eewing
66 lines
1.8 KiB
JavaScript
66 lines
1.8 KiB
JavaScript
import { getContext, hasContext, setContext } from "svelte";
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export class Context {
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#name;
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#key;
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/**
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* @param name The name of the context.
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* This is used for generating the context key and error messages.
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*/
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constructor(name) {
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this.#name = name;
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this.#key = Symbol(name);
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}
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/**
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* The key used to get and set the context.
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*
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* It is not recommended to use this value directly.
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* Instead, use the methods provided by this class.
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*/
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get key() {
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return this.#key;
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}
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/**
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* Checks whether this has been set in the context of a parent component.
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*
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* Must be called during component initialisation.
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*/
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exists() {
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return hasContext(this.#key);
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}
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/**
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* Retrieves the context that belongs to the closest parent component.
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*
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* Must be called during component initialisation.
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*
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* @throws An error if the context does not exist.
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*/
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get() {
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const context = getContext(this.#key);
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if (context === undefined) {
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throw new Error(`Context "${this.#name}" not found`);
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}
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return context;
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}
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/**
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* Retrieves the context that belongs to the closest parent component,
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* or the given fallback value if the context does not exist.
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*
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* Must be called during component initialisation.
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*/
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getOr(fallback) {
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const context = getContext(this.#key);
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if (context === undefined) {
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return fallback;
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}
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return context;
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}
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/**
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* Associates the given value with the current component and returns it.
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*
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* Must be called during component initialisation.
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*/
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set(context) {
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return setContext(this.#key, context);
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}
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}
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