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'use strict';
const Assert = require('./assert'); const Clone = require('./clone'); const Merge = require('./merge'); const Utils = require('./utils');
const internals = {};
module.exports = function (defaults, source, options = {}) {
Assert(defaults && typeof defaults === 'object', 'Invalid defaults value: must be an object'); Assert(!source || source === true || typeof source === 'object', 'Invalid source value: must be true, falsy or an object'); Assert(typeof options === 'object', 'Invalid options: must be an object');
if (!source) { // If no source, return null
return null; }
if (options.shallow) { return internals.applyToDefaultsWithShallow(defaults, source, options); }
const copy = Clone(defaults);
if (source === true) { // If source is set to true, use defaults
return copy; }
const nullOverride = options.nullOverride !== undefined ? options.nullOverride : false; return Merge(copy, source, { nullOverride, mergeArrays: false }); };
internals.applyToDefaultsWithShallow = function (defaults, source, options) {
const keys = options.shallow; Assert(Array.isArray(keys), 'Invalid keys');
options = Object.assign({}, options); options.shallow = false;
const copy = Clone(defaults, { shallow: keys });
if (source === true) { // If source is set to true, use defaults
return copy; }
const storage = Utils.store(source, keys); // Move shallow copy items to storage
Merge(copy, source, { mergeArrays: false, nullOverride: false }); // Deep copy the rest
Utils.restore(copy, source, storage); // Shallow copy the stored items and restore
return copy; };
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