Add is_list function

ext/standard/basic_functions.c

@@ -982,6 +982,10 @@ ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO(arginfo_is_array, _IS_BOOL, 0)
 	ZEND_ARG_INFO(0, var)
 ZEND_END_ARG_INFO()
 
+ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO(arginfo_is_list, _IS_BOOL, 0)
+	ZEND_ARG_INFO(0, var)
+ZEND_END_ARG_INFO()
+
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_INFO(arginfo_is_object, _IS_BOOL, 0)
 	ZEND_ARG_INFO(0, var)
 ZEND_END_ARG_INFO()
@@ -1539,6 +1543,7 @@ static const zend_function_entry basic_functions[] = { /* {{{ */
 	PHP_FE(is_numeric,														arginfo_is_numeric)
 	PHP_FE(is_string,														arginfo_is_string)
 	PHP_FE(is_array,														arginfo_is_array)
+	PHP_FE(is_list,															arginfo_is_list)
 	PHP_FE(is_object,														arginfo_is_object)
 	PHP_FE(is_scalar,														arginfo_is_scalar)
 	PHP_FE(is_callable,														arginfo_is_callable)

ext/standard/php_type.h

@@ -31,6 +31,7 @@ PHP_FUNCTION(is_float);
 PHP_FUNCTION(is_numeric);
 PHP_FUNCTION(is_string);
 PHP_FUNCTION(is_array);
+PHP_FUNCTION(is_list);
 PHP_FUNCTION(is_object);
 PHP_FUNCTION(is_scalar);
 PHP_FUNCTION(is_callable);

ext/standard/tests/general_functions/is_list.phpt

@@ -0,0 +1,94 @@
+--TEST--
+Test is_list() function
+--FILE--
+<?php
+
+function test_is_list(string $desc, $val) : void {
+	printf("%s: %s\n", $desc, is_list($val) ? "true" : "false");
+}
+
+test_is_list("empty", []);
+test_is_list("one", [1]);
+test_is_list("two", [1,2]);
+test_is_list("three", [1,2,3]);
+test_is_list("four", [1,2,3,4]);
+test_is_list("ten", range(0, 10));
+
+test_is_list("null", null);
+test_is_list("int", 123);
+test_is_list("float", 1.23);
+test_is_list("string", "string");
+test_is_list("object", new stdclass);
+test_is_list("true", true);
+test_is_list("false", false);
+
+test_is_list("string key", ["a" => 1]);
+test_is_list("mixed keys", [0 => 0, "a" => 1]);
+test_is_list("ordered keys", [0 => 0, 1 => 1]);
+test_is_list("shuffled keys", [1 => 0, 0 => 1]);
+test_is_list("skipped keys", [0 => 0, 2 => 2]);
+
+$arr = [1, 2, 3];
+unset($arr[0]);
+test_is_list("unset first", $arr);
+
+$arr = [1, 2, 3];
+unset($arr[1]);
+test_is_list("unset middle", $arr);
+
+$arr = [1, 2, 3];
+unset($arr[2]);
+test_is_list("unset end", $arr);
+
+$arr = [1, "a" => "a", 2];
+unset($arr["a"]);
+test_is_list("unset string key", $arr);
+
+$arr = [1 => 1, 0 => 0];
+unset($arr[1]);
+test_is_list("unset into order", $arr);
+
+$arr = ["a" => 1];
+unset($arr["a"]);
+test_is_list("unset to empty", $arr);
+
+$arr = [1, 2, 3];
+$arr[] = 4;
+test_is_list("append implicit", $arr);
+
+$arr = [1, 2, 3];
+$arr[3] = 4;
+test_is_list("append explicit", $arr);
+
+$arr = [1, 2, 3];
+$arr[4] = 5;
+test_is_list("append with gap", $arr);
+
+--EXPECT--
+empty: true
+one: true
+two: true
+three: true
+four: true
+ten: true
+null: false
+int: false
+float: false
+string: false
+object: false
+true: false
+false: false
+string key: false
+mixed keys: false
+ordered keys: true
+shuffled keys: false
+skipped keys: false
+unset first: false
+unset middle: false
+unset end: true
+unset string key: true
+unset into order: true
+unset to empty: true
+append implicit: true
+append explicit: true
+append with gap: false

ext/standard/type.c

@@ -289,6 +289,43 @@ PHP_FUNCTION(is_array)
 }
 /* }}} */
 
+/* {{{ proto bool is_list(mixed var)
+   Returns true if variable is an array whose keys are all numeric, sequential,
+   and start at 0 */
+PHP_FUNCTION(is_list)
+{
+	zval *arg;
+	zend_array *arrval;
+	zend_ulong num_idx, expected_idx = 0;
+	zend_string *str_idx;
+
+	ZEND_PARSE_PARAMETERS_START(1, 1)
+		Z_PARAM_ZVAL(arg)
+	ZEND_PARSE_PARAMETERS_END();
+
+	if (Z_TYPE_P(arg) != IS_ARRAY)
+		RETURN_FALSE;
+
+	arrval = Z_ARRVAL_P(arg);
+
+	/* Empty arrays are lists */
+	if (zend_hash_num_elements(arrval) == 0)
+		RETURN_TRUE;
+
+	/* Packed arrays are lists */
+	if (HT_IS_PACKED(arrval) && HT_IS_WITHOUT_HOLES(arrval))
+		RETURN_TRUE;
+
+	/* Check if the list could theoretically be repacked */
+	ZEND_HASH_FOREACH_KEY(arrval, num_idx, str_idx) {
+		if (str_idx != NULL || num_idx != expected_idx++)
+			RETURN_FALSE;
+	} ZEND_HASH_FOREACH_END();
+
+	RETURN_TRUE;
+}
+/* }}} */
+
 /* {{{ proto bool is_object(mixed var)
    Returns true if variable is an object
    Warning: This function is special-cased by zend_compile.c and so is usually bypassed */