62 lines
1.9 KiB
TypeScript
62 lines
1.9 KiB
TypeScript
import { clonePlain } from './clone-plain';
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export class MutationProxy<T extends object> {
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private readonly getOriginal: () => T;
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private readonly getMutated: () => Partial<T>;
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constructor(
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getOriginal: () => T,
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getMutated: () => Partial<T>,
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) {
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this.getOriginal = getOriginal;
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this.getMutated = getMutated;
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}
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create(): T {
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return new Proxy({} as T, {
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get: (_target, prop: string | symbol) => {
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if (typeof prop !== 'string') {
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return undefined;
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}
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const key = prop as keyof T;
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const mutated = this.getMutated();
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const original = this.getOriginal();
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return key in mutated ? mutated[key] : original[key];
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},
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set: (_target, prop: string | symbol, value: unknown) => {
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if (typeof prop === 'string') {
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const key = prop as keyof T;
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(this.getMutated() as Record<keyof T, unknown>)[key] = clonePlain(value);
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}
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return true;
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},
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has: (_target, prop: string | symbol) => {
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if (typeof prop !== 'string') {
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return false;
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}
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const mutated = this.getMutated();
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const original = this.getOriginal();
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return prop in mutated || prop in original;
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},
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ownKeys: () => {
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const mutated = this.getMutated();
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const original = this.getOriginal();
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return Array.from(new Set([
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...Reflect.ownKeys(original),
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...Reflect.ownKeys(mutated),
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]));
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},
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getOwnPropertyDescriptor: () => ({
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enumerable: true,
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configurable: true,
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}),
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});
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}
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}
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