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cleanup code to avoid unnecessary type assertions #95

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Merged
cometkim merged 1 commit into from
Aug 5, 2025
Merged

cleanup code to avoid unnecessary type assertions #95

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4 changes: 2 additions & 2 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -220,7 +220,7 @@ Since [Hermes doesn't support the `Intl.Segmenter` API](https://github.com/faceb

| Name | Unicode® | ESM? | Size | Size (min) | Size (min+gzip) | Size (min+br) | Size (min+zstd) |
|------------------------------|----------|------|----------:|-----------:|----------------:|--------------:|----------------:|
| `unicode-segmenter/grapheme` | 16.0.0 | ✔️ | 15,919 | 12,187 | 5,057 | 3,738 | 4,745 |
| `unicode-segmenter/grapheme` | 16.0.0 | ✔️ | 15,625 | 12,166 | 5,044 | 3,752 | 4,724 |
| `graphemer` | 15.0.0 | ✖️ ️| 410,435 | 95,104 | 15,752 | 10,660 | 15,911 |
| `grapheme-splitter` | 10.0.0 | ✖️ | 122,252 | 23,680 | 7,852 | 4,841 | 6,750 |
| `@formatjs/intl-segmenter`* | 15.0.0 | ✖️ | 603,285 | 369,560 | 72,218 | 49,416 | 67,975 |
Expand All @@ -236,7 +236,7 @@ Since [Hermes doesn't support the `Intl.Segmenter` API](https://github.com/faceb

| Name | Bytecode size | Bytecode size (gzip)* |
|------------------------------|--------------:|----------------------:|
| `unicode-segmenter/grapheme` | 20,932 | 10,977 |
| `unicode-segmenter/grapheme` | 20,932 | 10,994 |
| `graphemer` | 133,978 | 31,713 |
| `grapheme-splitter` | 63,835 | 19,137 |

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44 changes: 18 additions & 26 deletions src/grapheme.js
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Expand Up @@ -43,30 +43,30 @@ export { GraphemeCategory };
* @return {GraphemeSegmenter} iterator for grapheme cluster segments
*/
export function* graphemeSegments(input) {
let cp = input.codePointAt(0);

// do nothing on empty string
if (input === '') {
return;
}
if (cp == null) return;

/** @type {number} Current cursor position. */
/** Current cursor position. */
let cursor = 0;

/** @type {number} Total length of the input string. */
/** Total length of the input string. */
let len = input.length;

/** @type {GraphemeCategoryNum | null} Category of codepoint immediately preceding cursor, if known. */
let catBefore = null;
/** @type {import('./_grapheme_data.js').GraphemeCategoryRange} */
let cache = [0, 0, 2 /* GC_Control */];

/** @type {GraphemeCategoryNum | null} Category of codepoint immediately preceding cursor, if known. */
let catAfter = null;
/** Category of codepoint immediately preceding cursor */
let catBefore = cat(cp, cache);

/** @type {GraphemeCategoryNum | null} Beginning category of a segment */
let catBegin = null;
/** Beginning category of a segment */
let catBegin = catBefore;

/** @type {import('./_grapheme_data.js').GraphemeCategoryRange} */
let cache = [0, 0, 2 /* GC_Control */];
/** @type {GraphemeCategoryNum | null} Category of codepoint immediately preceding cursor. */
let catAfter = null;

/** @type {number} The number of RIS codepoints preceding `cursor`. */
/** The number of RIS codepoints preceding `cursor`. */
let risCount = 0;

/** Emoji state */
Expand All @@ -81,8 +81,6 @@ export function* graphemeSegments(input) {
/** InCB=Consonant InCB=Linker x InCB=Consonant */
let incb = false;

let cp = /** @type {number} */ (input.codePointAt(cursor));

/** Memoize the beginnig code point a the segment. */
let _hd = cp;

Expand All @@ -91,21 +89,13 @@ export function* graphemeSegments(input) {
while (true) {
cursor += cp < 0xFFFF ? 1 : 2;

// Note: Of course the nullish coalescing is useful here,
// but avoid it for aggressive compatibility and perf claim
catBefore = catAfter;
if (catBefore === null) {
catBefore = cat(cp, cache);
catBegin = catBefore;
}

if (cursor >= len) {
yield {
segment: input.slice(index, cursor),
index,
input,
_hd,
_catBegin: /** @type {typeof catBefore} */ (catBegin),
_catBegin: catBegin,
_catEnd: catBefore,
};
return;
Expand Down Expand Up @@ -149,7 +139,7 @@ export function* graphemeSegments(input) {
index,
input,
_hd,
_catBegin: /** @type {typeof catBefore} */ (catBegin),
_catBegin: catBegin,
_catEnd: catBefore,
};

Expand All @@ -160,6 +150,8 @@ export function* graphemeSegments(input) {
catBegin = catAfter;
_hd = cp;
}

catBefore = catAfter;
}
}

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