rdesign/frontend/node_modules/langium/lib/dependency-injection.js

/******************************************************************************
 * Copyright 2021 TypeFox GmbH
 * This program and the accompanying materials are made available under the
 * terms of the MIT License, which is available in the project root.
 ******************************************************************************/
export var Module;
(function (Module) {
    /**
     * Merges two dependency injection modules into a new (third) one that is returned.
     * At that `m1` and `m2` stay unchanged. Therefore, `m1` is deep-copied first,
     * and m2 is merged onto the copy afterwards.
     *
     * Note that the leaf values of `m1` and `m2`, i.e. the service constructor functions,
     * cannot be copied generically, since they are functions. They are shared by the source and merged modules.
     *
     * @returns the merged module being a deep copy of `m1` with `m2` merged onto it.
     */
    Module.merge = (m1, m2) => _merge(_merge({}, m1), m2);
})(Module || (Module = {}));
/**
 * Given a set of modules, the inject function returns a lazily evaluated injector
 * that injects dependencies into the requested service when it is requested the
 * first time. Subsequent requests will return the same service.
 *
 * In the case of cyclic dependencies, an Error will be thrown. This can be fixed
 * by injecting a provider `() => T` instead of a `T`.
 *
 * Please note that the arguments may be objects or arrays. However, the result will
 * be an object. Using it with for..of will have no effect.
 *
 * @param module1 first Module
 * @param module2 (optional) second Module
 * @param module3 (optional) third Module
 * @param module4 (optional) fourth Module
 * @param module5 (optional) fifth Module
 * @param module6 (optional) sixth Module
 * @param module7 (optional) seventh Module
 * @param module8 (optional) eighth Module
 * @param module9 (optional) ninth Module
 * @returns a new object of type I
 */
export function inject(module1, module2, module3, module4, module5, module6, module7, module8, module9) {
    const module = [module1, module2, module3, module4, module5, module6, module7, module8, module9].reduce(_merge, {});
    return _inject(module);
}
const isProxy = Symbol('isProxy');
/**
 * Eagerly load all services in the given dependency injection container. This is sometimes
 * necessary because services can register event listeners in their constructors.
 */
export function eagerLoad(item) {
    if (item && item[isProxy]) {
        for (const value of Object.values(item)) {
            eagerLoad(value);
        }
    }
    return item;
}
/**
 * Helper function that returns an injector by creating a proxy.
 * Invariant: injector is of type I. If injector is undefined, then T = I.
 */
function _inject(module, injector) {
    const proxy = new Proxy({}, {
        deleteProperty: () => false,
        set: () => {
            throw new Error('Cannot set property on injected service container');
        },
        get: (obj, prop) => {
            if (prop === isProxy) {
                return true;
            }
            else {
                return _resolve(obj, prop, module, injector || proxy);
            }
        },
        getOwnPropertyDescriptor: (obj, prop) => (_resolve(obj, prop, module, injector || proxy), Object.getOwnPropertyDescriptor(obj, prop)), // used by for..in
        has: (_, prop) => prop in module, // used by ..in..
        ownKeys: () => [...Object.getOwnPropertyNames(module)] // used by for..in
    });
    return proxy;
}
/**
 * Internally used to tag a requested dependency, directly before calling the factory.
 * This allows us to find cycles during instance creation.
 */
const __requested__ = Symbol();
/**
 * Returns the value `obj[prop]`. If the value does not exist, yet, it is resolved from
 * the module description. The result of service factories is cached. Groups are
 * recursively proxied.
 *
 * @param obj an object holding all group proxies and services
 * @param prop the key of a value within obj
 * @param module an object containing groups and service factories
 * @param injector the first level proxy that provides access to all values
 * @returns the requested value `obj[prop]`
 * @throws Error if a dependency cycle is detected
 */
function _resolve(obj, prop, module, injector) {
    if (prop in obj) {
        if (obj[prop] instanceof Error) {
            throw new Error('Construction failure. Please make sure that your dependencies are constructable. Cause: ' + obj[prop]);
        }
        if (obj[prop] === __requested__) {
            throw new Error('Cycle detected. Please make "' + String(prop) + '" lazy. Visit https://langium.org/docs/reference/configuration-services/#resolving-cyclic-dependencies');
        }
        return obj[prop];
    }
    else if (prop in module) {
        const value = module[prop];
        obj[prop] = __requested__;
        try {
            obj[prop] = (typeof value === 'function') ? value(injector) : _inject(value, injector);
        }
        catch (error) {
            obj[prop] = error instanceof Error ? error : undefined;
            throw error;
        }
        return obj[prop];
    }
    else {
        return undefined;
    }
}
/**
 * Performs a deep-merge of two modules by writing source entries into the target module.
 *
 * @param target the module which is written
 * @param source the module which is read
 * @returns the target module
 */
function _merge(target, source) {
    if (source) {
        for (const [key, sourceValue] of Object.entries(source)) {
            if (sourceValue !== undefined && sourceValue !== null) {
                if (typeof sourceValue === 'object') {
                    const targetValue = target[key];
                    if (typeof targetValue === 'object' && targetValue !== null) {
                        // in case both values are real (non-null) objects merge them recursively
                        target[key] = _merge(targetValue, sourceValue);
                    }
                    else {
                        // in case 'target[key]' is not a non-null object
                        //  we overwrite any existing value with a deep copy of 'sourceValue'
                        //  by recursively calling this function with a new 'target' object to be populated
                        //  that is assigned to 'target[key]' afterwards
                        target[key] = _merge({}, sourceValue);
                    }
                }
                else {
                    // in case 'sourceValue' is defined and assigned (non-null) but not an object
                    //  we assume it to be a service constructor function according to the Module<I> type definition
                    target[key] = sourceValue;
                    // note the following for such service constructor functions:
                    // 'target[key]' will now reference the same function object being referenced by 'source[key]'.
                    // This is accepted here, since function objects cannot be safely copied in general.
                }
            }
        }
    }
    return target;
}
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