89 lines
1.6 KiB
JavaScript
89 lines
1.6 KiB
JavaScript
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'use strict';
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const isFullwidthCodePoint = require('is-fullwidth-code-point');
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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 ASTRAL_REGEX = /[\uD800-\uDBFF][\uDC00-\uDFFF]/;
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const ESCAPE_CODES = new Map([
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[0, 0],
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[1, 22],
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[2, 22],
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[3, 23],
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[4, 24],
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[7, 27],
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[8, 28],
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[9, 29],
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[30, 39],
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[31, 39],
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[32, 39],
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[33, 39],
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[34, 39],
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[35, 39],
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[36, 39],
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[37, 39],
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[90, 39],
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[40, 49],
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[41, 49],
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[42, 49],
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[43, 49],
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[44, 49],
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[45, 49],
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[46, 49],
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[47, 49]
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]);
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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 = Array.from(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;
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let visible = 0;
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let output = '';
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for (const item of arr.entries()) {
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const i = item[0];
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const x = item[1];
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let leftEscape = false;
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if (ESCAPES.indexOf(x) !== -1) {
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insideEscape = true;
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const code = /\d[^m]*/.exec(str.slice(i, i + 4));
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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 (!ASTRAL_REGEX.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 !== undefined && escapeCode !== END_CODE) {
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output += wrapAnsi(escapeCode);
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} else if (visible >= end) {
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if (escapeCode !== undefined) {
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output += wrapAnsi(ESCAPE_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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