import _ from 'lodash'; /** * Sets specific properties of a specific state to specific values and prevents * unnecessary state changes. * * @param {Object} target - The state on which the specified properties are to * be set. * @param {Object} source - The map of properties to values which are to be set * on the specified target. * @returns {Object} The specified target if the values of the specified * properties equal the specified values; otherwise, a new state constructed * from the specified target by setting the specified properties to the * specified values. */ export function assign(target, source) { let t = target; for (const property in source) { // eslint-disable-line guard-for-in t = set(t, property, source[property], t === target); } return t; } /** * Determines whether {@code a} equals {@code b} according to deep comparison * (which makes sense for Redux and its state definition). * * @param {*} a - The value to compare to {@code b}. * @param {*} b - The value to compare to {@code a}. * @returns {boolean} True if {@code a} equals {@code b} (according to deep * comparison); false, otherwise. */ export function equals(a, b) { return _.isEqual(a, b); } /** * Sets a specific property of a specific state to a specific value. Prevents * unnecessary state changes (when the specified value is equal to the * value of the specified property of the specified state). * * @param {Object} state - The (Redux) state from which a new state is to be * constructed by setting the specified property to the specified * value. * @param {string} property - The property of state which is to be * assigned the specified value (in the new state). * @param {*} value - The value to assign to the specified property. * @returns {Object} The specified state if the value of the specified * property equals the specified value/tt>; otherwise, a new state * constructed from the specified state by setting the specified * property to the specified value. */ export function set(state, property, value) { return _set(state, property, value, /* copyOnWrite */ true); } /* eslint-disable max-params */ /** * Sets a specific property of a specific state to a specific value. Prevents * unnecessary state changes (when the specified value is equal to the * value of the specified property of the specified state). * * @param {Object} state - The (Redux) state from which a state is to be * constructed by setting the specified property to the specified * value. * @param {string} property - The property of state which is to be * assigned the specified value. * @param {*} value - The value to assign to the specified property. * @param {boolean} copyOnWrite - If the specified state is to not be * modified, true; otherwise, false. * @returns {Object} The specified state if the value of the specified * property equals the specified value/tt> or copyOnWrite * is truthy; otherwise, a new state constructed from the specified * state by setting the specified property to the specified * value. */ function _set(state, property, value, copyOnWrite) { // Delete state properties that are to be set to undefined. (It is a matter // of personal preference, mostly.) if (typeof value === 'undefined' && Object.prototype.hasOwnProperty.call(state, property)) { const newState = copyOnWrite ? { ...state } : state; if (delete newState[property]) { return newState; } } if (state[property] !== value) { if (copyOnWrite) { return { ...state, [property]: value }; } state[property] = value; } return state; } /* eslint-enable max-params */