4 files changed, 116 insertions, 0 deletions
diff --git a/Userland/Libraries/LibWeb/CMakeLists.txt b/Userland/Libraries/LibWeb/CMakeLists.txt
index 911e28bd83..b31840bbb3 100644
--- a/Userland/Libraries/LibWeb/CMakeLists.txt
+++ b/Userland/Libraries/LibWeb/CMakeLists.txt
@@ -25,6 +25,7 @@ set(SOURCES
     CSS/ResolvedCSSStyleDeclaration.cpp
     CSS/DefaultStyleSheetSource.cpp
     CSS/Length.cpp
+    CSS/MediaList.cpp
     CSS/MediaQuery.cpp
     CSS/MediaQueryList.cpp
     CSS/Parser/Parser.cpp
diff --git a/Userland/Libraries/LibWeb/CSS/MediaList.cpp b/Userland/Libraries/LibWeb/CSS/MediaList.cpp
new file mode 100644
index 0000000000..aa8097f256
--- /dev/null
+++ b/Userland/Libraries/LibWeb/CSS/MediaList.cpp
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/CSS/MediaList.h>
+#include <LibWeb/CSS/Parser/Parser.h>
+
+namespace Web::CSS {
+
+MediaList::MediaList(NonnullRefPtrVector<MediaQuery>&& media)
+    : m_media(move(media))
+{
+}
+
+MediaList::~MediaList()
+{
+}
+
+// https://www.w3.org/TR/cssom-1/#dom-medialist-mediatext
+String MediaList::media_text() const
+{
+    StringBuilder builder;
+    builder.join(", ", m_media);
+    return builder.to_string();
+}
+
+// https://www.w3.org/TR/cssom-1/#dom-medialist-mediatext
+void MediaList::set_media_text(String const& text)
+{
+    m_media.clear();
+    if (text.is_empty())
+        return;
+    m_media = parse_media_query_list({}, text);
+}
+
+// https://www.w3.org/TR/cssom-1/#dom-medialist-item
+Optional<String> MediaList::item(size_t index) const
+{
+    if (index >= length())
+        return {};
+
+    return m_media[index].to_string();
+}
+
+// https://www.w3.org/TR/cssom-1/#dom-medialist-appendmedium
+void MediaList::append_medium(String medium)
+{
+    auto m = parse_media_query({}, medium);
+    if (!m)
+        return;
+    if (m_media.contains_slow(*m))
+        return;
+    m_media.append(m.release_nonnull());
+}
+
+// https://www.w3.org/TR/cssom-1/#dom-medialist-deletemedium
+void MediaList::delete_medium(String medium)
+{
+    auto m = parse_media_query({}, medium);
+    if (!m)
+        return;
+    m_media.remove_all_matching([&](auto& existing) -> bool {
+        return m->to_string() == existing->to_string();
+    });
+    // FIXME: If nothing was removed, then throw a NotFoundError exception.
+}
+
+}
diff --git a/Userland/Libraries/LibWeb/CSS/MediaList.h b/Userland/Libraries/LibWeb/CSS/MediaList.h
new file mode 100644
index 0000000000..4586f731bb
--- /dev/null
+++ b/Userland/Libraries/LibWeb/CSS/MediaList.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/NonnullRefPtrVector.h>
+#include <AK/Optional.h>
+#include <AK/RefCounted.h>
+#include <LibWeb/CSS/MediaQuery.h>
+
+namespace Web::CSS {
+
+// https://www.w3.org/TR/cssom-1/#the-medialist-interface
+class MediaList final : public RefCounted<MediaList> {
+public:
+    static NonnullRefPtr<MediaList> create(NonnullRefPtrVector<MediaQuery>&& media)
+    {
+        return adopt_ref(*new MediaList(move(media)));
+    }
+    ~MediaList();
+
+    String media_text() const;
+    void set_media_text(String const&);
+    size_t length() const { return m_media.size(); }
+    Optional<String> item(size_t index) const;
+    void append_medium(String);
+    void delete_medium(String);
+
+private:
+    explicit MediaList(NonnullRefPtrVector<MediaQuery>&&);
+
+    NonnullRefPtrVector<MediaQuery> m_media;
+};
+
+}
diff --git a/Userland/Libraries/LibWeb/CSS/MediaList.idl b/Userland/Libraries/LibWeb/CSS/MediaList.idl
new file mode 100644
index 0000000000..8ab4047b51
--- /dev/null
+++ b/Userland/Libraries/LibWeb/CSS/MediaList.idl
@@ -0,0 +1,7 @@
+interface MediaList {
+    stringifier attribute [LegacyNullToEmptyString] CSSOMString mediaText;
+    readonly attribute unsigned long length;
+    getter CSSOMString? item(unsigned long index);
+    undefined appendMedium(CSSOMString medium);
+    undefined deleteMedium(CSSOMString medium);
+};