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'use strict';
const isFullwidthCodePoint = require('is-fullwidth-code-point');
const ESCAPES = [
'\u001B',
'\u009B'
];
const END_CODE = 39;
const ASTRAL_REGEX = /[\uD800-\uDBFF][\uDC00-\uDFFF]/;
const ESCAPE_CODES = new Map([
[0, 0],
[1, 22],
[2, 22],
[3, 23],
[4, 24],
[7, 27],
[8, 28],
[9, 29],
[30, 39],
[31, 39],
[32, 39],
[33, 39],
[34, 39],
[35, 39],
[36, 39],
[37, 39],
[90, 39],
[40, 49],
[41, 49],
[42, 49],
[43, 49],
[44, 49],
[45, 49],
[46, 49],
[47, 49]
]);
const wrapAnsi = code => `${ESCAPES[0]}[${code}m`;
module.exports = (str, begin, end) => {
const arr = Array.from(str.normalize());
end = typeof end === 'number' ? end : arr.length;
let insideEscape = false;
let escapeCode;
let visible = 0;
let output = '';
for (const item of arr.entries()) {
const i = item[0];
const x = item[1];
let leftEscape = false;
if (ESCAPES.indexOf(x) !== -1) {
insideEscape = true;
const code = /\d[^m]*/.exec(str.slice(i, i + 4));
escapeCode = code === END_CODE ? null : code;
} else if (insideEscape && x === 'm') {
insideEscape = false;
leftEscape = true;
}
if (!insideEscape && !leftEscape) {
++visible;
}
if (!ASTRAL_REGEX.test(x) && isFullwidthCodePoint(x.codePointAt())) {
++visible;
}
if (visible > begin && visible <= end) {
output += x;
} else if (visible === begin && !insideEscape && escapeCode !== undefined && escapeCode !== END_CODE) {
output += wrapAnsi(escapeCode);
} else if (visible >= end) {
if (escapeCode !== undefined) {
output += wrapAnsi(ESCAPE_CODES.get(parseInt(escapeCode, 10)) || END_CODE);
}
break;
}
}
return output;
};
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