@frontmcp/di

Generic dependency injection container and registry utilities for TypeScript applications.

Features

Type-safe dependency injection with class tokens
Configurable token factory with custom prefixes
Hierarchical provider registries
Scoped providers (GLOBAL, CONTEXT)
Indexed registry base class with O(1) lookups
Adoption pattern for child registries
Change event subscriptions

Installation

npm install @frontmcp/di reflect-metadata zod

Usage

import 'reflect-metadata';
import { DiContainer, createTokenFactory, ProviderScope } from '@frontmcp/di';

// Create a token factory with custom prefix
const tokenFactory = createTokenFactory({ prefix: 'MyApp' });

// Define providers
class DatabaseService {
  static metadata = { name: 'Database', scope: ProviderScope.GLOBAL };
}

// Create container
const container = new DiContainer([DatabaseService]);
await container.ready;

// Resolve dependencies
const db = container.get(DatabaseService);

API

Token Factory

import { createTokenFactory } from '@frontmcp/di';

const tokens = createTokenFactory({ prefix: 'MyApp' });
const myToken = tokens.type('MyService'); // Symbol('MyApp:type:MyService')

Provider Normalizer

import { createProviderNormalizer } from '@frontmcp/di';

const normalizeProvider = createProviderNormalizer({
  type: Symbol('type'),
  name: Symbol('name'),
  scope: Symbol('scope'),
});

DiContainer

import { DiContainer } from '@frontmcp/di';

const container = new DiContainer(providers, parentContainer);
await container.ready;

container.get(Token); // Get GLOBAL provider
container.resolve(Class); // Resolve or construct
container.buildViews(key); // Build scoped views

IndexedRegistry

Base class for registries with fast lookups:

import { IndexedRegistry } from '@frontmcp/di';

class MyRegistry extends IndexedRegistry<MyInstance, MyRecord, MyIndexed, MyMetadata> {
  protected buildIndexes(rows: MyIndexed[]): void {
    // Build custom indexes
  }
}

License

Apache-2.0