linux/drivers/tty/vt/gen_ucs_width_table.py

#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-2.0
#
# Leverage Python's unicodedata module to generate ucs_width_table.h

import unicodedata
import sys
import argparse

# This script's file name
from pathlib import Path
this_file = Path(__file__).name

# Default output file name
DEFAULT_OUT_FILE = "ucs_width_table.h"

# --- Global Constants for Width Assignments ---

# Known zero-width characters
KNOWN_ZERO_WIDTH = (
    0x200B,  # ZERO WIDTH SPACE
    0x200C,  # ZERO WIDTH NON-JOINER
    0x200D,  # ZERO WIDTH JOINER
    0x2060,  # WORD JOINER
    0xFEFF   # ZERO WIDTH NO-BREAK SPACE (BOM)
)

# Zero-width emoji modifiers and components
# NOTE: Some of these characters would normally be single-width according to
# East Asian Width properties, but we deliberately override them to be
# zero-width because they function as modifiers in emoji sequences.
EMOJI_ZERO_WIDTH = [
    # Skin tone modifiers
    (0x1F3FB, 0x1F3FF),  # Emoji modifiers (skin tones)

    # Variation selectors (note: VS16 is treated specially in vt.c)
    (0xFE00, 0xFE0F),    # Variation Selectors 1-16

    # Gender and hair style modifiers
    # These would be single-width by Unicode properties, but are zero-width
    # when part of emoji
    (0x2640, 0x2640),    # Female sign
    (0x2642, 0x2642),    # Male sign
    (0x26A7, 0x26A7),    # Transgender symbol
    (0x1F9B0, 0x1F9B3),  # Hair components (red, curly, white, bald)

    # Tag characters
    (0xE0020, 0xE007E),  # Tags
]

# Regional indicators (flag components)
REGIONAL_INDICATORS = (0x1F1E6, 0x1F1FF)  # Regional indicator symbols A-Z

# Double-width emoji ranges
#
# Many emoji characters are classified as single-width according to Unicode
# Standard Annex #11 East Asian Width property (N or Neutral), but we
# deliberately override them to be double-width. References:
# 1. Unicode Technical Standard #51: Unicode Emoji
#    (https://www.unicode.org/reports/tr51/)
# 2. Principle of "emoji presentation" in WHATWG CSS Text specification
#    (https://drafts.csswg.org/css-text-3/#character-properties)
# 3. Terminal emulator implementations (iTerm2, Windows Terminal, etc.) which
#    universally render emoji as double-width characters regardless of their
#    Unicode EAW property
# 4. W3C Work Item: Requirements for Japanese Text Layout - Section 3.8.1
#    Emoji width (https://www.w3.org/TR/jlreq/)
EMOJI_RANGES = [
    (0x1F000, 0x1F02F),  # Mahjong Tiles (EAW: N, but displayed as double-width)
    (0x1F0A0, 0x1F0FF),  # Playing Cards (EAW: N, but displayed as double-width)
    (0x1F300, 0x1F5FF),  # Miscellaneous Symbols and Pictographs
    (0x1F600, 0x1F64F),  # Emoticons
    (0x1F680, 0x1F6FF),  # Transport and Map Symbols
    (0x1F700, 0x1F77F),  # Alchemical Symbols
    (0x1F780, 0x1F7FF),  # Geometric Shapes Extended
    (0x1F800, 0x1F8FF),  # Supplemental Arrows-C
    (0x1F900, 0x1F9FF),  # Supplemental Symbols and Pictographs
    (0x1FA00, 0x1FA6F),  # Chess Symbols
    (0x1FA70, 0x1FAFF),  # Symbols and Pictographs Extended-A
]

def create_width_tables():
    """
    Creates Unicode character width tables and returns the data structures.

    Returns:
        tuple: (zero_width_ranges, double_width_ranges)
    """

    # Width data mapping
    width_map = {}  # Maps code points to width (0, 1, 2)

    # Mark emoji modifiers as zero-width
    for start, end in EMOJI_ZERO_WIDTH:
        for cp in range(start, end + 1):
            width_map[cp] = 0

    # Mark all regional indicators as single-width as they are usually paired
    # providing a combined width of 2 when displayed together.
    start, end = REGIONAL_INDICATORS
    for cp in range(start, end + 1):
        width_map[cp] = 1

    # Process all assigned Unicode code points (Basic Multilingual Plane +
    # Supplementary Planes) Range 0x0 to 0x10FFFF (the full Unicode range)
    for block_start in range(0, 0x110000, 0x1000):
        block_end = block_start + 0x1000
        for cp in range(block_start, block_end):
            try:
                char = chr(cp)

                # Skip if already processed
                if cp in width_map:
                    continue

                # Check for combining marks and a format characters
                category = unicodedata.category(char)

                # Combining marks
                if category.startswith('M'):
                    width_map[cp] = 0
                    continue

                # Format characters
                # Since we have no support for bidirectional text, all format
                # characters (category Cf) can be treated with width 0 (zero)
                # for simplicity, as they don't need to occupy visual space
                # in a non-bidirectional text environment.
                if category == 'Cf':
                    width_map[cp] = 0
                    continue

                # Known zero-width characters
                if cp in KNOWN_ZERO_WIDTH:
                    width_map[cp] = 0
                    continue

                # Use East Asian Width property
                eaw = unicodedata.east_asian_width(char)
                if eaw in ('F', 'W'):  # Fullwidth or Wide
                    width_map[cp] = 2
                elif eaw in ('Na', 'H', 'N', 'A'):  # Narrow, Halfwidth, Neutral, Ambiguous
                    width_map[cp] = 1
                else:
                    # Default to single-width for unknown
                    width_map[cp] = 1

            except (ValueError, OverflowError):
                # Skip invalid code points
                continue

    # Process Emoji - generally double-width
    for start, end in EMOJI_RANGES:
        for cp in range(start, end + 1):
            if cp not in width_map or width_map[cp] != 0:  # Don't override zero-width
                try:
                    char = chr(cp)
                    width_map[cp] = 2
                except (ValueError, OverflowError):
                    continue

    # Optimize to create range tables
    def ranges_optimize(width_data, target_width):
        points = sorted([cp for cp, width in width_data.items() if width == target_width])
        if not points:
            return []

        # Group consecutive code points into ranges
        ranges = []
        start = points[0]
        prev = start

        for cp in points[1:]:
            if cp > prev + 1:
                ranges.append((start, prev))
                start = cp
            prev = cp

        # Add the last range
        ranges.append((start, prev))
        return ranges

    # Extract ranges for each width
    zero_width_ranges = ranges_optimize(width_map, 0)
    double_width_ranges = ranges_optimize(width_map, 2)

    return zero_width_ranges, double_width_ranges

def write_tables(zero_width_ranges, double_width_ranges, out_file=DEFAULT_OUT_FILE):
    """
    Write the generated tables to C header file.

    Args:
        zero_width_ranges: List of (start, end) ranges for zero-width characters
        double_width_ranges: List of (start, end) ranges for double-width characters
        out_file: Output file name (default: DEFAULT_OUT_FILE)
    """

    # Function to split ranges into BMP (16-bit) and non-BMP (above 16-bit)
    def split_ranges_by_size(ranges):
        bmp_ranges = []
        non_bmp_ranges = []

        for start, end in ranges:
            if end <= 0xFFFF:
                bmp_ranges.append((start, end))
            elif start > 0xFFFF:
                non_bmp_ranges.append((start, end))
            else:
                # Split the range at 0xFFFF
                bmp_ranges.append((start, 0xFFFF))
                non_bmp_ranges.append((0x10000, end))

        return bmp_ranges, non_bmp_ranges

    # Split ranges into BMP and non-BMP
    zero_width_bmp, zero_width_non_bmp = split_ranges_by_size(zero_width_ranges)
    double_width_bmp, double_width_non_bmp = split_ranges_by_size(double_width_ranges)

    # Function to generate code point description comments
    def get_code_point_comment(start, end):
        try:
            start_char_desc = unicodedata.name(chr(start))
            if start == end:
                return f"/* {start_char_desc} */"
            else:
                end_char_desc = unicodedata.name(chr(end))
                return f"/* {start_char_desc} - {end_char_desc} */"
        except:
            if start == end:
                return f"/* U+{start:04X} */"
            else:
                return f"/* U+{start:04X} - U+{end:04X} */"

    # Generate C tables
    with open(out_file, 'w') as f:
        f.write(f"""\
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * {out_file} - Unicode character width
 *
 * Auto-generated by {this_file}
 *
 * Unicode Version: {unicodedata.unidata_version}
 */

/* Zero-width character ranges (BMP - Basic Multilingual Plane, U+0000 to U+FFFF) */
static const struct ucs_interval16 ucs_zero_width_bmp_ranges[] = {{
""")

        for start, end in zero_width_bmp:
            comment = get_code_point_comment(start, end)
            f.write(f"\t{{ 0x{start:04X}, 0x{end:04X} }}, {comment}\n")

        f.write("""\
};

/* Zero-width character ranges (non-BMP, U+10000 and above) */
static const struct ucs_interval32 ucs_zero_width_non_bmp_ranges[] = {
""")

        for start, end in zero_width_non_bmp:
            comment = get_code_point_comment(start, end)
            f.write(f"\t{{ 0x{start:05X}, 0x{end:05X} }}, {comment}\n")

        f.write("""\
};

/* Double-width character ranges (BMP - Basic Multilingual Plane, U+0000 to U+FFFF) */
static const struct ucs_interval16 ucs_double_width_bmp_ranges[] = {
""")

        for start, end in double_width_bmp:
            comment = get_code_point_comment(start, end)
            f.write(f"\t{{ 0x{start:04X}, 0x{end:04X} }}, {comment}\n")

        f.write("""\
};

/* Double-width character ranges (non-BMP, U+10000 and above) */
static const struct ucs_interval32 ucs_double_width_non_bmp_ranges[] = {
""")

        for start, end in double_width_non_bmp:
            comment = get_code_point_comment(start, end)
            f.write(f"\t{{ 0x{start:05X}, 0x{end:05X} }}, {comment}\n")

        f.write("};\n")

if __name__ == "__main__":
    # Parse command line arguments
    parser = argparse.ArgumentParser(description="Generate Unicode width tables")
    parser.add_argument("-o", "--output", dest="output_file", default=DEFAULT_OUT_FILE,
                        help=f"Output file name (default: {DEFAULT_OUT_FILE})")
    args = parser.parse_args()

    # Write tables to header file
    zero_width_ranges, double_width_ranges = create_width_tables()
    write_tables(zero_width_ranges, double_width_ranges, out_file=args.output_file)

    # Print summary
    zero_width_count = sum(end - start + 1 for start, end in zero_width_ranges)
    double_width_count = sum(end - start + 1 for start, end in double_width_ranges)
    print(f"Generated {args.output_file} with:")
    print(f"- {len(zero_width_ranges)} zero-width ranges covering ~{zero_width_count} code points")
    print(f"- {len(double_width_ranges)} double-width ranges covering ~{double_width_count} code points")
    print(f"- Unicode Version: {unicodedata.unidata_version}")