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a83e397643
We move the memoize function to `lib/shared/utils.js` and expose it to modules across the project. Change-Type: patch Changelog-Entry: Move memoize function to shared utils.
140 lines
3.4 KiB
JavaScript
140 lines
3.4 KiB
JavaScript
/*
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* Copyright 2017 resin.io
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict'
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const _ = require('lodash')
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const errors = require('./errors')
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/**
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* @summary Minimum percentage value
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* @constant
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* @public
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* @type {Number}
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*/
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exports.PERCENTAGE_MINIMUM = 0
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/**
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* @summary Maximum percentage value
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* @constant
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* @public
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* @type {Number}
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*/
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exports.PERCENTAGE_MAXIMUM = 100
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/**
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* @summary Check if a percentage is valid
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* @function
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* @public
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*
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* @param {Number} percentage - percentage
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* @returns {Boolean} whether the percentage is valid
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*
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* @example
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* if (utils.isValidPercentage(85)) {
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* console.log('The percentage is valid');
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* }
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*/
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exports.isValidPercentage = (percentage) => {
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return _.every([
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_.isNumber(percentage),
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percentage >= exports.PERCENTAGE_MINIMUM,
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percentage <= exports.PERCENTAGE_MAXIMUM
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])
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}
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/**
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* @summary Convert a percentage to a float
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* @function
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* @public
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*
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* @param {Number} percentage - percentage
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* @returns {Number} float percentage
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*
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* @example
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* const value = utils.percentageToFloat(50);
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* console.log(value);
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* > 0.5
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*/
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exports.percentageToFloat = (percentage) => {
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if (!exports.isValidPercentage(percentage)) {
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throw errors.createError({
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title: `Invalid percentage: ${percentage}`
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})
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}
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return percentage / exports.PERCENTAGE_MAXIMUM
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}
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/**
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* @summary Memoize a function
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* @function
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* @private
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*
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* @description
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* This workaround is needed to avoid AngularJS from getting
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* caught in an infinite digest loop when using `ngRepeat`
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* over a function that returns a mutable version of an
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* ImmutableJS object.
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*
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* The problem is that every time you call `myImmutableObject.toJS()`
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* you will get a new object, whose reference is different from
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* the one you previously got, even if the data is exactly the same.
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*
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* @param {Function} func - function that returns an ImmutableJS list
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* @param {Function} comparer - function to compare old and new args and state
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* @returns {Function} memoized function
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*
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* @example
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* const getList = () => {
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* return Store.getState().toJS().myList;
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* };
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*
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* const memoizedFunction = memoize(getList, angular.equals);
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*/
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exports.memoize = (func, comparer) => {
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let previousTuples = []
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return (...restArgs) => {
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let areArgsInTuple = false
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let state = Reflect.apply(func, this, restArgs)
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previousTuples = _.map(previousTuples, ([ oldArgs, oldState ]) => {
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if (comparer(oldArgs, restArgs)) {
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areArgsInTuple = true
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if (comparer(state, oldState)) {
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// Use the previously memoized state for this argument
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state = oldState
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}
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// Update the tuple state
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return [ oldArgs, state ]
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}
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// Return the tuple unchanged
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return [ oldArgs, oldState ]
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})
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// Add the state associated with these args to be memoized
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if (!areArgsInTuple) {
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previousTuples.push([ restArgs, state ])
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}
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return state
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}
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}
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