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x/yargs/lib/middleware.ts

yargs the modern, pirate-themed successor to optimist.
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import {argsert} from './argsert.js';import {isPromise} from './utils/is-promise.js';import {YargsInstance, Arguments} from './yargs-factory.js';
export class GlobalMiddleware { globalMiddleware: Middleware[] = []; yargs: YargsInstance; frozens: Array<Middleware[]> = []; constructor(yargs: YargsInstance) { this.yargs = yargs; } addMiddleware( callback: MiddlewareCallback | MiddlewareCallback[], applyBeforeValidation: boolean, global = true, mutates = false ): YargsInstance { argsert( '<array|function> [boolean] [boolean] [boolean]', [callback, applyBeforeValidation, global], arguments.length ); if (Array.isArray(callback)) { for (let i = 0; i < callback.length; i++) { if (typeof callback[i] !== 'function') { throw Error('middleware must be a function'); } const m = callback[i] as Middleware; m.applyBeforeValidation = applyBeforeValidation; m.global = global; } Array.prototype.push.apply( this.globalMiddleware, callback as Middleware[] ); } else if (typeof callback === 'function') { const m = callback as Middleware; m.applyBeforeValidation = applyBeforeValidation; m.global = global; m.mutates = mutates; this.globalMiddleware.push(callback as Middleware); } return this.yargs; } // For "coerce" middleware, only one middleware instance can be registered // per option: addCoerceMiddleware( callback: MiddlewareCallback, option: string ): YargsInstance { const aliases = this.yargs.getAliases(); this.globalMiddleware = this.globalMiddleware.filter(m => { const toCheck = [...(aliases[option] || []), option]; if (!m.option) return true; else return !toCheck.includes(m.option); }); (callback as Middleware).option = option; return this.addMiddleware(callback, true, true, true); } getMiddleware() { return this.globalMiddleware; } freeze() { this.frozens.push([...this.globalMiddleware]); } unfreeze() { const frozen = this.frozens.pop(); if (frozen !== undefined) this.globalMiddleware = frozen; } reset() { this.globalMiddleware = this.globalMiddleware.filter(m => m.global); }}
export function commandMiddlewareFactory( commandMiddleware?: MiddlewareCallback[]): Middleware[] { if (!commandMiddleware) return []; return commandMiddleware.map(middleware => { (middleware as Middleware).applyBeforeValidation = false; return middleware; }) as Middleware[];}
export function applyMiddleware( argv: Arguments | Promise<Arguments>, yargs: YargsInstance, middlewares: Middleware[], beforeValidation: boolean) { return middlewares.reduce<Arguments | Promise<Arguments>>( (acc, middleware) => { if (middleware.applyBeforeValidation !== beforeValidation) { return acc; }
if (middleware.mutates) { if (middleware.applied) return acc; middleware.applied = true; }
if (isPromise(acc)) { return acc .then(initialObj => Promise.all([initialObj, middleware(initialObj, yargs)]) ) .then(([initialObj, middlewareObj]) => Object.assign(initialObj, middlewareObj) ); } else { const result = middleware(acc, yargs); return isPromise(result) ? result.then(middlewareObj => Object.assign(acc, middlewareObj)) : Object.assign(acc, result); } }, argv );}
export interface MiddlewareCallback { (argv: Arguments, yargs: YargsInstance): | Partial<Arguments> | Promise<Partial<Arguments>>;}
export interface Middleware extends MiddlewareCallback { applyBeforeValidation: boolean; global: boolean; option?: string; mutates?: boolean; applied?: boolean;}