCII character set. When the highest bit is
// set it means the code point has more than one code unit.
// - UTF-16: The number of code units is between 1 and 2. When the first
// code unit is in the range [0xd800,0xdfff) it means the code point uses two
// code units.
// - UTF-32: The number of code units is always one.
//
// The code point to the number of columns is specified in
// [format.string.std]/11. This list might change in the future.
//
// Another thing to be taken into account is Grapheme clustering. This means
// that in some cases multiple code points are combined one element in the
// output. For example:
// - an ASCII character with a combined diacritical mark
// - an emoji with a skin tone modifier
// - a group of combined people emoji to create a family
// - a combination of flag emoji
//
// See also:
// - [format.string.general]/11
// - https://en.wikipedia.org/wiki/UTF-8#Encoding
// - https://en.wikipedia.org/wiki/UTF-16#U+D800_to_U+DFFF
_LIBCPP_HIDE_FROM_ABI constexpr bool __is_ascii(char32_t __c) { return __c < 0x80; }
/// Determines the number of output columns needed to render the input.
///
/// \note When the scanner encounters malformed Unicode it acts as-if every
/// code unit is a one column code point. Typically a terminal uses the same
/// strategy and replaces every malformed code unit with a one column
/// replacement character.
///
/// \param __first Points to the first element of the input range.
/// \param __last Points beyond the last element of the input range.
/// \param __maximum The maximum number of output columns. The returned number
/// of estimated output columns will not exceed this value.
/// \param __rounding Selects the rounding method.
/// \c __down result.__width_ <= __maximum
/// \c __up result.__width_ <= __maximum + 1
template <class _CharT, class _Iterator = typename basic_string_view<_CharT>::const_iterator>
_LIBCPP_HIDE_FROM_ABI constexpr __column_width_result<_Iterator> __estimate_column_width(
basic_string_view<_CharT> __str, size_t __maximum, __column_width_rounding __rounding) noexcept {
// The width estimation is done in two steps:
// - Quickly process for the ASCII part. ASCII has the following properties
// - One code unit is one code point
// - Every code point has an estimated width of one
// - When needed it will a Unicode Grapheme clustering algorithm to find
// the proper place for truncation.
if (__str.empty() || __maximum == 0)
return {0, __str.begin()};
// ASCII has one caveat; when an ASCII character is followed by a non-ASCII
// character they might be part of an extended grapheme cluster. For example:
// an ASCII letter and a COMBINING ACUTE ACCENT
// The truncate should happen after the COMBINING ACUTE ACCENT. Therefore we
// need to scan one code unit beyond the requested precision. When this code
// unit is non-ASCII we omit the current code unit and let the Grapheme
// clustering algorithm do its work.
auto __it = __str.begin();
if (__format_spec::__is_ascii(*__it)) {
do {
--__maximum;
++__it;
if (__it == __str.end())
return {__str.size(), __str.end()};
if (__maximum == 0) {
if (__format_spec::__is_ascii(*__it))
return {static_cast<size_t>(__it - __str.begin()), __it};
break;
}
} while (__format_spec::__is_ascii(*__it));
--__it;
++__maximum;
}
ptrdiff_t __ascii_size = __it - __str.begin();
__column_width_result __result =
__detail::__estimate_column_width_grapheme_clustering(__it, __str.end(), __maximum, __rounding);
__result.__width_ += __ascii_size;
return __result;
}
# else // !defined(_LIBCPP_HAS_NO_UNICODE)
template <class _CharT>
_LIBCPP_HIDE_FROM_ABI constexpr __column_width_result<typename basic_string_view<_CharT>::const_iterator>
__estimate_column_width(basic_string_view<_CharT> __str, size_t __maximum, __column_width_rounding) noexcept {
// When Unicode isn't supported assume ASCII and every code unit is one code
// point. In ASCII the estimated column width is always one. Thus there's no
// need for rounding.
size_t __width_ = std::min(__str.size(), __maximum);
return {__width_, __str.begin() + __width_};
}
# endif // !defined(_LIBCPP_HAS_NO_UNICODE)
} // namespace __format_spec
#endif //_LIBCPP_STD_VER >= 20
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___FORMAT_PARSER_STD_FORMAT_SPEC_H