53 lines
2.1 KiB
JavaScript
53 lines
2.1 KiB
JavaScript
/**
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* The `GlobalValue` module ensures that a single instance of a value is created globally,
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* even when modules are imported multiple times (e.g., due to mixing CommonJS and ESM builds)
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* or during hot-reloading in development environments like Next.js or Remix.
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*
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* It achieves this by using a versioned global store, identified by a unique `Symbol` tied to
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* the current version of the `effect` library. The store holds values that are keyed by an identifier,
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* allowing the reuse of previously computed instances across imports or reloads.
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*
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* This pattern is particularly useful in scenarios where frequent reloading can cause services or
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* single-instance objects to be recreated unnecessarily, such as in development environments with hot-reloading.
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*
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* @since 2.0.0
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*/
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import * as version from "./internal/version.js";
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const globalStoreId = `effect/GlobalValue/globalStoreId/${/*#__PURE__*/version.getCurrentVersion()}`;
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let globalStore;
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/**
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* Retrieves or computes a global value associated with the given `id`. If the value for this `id`
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* has already been computed, it will be returned from the global store. If it does not exist yet,
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* the provided `compute` function will be executed to compute the value, store it, and then return it.
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*
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* This ensures that even in cases where the module is imported multiple times (e.g., in mixed environments
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* like CommonJS and ESM, or during hot-reloading in development), the value is computed only once and reused
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* thereafter.
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*
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* @example
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* ```ts
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* import { globalValue } from "effect/GlobalValue"
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*
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* // This cache will persist as long as the module is running,
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* // even if reloaded or imported elsewhere
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* const myCache = globalValue(
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* Symbol.for("myCache"),
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* () => new WeakMap<object, number>()
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* )
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* ```
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*
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* @since 2.0.0
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*/
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export const globalValue = (id, compute) => {
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if (!globalStore) {
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// @ts-expect-error
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globalThis[globalStoreId] ??= new Map();
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// @ts-expect-error
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globalStore = globalThis[globalStoreId];
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}
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if (!globalStore.has(id)) {
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globalStore.set(id, compute());
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}
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return globalStore.get(id);
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};
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//# sourceMappingURL=GlobalValue.js.map
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