Files
TSinjex/src/functions/inject.ts

221 lines
8.4 KiB
TypeScript

import { TSinjex } from '../classes/TSinjex.js';
import {
DependencyResolutionError,
InitializationError,
InjectorError,
NoInstantiationMethodError,
} from '../interfaces/Exceptions.js';
import { Identifier } from '../types/Identifier.js';
import { InitDelegate } from '../types/InitDelegate.js';
/**
* Resolves a dependency by its identifier without initialization or instantiation.
* @template T The expected type of the dependency.
* @param identifier The identifier used to resolve the dependency from the container.
* @returns The resolved dependency.
* @throws A {@link DependencyResolutionError} if the dependency is not found.
* @example
* ```ts
* const logger = inject<Logger>('Logger');
* ```
*/
export function inject<T>(identifier: Identifier): T;
/**
* Resolves and instantiates a dependency using its constructor.
* @template T The expected class type of the dependency.
* @param identifier The identifier used to resolve the dependency from the container.
* @param shouldInit Set to `true` to instantiate the dependency after resolution.
* @returns The resolved and instantiated dependency.
* @throws A {@link DependencyResolutionError} if the dependency is not found.
* @throws A {@link NoInstantiationMethodError} if the dependency has no constructor.
* @throws An {@link InitializationError} if instantiation fails.
* @example
* ```ts
* const instance = inject<Service>('Service', true);
* ```
*/
export function inject<T>(identifier: Identifier, shouldInit: true): T;
/**
* Resolves and instantiates a dependency using its constructor, optionally failing silently.
* @template T The expected class type of the dependency.
* @param identifier The identifier used to resolve the dependency from the container.
* @param shouldInit Set to `true` to instantiate the dependency.
* @param isNecessary If `false`, resolution or instantiation errors return `undefined` instead of throwing.
* @returns The resolved and instantiated dependency, or `undefined` if resolution or instantiation fails.
* @example
* ```ts
* const instance = inject<Service>('OptionalService', true, false);
* if (instance) instance.doSomething();
* ```
*/
export function inject<T>(
identifier: Identifier,
shouldInit: true,
isNecessary: false,
): T | undefined;
/**
* Resolves a dependency without instantiating it, optionally failing silently.
* @template T The expected type of the dependency.
* @param identifier The identifier used to resolve the dependency from the container.
* @param shouldInit Set to `false` to skip instantiation.
* @param isNecessary If `false`, resolution errors return `undefined` instead of throwing.
* @returns The resolved dependency, or `undefined` if not found.
* @example
* ```ts
* const config = inject<Config>('Config', false, false) ?? getDefaultConfig();
* ```
*/
export function inject<T>(
identifier: Identifier,
shouldInit: false,
isNecessary: false,
): T | undefined;
/**
* Resolves a dependency and applies a custom initializer function to transform the result.
* @template T The original dependency type.
* @template U The final return type after initialization.
* @param identifier The identifier used to resolve the dependency.
* @param init A function to transform or initialize the dependency.
* @returns The transformed dependency.
* @throws A {@link DependencyResolutionError} if the dependency is not found.
* @throws An {@link InitializationError} if the initializer throws.
* @example
* ```ts
* const client = inject<Api>('Api', (api) => api.getClient());
* ```
*/
export function inject<T, U>(
identifier: Identifier,
init: InitDelegate<T, U>,
): U;
/**
* Resolves a dependency and applies a custom initializer function, optionally failing silently.
* @template T The original dependency type.
* @template U The final return type after initialization.
* @param identifier The identifier used to resolve the dependency.
* @param init A function to transform or initialize the dependency.
* @param isNecessary If `false`, resolution or initializer errors return `undefined` instead of throwing.
* @returns The transformed dependency, or `undefined` if resolution or initialization fails.
* @example
* ```ts
* const db = inject<Database, Pool>('Database', (d) => d.getPool(), false);
* if (db) db.query('SELECT * FROM users');
* ```
*/
export function inject<T, U>(
identifier: Identifier,
init: InitDelegate<T, U>,
isNecessary: false,
): U | undefined;
/**
* A function to inject a dependency from a DI (Dependency Injection) container into a variable.
* This is the actual implementation that handles all overload variants.
* @template T The original dependency type.
* @template U The final return type after optional initialization or transformation.
* @param identifier The identifier used to resolve the dependency.
* @see {@link Identifier} for more information on identifiers.
* @param init Optional: either `true` to instantiate via constructor, `false` to skip, or a function to transform the dependency.
* @see {@link InitDelegate} for more information on initializer functions.
* @param isNecessary If `true`, throws on failure; if `false`, returns `undefined` on resolution or initialization errors.
* @returns The resolved dependency or result of initialization, or `undefined` if not necessary and resolution fails.
* @throws A {@link DependencyResolutionError} if the dependency is not found (and necessary).
* @throws A {@link NoInstantiationMethodError} if instantiation is requested but no constructor exists.
* @throws An {@link InitializationError} if the initializer throws an error.
* @throws A {@link InjectorError} for unknown errors during resolution or transformation.
* @example
* ```ts
* const service = inject<Service>('Service');
* ```
* @example
* ```ts
* const instance = inject<Service>('Service', true);
* ```
* @example
* ```ts
* const logger = inject<ILogger>('ILogger_', (x) => x.getLogger('Module'), false);
* ```
*/
export function inject<T, U>(
identifier: Identifier,
init?: InitDelegate<T, U> | true | false,
isNecessary = true,
): T | U | undefined {
let instance: T | U | undefined;
const dependency: T | undefined = tryAndCatch(
() => TSinjex.getInstance().resolve<T>(identifier, isNecessary),
isNecessary,
identifier,
DependencyResolutionError,
);
if (dependency != null) {
const initFunction: (() => U) | undefined =
typeof init === 'function' && dependency != null
? (): U => init(dependency)
: init === true && hasConstructor(dependency)
? (): U => new dependency() as U
: undefined;
if (init == null || init === false) instance = dependency;
else if (initFunction != null)
instance = tryAndCatch(
initFunction,
isNecessary,
identifier,
InitializationError,
);
else if (isNecessary) throw new NoInstantiationMethodError(identifier);
} else if (isNecessary) throw new DependencyResolutionError(identifier);
return instance as T | U;
}
/**
* Tries to execute a function and catches any errors that occur.
* If the function is necessary and an error occurs, it throws the error
* with the specified error class and identifier.
* @param fn The function to execute.
* @param necessary If true, throws an error if an error occurs.
* @param identifier The identifier of the dependency.
* @param errorClass The error class to throw if an error occurs.
* @returns The result of the function or undefined if an error occurs and the function is not necessary.
*/
function tryAndCatch<ReturnType, ErrorType>(
fn: () => ReturnType,
necessary: boolean,
identifier?: Identifier,
errorClass?: ErrorType,
): ReturnType | undefined {
try {
return fn();
} catch (error) {
if (necessary)
throw new (errorClass != null ? errorClass : error)(
identifier ?? 'not specified',
error,
);
else return undefined;
}
}
/**
* Checks if an object has a constructor.
* @param obj The object to check.
* @returns True if the object has a constructor, false otherwise.
*/
function hasConstructor<T>(obj: T): obj is T & { new (): unknown } {
const _obj = obj as unknown as { prototype?: { constructor?: unknown } };
return (
_obj?.prototype != null &&
typeof _obj.prototype.constructor === 'function'
);
}