TypeScriptgeneric-utils.ts
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// Typed in-memory cache
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class TypedCache<K, V> {
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  private store = new Map<K, V>();
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  set(key: K, value: V): void { this.store.set(key, value); }
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  get(key: K): V | undefined { return this.store.get(key); }
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  has(key: K): boolean { return this.store.has(key); }
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  clear(): void { this.store.clear(); }
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}
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// Generic repository interface
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interface Repository<T extends { id: string }> {
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  findById(id: string): Promise<T | null>;
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  findAll(): Promise<T[]>;
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  save(entity: T): Promise<T>;
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  delete(id: string): Promise<boolean>;
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}
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// In-memory implementation for testing
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class InMemoryRepository<T extends { id: string }> implements Repository<T> {
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  private items = new Map<string, T>();
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  async findById(id: string): Promise<T | null> {
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    return this.items.get(id) ?? null;
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  }
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  async findAll(): Promise<T[]> { return Array.from(this.items.values()); }
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  async save(entity: T): Promise<T> {
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    this.items.set(entity.id, entity);
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    return entity;
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  }
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  async delete(id: string): Promise<boolean> {
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    return this.items.delete(id);
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  }
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}
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// Usage
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interface User { id: string; name: string; email: string; }
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const userRepo = new InMemoryRepository<User>();
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const cache = new TypedCache<string, User>();
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async function main() {
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  const user = await userRepo.save({ id: '1', name: 'Alice', email: 'alice@example.com' });
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  cache.set(user.id, user);
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  console.log(await userRepo.findById('1')); // User
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  console.log(cache.get('1'));              // User from cache
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}