Add Array function to return only array entries based on matching key

A simple key based array filter

4dev/tests/Combined/CoreLibsCombinedArrayHandlerTest.php

@@ -1201,6 +1201,91 @@ final class CoreLibsCombinedArrayHandlerTest extends TestCase
 			'Find next key in array'
 		);
 	}
+
+	public function providerReturnMatchingKeyOnley(): array
+	{
+		return [
+			'limited entries' => [
+				[
+					'a' => 'foo',
+					'b' => 'bar',
+					'c' => 'foobar'
+				],
+				[
+					'a', 'b'
+				],
+				[
+					'a' => 'foo',
+					'b' => 'bar',
+				],
+			],
+			'limited entries, with one wrong key' => [
+				[
+					'a' => 'foo',
+					'b' => 'bar',
+					'c' => 'foobar'
+				],
+				[
+					'a', 'b', 'f'
+				],
+				[
+					'a' => 'foo',
+					'b' => 'bar',
+				],
+			],
+			'wrong keys only' => [
+				[
+					'a' => 'foo',
+					'b' => 'bar',
+					'c' => 'foobar'
+				],
+				[
+					'f', 'f'
+				],
+				[
+				],
+			],
+			'empty keys' => [
+				[
+					'a' => 'foo',
+					'b' => 'bar',
+					'c' => 'foobar'
+				],
+				[],
+				[
+					'a' => 'foo',
+					'b' => 'bar',
+					'c' => 'foobar'
+				],
+			],
+		];
+	}
+
+	/**
+	 * Undocumented function
+	 *
+	 * @covers ::arrayReturnMatchingKeyOnly
+	 * @dataProvider providerReturnMatchingKeyOnley
+	 * @testdox arrayReturnMatchingKeyOnly get only selected key entries from array [$_dataName]
+	 *
+	 * @param  array $input
+	 * @param  array $key_list
+	 * @param  array $expected
+	 * @return void
+	 */
+	public function testArrayReturnMatchingKeyOnly(
+		array $input,
+		array $key_list,
+		array $expected
+	): void {
+		$this->assertEquals(
+			$expected,
+			\CoreLibs\Combined\ArrayHandler::arrayReturnMatchingKeyOnly(
+				$input,
+				$key_list
+			)
+		);
+	}
 }
 
 // __END__

www/admin/class_test.array.php

@@ -250,6 +250,19 @@ foreach (array_keys($array) as $search) {
 }
 print "Key not exists: " . DgS::printAr(ArrayHandler::arrayGetNextKey($array, 'z')) . "<br>";
 
+print "<hr>";
+$keys = ['b', 'c', 'f'];
+print "Return only: " . DgS::printAr($keys) . ": "
+	. DgS::printAr(ArrayHandler::arrayReturnMatchingKeyOnly($array, $keys)) . "<br>";
+
+$out = array_filter($array, fn($key) => in_array($key, $keys), ARRAY_FILTER_USE_KEY);
+print "array filter: " . DgS::printAr($keys) . ": " . DgS::printAr($out) . "<br>";
+$out = array_intersect_key(
+	$array,
+	array_flip($keys)
+);
+print "array intersect key: " . DgS::printAr($keys) . ": " . DgS::printAr($out) . "<br>";
+
 print "</body></html>";
 
 // __END__

www/lib/CoreLibs/Combined/ArrayHandler.php

@@ -525,6 +525,30 @@ class ArrayHandler
 	{
 		return array_diff($array, $remove);
 	}
+
+	/**
+	 * From the array with key -> anything values return only the matching entries from key list
+	 * key list is a list[string]
+	 * if key list is empty, return array as is
+	 *
+	 * @param  array<string,mixed> $array
+	 * @param  array<string>       $key_list
+	 * @return array<string,mixed>
+	 */
+	public static function arrayReturnMatchingKeyOnly(
+		array $array,
+		array $key_list
+	): array {
+		// on empty return as is
+		if (empty($key_list)) {
+			return $array;
+		}
+		return array_filter(
+			$array,
+			fn($key) => in_array($key, $key_list),
+			ARRAY_FILTER_USE_KEY
+		);
+	}
 }
 
 // __END__