47 lines
1.1 KiB
JavaScript
47 lines
1.1 KiB
JavaScript
function isPromiseLike(thing) {
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return !!thing && typeof thing.then === 'function';
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}
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function InMemoryCache(initialValue, reportError) {
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if (typeof reportError !== 'function') {
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throw new Error(
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'No reportError function specified for this in-memory-cache'
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);
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}
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const cacheKey = Symbol('cacheKey');
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const cache = new Map();
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cache.set(cacheKey, initialValue);
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return {
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get() {
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const value = cache.get(cacheKey);
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return typeof value !== 'undefined' ? value : null;
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},
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async update(fn) {
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let maybePromisedValue;
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try {
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maybePromisedValue = fn();
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} catch (e) {
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const errMsg = `InMemoryCache > update > caught: ${e.message}`;
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e.message = errMsg;
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reportError(e);
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return null;
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}
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if (isPromiseLike(maybePromisedValue)) {
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return maybePromisedValue.then(value => cache.set(cacheKey, value));
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} else {
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const value = maybePromisedValue;
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cache.set(cacheKey, value);
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return null;
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}
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},
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clear() {
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return cache.delete(cacheKey);
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}
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};
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}
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export default InMemoryCache;
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