deno.land / std@0.224.0 / cli / unicode_width.ts

unicode_width.ts
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.// This module is browser compatible.// Ported from unicode_width rust crate, Copyright (c) 2015 The Rust Project Developers. MIT license.
import data from "./_data.json" with { type: "json" };import { runLengthDecode } from "./_run_length.ts";
let tables: Uint8Array[] | null = null;function lookupWidth(cp: number) { if (!tables) tables = data.tables.map(runLengthDecode);
const t1Offset = (tables[0] as Uint8Array)[(cp >> 13) & 0xff] as number; const t2Offset = (tables[1] as Uint8Array)[128 * t1Offset + ((cp >> 6) & 0x7f)] as number; const packedWidths = (tables[2] as Uint8Array)[16 * t2Offset + ((cp >> 2) & 0xf)] as number;
const width = (packedWidths >> (2 * (cp & 0b11))) & 0b11;
return width === 3 ? 1 : width;}
const cache = new Map<string, number | null>();function charWidth(ch: string) { if (cache.has(ch)) return cache.get(ch)!;
const cp = ch.codePointAt(0)!; let v: number | null = null;
if (cp < 0x7f) { v = cp >= 0x20 ? 1 : cp === 0 ? 0 : null; } else if (cp >= 0xa0) { v = lookupWidth(cp); } else { v = null; }
cache.set(ch, v); return v;}
/** * Calculate the physical width of a string in a TTY-like environment. This is * useful for cases such as calculating where a line-wrap will occur and * underlining strings. * * The physical width is given by the number of columns required to display * the string. The number of columns a given unicode character occupies can * vary depending on the character itself. * * @param str The string to measure. * @returns The unicode width of the string. * * @example Calculating the unicode width of a string * ```ts * import { unicodeWidth } from "https://deno.land/std@$STD_VERSION/cli/unicode_width.ts"; * * unicodeWidth("hello world"); // 11 * unicodeWidth("天地玄黃宇宙洪荒"); // 16 * unicodeWidth("fullwidth"); // 18 * ``` * * @example Calculating the unicode width of a color-encoded string * ```ts * import { unicodeWidth } from "https://deno.land/std@$STD_VERSION/cli/unicode_width.ts"; * import { stripAnsiCode } from "https://deno.land/std@$STD_VERSION/fmt/colors.ts"; * * unicodeWidth(stripAnsiCode("\x1b[36mголубой\x1b[39m")); // 7 * unicodeWidth(stripAnsiCode("\x1b[31m紅色\x1b[39m")); // 4 * unicodeWidth(stripAnsiCode("\x1B]8;;https://deno.land\x07🦕\x1B]8;;\x07")); // 2 * ``` * * Use * {@linkcode https://jsr.io/@std/fmt/doc/colors/~/stripAnsiCode | stripAnsiCode} * to remove ANSI escape codes from a string before passing it to * {@linkcode unicodeWidth}. */export function unicodeWidth(str: string): number { return [...str].map((ch) => charWidth(ch) ?? 0).reduce((a, b) => a + b, 0);}
std

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Tagged at
3 weeks ago