LibWeb: Implement DataTransfer.clearData()

Author: https://github.com/tcl3
Commit: 0c1532626f
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6088
Reviewed-by: https://github.com/gmta

Libraries/LibWeb/HTML/DataTransfer.cpp

@@ -264,6 +264,52 @@ void DataTransfer::remove_item(size_t index)
     update_data_transfer_types_list();
 }
 
+// https://html.spec.whatwg.org/multipage/dnd.html#dom-datatransfer-cleardata
+void DataTransfer::clear_data(Optional<String> maybe_format)
+{
+    // 1. If the DataTransfer object is no longer associated with a drag data store, return. Nothing happens.
+    if (!m_associated_drag_data_store)
+        return;
+
+    // 2. If the drag data store's mode is not the read/write mode, return. Nothing happens.
+    if (m_associated_drag_data_store->mode() != DragDataStore::Mode::ReadWrite)
+        return;
+
+    auto remove_items_from_drag_data_store = [&](Optional<String> const& format = {}) {
+        auto did_remove_item = false;
+        for (size_t i = m_associated_drag_data_store->item_list().size(); i > 0; --i) {
+            auto const& item = m_associated_drag_data_store->item_list().at(i - 1);
+            if (item.kind == DragDataStoreItem::Kind::Text && (!format.has_value() || item.type_string == *format)) {
+                m_associated_drag_data_store->remove_item_at(i - 1);
+                did_remove_item = true;
+            }
+        }
+        if (did_remove_item)
+            update_data_transfer_types_list();
+    };
+
+    // 3. If the method was called with no arguments, remove each item in the drag data store item list whose kind is
+    //    Plain Unicode string, and return.
+    if (!maybe_format.has_value()) {
+        remove_items_from_drag_data_store();
+        return;
+    }
+
+    // 4. Set format to format, converted to ASCII lowercase.
+    auto format = maybe_format->to_ascii_lowercase();
+
+    // 5. If format equals "text", change it to "text/plain".
+    //    If format equals "url", change it to "text/uri-list".
+    if (format == "text"sv) {
+        format = "text/plain"_string;
+    } else if (format == "url"sv) {
+        format = "text/uri-list"_string;
+    }
+
+    // 6. Remove each item in the drag data store item list whose kind is Plain Unicode string and whose type string is equal to format.
+    remove_items_from_drag_data_store(format);
+}
+
 bool DataTransfer::contains_item_with_type(DragDataStoreItem::Kind kind, String const& type) const
 {
     VERIFY(m_associated_drag_data_store);

Libraries/LibWeb/HTML/DataTransfer.h

@@ -54,6 +54,7 @@ public:
 
     ReadonlySpan<String> types() const;
     String get_data(String const& format) const;
+    void clear_data(Optional<String> maybe_format = {});
     GC::Ref<FileAPI::FileList> files() const;
 
     Optional<DragDataStore::Mode> mode() const;

Libraries/LibWeb/HTML/DataTransfer.idl

@@ -17,6 +17,6 @@ interface DataTransfer {
     readonly attribute FrozenArray<DOMString> types;
     DOMString getData(DOMString format);
     [FIXME] undefined setData(DOMString format, DOMString data);
-    [FIXME] undefined clearData(optional DOMString format);
+    undefined clearData(optional DOMString format);
     [SameObject] readonly attribute FileList files;
 };