@joist/di/target/lib/injector.js

Dependency Injection for Vanilla JS classes

import { callLifecycle } from "./lifecycle.js";
import { readInjector, readMetadata } from "./metadata.js";
import { StaticToken, } from "./provider.js";
export const INJECTOR = Symbol("JOIST_INJECTOR");
export class ProviderMap extends Map {
}
export class Injector {
    #instances = new WeakMap();
    name;
    parent;
    providers;
    constructor(opts) {
        this.parent = opts?.parent;
        this.providers = new ProviderMap(opts?.providers);
    }
    injectAll(token, collection = []) {
        collection.push(this.inject(token, { skipParent: true }));
        if (this.parent) {
            return this.parent.injectAll(token, collection);
        }
        return collection;
    }
    inject(token, opts) {
        if (this.#instances.has(token)) {
            const instance = this.#instances.get(token);
            const metadata = readMetadata(token);
            const injector = readInjector(instance);
            if (metadata) {
                callLifecycle(instance, injector ?? this, metadata.onInjected);
            }
            return instance;
        }
        const provider = this.providers.get(token);
        if (provider) {
            if ("use" in provider) {
                return this.#createAndCache(token, () => new provider.use());
            }
            if ("factory" in provider) {
                return this.#createAndCache(token, provider.factory);
            }
            throw new Error(`Provider for ${token.name} found but is missing either 'use' or 'factory'`);
        }
        if (this.parent && !opts?.skipParent) {
            return this.parent.inject(token);
        }
        if (token instanceof StaticToken) {
            if (!token.factory) {
                throw new Error(`Provider not found for "${token.name}"`);
            }
            return this.#createAndCache(token, token.factory);
        }
        return this.#createAndCache(token, () => new token());
    }
    clear() {
        this.#instances = new WeakMap();
    }
    #createAndCache(token, factory) {
        const instance = factory(this);
        this.#instances.set(token, instance);
        const injector = readInjector(instance);
        if (!injector) {
            return instance;
        }
        if (injector !== this) {
            injector.parent = this;
        }
        const metadata = readMetadata(token);
        if (metadata) {
            callLifecycle(instance ?? this, injector, metadata.onCreated);
            callLifecycle(instance ?? this, injector, metadata.onInjected);
        }
        return instance;
    }
}
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