add zipby

FunkyMuse · Oct 5, 2021 · 736b51b · 736b51b
1 parent e3bf7bf
commit 736b51b
Showing 1 changed file with 26 additions and 0 deletions.
diff --git a/collections/src/main/java/com/crazylegend/collections/CollectionsExtensions5.kt b/collections/src/main/java/com/crazylegend/collections/CollectionsExtensions5.kt
@@ -0,0 +1,26 @@
+package com.crazylegend.collections
+import kotlin.collections.associateBy
+
+/**
+ * Created by Hristijan, date 10/5/21
+ */
+fun <FIRST_LIST_TYPE, SECOND_LIST_TYPE, FIRST_LIST_TRANSFORMER, SECOND_LIST_TRANSFORMER, RETURN_TYPE>
+        Iterable<FIRST_LIST_TYPE>.zipBy(
+    other: Iterable<SECOND_LIST_TYPE>,
+    firstListTransformer: (FIRST_LIST_TYPE) -> FIRST_LIST_TRANSFORMER,
+    secondListTransformer: (SECOND_LIST_TYPE) -> SECOND_LIST_TRANSFORMER,
+    pairPredicate: (first: FIRST_LIST_TYPE?, second: SECOND_LIST_TYPE?) -> RETURN_TYPE?
+): List<RETURN_TYPE> {
+    val firstByKey: Map<FIRST_LIST_TRANSFORMER, FIRST_LIST_TYPE> = associateBy {
+        firstListTransformer(it)
+    }
+    val secondByKey: Map<SECOND_LIST_TRANSFORMER, SECOND_LIST_TYPE> = other.associateBy {
+        secondListTransformer(it)
+    }
+    val resultList = (firstByKey.keys + secondByKey.keys).map { (firstByKey[it]) to (secondByKey[it]) }
+    return resultList.asSequence().mapNotNull {
+        val firstPair = it.first
+        val secondPair = it.second
+        pairPredicate(firstPair, secondPair)
+    }.toList()
+}