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