[AA] Extract SublistMerger to analysis-api-providers utils

- This utility is useful for other places where sublists need to be merged.
2023-05-17 15:25:21 +02:00
parent 2540343159
commit 52f025f39b
2 changed files with 49 additions and 22 deletions
@@ -0,0 +1,47 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.analysis.providers.impl.util
+
+import org.jetbrains.kotlin.utils.addIfNotNull
+import org.jetbrains.kotlin.utils.addToStdlib.partitionIsInstance
+
+/**
+ * With each call to [merge], [SublistMerger] can merge all elements of a specific (reified) type into a single element using a supplied
+ * constructor and then add it to [destination]. Unmerged elements are added to [destination] using [finish].
+ *
+ * The purpose of [SublistMerger] is to merge multiple different types of elements from a single origin list without the need for
+ * intermediate list management and [partitionIsInstance] boilerplate.
+ */
+public class SublistMerger<A : Any>(
+    initialElements: List<A>,
+    public val destination: MutableList<A>,
+) {
+    public var remainingElements: List<A> = initialElements
+
+    public inline fun <reified R : A> merge(create: (List<R>) -> A?) {
+        val (specificElements, remainingElements) = this.remainingElements.partitionIsInstance<_, R>()
+        destination.addIfNotNull(create(specificElements))
+        this.remainingElements = remainingElements
+    }
+
+    public fun finish() {
+        destination.addAll(remainingElements)
+        remainingElements = emptyList()
+    }
+}
+
+public fun <A : Any> List<A>.mergeInto(destination: MutableList<A>, f: SublistMerger<A>.() -> Unit) {
+    SublistMerger(this, destination).apply {
+        f()
+        finish()
+    }
+}
+
+public fun <A : Any> List<A>.mergeWith(f: SublistMerger<A>.() -> Unit): List<A> =
+    mutableListOf<A>().also { destination -> mergeInto(destination, f) }
+
+public inline fun <A : Any, reified R : A> List<A>.mergeOnly(crossinline create: (List<R>) -> A?): List<A> =
+    mergeWith { merge<R>(create) }