tty-strings
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Tools for working with strings displayed in the terminal
58 lines • 2.29 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
const graphemeBreak_1 = require("./graphemeBreak");
/**
* A generator function that splits a string into its component graphemes. Does not handle ANSI escape codes,
* so make sure to remove them from input strings before calling this function.
*
* @remarks
* This function is an implementation of UAX #29 grapheme cluster boundary splitting:
* {@link https://www.unicode.org/reports/tr29/tr29-21.html#Grapheme_Cluster_Boundaries}
*
* @example
* ```js
* import { splitChars } from 'tty-strings';
*
* // [...'à̰ḇ́ĉ̥'] -> ['a', '\u0300', '\u0330', 'b', '\u0341', '\u0331', 'c', '\u0302', '\u0325']
* const chars = [...splitChars('à̰ḇ́ĉ̥')]; // ['à̰', 'ḇ́', 'ĉ̥']
* ```
*
* @param string - Input string to split.
* @returns A generator that yields each grapheme in the input string.
*/
function* splitChars(string) {
if (typeof string !== 'string' || string.length === 0)
return;
// lower string index of the first grapheme cluster
let i = 0,
// initialize array to store grapheme break properties
props = [],
// get first code point
cp = string.codePointAt(0),
// get grapheme break property of the first code point
prev = (0, graphemeBreak_1.graphemeBreakProperty)(cp);
for (let j = cp > 0xFFFF ? 2 : 1, n = string.length; j < n; j += 1) {
cp = string.codePointAt(j);
// get grapheme break property of the next code point
const next = (0, graphemeBreak_1.graphemeBreakProperty)(cp);
// check if there is a cluster boundary between the two adjacent code points
if ((0, graphemeBreak_1.shouldBreak)(props, prev, next)) {
// a cluster boundry exists, yield the current grapheme cluster
yield string.slice(i, j);
// reset grapheme break properties array
props = [];
// set lower string index of the next cluster
i = j;
}
else
props.push(prev);
// ignore surrogates
if (cp > 0xFFFF)
j += 1;
prev = next;
}
// yield the final grapheme cluster
yield string.slice(i);
}
exports.default = splitChars;
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