Everywhere: Hoist the Libraries folder to the top-level

Author: https://github.com/trflynn89
Commit: 93712b24bf
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2256
Reviewed-by: https://github.com/sideshowbarker

Libraries/LibWeb/Animations/PseudoElementParsing.cpp

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2024, Sam Atkins <sam@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "PseudoElementParsing.h"
+#include <LibWeb/CSS/Parser/Parser.h>
+
+namespace Web::Animations {
+
+// https://drafts.csswg.org/web-animations-1/#dom-keyframeeffect-pseudo-element-parsing
+WebIDL::ExceptionOr<Optional<CSS::Selector::PseudoElement>> pseudo_element_parsing(JS::Realm& realm, Optional<String> const& value)
+{
+    // 1. Given the value value, perform the following steps:
+
+    // 2. If value is not null and is an invalid <pseudo-element-selector>,
+    Optional<CSS::Selector::PseudoElement> pseudo_element;
+    if (value.has_value()) {
+        pseudo_element = parse_pseudo_element_selector(CSS::Parser::ParsingContext { realm }, *value);
+        if (!pseudo_element.has_value()) {
+            // 1. Throw a DOMException with error name "SyntaxError".
+            // 2. Abort.
+            return WebIDL::SyntaxError::create(realm, MUST(String::formatted("Invalid pseudo-element selector: \"{}\"", value.value())));
+        }
+    }
+
+    // 3. If value is one of the legacy Selectors Level 2 single-colon selectors (':before', ':after', ':first-letter', or ':first-line'),
+    // then return the equivalent two-colon selector (e.g. '::before').
+    if (value.has_value() && value->is_one_of(":before", ":after", ":first-letter", ":first-line")) {
+        return CSS::Selector::PseudoElement::from_string(MUST(value->substring_from_byte_offset(1)));
+    }
+
+    // 4. Otherwise, return value.
+    return pseudo_element;
+}
+
+}