import {Injectable} from "@angular/core"; import {isDefined} from "./util"; export abstract class TranslateParser { /** * Interpolates a string to replace parameters * "This is a {{ key }}" ==> "This is a value", with params = { key: "value" } * @param expr * @param params */ abstract interpolate(expr: string | Function, params?: any): string | undefined; /** * Gets a value from an object by composed key * parser.getValue({ key1: { keyA: 'valueI' }}, 'key1.keyA') ==> 'valueI' * @param target * @param key */ abstract getValue(target: any, key: string): any } @Injectable() export class TranslateDefaultParser extends TranslateParser { templateMatcher: RegExp = /{{\s?([^{}\s]*)\s?}}/g; public interpolate(expr: string | Function, params?: any): string { let result: string; if (typeof expr === 'string') { result = this.interpolateString(expr, params); } else if (typeof expr === 'function') { result = this.interpolateFunction(expr, params); } else { // this should not happen, but an unrelated TranslateService test depends on it result = expr as string; } return result; } getValue(target: any, key: string): any { let keys = typeof key === 'string' ? key.split('.') : [key]; key = ''; do { key += keys.shift(); if (isDefined(target) && isDefined(target[key]) && (typeof target[key] === 'object' || !keys.length)) { target = target[key]; key = ''; } else if (!keys.length) { target = undefined; } else { key += '.'; } } while (keys.length); return target; } private interpolateFunction(fn: Function, params?: any) { return fn(params); } private interpolateString(expr: string, params?: any) { if (!params) { return expr; } return expr.replace(this.templateMatcher, (substring: string, b: string) => { let r = this.getValue(params, b); return isDefined(r) ? r : substring; }); } }