Created
October 15, 2019 18:30
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package com.kondenko.pocketwaka.utils | |
import io.reactivex.Observable | |
import io.reactivex.ObservableOperator | |
import io.reactivex.Observer | |
import io.reactivex.disposables.Disposable | |
fun <T, R> Observable<T>.scanMap(initialValue: T? = null, scanMap: (T, T) -> R): Observable<R> = | |
lift(ScanMap(initialValue, scanMap)) | |
class ScanMap<T, R>(private val initialValue: T? = null, private val scanMap: (T, T) -> R) : ObservableOperator<R, T> { | |
override fun apply(observer: Observer<in R>): Observer<in T> = ActualObserver(observer) | |
private inner class ActualObserver(private val observer: Observer<in R>) : Observer<T> { | |
private var previousValue: T? = initialValue | |
override fun onNext(next: T) { | |
previousValue?.let { prev -> observer.onNext(scanMap(prev, next)) } | |
previousValue = next | |
} | |
override fun onComplete() = observer.onComplete() | |
override fun onSubscribe(d: Disposable) = observer.onSubscribe(d) | |
override fun onError(e: Throwable) = observer.onError(e) | |
} | |
} |
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