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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217const std = @import("std");const unicode = std.unicode;const testing = std.testing;const uucode = @import("uucode");
/// the method to use when calculating the width of a graphemepub const Method = enum { unicode, wcwidth, no_zwj,};
/// Calculate width from east asian width property and Unicode propertiesfn eawToWidth(cp: u21, eaw: uucode.types.EastAsianWidth) i16 { // Based on wcwidth implementation // Control characters if (cp == 0) return 0; if (cp < 32 or (cp >= 0x7f and cp < 0xa0)) return -1;
// Use general category for comprehensive zero-width detection const gc = uucode.get(.general_category, cp); switch (gc) { .mark_nonspacing, .mark_enclosing => return 0, else => {}, }
// Additional zero-width characters not covered by general category if (cp == 0x00ad) return 0; // soft hyphen if (cp == 0x200b) return 0; // zero-width space if (cp == 0x200c) return 0; // zero-width non-joiner if (cp == 0x200d) return 0; // zero-width joiner if (cp == 0x2060) return 0; // word joiner if (cp == 0x034f) return 0; // combining grapheme joiner if (cp == 0xfeff) return 0; // zero-width no-break space (BOM) if (cp >= 0x180b and cp <= 0x180d) return 0; // Mongolian variation selectors if (cp >= 0xfe00 and cp <= 0xfe0f) return 0; // variation selectors if (cp >= 0xe0100 and cp <= 0xe01ef) return 0; // Plane-14 variation selectors
// East Asian Width: fullwidth or wide = 2 // ambiguous in East Asian context = 2, otherwise 1 // halfwidth, narrow, or neutral = 1 return switch (eaw) { .fullwidth, .wide => 2, else => 1, };}
/// returns the width of the provided string, as measured by the method chosenpub fn gwidth(str: []const u8, method: Method) u16 { switch (method) { .unicode => { var total: u16 = 0; var grapheme_iter = uucode.grapheme.Iterator(uucode.utf8.Iterator).init(.init(str));
var grapheme_start: usize = 0; var prev_break: bool = true;
while (grapheme_iter.next()) |result| { if (prev_break and !result.is_break) { // Start of a new grapheme const cp_len: usize = std.unicode.utf8CodepointSequenceLength(result.cp) catch 1; grapheme_start = grapheme_iter.i - cp_len; }
if (result.is_break) { // End of a grapheme - calculate its width const grapheme_end = grapheme_iter.i; const grapheme_bytes = str[grapheme_start..grapheme_end];
// Calculate grapheme width var g_iter = uucode.utf8.Iterator.init(grapheme_bytes); var width: i16 = 0; var has_emoji_vs: bool = false; var has_text_vs: bool = false; var has_emoji_presentation: bool = false; var ri_count: u8 = 0;
while (g_iter.next()) |cp| { // Check for emoji variation selector (U+FE0F) if (cp == 0xfe0f) { has_emoji_vs = true; continue; }
// Check for text variation selector (U+FE0E) if (cp == 0xfe0e) { has_text_vs = true; continue; }
// Check if this codepoint has emoji presentation if (uucode.get(.is_emoji_presentation, cp)) { has_emoji_presentation = true; }
// Count regional indicators (for flag emojis) if (cp >= 0x1F1E6 and cp <= 0x1F1FF) { ri_count += 1; }
const eaw = uucode.get(.east_asian_width, cp); const w = eawToWidth(cp, eaw); // Take max of non-zero widths if (w > 0 and w > width) width = w; }
// Handle variation selectors and emoji presentation if (has_text_vs) { // Text presentation explicit - keep width as-is (usually 1) width = @max(1, width); } else if (has_emoji_vs or has_emoji_presentation or ri_count == 2) { // Emoji presentation or flag pair - force width 2 width = @max(2, width); }
total += @max(0, width);
grapheme_start = grapheme_end; } prev_break = result.is_break; }
return total; }, .wcwidth => { var total: u16 = 0; var iter = uucode.utf8.Iterator.init(str); while (iter.next()) |cp| { const w: i16 = switch (cp) { // undo an override in zg for emoji skintone selectors 0x1f3fb...0x1f3ff => 2, else => blk: { const eaw = uucode.get(.east_asian_width, cp); break :blk eawToWidth(cp, eaw); }, }; total += @intCast(@max(0, w)); } return total; }, .no_zwj => { var iter = std.mem.splitSequence(u8, str, "\u{200D}"); var result: u16 = 0; while (iter.next()) |s| { result += gwidth(s, .unicode); } return result; }, }}
test "gwidth: a" { try testing.expectEqual(1, gwidth("a", .unicode)); try testing.expectEqual(1, gwidth("a", .wcwidth)); try testing.expectEqual(1, gwidth("a", .no_zwj));}
test "gwidth: emoji with ZWJ" { try testing.expectEqual(2, gwidth("👩🚀", .unicode)); try testing.expectEqual(4, gwidth("👩🚀", .wcwidth)); try testing.expectEqual(4, gwidth("👩🚀", .no_zwj));}
test "gwidth: emoji with VS16 selector" { try testing.expectEqual(2, gwidth("\xE2\x9D\xA4\xEF\xB8\x8F", .unicode)); try testing.expectEqual(1, gwidth("\xE2\x9D\xA4\xEF\xB8\x8F", .wcwidth)); try testing.expectEqual(2, gwidth("\xE2\x9D\xA4\xEF\xB8\x8F", .no_zwj));}
test "gwidth: emoji with skin tone selector" { try testing.expectEqual(2, gwidth("👋🏿", .unicode)); try testing.expectEqual(4, gwidth("👋🏿", .wcwidth)); try testing.expectEqual(2, gwidth("👋🏿", .no_zwj));}
test "gwidth: zero-width space" { try testing.expectEqual(0, gwidth("\u{200B}", .unicode)); try testing.expectEqual(0, gwidth("\u{200B}", .wcwidth));}
test "gwidth: zero-width non-joiner" { try testing.expectEqual(0, gwidth("\u{200C}", .unicode)); try testing.expectEqual(0, gwidth("\u{200C}", .wcwidth));}
test "gwidth: combining marks" { // Hebrew combining mark try testing.expectEqual(0, gwidth("\u{05B0}", .unicode)); // Devanagari combining mark try testing.expectEqual(0, gwidth("\u{093C}", .unicode));}
test "gwidth: flag emoji (regional indicators)" { // US flag 🇺🇸 try testing.expectEqual(2, gwidth("🇺🇸", .unicode)); // UK flag 🇬🇧 try testing.expectEqual(2, gwidth("🇬🇧", .unicode));}
test "gwidth: text variation selector" { // U+2764 (heavy black heart) + U+FE0E (text variation selector) // Should be width 1 with text presentation try testing.expectEqual(1, gwidth("❤︎", .unicode));}
test "gwidth: keycap sequence" { // Digit 1 + U+FE0F + U+20E3 (combining enclosing keycap) // Should be width 2 try testing.expectEqual(2, gwidth("1️⃣", .unicode));}
test "gwidth: base letter with combining mark" { // 'a' + combining acute accent (NFD form) // Should be width 1 (combining mark is zero-width) try testing.expectEqual(1, gwidth("á", .unicode));}