diff options
| author | Linnea Gräf <nea@nea.moe> | 2025-01-29 00:26:56 +0100 |
|---|---|---|
| committer | Linnea Gräf <nea@nea.moe> | 2025-01-29 00:26:56 +0100 |
| commit | 29857bff0875c43e055e89d34bc0d616d5d7dc4f (patch) | |
| tree | 5875aed4144c0c1f004a86f6768eb5d6013d68f6 /src/main/kotlin/util/iterutil.kt | |
| parent | ad03f074c603f38f9319411d785e598e8a92e42c (diff) | |
| download | ultra-notifier-master.tar.gz ultra-notifier-master.tar.bz2 ultra-notifier-master.zip | |
Diffstat (limited to 'src/main/kotlin/util/iterutil.kt')
| -rw-r--r-- | src/main/kotlin/util/iterutil.kt | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/src/main/kotlin/util/iterutil.kt b/src/main/kotlin/util/iterutil.kt new file mode 100644 index 0000000..7845b05 --- /dev/null +++ b/src/main/kotlin/util/iterutil.kt @@ -0,0 +1,36 @@ +package moe.nea.ultranotifier.util + + +fun <T, K : Any> Sequence<T>.duplicatesBy(keyFunc: (T) -> K): Sequence<T> { + return object : Sequence<T> { + override fun iterator(): Iterator<T> { + val observed = HashSet<K>() + val oldIterator = this@duplicatesBy.iterator() + + return object : Iterator<T> { + var next: T? = null + var hasNext = false + override fun hasNext(): Boolean { + if (hasNext) return true + while (oldIterator.hasNext()) { + val elem = oldIterator.next() + val key = keyFunc(elem) + if (observed.add(key)) + continue + hasNext = true + next = elem + } + return hasNext + } + + override fun next(): T { + if (!hasNext()) throw NoSuchElementException() + hasNext = false + val elem = next as T + next = null + return elem + } + } + } + } +} |