BiSourceMergerLiveData.kt

import androidx.lifecycle.LiveData
import androidx.lifecycle.MediatorLiveData

class BiSourceMergerLiveData<T, U, R>(
    source1: LiveData<T>,
    source2: LiveData<U>,
    block: (T?, U?) -> R?

) : MediatorLiveData<R>() {

    init {
        addSource(source1) {
            block(it, source2.value)
                ?.run { value = this }
        }

        addSource(source2) {
            block(source1.value, it)
                ?.run { value = this }
        }
    }
}