60 lines
1.3 KiB
JavaScript
Executable File
60 lines
1.3 KiB
JavaScript
Executable File
'use strict';
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const isFullwidthCodePoint = require('is-fullwidth-code-point');
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const astralRegex = require('astral-regex');
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const ansiStyles = require('ansi-styles');
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const ESCAPES = [
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'\u001B',
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'\u009B'
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];
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const END_CODE = 39;
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const wrapAnsi = code => `${ESCAPES[0]}[${code}m`;
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module.exports = (str, begin, end) => {
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const arr = [...str.normalize()];
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end = typeof end === 'number' ? end : arr.length;
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let insideEscape = false;
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let escapeCode = null;
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let visible = 0;
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let output = '';
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for (const [i, x] of arr.entries()) {
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let leftEscape = false;
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if (ESCAPES.includes(x)) {
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insideEscape = true;
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const code = /\d[^m]*/.exec(str.slice(i, i + 18));
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escapeCode = code === END_CODE ? null : code;
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} else if (insideEscape && x === 'm') {
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insideEscape = false;
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leftEscape = true;
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}
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if (!insideEscape && !leftEscape) {
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++visible;
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}
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if (!astralRegex({exact: true}).test(x) && isFullwidthCodePoint(x.codePointAt())) {
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++visible;
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}
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if (visible > begin && visible <= end) {
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output += x;
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} else if (visible === begin && !insideEscape && escapeCode !== null && escapeCode !== END_CODE) {
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output += wrapAnsi(escapeCode);
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} else if (visible >= end) {
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if (escapeCode !== null) {
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output += wrapAnsi(ansiStyles.codes.get(parseInt(escapeCode, 10)) || END_CODE);
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}
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break;
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}
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}
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return output;
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};
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