width_estimation_table.h | Explore in Territory

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// WARNING, this entire header is generated by
// utils/generate_width_estimation_table.py
// DO NOT MODIFY!

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#ifndef _LIBCPP___FORMAT_WIDTH_ESTIMATION_TABLE_H
#define _LIBCPP___FORMAT_WIDTH_ESTIMATION_TABLE_H

#include <__algorithm/ranges_upper_bound.h>
#include <__config>
#include <cstddef>
#include <cstdint>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if _LIBCPP_STD_VER >= 20

namespace __width_estimation_table {

/// The entries of the characters with an estimated width of 2.
///
/// Contains the entries for [format.string.std]/12
///  -  Any code point with the East_Asian_Width="W" or East_Asian_Width="F"
///     Derived Extracted Property as described by UAX #44
/// - U+4DC0 - U+4DFF (Yijing Hexagram Symbols)
/// - U+1F300 - U+1F5FF (Miscellaneous Symbols and Pictographs)
/// - U+1F900 - U+1F9FF (Supplemental Symbols and Pictographs)
///
/// The data is generated from
/// - https://www.unicode.org/Public/UCD/latest/ucd/EastAsianWidth.txt
/// - The "overrides" in [format.string.std]/12
///
/// The format of EastAsianWidth.txt is two fields separated by a semicolon.
/// Field 0: Unicode code point value or range of code point values
/// Field 1: East_Asian_Width property, consisting of one of the following values:
///         "A", "F", "H", "N", "Na", "W"
///  - All code points, assigned or unassigned, that are not listed
///      explicitly are given the value "N".
///  - The unassigned code points in the following blocks default to "W":
///         CJK Unified Ideographs Extension A: U+3400..U+4DBF
///         CJK Unified Ideographs:             U+4E00..U+9FFF
///         CJK Compatibility Ideographs:       U+F900..U+FAFF
///  - All undesignated code points in Planes 2 and 3, whether inside or
///      outside of allocated blocks, default to "W":
///         Plane 2:                            U+20000..U+2FFFD
///         Plane 3:                            U+30000..U+3FFFD
///
/// The table is similar to the table
///  __extended_grapheme_custer_property_boundary::__entries
/// which explains the details of these classes. The only difference is this
/// table lacks a property, thus having more bits available for the size.
///
/// The maximum code point that has an estimated width of 2 is U+3FFFD. This
/// value can be encoded in 18 bits. Thus the upper 3 bits of the code point
/// are always 0. These 3 bits are used to enlarge the offset range. This
/// optimization reduces the table in Unicode 15 from 184 to 104 entries,
/// saving 320 bytes.
///
/// The data has 2 values:
/// - bits [0, 13] The size of the range, allowing 16384 elements.
/// - bits [14, 31] The lower bound code point of the range. The upper bound of
///   the range is lower bound + size.
_LIBCPP_HIDE_FROM_ABI inline constexpr uint32_t __entries[107] = …;

/// The upper bound entry of EastAsianWidth.txt.
///
/// Values greater than this value may have more than 18 significant bits.
/// They always have a width of 1. This property makes it possible to store
/// the table in its compact form.
inline constexpr uint32_t __table_upper_bound = …;

/// Returns the estimated width of a Unicode code point.
///
/// \\pre The code point is a valid Unicode code point.
[[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr int __estimated_width(const char32_t __code_point) noexcept { … }

} // namespace __width_estimation_table

#endif // _LIBCPP_STD_VER >= 20

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___FORMAT_WIDTH_ESTIMATION_TABLE_H
chromium/third_party/libc++/src/include/__format/width_estimation_table.h
