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+/* 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/. */
+"use strict";
+
+module.metadata = {
+ "stability": "unstable"
+};
+
+const { flatten } = require('./array');
+
+/**
+ * Merges all the properties of all arguments into first argument. If two or
+ * more argument objects have own properties with the same name, the property
+ * is overridden, with precedence from right to left, implying, that properties
+ * of the object on the left are overridden by a same named property of the
+ * object on the right.
+ *
+ * Any argument given with "falsy" value - commonly `null` and `undefined` in
+ * case of objects - are skipped.
+ *
+ * @examples
+ * var a = { bar: 0, a: 'a' }
+ * var b = merge(a, { foo: 'foo', bar: 1 }, { foo: 'bar', name: 'b' });
+ * b === a // true
+ * b.a // 'a'
+ * b.foo // 'bar'
+ * b.bar // 1
+ * b.name // 'b'
+ */
+function merge(source) {
+ let descriptor = {};
+
+ // `Boolean` converts the first parameter to a boolean value. Any object is
+ // converted to `true` where `null` and `undefined` becames `false`. Therefore
+ // the `filter` method will keep only objects that are defined and not null.
+ Array.slice(arguments, 1).filter(Boolean).forEach(function onEach(properties) {
+ getOwnPropertyIdentifiers(properties).forEach(function(name) {
+ descriptor[name] = Object.getOwnPropertyDescriptor(properties, name);
+ });
+ });
+ return Object.defineProperties(source, descriptor);
+}
+exports.merge = merge;
+
+/**
+ * Returns an object that inherits from the first argument and contains all the
+ * properties from all following arguments.
+ * `extend(source1, source2, source3)` is equivalent of
+ * `merge(Object.create(source1), source2, source3)`.
+ */
+function extend(source) {
+ let rest = Array.slice(arguments, 1);
+ rest.unshift(Object.create(source));
+ return merge.apply(null, rest);
+}
+exports.extend = extend;
+
+function has(obj, key) {
+ return obj.hasOwnProperty(key);
+}
+exports.has = has;
+
+function each(obj, fn) {
+ for (let key in obj) has(obj, key) && fn(obj[key], key, obj);
+}
+exports.each = each;
+
+/**
+ * Like `merge`, except no property descriptors are manipulated, for use
+ * with platform objects. Identical to underscore's `extend`. Useful for
+ * merging XPCOM objects
+ */
+function safeMerge(source) {
+ Array.slice(arguments, 1).forEach(function onEach (obj) {
+ for (let prop in obj) source[prop] = obj[prop];
+ });
+ return source;
+}
+exports.safeMerge = safeMerge;
+
+/*
+ * Returns a copy of the object without omitted properties
+ */
+function omit(source, ...values) {
+ let copy = {};
+ let keys = flatten(values);
+ for (let prop in source)
+ if (!~keys.indexOf(prop))
+ copy[prop] = source[prop];
+ return copy;
+}
+exports.omit = omit;
+
+// get object's own property Symbols and/or Names, including nonEnumerables by default
+function getOwnPropertyIdentifiers(object, options = { names: true, symbols: true, nonEnumerables: true }) {
+ const symbols = !options.symbols ? [] :
+ Object.getOwnPropertySymbols(object);
+ const names = !options.names ? [] :
+ options.nonEnumerables ? Object.getOwnPropertyNames(object) :
+ Object.keys(object);
+ return [...names, ...symbols];
+}
+exports.getOwnPropertyIdentifiers = getOwnPropertyIdentifiers;