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perf(ui): cache variable highlight RegExp creation (#71)

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Caching the RegExp compilation for highlighting variables under the cursor avoids creating an assignment RegExp and a highlight RegExp constantly when typing, saving roughly ~40% of the overhead time for this function as tested.

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
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Horizontal42 2026-08-12 22:07:38 +03:00 • committed by GitHub
parent 445f965c8e
commit b559c94ffa
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1 changed files with 16 additions and 4 deletions
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20
src/ui/editor.ts
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@ -75,6 +75,8 @@ const highlightField = StateField.define<DecorationSet>({
provide: (f) => EditorView.decorations.from(f),
});
const varHighlightReCache = new Map<string, { assignment: RegExp; highlight: RegExp }>();
/** Highlights every occurrence of the variable under the cursor. */
function buildVarHighlight(state: EditorState): DecorationSet {
const builder = new RangeSetBuilder<Decoration>();
@ -90,11 +92,21 @@ function buildVarHighlight(state: EditorState): DecorationSet {
if (a === b) return builder.finish();
const word = text.slice(a, b);
if (!/^[\p{L}_][\p{L}\d_]*$/u.test(word)) return builder.finish();
// only highlight if the word is actually assigned somewhere in the document
let cachedRe = varHighlightReCache.get(word);
if (!cachedRe) {
const esc = word.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
if (!new RegExp(`^\\s*${esc}\\s*=`, "mu").test(text)) return builder.finish();
const re = new RegExp(`(?<![\\p{L}\\d_])${esc}(?![\\p{L}\\d_])`, "gu");
for (const m of text.matchAll(re)) {
cachedRe = {
assignment: new RegExp(`^\\s*${esc}\\s*=`, "mu"),
highlight: new RegExp(`(?<![\\p{L}\\d_])${esc}(?![\\p{L}\\d_])`, "gu"),
};
if (varHighlightReCache.size > 1000) varHighlightReCache.clear();
varHighlightReCache.set(word, cachedRe);
}
// only highlight if the word is actually assigned somewhere in the document
if (!cachedRe.assignment.test(text)) return builder.finish();
for (const m of text.matchAll(cachedRe.highlight)) {
builder.add(m.index, m.index + word.length, Decoration.mark({ class: "tok-var-active" }));
}
return builder.finish();