@loopback/context
Version:
Facilities to manage artifacts and their dependencies in your Node.js applications. The module exposes TypeScript/JavaScript APIs and decorators to register artifacts, declare dependencies, and resolve artifacts by keys. It also serves as an IoC container
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JavaScript
;
// Copyright IBM Corp. and LoopBack contributors 2018,2020. All Rights Reserved.
// Node module: @loopback/context
// This file is licensed under the MIT License.
// License text available at https://opensource.org/licenses/MIT
Object.defineProperty(exports, "__esModule", { value: true });
exports.UUID_PATTERN = exports.uuid = exports.transformValueOrPromise = exports.resolveUntil = exports.tryCatchFinally = exports.tryWithFinally = exports.resolveList = exports.resolveMap = exports.getDeepProperty = exports.isPromiseLike = void 0;
/**
* This module contains types for values and/or promises as well as a set of
* utility methods to handle values and/or promises.
*/
const uuid_1 = require("uuid");
/**
* Check whether a value is a Promise-like instance.
* Recognizes both native promises and third-party promise libraries.
*
* @param value - The value to check.
*/
function isPromiseLike(value) {
if (!value)
return false;
if (typeof value !== 'object' && typeof value !== 'function')
return false;
return typeof value.then === 'function';
}
exports.isPromiseLike = isPromiseLike;
/**
* Get nested properties of an object by path
* @param value - Value of the source object
* @param path - Path to the property
*/
function getDeepProperty(value, path) {
let result = value;
const props = path.split('.').filter(Boolean);
for (const p of props) {
if (result == null) {
return undefined;
}
result = result[p];
}
return result;
}
exports.getDeepProperty = getDeepProperty;
/**
* Resolve entries of an object into a new object with the same keys. If one or
* more entries of the source object are resolved to a promise by the `resolver`
* function, this method returns a promise which will be resolved to the new
* object with fully resolved entries.
*
* @example
*
* - Example 1: resolve all entries synchronously
* ```ts
* const result = resolveMap({a: 'x', b: 'y'}, v => v.toUpperCase());
* ```
* The `result` will be `{a: 'X', b: 'Y'}`.
*
* - Example 2: resolve one or more entries asynchronously
* ```ts
* const result = resolveMap({a: 'x', b: 'y'}, v =>
* Promise.resolve(v.toUpperCase()),
* );
* ```
* The `result` will be a promise of `{a: 'X', b: 'Y'}`.
*
* @param map - The original object containing the source entries
* @param resolver - A function resolves an entry to a value or promise. It will
* be invoked with the property value, the property name, and the source object.
*/
function resolveMap(map, resolver) {
const result = {};
let asyncResolvers = undefined;
const setter = (key) => (val) => {
if (val !== undefined) {
// Only set the value if it's not undefined so that the default value
// for a key will be honored
result[key] = val;
}
};
for (const key in map) {
const valueOrPromise = resolver(map[key], key, map);
if (isPromiseLike(valueOrPromise)) {
if (!asyncResolvers)
asyncResolvers = [];
asyncResolvers.push(valueOrPromise.then(setter(key)));
}
else {
if (valueOrPromise !== undefined) {
// Only set the value if it's not undefined so that the default value
// for a key will be honored
result[key] = valueOrPromise;
}
}
}
if (asyncResolvers) {
return Promise.all(asyncResolvers).then(() => result);
}
else {
return result;
}
}
exports.resolveMap = resolveMap;
/**
* Resolve entries of an array into a new array with the same indexes. If one or
* more entries of the source array are resolved to a promise by the `resolver`
* function, this method returns a promise which will be resolved to the new
* array with fully resolved entries.
*
* @example
*
* - Example 1: resolve all entries synchronously
* ```ts
* const result = resolveList(['a', 'b'], v => v.toUpperCase());
* ```
* The `result` will be `['A', 'B']`.
*
* - Example 2: resolve one or more entries asynchronously
* ```ts
* const result = resolveList(['a', 'b'], v =>
* Promise.resolve(v.toUpperCase()),
* );
* ```
* The `result` will be a promise of `['A', 'B']`.
*
* @param list - The original array containing the source entries
* @param resolver - A function resolves an entry to a value or promise. It will
* be invoked with the property value, the property index, and the source array.
*/
function resolveList(list, resolver) {
const result = new Array(list.length);
let asyncResolvers = undefined;
const setter = (index) => (val) => {
result[index] = val;
};
for (let ix = 0; ix < list.length; ix++) {
const valueOrPromise = resolver(list[ix], ix, list);
if (isPromiseLike(valueOrPromise)) {
if (!asyncResolvers)
asyncResolvers = [];
asyncResolvers.push(valueOrPromise.then(setter(ix)));
}
else {
result[ix] = valueOrPromise;
}
}
if (asyncResolvers) {
return Promise.all(asyncResolvers).then(() => result);
}
else {
return result;
}
}
exports.resolveList = resolveList;
/**
* Try to run an action that returns a promise or a value
* @param action - A function that returns a promise or a value
* @param finalAction - A function to be called once the action
* is fulfilled or rejected (synchronously or asynchronously)
*
* @typeParam T - Type for the return value
*/
function tryWithFinally(action, finalAction) {
return tryCatchFinally(action, undefined, finalAction);
}
exports.tryWithFinally = tryWithFinally;
/**
* Try to run an action that returns a promise or a value with error and final
* actions to mimic `try {} catch(err) {} finally {}` for a value or promise.
*
* @param action - A function that returns a promise or a value
* @param errorAction - A function to be called once the action
* is rejected (synchronously or asynchronously). It must either return a new
* value or throw an error.
* @param finalAction - A function to be called once the action
* is fulfilled or rejected (synchronously or asynchronously)
*
* @typeParam T - Type for the return value
*/
function tryCatchFinally(action, errorAction = err => {
throw err;
}, finalAction = () => { }) {
let result;
try {
result = action();
}
catch (err) {
result = reject(err);
}
if (isPromiseLike(result)) {
return result.then(resolve, reject);
}
return resolve(result);
function resolve(value) {
try {
return value;
}
finally {
finalAction();
}
}
function reject(err) {
try {
return errorAction(err);
}
finally {
finalAction();
}
}
}
exports.tryCatchFinally = tryCatchFinally;
/**
* Resolve an iterator of source values into a result until the evaluator
* returns `true`
* @param source - The iterator of source values
* @param resolver - The resolve function that maps the source value to a result
* @param evaluator - The evaluate function that decides when to stop
*/
function resolveUntil(source, resolver, evaluator) {
// Do iteration in loop for synchronous values to avoid stack overflow
// eslint-disable-next-line no-constant-condition
while (true) {
const next = source.next();
if (next.done)
return undefined; // End of the iterator
const sourceVal = next.value;
const valueOrPromise = resolver(sourceVal);
if (isPromiseLike(valueOrPromise)) {
return valueOrPromise.then(v => {
if (evaluator(sourceVal, v)) {
return v;
}
else {
return resolveUntil(source, resolver, evaluator);
}
});
}
else {
if (evaluator(sourceVal, valueOrPromise)) {
return valueOrPromise;
}
// Continue with the while loop
}
}
}
exports.resolveUntil = resolveUntil;
/**
* Transform a value or promise with a function that produces a new value or
* promise
* @param valueOrPromise - The value or promise
* @param transformer - A function that maps the source value to a value or promise
*/
function transformValueOrPromise(valueOrPromise, transformer) {
if (isPromiseLike(valueOrPromise)) {
return valueOrPromise.then(transformer);
}
else {
return transformer(valueOrPromise);
}
}
exports.transformValueOrPromise = transformValueOrPromise;
/**
* A utility to generate uuid v4
*
* @deprecated Use `generateUniqueId`, [uuid](https://www.npmjs.com/package/uuid)
* or [hyperid](https://www.npmjs.com/package/hyperid) instead.
*/
function uuid() {
return (0, uuid_1.v4)();
}
exports.uuid = uuid;
/**
* A regular expression for testing uuid v4 PATTERN
* @deprecated This pattern is an internal helper used by unit-tests, we are no
* longer using it.
*/
exports.UUID_PATTERN = /[0-9A-F]{8}-[0-9A-F]{4}-[4][0-9A-F]{3}-[89AB][0-9A-F]{3}-[0-9A-F]{12}/i;
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