Add array_is_list(array $array) function

This function tests if an array contains only sequential integer keys. While
list isn't an official type, this usage is consistent with the community usage
of "list" as an annotation type, cf.
https://psalm.dev/docs/annotating_code/type_syntax/array_types/#lists

Rebased and modified version of #4886

- Use .stub.php files
- Add opcache constant evaluation when argument is a constant
- Change from is_list(mixed $value) to array_is_list(array $array)

RFC: https://wiki.php.net/rfc/is_list

Co-Authored-By: Tyson Andre <tysonandre775@hotmail.com>
Co-Authored-By: Dusk <dusk@woofle.net>

Closes GH-6070

1 files changed, 3 insertions, 22 deletions

diff --git a/ext/json/json_encoder.c b/ext/json/json_encoder.c
index 92e4a10933..f608936349 100644
--- a/ext/json/json_encoder.c
+++ b/ext/json/json_encoder.c
@@ -36,29 +36,10 @@ static int php_json_escape_string(
 
 static int php_json_determine_array_type(zval *val) /* {{{ */
 {
-	int i;
-	HashTable *myht = Z_ARRVAL_P(val);
-
-	i = myht ? zend_hash_num_elements(myht) : 0;
-	if (i > 0) {
-		zend_string *key;
-		zend_ulong index, idx;
+	zend_array *myht = Z_ARRVAL_P(val);
 
-		if (HT_IS_PACKED(myht) && HT_IS_WITHOUT_HOLES(myht)) {
-			return PHP_JSON_OUTPUT_ARRAY;
-		}
-
-		idx = 0;
-		ZEND_HASH_FOREACH_KEY(myht, index, key) {
-			if (key) {
-				return PHP_JSON_OUTPUT_OBJECT;
-			} else {
-				if (index != idx) {
-					return PHP_JSON_OUTPUT_OBJECT;
-				}
-			}
-			idx++;
-		} ZEND_HASH_FOREACH_END();
+	if (myht) {
+		return zend_array_is_list(myht) ? PHP_JSON_OUTPUT_ARRAY : PHP_JSON_OUTPUT_OBJECT;
 	}
 
 	return PHP_JSON_OUTPUT_ARRAY;