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103 lines
3.3 KiB
JavaScript
103 lines
3.3 KiB
JavaScript
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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"use strict";
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module.metadata = {
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"stability": "unstable"
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};
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const { flatten } = require('./array');
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/**
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* Merges all the properties of all arguments into first argument. If two or
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* more argument objects have own properties with the same name, the property
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* is overridden, with precedence from right to left, implying, that properties
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* of the object on the left are overridden by a same named property of the
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* object on the right.
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*
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* Any argument given with "falsy" value - commonly `null` and `undefined` in
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* case of objects - are skipped.
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*
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* @examples
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* var a = { bar: 0, a: 'a' }
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* var b = merge(a, { foo: 'foo', bar: 1 }, { foo: 'bar', name: 'b' });
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* b === a // true
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* b.a // 'a'
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* b.foo // 'bar'
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* b.bar // 1
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* b.name // 'b'
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*/
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function merge(source) {
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let descriptor = {};
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// `Boolean` converts the first parameter to a boolean value. Any object is
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// converted to `true` where `null` and `undefined` becames `false`. Therefore
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// the `filter` method will keep only objects that are defined and not null.
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Array.slice(arguments, 1).filter(Boolean).forEach(function onEach(properties) {
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getOwnPropertyIdentifiers(properties).forEach(function(name) {
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descriptor[name] = Object.getOwnPropertyDescriptor(properties, name);
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});
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});
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return Object.defineProperties(source, descriptor);
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}
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exports.merge = merge;
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/**
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* Returns an object that inherits from the first argument and contains all the
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* properties from all following arguments.
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* `extend(source1, source2, source3)` is equivalent of
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* `merge(Object.create(source1), source2, source3)`.
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*/
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function extend(source) {
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let rest = Array.slice(arguments, 1);
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rest.unshift(Object.create(source));
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return merge.apply(null, rest);
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}
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exports.extend = extend;
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function has(obj, key) obj.hasOwnProperty(key);
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exports.has = has;
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function each(obj, fn) {
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for (let key in obj) has(obj, key) && fn(obj[key], key, obj);
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}
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exports.each = each;
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/**
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* Like `merge`, except no property descriptors are manipulated, for use
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* with platform objects. Identical to underscore's `extend`. Useful for
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* merging XPCOM objects
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*/
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function safeMerge(source) {
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Array.slice(arguments, 1).forEach(function onEach (obj) {
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for (let prop in obj) source[prop] = obj[prop];
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});
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return source;
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}
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exports.safeMerge = safeMerge;
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/*
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* Returns a copy of the object without blacklisted properties
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*/
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function omit(source, ...values) {
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let copy = {};
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let keys = flatten(values);
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for (let prop in source)
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if (!~keys.indexOf(prop))
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copy[prop] = source[prop];
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return copy;
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}
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exports.omit = omit;
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// get object's own property Symbols and/or Names, including nonEnumerables by default
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function getOwnPropertyIdentifiers(object, options = { names: true, symbols: true, nonEnumerables: true }) {
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const symbols = !options.symbols ? [] :
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Object.getOwnPropertySymbols(object);
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const names = !options.names ? [] :
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options.nonEnumerables ? Object.getOwnPropertyNames(object) :
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Object.keys(object);
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return [...names, ...symbols];
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}
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exports.getOwnPropertyIdentifiers = getOwnPropertyIdentifiers;
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