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79 lines
2.4 KiB
79 lines
2.4 KiB
3 years ago
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'use strict';
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const Assert = require('./assert');
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const Clone = require('./clone');
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const Utils = require('./utils');
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const internals = {};
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module.exports = internals.merge = function (target, source, options) {
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Assert(target && typeof target === 'object', 'Invalid target value: must be an object');
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Assert(source === null || source === undefined || typeof source === 'object', 'Invalid source value: must be null, undefined, or an object');
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if (!source) {
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return target;
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}
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options = Object.assign({ nullOverride: true, mergeArrays: true }, options);
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if (Array.isArray(source)) {
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Assert(Array.isArray(target), 'Cannot merge array onto an object');
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if (!options.mergeArrays) {
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target.length = 0; // Must not change target assignment
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}
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for (let i = 0; i < source.length; ++i) {
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target.push(Clone(source[i], { symbols: options.symbols }));
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}
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return target;
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}
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const keys = Utils.keys(source, options);
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for (let i = 0; i < keys.length; ++i) {
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const key = keys[i];
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if (key === '__proto__' ||
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!Object.prototype.propertyIsEnumerable.call(source, key)) {
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continue;
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}
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const value = source[key];
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if (value &&
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typeof value === 'object') {
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if (target[key] === value) {
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continue; // Can occur for shallow merges
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}
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if (!target[key] ||
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typeof target[key] !== 'object' ||
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(Array.isArray(target[key]) !== Array.isArray(value)) ||
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value instanceof Date ||
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(Buffer && Buffer.isBuffer(value)) || // $lab:coverage:ignore$
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value instanceof RegExp) {
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target[key] = Clone(value, { symbols: options.symbols });
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}
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else {
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internals.merge(target[key], value, options);
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}
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}
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else {
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if (value !== null &&
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value !== undefined) { // Explicit to preserve empty strings
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target[key] = value;
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}
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else if (options.nullOverride) {
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target[key] = value;
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}
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}
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}
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return target;
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};
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