//
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// GroupedObservable.swift
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// RxSwift
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//
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// Created by Tomi Koskinen on 01/12/15.
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// Copyright © 2015 Krunoslav Zaher. All rights reserved.
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//
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/// Represents an observable sequence of elements that share a common key.
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/// `GroupedObservable` is typically created by the `groupBy` operator.
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/// Each `GroupedObservable` instance represents a collection of elements
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/// that are grouped by a specific key.
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///
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/// Example usage:
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/// ```
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/// let observable = Observable.of("Apple", "Banana", "Apricot", "Blueberry", "Avocado")
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///
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/// let grouped = observable.groupBy { fruit in
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/// fruit.first! // Grouping by the first letter of each fruit
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/// }
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///
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/// _ = grouped.subscribe { group in
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/// print("Group: \(group.key)")
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/// _ = group.subscribe { event in
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/// print(event)
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/// }
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/// }
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/// ```
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/// This will print:
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/// ```
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/// Group: A
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/// next(Apple)
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/// next(Apricot)
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/// next(Avocado)
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/// Group: B
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/// next(Banana)
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/// next(Blueberry)
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/// ```
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public struct GroupedObservable<Key, Element> : ObservableType {
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/// The key associated with this grouped observable sequence.
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/// All elements emitted by this observable share this common key.
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public let key: Key
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private let source: Observable<Element>
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/// Initializes a grouped observable sequence with a key and a source observable sequence.
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///
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/// - Parameters:
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/// - key: The key associated with this grouped observable sequence.
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/// - source: The observable sequence of elements for the specified key.
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///
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/// Example usage:
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/// ```
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/// let sourceObservable = Observable.of("Apple", "Apricot", "Avocado")
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/// let groupedObservable = GroupedObservable(key: "A", source: sourceObservable)
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///
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/// _ = groupedObservable.subscribe { event in
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/// print(event)
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/// }
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/// ```
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/// This will print:
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/// ```
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/// next(Apple)
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/// next(Apricot)
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/// next(Avocado)
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/// ```
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public init(key: Key, source: Observable<Element>) {
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self.key = key
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self.source = source
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}
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/// Subscribes an observer to receive events emitted by the source observable sequence.
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///
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/// - Parameter observer: The observer that will receive the events of the source observable.
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/// - Returns: A `Disposable` representing the subscription, which can be used to cancel the subscription.
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///
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/// Example usage:
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/// ```
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/// let fruitsObservable = Observable.of("Apple", "Banana", "Apricot", "Blueberry", "Avocado")
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/// let grouped = fruitsObservable.groupBy { $0.first! } // Group by first letter
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///
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/// _ = grouped.subscribe { group in
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/// if group.key == "A" {
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/// _ = group.subscribe { event in
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/// print(event)
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/// }
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/// }
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/// }
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/// ```
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/// This will print:
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/// ```
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/// next(Apple)
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/// next(Apricot)
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/// next(Avocado)
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/// ```
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public func subscribe<Observer: ObserverType>(_ observer: Observer) -> Disposable where Observer.Element == Element {
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self.source.subscribe(observer)
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}
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/// Converts this `GroupedObservable` into a regular `Observable` sequence.
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/// This allows you to work with the sequence without directly interacting with the key.
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///
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/// - Returns: The underlying `Observable` sequence of elements for the specified key.
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///
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/// Example usage:
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/// ```
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/// let fruitsObservable = Observable.of("Apple", "Banana", "Apricot", "Blueberry", "Avocado")
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/// let grouped = fruitsObservable.groupBy { $0.first! } // Group by first letter
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///
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/// _ = grouped.subscribe { group in
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/// if group.key == "A" {
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/// let regularObservable = group.asObservable()
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/// _ = regularObservable.subscribe { event in
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/// print(event)
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/// }
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/// }
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/// }
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/// ```
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/// This will print:
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/// ```
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/// next(Apple)
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/// next(Apricot)
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/// next(Avocado)
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/// ```
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public func asObservable() -> Observable<Element> {
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self.source
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}
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}
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