mirror of
https://github.com/denoland/std.git
synced 2024-11-22 04:59:05 +00:00
80 lines
2.8 KiB
TypeScript
80 lines
2.8 KiB
TypeScript
// 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]![(cp >> 13) & 0xff]!;
|
||
const t2Offset = tables[1]![128 * t1Offset + ((cp >> 6) & 0x7f)]!;
|
||
const packedWidths = tables[2]![16 * t2Offset + ((cp >> 2) & 0xf)]!;
|
||
|
||
const width = (packedWidths >> (2 * (cp & 0b11))) & 0b11;
|
||
|
||
return width === 3 ? 1 : width;
|
||
}
|
||
|
||
const cache = new Map<string, number | null>();
|
||
function charWidth(char: string) {
|
||
if (cache.has(char)) return cache.get(char)!;
|
||
|
||
const codePoint = char.codePointAt(0)!;
|
||
let width: number | null = null;
|
||
|
||
if (codePoint < 0x7f) {
|
||
width = codePoint >= 0x20 ? 1 : codePoint === 0 ? 0 : null;
|
||
} else if (codePoint >= 0xa0) {
|
||
width = lookupWidth(codePoint);
|
||
} else {
|
||
width = null;
|
||
}
|
||
|
||
cache.set(char, width);
|
||
return width;
|
||
}
|
||
|
||
/**
|
||
* 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 "@std/cli/unicode-width";
|
||
* import { assertEquals } from "@std/assert";
|
||
*
|
||
* assertEquals(unicodeWidth("hello world"), 11);
|
||
* assertEquals(unicodeWidth("天地玄黃宇宙洪荒"), 16);
|
||
* assertEquals(unicodeWidth("ｆｕｌｌｗｉｄｔｈ"), 18);
|
||
* ```
|
||
*
|
||
* @example Calculating the unicode width of a color-encoded string
|
||
* ```ts
|
||
* import { unicodeWidth } from "@std/cli/unicode-width";
|
||
* import { stripAnsiCode } from "@std/fmt/colors";
|
||
* import { assertEquals } from "@std/assert";
|
||
*
|
||
* assertEquals(unicodeWidth(stripAnsiCode("\x1b[36mголубой\x1b[39m")), 7);
|
||
* assertEquals(unicodeWidth(stripAnsiCode("\x1b[31m紅色\x1b[39m")), 4);
|
||
* assertEquals(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);
|
||
}
|