fast-string-truncated-width
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A fast function for calculating where a string should be truncated, given an optional width limit and an ellipsis string.
172 lines (171 loc) • 7.04 kB
JavaScript
/* IMPORT */
import { isAmbiguous, isFullWidth, isWide } from './utils.js';
/* HELPERS */
const ANSI_RE = /[\u001b\u009b][[()#;?]*(?:[0-9]{1,4}(?:;[0-9]{0,4})*)?[0-9A-ORZcf-nqry=><]/y;
const CONTROL_RE = /[\x00-\x08\x0A-\x1F\x7F-\x9F]{1,1000}/y;
const TAB_RE = /\t{1,1000}/y;
const EMOJI_RE = /[\u{1F1E6}-\u{1F1FF}]{2}|\u{1F3F4}[\u{E0061}-\u{E007A}]{2}[\u{E0030}-\u{E0039}\u{E0061}-\u{E007A}]{1,3}\u{E007F}|(?:\p{Emoji}\uFE0F\u20E3?|\p{Emoji_Modifier_Base}\p{Emoji_Modifier}?|\p{Emoji_Presentation})(?:\u200D(?:\p{Emoji_Modifier_Base}\p{Emoji_Modifier}?|\p{Emoji_Presentation}|\p{Emoji}\uFE0F\u20E3?))*/yu;
const LATIN_RE = /(?:[\x20-\x7E\xA0-\xFF](?!\uFE0F)){1,1000}/y;
const MODIFIER_RE = /\p{M}+/gu;
const NO_TRUNCATION = { limit: Infinity, ellipsis: '' };
/* MAIN */
//TODO: Optimize matching non-latin letters
const getStringTruncatedWidth = (input, truncationOptions = {}, widthOptions = {}) => {
/* CONSTANTS */
const LIMIT = truncationOptions.limit ?? Infinity;
const ELLIPSIS = truncationOptions.ellipsis ?? '';
const ELLIPSIS_WIDTH = truncationOptions?.ellipsisWidth ?? (ELLIPSIS ? getStringTruncatedWidth(ELLIPSIS, NO_TRUNCATION, widthOptions).width : 0);
const ANSI_WIDTH = widthOptions.ansiWidth ?? 0;
const CONTROL_WIDTH = widthOptions.controlWidth ?? 0;
const TAB_WIDTH = widthOptions.tabWidth ?? 8;
const AMBIGUOUS_WIDTH = widthOptions.ambiguousWidth ?? 1;
const EMOJI_WIDTH = widthOptions.emojiWidth ?? 2;
const FULL_WIDTH_WIDTH = widthOptions.fullWidthWidth ?? 2;
const REGULAR_WIDTH = widthOptions.regularWidth ?? 1;
const WIDE_WIDTH = widthOptions.wideWidth ?? 2;
/* STATE */
let indexPrev = 0;
let index = 0;
let length = input.length;
let lengthExtra = 0;
let truncationEnabled = false;
let truncationIndex = length;
let truncationLimit = Math.max(0, LIMIT - ELLIPSIS_WIDTH);
let unmatchedStart = 0;
let unmatchedEnd = 0;
let width = 0;
let widthExtra = 0;
/* PARSE LOOP */
outer: while (true) {
/* UNMATCHED */
if ((unmatchedEnd > unmatchedStart) || (index >= length && index > indexPrev)) {
const unmatched = input.slice(unmatchedStart, unmatchedEnd) || input.slice(indexPrev, index);
lengthExtra = 0;
for (const char of unmatched.replaceAll(MODIFIER_RE, '')) {
const codePoint = char.codePointAt(0) || 0;
if (isFullWidth(codePoint)) {
widthExtra = FULL_WIDTH_WIDTH;
}
else if (isWide(codePoint)) {
widthExtra = WIDE_WIDTH;
}
else if (AMBIGUOUS_WIDTH !== REGULAR_WIDTH && isAmbiguous(codePoint)) {
widthExtra = AMBIGUOUS_WIDTH;
}
else {
widthExtra = REGULAR_WIDTH;
}
if ((width + widthExtra) > truncationLimit) {
truncationIndex = Math.min(truncationIndex, Math.max(unmatchedStart, indexPrev) + lengthExtra);
}
if ((width + widthExtra) > LIMIT) {
truncationEnabled = true;
break outer;
}
lengthExtra += char.length;
width += widthExtra;
}
unmatchedStart = unmatchedEnd = 0;
}
/* EXITING */
if (index >= length)
break;
/* LATIN */
LATIN_RE.lastIndex = index;
if (LATIN_RE.test(input)) {
lengthExtra = LATIN_RE.lastIndex - index;
widthExtra = lengthExtra * REGULAR_WIDTH;
if ((width + widthExtra) > truncationLimit) {
truncationIndex = Math.min(truncationIndex, index + Math.floor((truncationLimit - width) / REGULAR_WIDTH));
}
if ((width + widthExtra) > LIMIT) {
truncationEnabled = true;
break;
}
width += widthExtra;
unmatchedStart = indexPrev;
unmatchedEnd = index;
index = indexPrev = LATIN_RE.lastIndex;
continue;
}
/* ANSI */
ANSI_RE.lastIndex = index;
if (ANSI_RE.test(input)) {
if ((width + ANSI_WIDTH) > truncationLimit) {
truncationIndex = Math.min(truncationIndex, index);
}
if ((width + ANSI_WIDTH) > LIMIT) {
truncationEnabled = true;
break;
}
width += ANSI_WIDTH;
unmatchedStart = indexPrev;
unmatchedEnd = index;
index = indexPrev = ANSI_RE.lastIndex;
continue;
}
/* CONTROL */
CONTROL_RE.lastIndex = index;
if (CONTROL_RE.test(input)) {
lengthExtra = CONTROL_RE.lastIndex - index;
widthExtra = lengthExtra * CONTROL_WIDTH;
if ((width + widthExtra) > truncationLimit) {
truncationIndex = Math.min(truncationIndex, index + Math.floor((truncationLimit - width) / CONTROL_WIDTH));
}
if ((width + widthExtra) > LIMIT) {
truncationEnabled = true;
break;
}
width += widthExtra;
unmatchedStart = indexPrev;
unmatchedEnd = index;
index = indexPrev = CONTROL_RE.lastIndex;
continue;
}
/* TAB */
TAB_RE.lastIndex = index;
if (TAB_RE.test(input)) {
lengthExtra = TAB_RE.lastIndex - index;
widthExtra = lengthExtra * TAB_WIDTH;
if ((width + widthExtra) > truncationLimit) {
truncationIndex = Math.min(truncationIndex, index + Math.floor((truncationLimit - width) / TAB_WIDTH));
}
if ((width + widthExtra) > LIMIT) {
truncationEnabled = true;
break;
}
width += widthExtra;
unmatchedStart = indexPrev;
unmatchedEnd = index;
index = indexPrev = TAB_RE.lastIndex;
continue;
}
/* EMOJI */
EMOJI_RE.lastIndex = index;
if (EMOJI_RE.test(input)) {
if ((width + EMOJI_WIDTH) > truncationLimit) {
truncationIndex = Math.min(truncationIndex, index);
}
if ((width + EMOJI_WIDTH) > LIMIT) {
truncationEnabled = true;
break;
}
width += EMOJI_WIDTH;
unmatchedStart = indexPrev;
unmatchedEnd = index;
index = indexPrev = EMOJI_RE.lastIndex;
continue;
}
/* UNMATCHED INDEX */
index += 1;
}
/* RETURN */
return {
width: truncationEnabled ? truncationLimit : width,
index: truncationEnabled ? truncationIndex : length,
truncated: truncationEnabled,
ellipsed: truncationEnabled && LIMIT >= ELLIPSIS_WIDTH
};
};
/* EXPORT */
export default getStringTruncatedWidth;