Arrays::firstKey(), lastKey(): predicate is optional [WIP]

Author: dg

src/Utils/Arrays.php

@@ -129,9 +129,7 @@ public static function contains(array $array, mixed $value): bool
 	 */
 	public static function first(array $array, ?callable $predicate = null): mixed
 	{
-		$key = $predicate
-			? self::firstKey($array, $predicate)
-			: array_key_first($array);
+		$key = self::firstKey($array, $predicate);
 		return $key === null ? null : $array[$key];
 	}
 
@@ -145,19 +143,20 @@ public static function first(array $array, ?callable $predicate = null): mixed
 	 */
 	public static function last(array $array, ?callable $predicate = null): mixed
 	{
-		$key = $predicate
-			? self::firstKey(array_reverse($array, preserve_keys: true), $predicate)
-			: array_key_last($array);
+		$key = self::lastKey($array, $predicate);
 		return $key === null ? null : $array[$key];
 	}
 
 
 	/**
-	 * Returns the key of first matching item the specified predicate or null if there is no such item.
+	 * Returns the key of first item (matching the specified predicate if given) or null if there is no such item.
 	 * The callback has the signature `function ($value, $key, $array): bool`.
 	 */
-	public static function firstKey(array $array, callable $predicate): int|string|null
+	public static function firstKey(array $array, ?callable $predicate = null): int|string|null
 	{
+		if (!$predicate) {
+			return array_key_first($array);
+		}
 		foreach ($array as $k => $v) {
 			if ($predicate($v, $k, $array)) {
 				return $k;
@@ -168,12 +167,14 @@ public static function firstKey(array $array, callable $predicate): int|string|n
 
 
 	/**
-	 * Returns the key of last matching item the specified predicate or null if there is no such item.
+	 * Returns the key of last item (matching the specified predicate if given) or null if there is no such item.
 	 * The callback has the signature `function ($value, $key, $array): bool`.
 	 */
-	public static function lastKey(array $array, callable $predicate): int|string|null
+	public static function lastKey(array $array, ?callable $predicate = null): int|string|null
 	{
-		return self::firstKey(array_reverse($array, preserve_keys: true), $predicate);
+		return $predicate
+			? self::firstKey(array_reverse($array, preserve_keys: true), $predicate)
+			: array_key_last($array);
 	}
 
 

tests/Utils/Arrays.firstKey().phpt

@@ -8,10 +8,17 @@ use Tester\Assert;
 require __DIR__ . '/../bootstrap.php';
 
 
+test('no predicate', function () {
+	Assert::null(Arrays::firstKey([]));
+	Assert::same(0, Arrays::firstKey([null]));
+	Assert::same(0, Arrays::firstKey([1, 2, 3]));
+	Assert::same(5, Arrays::firstKey([5 => 1, 2, 3]));
+});
+
 test('internal array pointer is not affected', function () {
 	$arr = [1, 2, 3];
 	end($arr);
-	Assert::null(Arrays::firstKey($arr, fn() => false));
+	Assert::same(0, Arrays::firstKey($arr));
 	Assert::same(3, current($arr));
 });
 

tests/Utils/Arrays.lastKey().phpt

@@ -8,9 +8,16 @@ use Tester\Assert;
 require __DIR__ . '/../bootstrap.php';
 
 
+test('no predicate', function () {
+	Assert::null(Arrays::lastKey([]));
+	Assert::same(0, Arrays::lastKey([null]));
+	Assert::same(2, Arrays::lastKey([1, 2, 3]));
+	Assert::same(7, Arrays::lastKey([5 => 1, 2, 3]));
+});
+
 test('internal array pointer is not affected', function () {
 	$arr = [1, 2, 3];
-	Assert::same(2, Arrays::lastKey($arr, fn() => true));
+	Assert::same(2, Arrays::lastKey($arr));
 	Assert::same(1, current($arr));
 });