From fca2bbb90e07a6d90ce1144697d76589ac8d5409 Mon Sep 17 00:00:00 2001
From: Niels Dossche <7771979+nielsdos@users.noreply.github.com>
Date: Fri, 11 Jul 2025 23:03:22 +0200
Subject: [PATCH 1/6] Implement GH-18550: Implement getElementsByClassName()

Spec: https://dom.spec.whatwg.org/#ref-for-dom-element-getelementsbyclassname
---
 ext/dom/element.c                             | 38 ++++++++
 ext/dom/obj_map.c                             | 97 ++++++++++++++++++-
 ext/dom/obj_map.h                             |  1 +
 ext/dom/php_dom.stub.php                      |  3 +
 ext/dom/php_dom_arginfo.h                     | 11 ++-
 .../Element_getElementsByClassName.phpt       | 42 ++++++++
 .../Element_getElementsByClassName_empty.phpt | 32 ++++++
 ext/dom/token_list.c                          | 54 ++++++++++-
 ext/dom/token_list.h                          |  2 +
 9 files changed, 276 insertions(+), 4 deletions(-)
 create mode 100644 ext/dom/tests/modern/common/Element_getElementsByClassName.phpt
 create mode 100644 ext/dom/tests/modern/common/Element_getElementsByClassName_empty.phpt

diff --git a/ext/dom/element.c b/ext/dom/element.c
index ea18d0a817ede..f0afcf07eb2fe 100644
--- a/ext/dom/element.c
+++ b/ext/dom/element.c
@@ -842,6 +842,44 @@ PHP_METHOD(Dom_Element, getElementsByTagName)
 }
 /* }}} end dom_element_get_elements_by_tag_name */
 
+PHP_METHOD(Dom_Element, getElementsByClassName)
+{
+	dom_object *intern, *namednode;
+	zend_string *class_names;
+
+	if (zend_parse_parameters(ZEND_NUM_ARGS(), "P", &class_names) == FAILURE) {
+		RETURN_THROWS();
+	}
+
+	if (ZSTR_LEN(class_names) > INT_MAX) {
+		zend_argument_value_error(1, "is too long");
+		RETURN_THROWS();
+	}
+
+	DOM_GET_THIS_INTERN(intern);
+
+	object_init_ex(return_value, dom_html_collection_class_entry);
+	namednode = Z_DOMOBJ_P(return_value);
+
+	HashTable *token_set;
+	ALLOC_HASHTABLE(token_set);
+	zend_hash_init(token_set, 0, NULL, NULL, false);
+	dom_ordered_set_parser(token_set, ZSTR_VAL(class_names), intern->document->quirks_mode == PHP_LIBXML_QUIRKS);
+
+	if (zend_hash_num_elements(token_set) == 0) {
+		php_dom_create_obj_map(intern, namednode, NULL, NULL, NULL, &php_dom_obj_map_noop);
+
+		zend_hash_destroy(token_set);
+		FREE_HASHTABLE(token_set);
+	} else {
+		php_dom_create_obj_map(intern, namednode, NULL, NULL, NULL, &php_dom_obj_map_by_class_name);
+
+		dom_nnodemap_object *map = namednode->ptr;
+		map->array = token_set;
+		map->release_array = true;
+	}
+}
+
 /* should_free_result must be initialized to false */
 static const xmlChar *dom_get_attribute_ns(dom_object *intern, xmlNodePtr elemp, const char *uri, size_t uri_len, const char *name, bool *should_free_result)
 {
diff --git a/ext/dom/obj_map.c b/ext/dom/obj_map.c
index 64e4cff7b6ffe..72ecead3d7b48 100644
--- a/ext/dom/obj_map.c
+++ b/ext/dom/obj_map.c
@@ -24,6 +24,7 @@
 #if defined(HAVE_LIBXML) && defined(HAVE_DOM)
 #include "php_dom.h"
 #include "obj_map.h"
+#include "token_list.h"
 
 static zend_always_inline void objmap_cache_release_cached_obj(dom_nnodemap_object *objmap)
 {
@@ -40,6 +41,30 @@ static zend_always_inline void reset_objmap_cache(dom_nnodemap_object *objmap)
 	objmap->cached_length = -1;
 }
 
+static bool dom_matches_class_name(const dom_nnodemap_object *map, const xmlNode *nodep)
+{
+	bool ret = false;
+
+	if (nodep->type == XML_ELEMENT_NODE) {
+		xmlAttrPtr classes = xmlHasNsProp(nodep, BAD_CAST "class", NULL);
+		if (classes != NULL) {
+			bool should_free;
+			xmlChar *value = php_libxml_attr_value(classes, &should_free);
+
+			bool quirks = map->baseobj->document->quirks_mode == PHP_LIBXML_QUIRKS;
+			if (dom_ordered_set_all_contained(map->array, (const char *) value, quirks)) {
+				ret = true;
+			}
+
+			if (should_free) {
+				xmlFree(value);
+			}
+		}
+	}
+
+	return ret;
+}
+
 /**************************
  * === Length methods === *
  **************************/
@@ -106,6 +131,24 @@ static zend_long dom_map_get_by_tag_name_length(dom_nnodemap_object *map)
 	return count;
 }
 
+static zend_long dom_map_get_by_class_name_length(dom_nnodemap_object *map)
+{
+	xmlNodePtr nodep = dom_object_get_node(map->baseobj);
+	zend_long count = 0;
+	if (nodep) {
+		xmlNodePtr basep = nodep;
+		nodep = php_dom_first_child_of_container_node(basep);
+
+		while (nodep != NULL) {
+			if (dom_matches_class_name(map, nodep)) {
+				count++;
+			}
+			nodep = php_dom_next_in_tree_order(nodep, basep);
+		}
+	}
+	return count;
+}
+
 static zend_long dom_map_get_zero_length(dom_nnodemap_object *map)
 {
 	return 0;
@@ -276,6 +319,10 @@ static void dom_map_collection_named_item_elements_iter(dom_nnodemap_object *map
 	}
 }
 
+static void dom_map_collection_named_item_null(dom_nnodemap_object *map, php_dom_obj_map_collection_iter *iter)
+{
+}
+
 static void dom_map_get_by_tag_name_item(dom_nnodemap_object *map, zend_long index, zval *return_value)
 {
 	xmlNodePtr nodep = dom_object_get_node(map->baseobj);
@@ -292,12 +339,50 @@ static void dom_map_get_by_tag_name_item(dom_nnodemap_object *map, zend_long ind
 	}
 }
 
+static void dom_map_get_by_class_name_item(dom_nnodemap_object *map, zend_long index, zval *return_value)
+{
+	xmlNodePtr nodep = dom_object_get_node(map->baseobj);
+	xmlNodePtr itemnode = NULL;
+	if (nodep && index >= 0) {
+		xmlNodePtr basep = nodep;
+		dom_node_idx_pair start_point = dom_obj_map_get_start_point(map, nodep, index);
+		if (start_point.node) {
+			itemnode = php_dom_next_in_tree_order(start_point.node, basep);
+		} else {
+			itemnode = php_dom_first_child_of_container_node(nodep);
+		}
+
+		do {
+			--start_point.index;
+			while (itemnode != NULL && !dom_matches_class_name(map, itemnode)) {
+				itemnode = php_dom_next_in_tree_order(itemnode, basep);
+			}
+		} while (start_point.index > 0 && itemnode);
+	}
+	dom_ret_node_to_zobj(map, itemnode, return_value);
+	if (itemnode) {
+		dom_map_cache_obj(map, itemnode, index, return_value);
+	}
+}
+
 static void dom_map_collection_named_item_by_tag_name_iter(dom_nnodemap_object *map, php_dom_obj_map_collection_iter *iter)
 {
 	iter->candidate = dom_get_elements_by_tag_name_ns_raw(iter->basep, iter->candidate, map->ns, map->local, map->local_lower, &iter->cur, iter->next);
 	iter->next = iter->cur + 1;
 }
 
+static void dom_map_collection_named_item_by_class_name_iter(dom_nnodemap_object *map, php_dom_obj_map_collection_iter *iter)
+{
+	xmlNodePtr basep = iter->basep;
+	xmlNodePtr nodep = iter->candidate ? php_dom_next_in_tree_order(iter->candidate, basep) : php_dom_first_child_of_container_node(basep);
+
+	while (nodep != NULL && !dom_matches_class_name(map, nodep)) {
+		nodep = php_dom_next_in_tree_order(nodep, basep);
+	}
+
+	iter->candidate = nodep;
+}
+
 static void dom_map_get_null_item(dom_nnodemap_object *map, zend_long index, zval *return_value)
 {
 	RETURN_NULL();
@@ -478,6 +563,16 @@ const php_dom_obj_map_handler php_dom_obj_map_by_tag_name = {
 	.nameless = true,
 };
 
+const php_dom_obj_map_handler php_dom_obj_map_by_class_name = {
+	.length = dom_map_get_by_class_name_length,
+	.get_item = dom_map_get_by_class_name_item,
+	.get_ns_named_item = dom_map_get_ns_named_item_null,
+	.has_ns_named_item = dom_map_has_ns_named_item_null,
+	.collection_named_item_iter = dom_map_collection_named_item_by_class_name_iter,
+	.use_cache = true,
+	.nameless = true,
+};
+
 const php_dom_obj_map_handler php_dom_obj_map_child_nodes = {
 	.length = dom_map_get_nodes_length,
 	.get_item = dom_map_get_nodes_item,
@@ -533,7 +628,7 @@ const php_dom_obj_map_handler php_dom_obj_map_noop = {
 	.get_item = dom_map_get_null_item,
 	.get_ns_named_item = dom_map_get_ns_named_item_null,
 	.has_ns_named_item = dom_map_has_ns_named_item_null,
-	.collection_named_item_iter = NULL,
+	.collection_named_item_iter = dom_map_collection_named_item_null,
 	.use_cache = false,
 	.nameless = true,
 };
diff --git a/ext/dom/obj_map.h b/ext/dom/obj_map.h
index 97ec43f0011f8..e7231eb7b10a8 100644
--- a/ext/dom/obj_map.h
+++ b/ext/dom/obj_map.h
@@ -63,6 +63,7 @@ zend_long php_dom_get_nodelist_length(dom_object *obj);
 
 extern const php_dom_obj_map_handler php_dom_obj_map_attributes;
 extern const php_dom_obj_map_handler php_dom_obj_map_by_tag_name;
+extern const php_dom_obj_map_handler php_dom_obj_map_by_class_name;
 extern const php_dom_obj_map_handler php_dom_obj_map_child_elements;
 extern const php_dom_obj_map_handler php_dom_obj_map_child_nodes;
 extern const php_dom_obj_map_handler php_dom_obj_map_nodeset;
diff --git a/ext/dom/php_dom.stub.php b/ext/dom/php_dom.stub.php
index fd0927fc0ea12..7236e80b4d247 100644
--- a/ext/dom/php_dom.stub.php
+++ b/ext/dom/php_dom.stub.php
@@ -1659,6 +1659,7 @@ public function removeAttributeNode(Attr $attr) : Attr {}
 
         public function getElementsByTagName(string $qualifiedName): HTMLCollection {}
         public function getElementsByTagNameNS(?string $namespace, string $localName): HTMLCollection {}
+        public function getElementsByClassName(string $classNames): HTMLCollection {}
 
         public function insertAdjacentElement(AdjacentPosition $where, Element $element): ?Element {}
         public function insertAdjacentText(AdjacentPosition $where, string $data): void {}
@@ -1986,6 +1987,8 @@ abstract class Document extends Node implements ParentNode
         public function getElementsByTagName(string $qualifiedName): HTMLCollection {}
         /** @implementation-alias Dom\Element::getElementsByTagNameNS */
         public function getElementsByTagNameNS(?string $namespace, string $localName): HTMLCollection {}
+        /** @implementation-alias Dom\Element::getElementsByClassName */
+        public function getElementsByClassName(string $classNames): HTMLCollection {}
 
         public function createElement(string $localName): Element {}
         public function createElementNS(?string $namespace, string $qualifiedName): Element {}
diff --git a/ext/dom/php_dom_arginfo.h b/ext/dom/php_dom_arginfo.h
index be7a5c0713ad4..73efc8696e92f 100644
--- a/ext/dom/php_dom_arginfo.h
+++ b/ext/dom/php_dom_arginfo.h
@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 2119512797f6d51d9835660cd0eccd3ba83417a9 */
+ * Stub hash: 757889c0ca89cc8e9905ba465e0621fe89b6e716 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_OBJ_TYPE_MASK_EX(arginfo_dom_import_simplexml, 0, 1, DOMAttr|DOMElement, 0)
 	ZEND_ARG_TYPE_INFO(0, node, IS_OBJECT, 0)
@@ -775,6 +775,10 @@ ZEND_BEGIN_ARG_WITH_RETURN_OBJ_INFO_EX(arginfo_class_Dom_Element_getElementsByTa
 	ZEND_ARG_TYPE_INFO(0, localName, IS_STRING, 0)
 ZEND_END_ARG_INFO()
 
+ZEND_BEGIN_ARG_WITH_RETURN_OBJ_INFO_EX(arginfo_class_Dom_Element_getElementsByClassName, 0, 1, Dom\\HTMLCollection, 0)
+	ZEND_ARG_TYPE_INFO(0, classNames, IS_STRING, 0)
+ZEND_END_ARG_INFO()
+
 ZEND_BEGIN_ARG_WITH_RETURN_OBJ_INFO_EX(arginfo_class_Dom_Element_insertAdjacentElement, 0, 2, Dom\\Element, 1)
 	ZEND_ARG_OBJ_INFO(0, where, Dom\\AdjacentPosition, 0)
 	ZEND_ARG_OBJ_INFO(0, element, Dom\\Element, 0)
@@ -906,6 +910,8 @@ ZEND_END_ARG_INFO()
 
 #define arginfo_class_Dom_Document_getElementsByTagNameNS arginfo_class_Dom_Element_getElementsByTagNameNS
 
+#define arginfo_class_Dom_Document_getElementsByClassName arginfo_class_Dom_Element_getElementsByClassName
+
 ZEND_BEGIN_ARG_WITH_RETURN_OBJ_INFO_EX(arginfo_class_Dom_Document_createElement, 0, 1, Dom\\Element, 0)
 	ZEND_ARG_TYPE_INFO(0, localName, IS_STRING, 0)
 ZEND_END_ARG_INFO()
@@ -1278,6 +1284,7 @@ ZEND_METHOD(Dom_Element, setAttributeNodeNS);
 ZEND_METHOD(Dom_Element, removeAttributeNode);
 ZEND_METHOD(Dom_Element, getElementsByTagName);
 ZEND_METHOD(Dom_Element, getElementsByTagNameNS);
+ZEND_METHOD(Dom_Element, getElementsByClassName);
 ZEND_METHOD(Dom_Element, insertAdjacentElement);
 ZEND_METHOD(Dom_Element, insertAdjacentText);
 ZEND_METHOD(Dom_Element, insertAdjacentHTML);
@@ -1653,6 +1660,7 @@ static const zend_function_entry class_Dom_Element_methods[] = {
 	ZEND_ME(Dom_Element, removeAttributeNode, arginfo_class_Dom_Element_removeAttributeNode, ZEND_ACC_PUBLIC)
 	ZEND_ME(Dom_Element, getElementsByTagName, arginfo_class_Dom_Element_getElementsByTagName, ZEND_ACC_PUBLIC)
 	ZEND_ME(Dom_Element, getElementsByTagNameNS, arginfo_class_Dom_Element_getElementsByTagNameNS, ZEND_ACC_PUBLIC)
+	ZEND_ME(Dom_Element, getElementsByClassName, arginfo_class_Dom_Element_getElementsByClassName, ZEND_ACC_PUBLIC)
 	ZEND_ME(Dom_Element, insertAdjacentElement, arginfo_class_Dom_Element_insertAdjacentElement, ZEND_ACC_PUBLIC)
 	ZEND_ME(Dom_Element, insertAdjacentText, arginfo_class_Dom_Element_insertAdjacentText, ZEND_ACC_PUBLIC)
 	ZEND_ME(Dom_Element, insertAdjacentHTML, arginfo_class_Dom_Element_insertAdjacentHTML, ZEND_ACC_PUBLIC)
@@ -1721,6 +1729,7 @@ static const zend_function_entry class_Dom_DocumentFragment_methods[] = {
 static const zend_function_entry class_Dom_Document_methods[] = {
 	ZEND_RAW_FENTRY("getElementsByTagName", zim_Dom_Element_getElementsByTagName, arginfo_class_Dom_Document_getElementsByTagName, ZEND_ACC_PUBLIC, NULL, NULL)
 	ZEND_RAW_FENTRY("getElementsByTagNameNS", zim_Dom_Element_getElementsByTagNameNS, arginfo_class_Dom_Document_getElementsByTagNameNS, ZEND_ACC_PUBLIC, NULL, NULL)
+	ZEND_RAW_FENTRY("getElementsByClassName", zim_Dom_Element_getElementsByClassName, arginfo_class_Dom_Document_getElementsByClassName, ZEND_ACC_PUBLIC, NULL, NULL)
 	ZEND_ME(Dom_Document, createElement, arginfo_class_Dom_Document_createElement, ZEND_ACC_PUBLIC)
 	ZEND_ME(Dom_Document, createElementNS, arginfo_class_Dom_Document_createElementNS, ZEND_ACC_PUBLIC)
 	ZEND_RAW_FENTRY("createDocumentFragment", zim_DOMDocument_createDocumentFragment, arginfo_class_Dom_Document_createDocumentFragment, ZEND_ACC_PUBLIC, NULL, NULL)
diff --git a/ext/dom/tests/modern/common/Element_getElementsByClassName.phpt b/ext/dom/tests/modern/common/Element_getElementsByClassName.phpt
new file mode 100644
index 0000000000000..0d40ac785afda
--- /dev/null
+++ b/ext/dom/tests/modern/common/Element_getElementsByClassName.phpt
@@ -0,0 +1,42 @@
+--TEST--
+Dom\Element::getElementsByClassName()
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$dom = Dom\HTMLDocument::createFromString(<<<HTML
+<div class="  foo bar ">
+    <p class="bar">
+        <p class="bar" name="here">1</p>
+        <p name="here">2</p>
+        <p name="here">3</p>
+        <p class="bar" name="here">4</p>
+    </p>
+    <b class="foo bars"></b>
+</div>
+HTML, LIBXML_NOERROR);
+$collection = $dom->documentElement->getElementsByClassName("bar");
+
+echo "There are {$dom->getElementsByClassName("foo \n bar")->count()} items in the document in total that have both \"foo\" and \"bar\"\n";
+
+echo "There are {$collection->count()} \"bar\" items\n";
+
+foreach ($collection as $key => $node) {
+    var_dump($key, $node->tagName);
+    var_dump($node === $collection->item($key));
+}
+
+var_dump($collection->namedItem("here")->textContent);
+
+?>
+--EXPECT--
+There are 1 items in the document in total that have both "foo" and "bar"
+There are 4 "bar" items
+int(0)
+string(3) "DIV"
+bool(false)
+int(1)
+string(1) "P"
+bool(false)
+string(1) "1"
diff --git a/ext/dom/tests/modern/common/Element_getElementsByClassName_empty.phpt b/ext/dom/tests/modern/common/Element_getElementsByClassName_empty.phpt
new file mode 100644
index 0000000000000..719819c742d09
--- /dev/null
+++ b/ext/dom/tests/modern/common/Element_getElementsByClassName_empty.phpt
@@ -0,0 +1,32 @@
+--TEST--
+Dom\Element::getElementsByClassName() empty class names
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$dom = Dom\HTMLDocument::createFromString(<<<HTML
+<div class="  foo bar ">
+    <p id="child"></p>
+</div>
+HTML, LIBXML_NOERROR);
+
+$collection = $dom->documentElement->getElementsByClassName("");
+var_dump($collection->count());
+
+foreach ($collection as $node) {
+    throw new Error("unreachable");
+}
+
+var_dump($dom->getElementsByClassName(" ")->count());
+var_dump($dom->getElementsByClassName("\t")->count());
+var_dump($dom->getElementsByClassName("\t\n\f\v")->count());
+var_dump($dom->getElementsByClassName("\t\n\f\v")->namedItem("cjild"));
+
+?>
+--EXPECT--
+int(0)
+int(0)
+int(0)
+int(0)
+NULL
diff --git a/ext/dom/token_list.c b/ext/dom/token_list.c
index fe768e17b2e9c..cdfb408d4548d 100644
--- a/ext/dom/token_list.c
+++ b/ext/dom/token_list.c
@@ -51,7 +51,7 @@ static zend_always_inline void dom_add_token(HashTable *ht, zend_string *token)
 
 /* https://dom.spec.whatwg.org/#concept-ordered-set-parser
  * and https://infra.spec.whatwg.org/#split-on-ascii-whitespace */
-static void dom_ordered_set_parser(HashTable *token_set, const char *position)
+void dom_ordered_set_parser(HashTable *token_set, const char *position, bool to_lowercase)
 {
 	/* Adapted steps from "split on ASCII whitespace" such that that loop directly appends to the token set. */
 
@@ -72,6 +72,9 @@ static void dom_ordered_set_parser(HashTable *token_set, const char *position)
 
 		/* 4.2. Append token to tokens. */
 		zend_string *token = zend_string_init(start, length, false);
+		if (to_lowercase) {
+			zend_str_tolower(ZSTR_VAL(token), length);
+		}
 		dom_add_token(token_set, token);
 		zend_string_release_ex(token, false);
 
@@ -83,6 +86,53 @@ static void dom_ordered_set_parser(HashTable *token_set, const char *position)
 	 *    => That's the token set. */
 }
 
+/* This returns true if all tokens in "token_set" are found in "value". */
+bool dom_ordered_set_all_contained(HashTable *token_set, const char *value, bool to_lowercase)
+{
+	/* This code is conceptually close to dom_ordered_set_parser(),
+	 * but without building a hash table.
+	 * Since the storage of the token set maps a value on itself,
+	 * we can reuse that storage as a "seen" flag by setting it to NULL. */
+	zval *zv;
+
+	uint32_t still_needed = zend_hash_num_elements(token_set);
+
+	value += strspn(value, ascii_whitespace);
+
+	while (*value != '\0' && still_needed > 0) {
+		const char *start = value;
+		value += strcspn(value, ascii_whitespace);
+		size_t length = value - start;
+
+		if (to_lowercase) {
+			ALLOCA_FLAG(use_heap)
+			char *lc_str = zend_str_tolower_copy(do_alloca(length + 1, use_heap), start, length);
+			zv = zend_hash_str_find(token_set, lc_str, length);
+			free_alloca(lc_str, use_heap);
+		} else {
+			zv = zend_hash_str_find(token_set, start, length);
+		}
+		if (zv) {
+			if (Z_STR_P(zv)) {
+				still_needed--;
+				Z_STR_P(zv) = NULL;
+			}
+		}
+
+		value += strspn(value, ascii_whitespace);
+	}
+
+	/* Restore "seen" flag. */
+	zend_string *k;
+	ZEND_HASH_FOREACH_STR_KEY_VAL(token_set, k, zv) {
+		if (!Z_STR_P(zv)) {
+			Z_STR_P(zv) = k;
+		}
+	} ZEND_HASH_FOREACH_END();
+
+	return still_needed == 0;
+}
+
 /* https://dom.spec.whatwg.org/#concept-ordered-set-serializer */
 static char *dom_ordered_set_serializer(HashTable *token_set)
 {
@@ -166,7 +216,7 @@ static void dom_token_list_update_set(dom_token_list_object *intern, HashTable *
 	xmlChar *value = dom_token_list_get_class_value(attr, &should_free);
 	if (value != NULL) {
 		/* 2. Otherwise, parse the token set. */
-		dom_ordered_set_parser(token_set, (const char *) value);
+		dom_ordered_set_parser(token_set, (const char *) value, false);
 		intern->cached_string = estrdup((const char *) value);
 	} else {
 		intern->cached_string = NULL;
diff --git a/ext/dom/token_list.h b/ext/dom/token_list.h
index 4711852c4d876..7c8a6f612ffa4 100644
--- a/ext/dom/token_list.h
+++ b/ext/dom/token_list.h
@@ -35,6 +35,8 @@ static inline dom_token_list_object *php_dom_token_list_from_dom_obj(dom_object
 	return (dom_token_list_object *)((char *) obj - XtOffsetOf(dom_token_list_object, dom));
 }
 
+void dom_ordered_set_parser(HashTable *token_set, const char *position, bool to_lowercase);
+bool dom_ordered_set_all_contained(HashTable *token_set, const char *value, bool to_lowercase);
 void dom_token_list_ctor(dom_token_list_object *intern, dom_object *element_obj);
 void dom_token_list_free_obj(zend_object *object);
 zval *dom_token_list_read_dimension(zend_object *object, zval *offset, int type, zval *rv);

From 00e23031cce0563a795dd458f4030f92aaabad17 Mon Sep 17 00:00:00 2001
From: Niels Dossche <7771979+nielsdos@users.noreply.github.com>
Date: Sun, 13 Jul 2025 21:19:39 +0200
Subject: [PATCH 2/6] fixes

---
 ext/dom/obj_map.c                             | 10 +++--
 .../Element_getElementsByClassName.phpt       | 42 -------------------
 .../Element_getElementsByClassName_empty.phpt |  2 +-
 3 files changed, 8 insertions(+), 46 deletions(-)
 delete mode 100644 ext/dom/tests/modern/common/Element_getElementsByClassName.phpt

diff --git a/ext/dom/obj_map.c b/ext/dom/obj_map.c
index 72ecead3d7b48..9c017c4d11a6b 100644
--- a/ext/dom/obj_map.c
+++ b/ext/dom/obj_map.c
@@ -344,10 +344,14 @@ static void dom_map_get_by_class_name_item(dom_nnodemap_object *map, zend_long i
 	xmlNodePtr nodep = dom_object_get_node(map->baseobj);
 	xmlNodePtr itemnode = NULL;
 	if (nodep && index >= 0) {
-		xmlNodePtr basep = nodep;
 		dom_node_idx_pair start_point = dom_obj_map_get_start_point(map, nodep, index);
 		if (start_point.node) {
-			itemnode = php_dom_next_in_tree_order(start_point.node, basep);
+			if (start_point.index > 0) {
+				/* Only start iteration at next point if we actually have an index to seek to. */
+				itemnode = php_dom_next_in_tree_order(start_point.node, nodep);
+			} else {
+				itemnode = start_point.node;
+			}
 		} else {
 			itemnode = php_dom_first_child_of_container_node(nodep);
 		}
@@ -355,7 +359,7 @@ static void dom_map_get_by_class_name_item(dom_nnodemap_object *map, zend_long i
 		do {
 			--start_point.index;
 			while (itemnode != NULL && !dom_matches_class_name(map, itemnode)) {
-				itemnode = php_dom_next_in_tree_order(itemnode, basep);
+				itemnode = php_dom_next_in_tree_order(itemnode, nodep);
 			}
 		} while (start_point.index > 0 && itemnode);
 	}
diff --git a/ext/dom/tests/modern/common/Element_getElementsByClassName.phpt b/ext/dom/tests/modern/common/Element_getElementsByClassName.phpt
deleted file mode 100644
index 0d40ac785afda..0000000000000
--- a/ext/dom/tests/modern/common/Element_getElementsByClassName.phpt
+++ /dev/null
@@ -1,42 +0,0 @@
---TEST--
-Dom\Element::getElementsByClassName()
---EXTENSIONS--
-dom
---FILE--
-<?php
-
-$dom = Dom\HTMLDocument::createFromString(<<<HTML
-<div class="  foo bar ">
-    <p class="bar">
-        <p class="bar" name="here">1</p>
-        <p name="here">2</p>
-        <p name="here">3</p>
-        <p class="bar" name="here">4</p>
-    </p>
-    <b class="foo bars"></b>
-</div>
-HTML, LIBXML_NOERROR);
-$collection = $dom->documentElement->getElementsByClassName("bar");
-
-echo "There are {$dom->getElementsByClassName("foo \n bar")->count()} items in the document in total that have both \"foo\" and \"bar\"\n";
-
-echo "There are {$collection->count()} \"bar\" items\n";
-
-foreach ($collection as $key => $node) {
-    var_dump($key, $node->tagName);
-    var_dump($node === $collection->item($key));
-}
-
-var_dump($collection->namedItem("here")->textContent);
-
-?>
---EXPECT--
-There are 1 items in the document in total that have both "foo" and "bar"
-There are 4 "bar" items
-int(0)
-string(3) "DIV"
-bool(false)
-int(1)
-string(1) "P"
-bool(false)
-string(1) "1"
diff --git a/ext/dom/tests/modern/common/Element_getElementsByClassName_empty.phpt b/ext/dom/tests/modern/common/Element_getElementsByClassName_empty.phpt
index 719819c742d09..d2e3b0ea22b9b 100644
--- a/ext/dom/tests/modern/common/Element_getElementsByClassName_empty.phpt
+++ b/ext/dom/tests/modern/common/Element_getElementsByClassName_empty.phpt
@@ -21,7 +21,7 @@ foreach ($collection as $node) {
 var_dump($dom->getElementsByClassName(" ")->count());
 var_dump($dom->getElementsByClassName("\t")->count());
 var_dump($dom->getElementsByClassName("\t\n\f\v")->count());
-var_dump($dom->getElementsByClassName("\t\n\f\v")->namedItem("cjild"));
+var_dump($dom->getElementsByClassName("\t\n\f\v")->namedItem("child"));
 
 ?>
 --EXPECT--

From 85af612afa33e7a976903e68eff9229c4e7902b5 Mon Sep 17 00:00:00 2001
From: Niels Dossche <7771979+nielsdos@users.noreply.github.com>
Date: Sun, 13 Jul 2025 21:19:54 +0200
Subject: [PATCH 3/6] Tests

---
 ...ent_getElementsByClassName_non_quirks.phpt | 55 ++++++++++++++++
 ...Element_getElementsByClassName_quirks.phpt | 62 +++++++++++++++++++
 2 files changed, 117 insertions(+)
 create mode 100644 ext/dom/tests/modern/common/Element_getElementsByClassName_non_quirks.phpt
 create mode 100644 ext/dom/tests/modern/common/Element_getElementsByClassName_quirks.phpt

diff --git a/ext/dom/tests/modern/common/Element_getElementsByClassName_non_quirks.phpt b/ext/dom/tests/modern/common/Element_getElementsByClassName_non_quirks.phpt
new file mode 100644
index 0000000000000..e658e3399ca0d
--- /dev/null
+++ b/ext/dom/tests/modern/common/Element_getElementsByClassName_non_quirks.phpt
@@ -0,0 +1,55 @@
+--TEST--
+Dom\Element::getElementsByClassName() non quirks mode
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$dom = Dom\HTMLDocument::createFromString(<<<HTML
+<!DOCTYPE html>
+<div id="container">
+    <p class="Bar">1</p>
+    <p class="bar">2</p>
+    <p class="Bar Foo">3</p>
+    <p class="Bar foo">4</p>
+    <p class="foo bar">5</p>
+    <p class="foo bar" name="here">6</p>
+</div>
+<div>
+    <p class="Bar">7</p>
+    <p class="bar">8</p>
+    <p class="Bar Foo">9</p>
+    <p class="Bar foo">10</p>
+    <p class="foo bar">11</p>
+</div>
+HTML);
+
+$collection = $dom->getElementsByClassName("foo \n bar");
+
+echo "There are {$collection->length} items in the document in total that have both \"foo\" and \"bar\"\n";
+
+$collection = $dom->getElementById('container')->getElementsByClassName("foo \n bar");
+
+echo "There are {$collection->length} items in #container in total that have both \"foo\" and \"bar\"\n";
+
+foreach ($collection as $key => $node) {
+    echo "--- Key $key ---\n";
+    var_dump($node->tagName, $node->textContent);
+    var_dump($node === $collection->item($key));
+}
+
+var_dump($collection->namedItem("here")->textContent);
+
+?>
+--EXPECT--
+There are 3 items in the document in total that have both "foo" and "bar"
+There are 2 items in #container in total that have both "foo" and "bar"
+--- Key 0 ---
+string(1) "P"
+string(1) "5"
+bool(true)
+--- Key 1 ---
+string(1) "P"
+string(1) "6"
+bool(true)
+string(1) "6"
diff --git a/ext/dom/tests/modern/common/Element_getElementsByClassName_quirks.phpt b/ext/dom/tests/modern/common/Element_getElementsByClassName_quirks.phpt
new file mode 100644
index 0000000000000..a02679f2f8626
--- /dev/null
+++ b/ext/dom/tests/modern/common/Element_getElementsByClassName_quirks.phpt
@@ -0,0 +1,62 @@
+--TEST--
+Dom\Element::getElementsByClassName() quirks mode
+--EXTENSIONS--
+dom
+--FILE--
+<?php
+
+$dom = Dom\HTMLDocument::createFromString(<<<HTML
+<div class="  foo bar ">
+    <p class="bar">
+        <p class="bar" name="here">1</p>
+        <p name="here">2</p>
+        <p name="here">3</p>
+        <p class="bAR" name="here">4</p>
+    </p>
+    <b class="foo bars"></b>
+</div>
+HTML, LIBXML_NOERROR);
+$collection = $dom->documentElement->getElementsByClassName("Bar");
+
+echo "There are {$dom->getElementsByClassName("foo \n bar")->count()} items in the document in total that have both \"foo\" and \"bar\"\n";
+
+echo "There are {$collection->count()} \"Bar\" items\n";
+
+foreach ($collection as $key => $node) {
+    echo "--- Key $key ---\n";
+    var_dump($node->tagName, $node->textContent);
+    var_dump($node === $collection->item($key));
+}
+
+var_dump($collection->namedItem("here")->textContent);
+
+?>
+--EXPECT--
+There are 1 items in the document in total that have both "foo" and "bar"
+There are 4 "Bar" items
+--- Key 0 ---
+string(3) "DIV"
+string(56) "
+    
+        1
+        2
+        3
+        4
+    
+    
+"
+bool(true)
+--- Key 1 ---
+string(1) "P"
+string(9) "
+        "
+bool(true)
+--- Key 2 ---
+string(1) "P"
+string(1) "1"
+bool(true)
+--- Key 3 ---
+string(1) "P"
+string(1) "4"
+bool(true)
+string(1) "1"

From 8e7f3201612b4652f3f730cf85318db53992fc97 Mon Sep 17 00:00:00 2001
From: Niels Dossche <7771979+nielsdos@users.noreply.github.com>
Date: Sun, 13 Jul 2025 23:12:36 +0200
Subject: [PATCH 4/6] Can use HASH_MAP

---
 ext/dom/token_list.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ext/dom/token_list.c b/ext/dom/token_list.c
index cdfb408d4548d..84a3dc10afebc 100644
--- a/ext/dom/token_list.c
+++ b/ext/dom/token_list.c
@@ -124,7 +124,7 @@ bool dom_ordered_set_all_contained(HashTable *token_set, const char *value, bool
 
 	/* Restore "seen" flag. */
 	zend_string *k;
-	ZEND_HASH_FOREACH_STR_KEY_VAL(token_set, k, zv) {
+	ZEND_HASH_MAP_FOREACH_STR_KEY_VAL(token_set, k, zv) {
 		if (!Z_STR_P(zv)) {
 			Z_STR_P(zv) = k;
 		}

From fd749fb8c896024cdafa099c4dde5586f27471dc Mon Sep 17 00:00:00 2001
From: Niels Dossche <7771979+nielsdos@users.noreply.github.com>
Date: Mon, 14 Jul 2025 19:52:49 +0200
Subject: [PATCH 5/6] Make test a bit more logical

---
 ...Element_getElementsByClassName_quirks.phpt | 25 ++++++++++++-------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/ext/dom/tests/modern/common/Element_getElementsByClassName_quirks.phpt b/ext/dom/tests/modern/common/Element_getElementsByClassName_quirks.phpt
index a02679f2f8626..52e964ea43177 100644
--- a/ext/dom/tests/modern/common/Element_getElementsByClassName_quirks.phpt
+++ b/ext/dom/tests/modern/common/Element_getElementsByClassName_quirks.phpt
@@ -7,12 +7,12 @@ dom
 
 $dom = Dom\HTMLDocument::createFromString(<<<HTML
 <div class="  foo bar ">
-    <p class="bar">
-        <p class="bar" name="here">1</p>
-        <p name="here">2</p>
+    <main class="bar">
+        <p name="here">1</p>
+        <p class="bar" name="here">2</p>
         <p name="here">3</p>
         <p class="bAR" name="here">4</p>
-    </p>
+    </main>
     <b class="foo bars"></b>
 </div>
 HTML, LIBXML_NOERROR);
@@ -28,6 +28,8 @@ foreach ($collection as $key => $node) {
     var_dump($node === $collection->item($key));
 }
 
+echo "--- named item \"here\" ---\n";
+
 var_dump($collection->namedItem("here")->textContent);
 
 ?>
@@ -47,16 +49,21 @@ string(56) "
 "
 bool(true)
 --- Key 1 ---
-string(1) "P"
-string(9) "
-        "
+string(4) "MAIN"
+string(45) "
+        1
+        2
+        3
+        4
+    "
 bool(true)
 --- Key 2 ---
 string(1) "P"
-string(1) "1"
+string(1) "2"
 bool(true)
 --- Key 3 ---
 string(1) "P"
 string(1) "4"
 bool(true)
-string(1) "1"
+--- named item "here" ---
+string(1) "2"

From 210397fd2e8cc9dea68f5223cc8e92d13e456263 Mon Sep 17 00:00:00 2001
From: Niels Dossche <7771979+nielsdos@users.noreply.github.com>
Date: Mon, 14 Jul 2025 19:53:25 +0200
Subject: [PATCH 6/6] NEWS and UPGRADING

---
 NEWS      | 1 +
 UPGRADING | 1 +
 2 files changed, 2 insertions(+)

diff --git a/NEWS b/NEWS
index b12686c5d3cef..7df251f85508d 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,7 @@ PHP                                                                        NEWS
 
 - DOM:
   . Make cloning DOM node lists, maps, and collections fail. (nielsdos)
+  . Added Dom\Element::getElementsByClassName(). (nielsdos)
 
 - PDO_ODBC
   . Fetch larger block sizes and better handle SQL_NO_TOTAL when calling
diff --git a/UPGRADING b/UPGRADING
index fb76c9a46ba0e..e96b92683caa1 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -408,6 +408,7 @@ PHP 8.5 UPGRADE NOTES
     RFC: https://wiki.php.net/rfc/curl_share_persistence_improvement
 
 - DOM:
+  . Added Dom\Element::getElementsByClassName().
   . Added Dom\Element::insertAdjacentHTML().
 
 - Enchant: