utils.ts

/*
 * Licensed to Elasticsearch B.V. under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import { Stringified } from '@spec_utils/Stringified'

/**
 * A `null` value that is to be interpreted as an actual value, unless other uses of `null` that are equivalent
 * to a missing value. It is used for exemple in settings, where using the `NullValue` for a setting will reset
 * it to its default value.
 */
export type NullValue = null

/**
 * `WithNullValue<T>` allows for explicit null assignments in contexts where `null` should be interpreted as an
 * actual value.
 */
export type WithNullValue<T> = T | NullValue

/**
 * Settings in Elasticsearch are values that can be reset to their default by setting them to the `null` value.
 *
 * @es_quirk Because of how they are implemented internally, settings are always returned as strings, even
 *           if their value has been set using a primitive type.
 */
export type Setting<T> = WithNullValue<Stringified<T>>