transformWhile

Applies transform function to each value of the given flow while this function returns true.

The receiver of the transformWhile is FlowCollector and thus transformWhile is a flexible function that may transform emitted element, skip it or emit it multiple times.

This operator generalizes takeWhile and can be used as a building block for other operators. For example, a flow of download progress messages can be completed when the download is done but emit this last message (unlike takeWhile):

fun Flow<DownloadProgress>.completeWhenDone(): Flow<DownloadProgress> =
    transformWhile { progress ->
        emit(progress) // always emit progress
        !progress.isDone() // continue while download is not done
    }