50 lines
1.4 KiB
JavaScript
50 lines
1.4 KiB
JavaScript
/**
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* Build a lazy getter descriptor that caches the value on first access.
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*/
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export function lazyProp(key, get) {
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return {
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get() {
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const value = get();
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Object.defineProperty(this, key, {
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value,
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writable: true,
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configurable: true,
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enumerable: true,
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});
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return value;
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},
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configurable: true,
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enumerable: true,
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};
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}
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/**
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* First access to any field in the group resolves all fields from one reader call.
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* Uses a shared resolve-once pattern: the first getter to fire reads all data,
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* defines own properties for every key, then each per-key getter returns its value.
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*/
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export function lazyGroup(node, keys, resolve) {
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let cached;
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const ensureResolved = () => {
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if (cached)
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return cached;
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cached = resolve();
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for (const k of keys) {
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Object.defineProperty(node, k, {
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value: cached[k],
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writable: true,
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configurable: true,
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enumerable: true,
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});
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}
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return cached;
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};
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for (const key of keys) {
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Object.defineProperty(node, key, {
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get() {
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return ensureResolved()[key];
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},
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configurable: true,
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enumerable: true,
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});
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}
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}
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