LibWeb/CSS: Stub out StylePropertyMap

Author: https://github.com/AtkinsSJ
Commit: 3bb54ffd59
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5823
Reviewed-by: https://github.com/trflynn89

Libraries/LibWeb/CMakeLists.txt

@@ -187,6 +187,7 @@ set(SOURCES
     CSS/StyleInvalidationData.cpp
     CSS/StyleProperty.cpp
     CSS/StylePropertyMapReadOnly.cpp
+    CSS/StylePropertyMap.cpp
     CSS/StyleSheet.cpp
     CSS/StyleSheetIdentifier.cpp
     CSS/StyleSheetList.cpp

Libraries/LibWeb/CSS/StylePropertyMap.cpp

@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "StylePropertyMap.h"
+#include <LibWeb/Bindings/Intrinsics.h>
+#include <LibWeb/Bindings/StylePropertyMapPrototype.h>
+#include <LibWeb/CSS/PropertyName.h>
+#include <LibWeb/WebIDL/ExceptionOr.h>
+
+namespace Web::CSS {
+
+GC_DEFINE_ALLOCATOR(StylePropertyMap);
+
+GC::Ref<StylePropertyMap> StylePropertyMap::create(JS::Realm& realm, GC::Ref<CSSStyleDeclaration> declaration)
+{
+    return realm.create<StylePropertyMap>(realm, declaration);
+}
+
+StylePropertyMap::StylePropertyMap(JS::Realm& realm, GC::Ref<CSSStyleDeclaration> declaration)
+    : StylePropertyMapReadOnly(realm, declaration)
+{
+}
+
+StylePropertyMap::~StylePropertyMap() = default;
+
+void StylePropertyMap::initialize(JS::Realm& realm)
+{
+    WEB_SET_PROTOTYPE_FOR_INTERFACE(StylePropertyMap);
+    Base::initialize(realm);
+}
+
+// https://drafts.css-houdini.org/css-typed-om-1/#dom-stylepropertymap-set
+WebIDL::ExceptionOr<void> StylePropertyMap::set(String property, Vector<Variant<GC::Root<CSSStyleValue>, String>> values)
+{
+    // The set(property, ...values) method, when called on a StylePropertyMap this, must perform the following steps:
+
+    // 1. If property is not a custom property name string, set property to property ASCII lowercased.
+    if (!is_a_custom_property_name_string(property))
+        property = property.to_ascii_lowercase();
+
+    // 2. If property is not a valid CSS property, throw a TypeError.
+    if (!is_a_valid_css_property(property))
+        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, MUST(String::formatted("'{}' is not a valid CSS property", property)) };
+
+    // FIXME: 3. If property is a single-valued property and values has more than one item, throw a TypeError.
+
+    // FIXME: 4. If any of the items in values have a non-null [[associatedProperty]] internal slot, and that slot’s value is anything other than property, throw a TypeError.
+
+    // FIXME: 5. If the size of values is two or more, and one or more of the items are a CSSUnparsedValue or CSSVariableReferenceValue object, throw a TypeError.
+    // NOTE: Having 2+ values implies that you’re setting multiple items of a list-valued property, but the presence of
+    //       a var() function in the string-based OM disables all syntax parsing, including splitting into individual
+    //       iterations (because there might be more commas inside of the var() value, so you can’t tell how many items
+    //       are actually going to show up). This step’s restriction preserves the same semantics in the Typed OM.
+
+    // 6. Let props be the value of this’s [[declarations]] internal slot.
+    auto& props = m_declarations;
+
+    // 7. If props[property] exists, remove it.
+    props.remove(property);
+
+    // FIXME: 8. Let values to set be an empty list.
+
+    // FIXME: 9. For each value in values, create an internal representation for property and value, and append the result to values to set.
+    (void)values;
+
+    // FIXME: 10. Set props[property] to values to set.
+    // NOTE: The property is deleted then added back so that it gets put at the end of the ordered map, which gives the
+    //       expected behavior in the face of shorthand properties.
+
+    return {};
+}
+
+// https://drafts.css-houdini.org/css-typed-om-1/#dom-stylepropertymap-append
+WebIDL::ExceptionOr<void> StylePropertyMap::append(String property, Vector<Variant<GC::Root<CSSStyleValue>, String>> values)
+{
+    // The append(property, ...values) method, when called on a StylePropertyMap this, must perform the following steps:
+
+    // 1. If property is not a custom property name string, set property to property ASCII lowercased.
+    if (!is_a_custom_property_name_string(property))
+        property = property.to_ascii_lowercase();
+
+    // 2. If property is not a valid CSS property, throw a TypeError.
+    if (!is_a_valid_css_property(property))
+        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, MUST(String::formatted("'{}' is not a valid CSS property", property)) };
+
+    // FIXME: 3. If property is not a list-valued property, throw a TypeError.
+
+    // FIXME: 4. If any of the items in values have a non-null [[associatedProperty]] internal slot, and that slot’s value is anything other than property, throw a TypeError.
+
+    // FIXME: 5. If any of the items in values are a CSSUnparsedValue or CSSVariableReferenceValue object, throw a TypeError.
+
+    // NOTE: When a property is set via string-based APIs, the presence of var() in a property prevents the entire thing from being interpreted. In other words, everything besides the var() is a plain component value, not a meaningful type. This step’s restriction preserves the same semantics in the Typed OM.
+
+    // 6. Let props be the value of this’s [[declarations]] internal slot.
+    auto& props = m_declarations;
+
+    // FIXME: 7. If props[property] does not exist, set props[property] to an empty list.
+    (void)props;
+
+    // FIXME: 8. If props[property] contains a var() reference, throw a TypeError.
+
+    // FIXME: 9. Let temp values be an empty list.
+
+    // FIXME: 10. For each value in values, create an internal representation with property and value, and append the returned value to temp values.
+    (void)values;
+
+    // FIXME: 11. Append the entries of temp values to props[property].
+
+    return {};
+}
+
+// https://drafts.css-houdini.org/css-typed-om-1/#dom-stylepropertymap-delete
+WebIDL::ExceptionOr<void> StylePropertyMap::delete_(String property)
+{
+    // The delete(property) method, when called on a StylePropertyMap this, must perform the following steps:
+
+    // 1. If property is not a custom property name string, set property to property ASCII lowercased.
+    if (!is_a_custom_property_name_string(property))
+        property = property.to_ascii_lowercase();
+
+    // 2. If property is not a valid CSS property, throw a TypeError.
+    if (!is_a_valid_css_property(property))
+        return WebIDL::SimpleException { WebIDL::SimpleExceptionType::TypeError, MUST(String::formatted("'{}' is not a valid CSS property", property)) };
+
+    // 3. If this’s [[declarations]] internal slot contains property, remove it.
+    m_declarations.remove(property);
+    return {};
+}
+
+// https://drafts.css-houdini.org/css-typed-om-1/#dom-stylepropertymap-clear
+void StylePropertyMap::clear()
+{
+    // The clear() method, when called on a StylePropertyMap this, must perform the following steps:
+
+    // 1. Remove all of the declarations in this’s [[declarations]] internal slot.
+    m_declarations.clear();
+}
+
+}

Libraries/LibWeb/CSS/StylePropertyMap.h

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2025, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibWeb/CSS/StylePropertyMapReadOnly.h>
+
+namespace Web::CSS {
+
+// https://drafts.css-houdini.org/css-typed-om-1/#stylepropertymap
+class StylePropertyMap : public StylePropertyMapReadOnly {
+    WEB_PLATFORM_OBJECT(StylePropertyMap, StylePropertyMapReadOnly);
+    GC_DECLARE_ALLOCATOR(StylePropertyMap);
+
+public:
+    [[nodiscard]] static GC::Ref<StylePropertyMap> create(JS::Realm&, GC::Ref<CSSStyleDeclaration>);
+
+    virtual ~StylePropertyMap() override;
+
+    WebIDL::ExceptionOr<void> set(String property, Vector<Variant<GC::Root<CSSStyleValue>, String>> values);
+    WebIDL::ExceptionOr<void> append(String property, Vector<Variant<GC::Root<CSSStyleValue>, String>> values);
+    WebIDL::ExceptionOr<void> delete_(String property);
+    void clear();
+
+private:
+    explicit StylePropertyMap(JS::Realm&, GC::Ref<CSSStyleDeclaration>);
+
+    virtual void initialize(JS::Realm&) override;
+};
+
+}

Libraries/LibWeb/CSS/StylePropertyMap.idl

@@ -0,0 +1,10 @@
+#import <CSS/StylePropertyMapReadOnly.idl>
+
+// https://drafts.css-houdini.org/css-typed-om-1/#stylepropertymap
+[Exposed=Window]
+interface StylePropertyMap : StylePropertyMapReadOnly {
+    undefined set(USVString property, (CSSStyleValue or USVString)... values);
+    undefined append(USVString property, (CSSStyleValue or USVString)... values);
+    undefined delete(USVString property);
+    undefined clear();
+};

Libraries/LibWeb/Forward.h

@@ -337,6 +337,7 @@ class Size;
 class ScrollbarColorStyleValue;
 class StringStyleValue;
 class StyleComputer;
+class StylePropertyMap;
 class StylePropertyMapReadOnly;
 class StyleSheet;
 class StyleSheetList;

Libraries/LibWeb/idl_files.cmake

@@ -58,6 +58,7 @@ libweb_js_bindings(CSS/MediaQueryList)
 libweb_js_bindings(CSS/MediaQueryListEvent)
 libweb_js_bindings(CSS/Screen)
 libweb_js_bindings(CSS/ScreenOrientation)
+libweb_js_bindings(CSS/StylePropertyMap)
 libweb_js_bindings(CSS/StylePropertyMapReadOnly)
 libweb_js_bindings(CSS/StyleSheet)
 libweb_js_bindings(CSS/StyleSheetList)

Tests/LibWeb/Text/expected/all-window-properties.txt

@@ -409,6 +409,7 @@ Storage
 StorageEvent
 StorageManager
 String
+StylePropertyMap
 StylePropertyMapReadOnly
 StyleSheet
 StyleSheetList