From c9c8bc6b42bb83727e0653acf74ba1e516c120d5 Mon Sep 17 00:00:00 2001
From: Simon Podlipsky <simon@podlipsky.net>
Date: Mon, 12 Jun 2023 13:02:44 +0300
Subject: [PATCH] feat: allow noop mapper for `mapFromIterable`

---
 src/ds.php       |  6 ++++--
 tests/DsTest.php | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/ds.php b/src/ds.php
index ac9885c..9a58698 100644
--- a/src/ds.php
+++ b/src/ds.php
@@ -31,7 +31,7 @@ function mapFromEntries(iterable $entries): Map
 
 /**
  * @param iterable<K, V> $iterable
- * @param callable(K, V): Pair<KReturn, VReturn> $mapper
+ * @param callable(K, V): Pair<KReturn, VReturn>|null $mapper   If not provided then the output for `iterable<K, V>` is `Map<K, V>`
  *
  * @return Map<KReturn, VReturn>
  *
@@ -40,11 +40,13 @@ function mapFromEntries(iterable $entries): Map
  * @template KReturn
  * @template VReturn
  */
-function mapFromIterable(iterable $iterable, callable $mapper): Map
+function mapFromIterable(iterable $iterable, callable|null $mapper = null): Map
 {
     /** @var Map<KReturn, VReturn> $map */
     $map = new Map();
 
+    $mapper ??= static fn ($key, $value) => new Pair($key, $value);
+
     foreach ($iterable as $key => $value) {
         $keyValue = $mapper($key, $value);
         $map->put($keyValue->key, $keyValue->value);
diff --git a/tests/DsTest.php b/tests/DsTest.php
index b5602a6..b20d688 100644
--- a/tests/DsTest.php
+++ b/tests/DsTest.php
@@ -53,6 +53,22 @@ public function testMapFromIterable(): void
         self::assertFalse($map->get(4));
     }
 
+    public function testMapFromIterableNoopMapper(): void
+    {
+        /** @var callable():Generator<int, bool> $iterableFactory */
+        $iterableFactory = static function (): Generator {
+            yield 1 => true;
+            yield 2 => false;
+            yield 2 => true;
+        };
+
+        $map = mapFromIterable($iterableFactory());
+
+        self::assertCount(2, $map);
+        self::assertTrue($map->get(1));
+        self::assertTrue($map->get(2));
+    }
+
     public function testMappedValueSetsFromIterable(): void
     {
         /** @var callable():Generator<int, string> $iterableFactory */