Added collectFirst to Chain and NonEmptyChain

typelevel · Apr 17, 2019 · 92fc8b3 · 92fc8b3
1 parent 65bee09
commit 92fc8b3
Show file tree

Hide file tree

Showing 2 changed files with 23 additions and 0 deletions.
diff --git a/core/src/main/scala/cats/data/Chain.scala b/core/src/main/scala/cats/data/Chain.scala
@@ -145,6 +145,23 @@ sealed abstract class Chain[+A] {
       else acc
     }
 
+  /**
+    * Finds the first element of this `Chain` for which the given partial
+    * function is defined, and applies the partial function to it.
+    */
+  final def collectFirst[B](pf: PartialFunction[A, B]): Option[B] = {
+    var result: Option[B] = None
+    foreachUntil { a =>
+      // trick from TraversableOnce, used to avoid calling both isDefined and apply (or calling lift)
+      val x = pf.applyOrElse(a, sentinel)
+      if (x.asInstanceOf[AnyRef] ne sentinel) {
+        result = Some(x.asInstanceOf[B])
+        true
+      } else false
+    }
+    result
+  }
+
   /**
    * Remove elements not matching the predicate
    */

diff --git a/core/src/main/scala/cats/data/NonEmptyChain.scala b/core/src/main/scala/cats/data/NonEmptyChain.scala
@@ -239,6 +239,12 @@ class NonEmptyChainOps[A](private val value: NonEmptyChain[A]) extends AnyVal {
    */
   final def collect[B](pf: PartialFunction[A, B]): Chain[B] = toChain.collect(pf)
 
+  /**
+    * Finds the first element of this `NonEmptyChain` for which the given partial
+    * function is defined, and applies the partial function to it.
+    */
+  final def collectFirst[B](pf: PartialFunction[A, B]): Option[B] = toChain.collectFirst(pf)
+
   /**
    * Filters all elements of this chain that do not satisfy the given predicate.
    */