/* This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ String.prototype.format = function string_format() { // there are two modes of operation... unnamed indices are read in order; // named indices using %(name)s. The two styles cannot be mixed. // Unnamed indices can be passed as either a single argument to this function, // multiple arguments to this function, or as a single array argument let curindex = 0; let d; if (arguments.length > 1) { d = arguments; } else d = arguments[0]; function r(s, key, type) { if (type == '%') return '%'; let v; if (key == "") { if (curindex == -1) throw Error("Cannot mix named and positional indices in string formatting."); if (curindex == 0 && (!(d instanceof Object) || !(0 in d))) { v = d; } else if (!(curindex in d)) throw Error("Insufficient number of items in format, requesting item %i".format(curindex)); else { v = d[curindex]; } ++curindex; } else { key = key.slice(1, -1); if (curindex > 0) throw Error("Cannot mix named and positional indices in string formatting."); curindex = -1; if (!(key in d)) throw Error("Key '%s' not present during string substitution.".format(key)); v = d[key]; } switch (type) { case "s": if (v === undefined) return "<undefined>"; return v.toString(); case "r": return uneval(v); case "i": return parseInt(v); case "f": return Number(v); default: throw Error("Unexpected format character '%s'.".format(type)); } } return this.replace(/%(\([^)]+\))?(.)/g, r); };