105 lines
2.9 KiB
JavaScript
105 lines
2.9 KiB
JavaScript
// Copyright IBM Corp. 2011,2018. All Rights Reserved.
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// Node module: loopback-datasource-juggler
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// This file is licensed under the MIT License.
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// License text available at https://opensource.org/licenses/MIT
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'use strict';
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const util = require('util');
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/**
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*
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* @param newClass
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* @param baseClass
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*/
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exports.inherits = function(newClass, baseClass, options) {
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util.inherits(newClass, baseClass);
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options = options || {
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staticProperties: true,
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override: false,
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};
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if (options.staticProperties) {
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Object.keys(baseClass).forEach(function(classProp) {
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if (classProp !== 'super_' && (!newClass.hasOwnProperty(classProp) ||
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options.override)) {
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const pd = Object.getOwnPropertyDescriptor(baseClass, classProp);
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Object.defineProperty(newClass, classProp, pd);
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}
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});
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}
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};
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/**
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* Mix in the a class into the new class
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* @param newClass The target class to receive the mixin
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* @param mixinClass The class to be mixed in
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* @param options
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*/
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exports.mixin = function(newClass, mixinClass, options) {
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if (Array.isArray(newClass._mixins)) {
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if (newClass._mixins.indexOf(mixinClass) !== -1) {
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return;
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}
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newClass._mixins.push(mixinClass);
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} else {
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newClass._mixins = [mixinClass];
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}
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options = options || {
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staticProperties: true,
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instanceProperties: true,
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override: false,
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proxyFunctions: false,
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};
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if (options.staticProperties === undefined) {
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options.staticProperties = true;
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}
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if (options.instanceProperties === undefined) {
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options.instanceProperties = true;
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}
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if (options.staticProperties) {
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mixInto(mixinClass, newClass, options);
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}
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if (options.instanceProperties && mixinClass.prototype) {
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mixInto(mixinClass.prototype, newClass.prototype, options);
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}
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return newClass;
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};
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function mixInto(sourceScope, targetScope, options) {
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Object.keys(sourceScope).forEach(function(propertyName) {
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const targetPropertyExists = targetScope.hasOwnProperty(propertyName);
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const sourceProperty = Object.getOwnPropertyDescriptor(sourceScope, propertyName);
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const targetProperty = targetPropertyExists && Object.getOwnPropertyDescriptor(targetScope, propertyName);
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const sourceIsFunc = typeof sourceProperty.value === 'function';
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const isFunc = targetPropertyExists && typeof targetProperty.value === 'function';
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const isDelegate = isFunc && targetProperty.value._delegate;
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const shouldOverride = options.override || !targetPropertyExists || isDelegate;
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if (propertyName == '_mixins') {
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mergeMixins(sourceScope._mixins, targetScope._mixins);
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return;
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}
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if (shouldOverride) {
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Object.defineProperty(targetScope, propertyName, sourceProperty);
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}
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});
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}
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function mergeMixins(source, target) {
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// hand-written equivalent of lodash.union()
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for (const ix in source) {
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const mx = source[ix];
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if (target.indexOf(mx) === -1)
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target.push(mx);
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}
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}
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