Add mappedVectorsFromIterable helper (#82)

Author: simPod

src/ds.php

@@ -148,6 +148,37 @@ function mappedSetsFromIterable(iterable $iterable, callable $mapper): Map
     return $map;
 }
 
+/**
+ * @param iterable<K, V> $iterable
+ * @param callable(K, V): Pair<KReturn, VReturn> $mapper
+ *
+ * @return Map<KReturn, Vector<VReturn>>
+ *
+ * @template K
+ * @template V
+ * @template KReturn
+ * @template VReturn
+ */
+function mappedVectorsFromIterable(iterable $iterable, callable $mapper): Map
+{
+    /** @var Map<KReturn, Vector<VReturn>> $map */
+    $map = new Map();
+
+    foreach ($iterable as $key => $value) {
+        $keyValue = $mapper($key, $value);
+        $vector = $map->get($keyValue->key, null);
+        if ($vector === null) {
+            /** @var Vector<VReturn> $vector */
+            $vector = new Vector();
+            $map->put($keyValue->key, $vector);
+        }
+
+        $vector->push($keyValue->value);
+    }
+
+    return $map;
+}
+
 /**
  * @param iterable<K, V> $iterable
  * @param callable(K,V): VReturn $mapper

tests/DsTest.php

@@ -14,13 +14,15 @@
 use function Cdn77\Functions\mappedMapsFromIterable;
 use function Cdn77\Functions\mappedQueuesFromIterable;
 use function Cdn77\Functions\mappedSetsFromIterable;
+use function Cdn77\Functions\mappedVectorsFromIterable;
 use function Cdn77\Functions\setFromIterable;
 use function Cdn77\Functions\vectorFromIterable;
 
 #[CoversFunction('Cdn77\Functions\mapFromIterable')]
 #[CoversFunction('Cdn77\Functions\mappedMapsFromIterable')]
 #[CoversFunction('Cdn77\Functions\mappedQueuesFromIterable')]
 #[CoversFunction('Cdn77\Functions\mappedSetsFromIterable')]
+#[CoversFunction('Cdn77\Functions\mappedVectorsFromIterable')]
 #[CoversFunction('Cdn77\Functions\setFromIterable')]
 #[CoversFunction('Cdn77\Functions\vectorFromIterable')]
 final class DsTest extends TestCase
@@ -93,7 +95,12 @@ public function testMappedQueuesFromIterable(): void
 
         $map = mappedQueuesFromIterable(
             $iterableFactory(),
-            static fn (int $key, string $value) => new Pair($key * 2, $value . '_'),
+            static function (int $key, string $value): Pair {
+                /** @phpstan-var non-falsy-string $mappedValue */
+                $mappedValue = $value . '_';
+
+                return new Pair($key * 2, $mappedValue);
+            },
         );
 
         self::assertCount(2, $map);
@@ -118,14 +125,43 @@ public function testMappedSetsFromIterable(): void
 
         $map = mappedSetsFromIterable(
             $iterableFactory(),
-            static fn (int $key, string $value) => new Pair($key * 2, $value . '_'),
+            static function (int $key, string $value): Pair {
+                /** @phpstan-var non-falsy-string $mappedValue */
+                $mappedValue = $value . '_';
+
+                return new Pair($key * 2, $mappedValue);
+            },
         );
 
         self::assertCount(2, $map);
         self::assertTrue($map->get(2)->contains('a_', 'b_'));
         self::assertTrue($map->get(4)->contains('a_', 'b_'));
     }
 
+    public function testMappedVectorsFromIterable(): void
+    {
+        $iterableFactory = static function (): Generator {
+            yield 1 => 'a';
+            yield 1 => 'b';
+            yield 2 => 'c';
+            yield 2 => 'd';
+        };
+
+        $map = mappedVectorsFromIterable(
+            $iterableFactory(),
+            static function (int $key, string $value): Pair {
+                /** @phpstan-var non-falsy-string $mappedValue */
+                $mappedValue = $value . '_';
+
+                return new Pair($key * 2, $mappedValue);
+            },
+        );
+
+        self::assertCount(2, $map);
+        self::assertSame(['a_', 'b_'], $map->get(2)->toArray());
+        self::assertSame(['c_', 'd_'], $map->get(4)->toArray());
+    }
+
     public function testSetFromIterable(): void
     {
         $iterableFactory = static function (): Generator {