realm-js/docs/collection.js

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// Copyright 2016 Realm Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
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// http://www.apache.org/licenses/LICENSE-2.0
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/**
 * Abstract base class containing methods shared by {@link Realm.List} and {@link Realm.Results}.
 *
 * A Realm Collection is a homogenous sequence of values of any of the types
 * that can be stored as properties of Realm objects. A collection can be
 * accessed in any of the ways that a normal Javascript Array can, including
 * subscripting, enumerating with `for-of` and so on.
 *
 * A Collection always reflect the current state of the Realm. The one exception to this is
 * when using `for...in` or `for...of` enumeration, which will always enumerate over the
 * objects which matched the query when the enumeration is begun, even if some of them are
 * deleted or modified to be excluded by the filter during the enumeration.
 *
 * @memberof Realm
 * @since 0.11.0
 */
class Collection {
    /**
     * The number of values in the collection.
     * @type {number}
     * @readonly
     */
    get length() {}

    /**
     * The {@linkplain Realm~PropertyType type} of values in the collection.
     * @type {string}
     * @readonly
     * @since 2.0.0
     */
    get type() {}

    /**
     * Whether `null` is a valid value for the collection.
     * @type {boolean}
     * @readonly
     * @since 2.0.0
     */
    get optional() {}

    /**
     * Checks if this collection has not been deleted and is part of a valid Realm.
     * @returns {boolean} indicating if the collection can be safely accessed.
     * @since 0.14.0
     */
    isValid() {}

    /**
     * Returns new _Results_ that represent this collection being filtered by the provided query.
     *
     * @param {string} query - Query used to filter objects from the collection.
     * @param {...any} [arg] - Each subsequent argument is used by the placeholders
     *   (e.g. `$0`, `$1`, `$2`, …) in the query.
     * @throws {Error} If the query or any other argument passed into this method is invalid.
     * @returns {Realm.Results<T>} filtered according to the provided query.
     *
     * This is currently only supported for collections of Realm Objects.
     *
     * See {@tutorial query-language} for details about the query language.
     * @example
     * let merlots = wines.filtered('variety == "Merlot" && vintage <= $0', maxYear);
     */
    filtered(query, ...arg) {}

    /**
     * Returns new _Results_ that represent a sorted view of this collection.
     *
     * A collection of Realm Objects can be sorted on one or more properties of
     * those objects, or of properties of objects linked to by those objects.
     * To sort by a single property, simply pass the name of that property to
     * `sorted()`, optionally followed by a boolean indicating if the sort should be reversed.
     * For more than one property, you must pass an array of
     * {@linkplain Realm.Collection~SortDescriptor sort descriptors} which list
     * which properties to sort on.
     *
     * Collections of other types sort on the values themselves rather than
     * properties of the values, and so no property name or sort descriptors
     * should be supplied.
     *
     * @example
     * // Sort wines by age
     * wines.sorted('age')
     * @example
     * // Sort wines by price in descending order, then sort ties by age in
     * // ascending order
     * wines.sorted([['price', false], ['age'])
     * @example
     * // Sort a list of numbers in ascending order
     * let sortedPrices = wine.pricesSeen.sort()
     * @example
     * // Sort people by how expensive their favorite wine is
     * people.sort("favoriteWine.price")
     *
     * @param {string|Realm.Collection~SortDescriptor[]} [descriptor] - The property name(s) to sort the collection on.
     * @param {boolean} [reverse=false] - Sort in descending order rather than ascended.
     *   May not be supplied if `descriptor` is an array of sort descriptors.
     * @throws {Error} If a specified property does not exist.
     * @returns {Realm.Results<T>} sorted according to the arguments passed in.
     */
    sorted(descriptor, reverse) {}

    /**
     * Create a frozen snapshot of the collection.
     *
     * Values added to and removed from the original collection will not be
     * reflected in the _Results_ returned by this method, including if the
     * values of properties are changed to make them match or not match any
     * filters applied.
     *
     * This is **not** a _deep_ snapshot. Realm objects contained in this
     * snapshot will continue to update as changes are made to them, and if
     * they are deleted from the Realm they will be replaced by `null` at the
     * respective indices.
     *
     * @returns {Realm.Results<T>} which will **not** live update.
     */
    snapshot() {}

    /**
     * Subscribe to a subset of objects matching the query of the collection. The Realm will only be
     * partially synced. Not all queries are currently supported. Once subscribed, it is highly recommended
     * to add a listener.
     *
     * @example
     * let wines = realm.objects('Wine').filtered('vintage <= $0', maxYear).subscribe();
     * wines.addListener((collection, changes) => {
     *     if (changes.partial_sync.new_state == Realm.Sync.SubscriptionState.Initialized) {
     *         // update UI
     *     }
     * });
     *
     * @param {string} subscriptionName - an optional name for the subscription.
     * @returns {Realm.Sync.Subscription} - the Realm.Sync.Subscription instance.
     * @throws {Error} if the partial sync is not enabled in the configuration or the query is not supported by Realm Object Server.
     * @since 2.3.0
     */
    subscribe(subscriptionName) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/entries Array.prototype.entries}
     * @returns {Realm.Collection~Iterator<T>} of each `[index, object]` pair in the collection
     * @since 0.11.0
     */
    entries() {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/keys Array.prototype.keys}
     * @returns {Realm.Collection~Iterator<T>} of each index in the collection
     * @since 0.11.0
     */
    keys() {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/values Array.prototype.values}
     * @returns {Realm.Collection~Iterator<T>} of each Realm object in the collection
     * @since 0.11.0
     */
    values() {}

    /**
     * This is the same method as the {@link Realm.Collection#values values()} method.
     * Its presence makes collections _iterable_, thus able to be used with ES6
     * {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of `for-of`}
     * loops,
     * {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator `...`}
     * spread operators, and more.
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol/iterator Symbol.iterator}
     *   and the {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#iterable iterable protocol}
     * @returns {Realm.Collection~Iterator<T>} of each Realm object in the collection
     * @since 0.11.0
     * @example
     * for (let object of collection) {
     *   // do something with each object
     * }
     */
    [Symbol.iterator]() {}

    /**
     * Joins all objects in the collection into a string.
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/join Array.prototype.join}
     * @param {string} [separator=","] - A string to separate the return values of the
     *   `toString()` method being called on each object in the collection.
     * @returns {string}
     * @since 0.11.0
     */
    join(separator) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice Array.prototype.slice}
     * @param {number} [start=0] - The start index. If negative, then the start index will be
     *   counted from the end of the collection.
     * @param {number} [end] - The end index. The objects up to, but not including, the end
     *   index will be include in the return value. If negative, then the end index will be
     *   counted from the end of the collection. If omitted, then all objects from the start
     *   index will be included in the return value.
     * @returns {T[]} containing the objects from the start index up to, but not
     *   including, the end index.
     * @since 0.11.0
     */
    slice(start, end) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find Array.prototype.find}
     * @param {function} callback - Function to execute on each object in the collection.
     *   If this function returns `true`, then that object will be returned by this method.
     *   This function takes three arguments:
     *   - `object` – The current object being processed in the collection.
     *   - `index` – The index of the object being processed in the collection.
     *   - `collection` – The collection itself.
     * @param {object} [thisArg] - The value of `this` when `callback` is called.
     * @returns {T|undefined} if the `callback` did not return `true` for any object
     *   in the collection.
     * @since 0.11.0
     */
    find(callback, thisArg) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex Array.prototype.findIndex}
     * @param {function} callback - Function to execute on each object in the collection.
     *   If this function returns `true`, then the index of that object will be returned
     *   by this method. This function takes three arguments:
     *   - `object` – The current object being processed in the collection.
     *   - `index` – The index of the object being processed in the collection.
     *   - `collection` – The collection itself.
     * @param {object} [thisArg] - The value of `this` when `callback` is called.
     * @returns {number} representing the index where the `callback` returned `true`, or `-1`
     *   if `true` was never returned.
     * @since 0.11.0
     */
    findIndex(callback, thisArg) {}

   /**
    Finds the index of the given object in the collection.
    * @param {T} object - The value to search for in the collection.
    * @throws {Error} If the argument is a {@link Realm.Object} that does not
    *                 belong to the same Realm as the collection.
    * @returns {number} representing the index where the value was found, or
    *          `-1` if not in collection.
    * @since 1.8.2
    */
   indexOf(object) {}

    /**
     * Returns the minimum value of the values in the collection or of the
     * given property among all the objects in the collection, or `undefined`
     * if the collection is empty.
     *
     * Only supported for int, float, double and date properties. `null` values
     * are ignored entirely by this method and will not be returned.
     *
     * @param {string} [property] - For a collection of objects, the property to take the minimum of.
     * @throws {Error} If no property with the name exists or if property is not numeric/date.
     * @returns {number} the minimum value.
     * @since 1.12.1
     */
    min(property) {}

    /**
     * Returns the maximum value of the values in the collection or of the
     * given property among all the objects in the collection, or `undefined`
     * if the collection is empty.
     *
     * Only supported for int, float, double and date properties. `null` values
     * are ignored entirely by this method and will not be returned.
     *
     * @param {string} [property] - For a collection of objects, the property to take the maximum of.
     * @throws {Error} If no property with the name exists or if property is not numeric/date.
     * @returns {number} the maximum value.
     * @since 1.12.1
     */
    max(property) {}

    /**
     * Computes the sum of the values in the collection or of the given
     * property among all the objects in the collection, or 0 if the collection
     * is empty.
     *
     * Only supported for int, float and double properties. `null` values are
     * ignored entirely by this method.
     * @param {string} [property] - For a collection of objects, the property to take the sum of.
     * @throws {Error} If no property with the name exists or if property is not numeric.
     * @returns {number} the sum.
     * @since 1.12.1
     */
    sum(property) {}

    /**
     * Computes the average of the values in the collection or of the given
     * property among all the objects in the collection, or `undefined` if the collection
     * is empty.
     *
     * Only supported for int, float and double properties. `null` values are
     * ignored entirely by this method and will not be factored into the average.
     * @param {string} [property] - For a collection of objects, the property to take the average of.
     * @throws {Error} If no property with the name exists or if property is not numeric.
     * @returns {number} the sum.
     * @since 1.12.1
     */
    avg(property) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach Array.prototype.forEach}
     * @param {function} callback - Function to execute on each object in the collection.
     *   This function takes three arguments:
     *   - `object` – The current object being processed in the collection.
     *   - `index` – The index of the object being processed in the collection.
     *   - `collection` – The collection itself.
     * @param {object} [thisArg] - The value of `this` when `callback` is called.
     * @since 0.11.0
     */
    forEach(callback, thisArg) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every Array.prototype.every}
     * @param {function} callback - Function to execute on each object in the collection.
     *   If this function returns `true` for every object, then this method will return `true`.
     *   This function takes three arguments:
     *   - `object` – The current object being processed in the collection.
     *   - `index` – The index of the object being processed in the collection.
     *   - `collection` – The collection itself.
     * @param {object} [thisArg] - The value of `this` when `callback` is called.
     * @returns {boolean} representing if `callback` returned `true` for every object in the
     *   collection.
     * @since 0.11.0
     */
    every(callback, thisArg) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some Array.prototype.some}
     * @param {function} callback - Function to execute on each object in the collection.
     *   If this function ever returns `true`, then this method will return `true`.
     *   This function takes three arguments:
     *   - `object` – The current object being processed in the collection.
     *   - `index` – The index of the object being processed in the collection.
     *   - `collection` – The collection itself.
     * @param {object} [thisArg] - The value of `this` when `callback` is called.
     * @returns {boolean} – `true` when `callback` returns `true` for an object in the collection,
     *   otherwise `false`.
     * @since 0.11.0
     */
    some(callback, thisArg) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map Array.prototype.map}
     * @param {function} callback - Function to execute on each object in the collection.
     *   This function takes three arguments:
     *   - `object` – The current object being processed in the collection.
     *   - `index` – The index of the object being processed in the collection.
     *   - `collection` – The collection itself.
     * @param {object} [thisArg] - The value of `this` when `callback` is called.
     * @returns {any[]} – the return values of `callback` after being called on every object
     *   in the collection.
     * @since 0.11.0
     */
    map(callback, thisArg) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduce Array.prototype.reduce}
     * @param {function} callback - Function to execute on each object in the collection.
     *   This function takes four arguments:
     *   - `previousValue` – The value previously returned in the last invocation of the callback,
     *     or `initialValue`, if supplied.
     *   - `object` – The current object being processed in the collection.
     *   - `index` – The index of the object being processed in the collection.
     *   - `collection` – The collection itself.
     * @param {object} [initialValue] - The value to use as the first argument to the first call
     *   of the `callback`.
     * @throws {TypeError} If the collection is empty and no `initialValue` was supplied.
     * @returns {any} – the value returned by the final invocation of `callback`, _except_ for
     *   the following special cases:
     *   - If collection consists of a single object, and no `initalValue` was supplied, then
     *     that object will be returned.
     *   - If the collection is empty, then `initialValue` _must_ be supplied and will be returned.
     * @since 0.11.0
     */
    reduce(callback, initialValue) {}

    /**
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/reduceRight Array.prototype.reduceRight}
     * @param {function} callback - Function to execute on each object, from **right to left**,
     *   in the collection. This function takes four arguments:
     *   - `previousValue` – The value previously returned in the last invocation of the callback,
     *     or `initialValue`, if supplied.
     *   - `object` – The current object being processed in the collection.
     *   - `index` – The index of the object being processed in the collection.
     *   - `collection` – The collection itself.
     * @param {object} [initialValue] - The value to use as the first argument to the first call
     *   of the `callback`.
     * @throws {TypeError} If the collection is empty and no `initialValue` was supplied.
     * @returns {any} – the value returned by the final invocation of `callback`, _except_ for
     *   the following special cases:
     *   - If collection consists of a single object, and no `initalValue` was supplied, then
     *     that object will be returned.
     *   - If the collection is empty, then `initialValue` _must_ be supplied and will be returned.
     * @since 0.11.0
     */
    reduceRight(callback, initialValue) {}

    /**
     * Add a listener `callback` which will be called when a **live** collection instance changes.
     * @param {function(collection, changes)} callback - A function to be called when changes occur.
     *   The callback function is called with two arguments:
     *   - `collection`: the collection instance that changed,
     *   - `changes`: a dictionary with keys `insertions`, `modifications` and `deletions`,
     *      each containing a list of indices that were inserted, updated or deleted respectively. If
     *      partial sync is enabled, an additional key `partial_sync` is added.
     *   - `changes.partial_sync`: `error` indicates if an error has occurred, `old_state` is the previous
     *      state, and `new_state` is the current state.
     * @throws {Error} If `callback` is not a function.
     * @example
     * wines.addListener((collection, changes) => {
     *  // collection === wines
     *  if (changes.partial_sync.new_state == Realm.Sync.SubscriptionState.Initialized) {
     *     console.log('Our subset is ready');
     *     console.log(`${changes.insertions.length} insertions`);
     *     console.log(`${changes.modifications.length} modifications`);
     *     console.log(`${changes.deletions.length} deletions`);
     *     console.log(`new size of collection: ${collection.length}`);
     *   }
     * });
     */
    addListener(callback) {}

    /**
     * Remove the listener `callback` from the collection instance.
     * @param {function(collection, changes)} callback - Callback function that was previously
     *   added as a listener through the {@link Collection#addListener addListener} method.
     * @throws {Error} If `callback` is not a function.
     */
    removeListener(callback) {}

    /**
     * Remove all `callback` listeners from the collection instance.
     */
    removeAllListeners(name) {}

}

/**
 * This is an ES6 iterator.
 * @typedef Realm.Collection~Iterator
 * @property {function} next - Returns an object with two properties:
 *   - `done` – `true` if the iterator is done iterating through items in the collection,
 *     otherwise `false`
 *   - `value` – the next item being iterated through in the collection, or `undefined` when
 *     `done` is `true`
 * @property {function} Symbol.iterator - This method simply returns `this`, thus making this
 *   iterator itself _iterable_ (i.e. usable in
 *   {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of `for-of`}
 *   loops, with the
 *   {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_operator `...`}
 *   spread operator, and more).
 * @see {@link https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#iterator iterator protocol}
 */

/**
 * A sort descriptor is either a string containing one or more property names
 * separate by dots, **or** an array with two items: `[propertyName, reverse]`.
 *
 * @typedef Realm.Collection~SortDescriptor
 * @type {string|Array}
 */