Kotlin: multiple if let

multi_if_let.kt

// taken from Jayson Minard's answer to the 
// StackOverflow question "Multiple variable let in Kotlin" by Daniel Gomez Rico
// source: https://stackoverflow.com/a/35522422/3926619

// 2
inline fun <T1: Any, T2: Any, R: Any> multiIfLet(p1: T1?, p2: T2?, block: (T1, T2)->R?): R? {
  return if (p1 != null && p2 != null) block(p1, p2) else null
}
// 3
inline fun <T1: Any, T2: Any, T3: Any, R: Any> multiIfLet(p1: T1?, p2: T2?, p3: T3?, block: (T1, T2, T3)->R?): R? {
  return if (p1 != null && p2 != null && p3 != null) block(p1, p2, p3) else null
}
// 4
inline fun <T1: Any, T2: Any, T3: Any, T4: Any, R: Any> multiIfLet(p1: T1?, p2: T2?, p3: T3?, p4: T4?, block: (T1, T2, T3, T4)->R?): R? {
  return if (p1 != null && p2 != null && p3 != null && p4 != null) block(p1, p2, p3, p4) else null
}
// 5
inline fun <T1: Any, T2: Any, T3: Any, T4: Any, T5: Any, R: Any> multiIfLet(p1: T1?, p2: T2?, p3: T3?, p4: T4?, p5: T5?, block: (T1, T2, T3, T4, T5)->R?): R? {
  return if (p1 != null && p2 != null && p3 != null && p4 != null && p5 != null) block(p1, p2, p3, p4, p5) else null
}
// 6
inline fun <T1: Any, T2: Any, T3: Any, T4: Any, T5: Any, T6: Any, R: Any> multiIfLet(p1: T1?, p2: T2?, p3: T3?, p4: T4?, p5: T5?, p6: T6?, block: (T1, T2, T3, T4, T5, T6)->R?): R? {
  return if (p1 != null && p2 != null && p3 != null && p4 != null && p5 != null && p6 != null) block(p1, p2, p3, p4, p5, p6) else null
}

@Composable
override fun uiState(): StatisticsUIState {
  val ensembleCount by remember { ensembleRepository.getCountEnsembles () }.collectAsState(null)
  val articleCount by remember { articleRepository.getCountArticles() }.collectAsState(null)
  val articleImageCount by remember { articleRepository.getCountArticleImages() }.collectAsState(null)
  val mostPopularEnsembles by remember { ensembleRepository.getMostPopularEnsembles(TOP_ENSEMBLES_COUNT) }.collectAsState(null)
  val mostPopularArticleByImages by remember { articleRepository.getMostPopularArticlesImageCount(1) }.collectAsState(null)
  val mostPopularArticleByEnsembles by remember { ensembleRepository.getMostPopularArticlesEnsembleCount(1) }.collectAsState(null)

  val result = multiIfLet(ensembleCount, articleCount, articleImageCount, mostPopularEnsembles, mostPopularArticleByImages, mostPopularArticleByEnsembles){
    ensembleCount, articleCount, articleImageCount, mostPopularEnsembles, mostPopularArticleByImages, mostPopularArticleByEnsembles ->
    StatisticsUIState.Success(
      ensembleCount = ensembleCount,
      articleCount = articleCount,
      articleImageCount = articleImageCount,
      ensemblesWithMostArticles = mostPopularEnsembles,
      articleWithMostImagesUriStrings = mostPopularArticleByImages,
      articleWithMostEnsembles = mostPopularArticleByEnsembles,
    )
  } ?: StatisticsUIState.Loading
  return result
}