LibWeb: Make a elements honor base element's target

Author: https://github.com/Psychpsyo
Commit: f839f1b44b
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3576

Libraries/LibWeb/DOM/Document.cpp

@@ -536,6 +536,7 @@ void Document::visit_edges(Cell::Visitor& visitor)
     visitor.visit(m_fonts);
     visitor.visit(m_selection);
     visitor.visit(m_first_base_element_with_href_in_tree_order);
+    visitor.visit(m_first_base_element_with_target_in_tree_order);
     visitor.visit(m_parser);
     visitor.visit(m_lazy_load_intersection_observer);
     visitor.visit(m_visual_viewport);
@@ -1075,18 +1076,26 @@ Vector<CSS::BackgroundLayerData> const* Document::background_layers() const
 
 void Document::update_base_element(Badge<HTML::HTMLBaseElement>)
 {
-    GC::Ptr<HTML::HTMLBaseElement const> base_element;
+    GC::Ptr<HTML::HTMLBaseElement const> base_element_with_href = nullptr;
+    GC::Ptr<HTML::HTMLBaseElement const> base_element_with_target = nullptr;
 
-    for_each_in_subtree_of_type<HTML::HTMLBaseElement>([&base_element](HTML::HTMLBaseElement const& base_element_in_tree) {
-        if (base_element_in_tree.has_attribute(HTML::AttributeNames::href)) {
-            base_element = &base_element_in_tree;
+    for_each_in_subtree_of_type<HTML::HTMLBaseElement>([&base_element_with_href, &base_element_with_target](HTML::HTMLBaseElement const& base_element_in_tree) {
+        if (!base_element_with_href && base_element_in_tree.has_attribute(HTML::AttributeNames::href)) {
+            base_element_with_href = &base_element_in_tree;
+            if (base_element_with_target)
+                return TraversalDecision::Break;
+        }
+        if (!base_element_with_target && base_element_in_tree.has_attribute(HTML::AttributeNames::target)) {
+            base_element_with_target = &base_element_in_tree;
+            if (base_element_with_href)
                 return TraversalDecision::Break;
         }
 
         return TraversalDecision::Continue;
     });
 
-    m_first_base_element_with_href_in_tree_order = base_element;
+    m_first_base_element_with_href_in_tree_order = base_element_with_href;
+    m_first_base_element_with_target_in_tree_order = base_element_with_target;
 }
 
 GC::Ptr<HTML::HTMLBaseElement const> Document::first_base_element_with_href_in_tree_order() const
@@ -1094,6 +1103,11 @@ GC::Ptr<HTML::HTMLBaseElement const> Document::first_base_element_with_href_in_t
     return m_first_base_element_with_href_in_tree_order;
 }
 
+GC::Ptr<HTML::HTMLBaseElement const> Document::first_base_element_with_target_in_tree_order() const
+{
+    return m_first_base_element_with_target_in_tree_order;
+}
+
 // https://html.spec.whatwg.org/multipage/urls-and-fetching.html#fallback-base-url
 URL::URL Document::fallback_base_url() const
 {

Libraries/LibWeb/DOM/Document.h

@@ -152,6 +152,7 @@ public:
 
     void update_base_element(Badge<HTML::HTMLBaseElement>);
     GC::Ptr<HTML::HTMLBaseElement const> first_base_element_with_href_in_tree_order() const;
+    GC::Ptr<HTML::HTMLBaseElement const> first_base_element_with_target_in_tree_order() const;
 
     String url_string() const { return m_url.to_string(); }
     String document_uri() const { return url_string(); }
@@ -1022,8 +1023,9 @@ private:
     // https://w3c.github.io/selection-api/#dfn-selection
     GC::Ptr<Selection::Selection> m_selection;
 
-    // NOTE: This is a cache to make finding the first <base href> element O(1).
+    // NOTE: This is a cache to make finding the first <base href> or <base target> element O(1).
     GC::Ptr<HTML::HTMLBaseElement const> m_first_base_element_with_href_in_tree_order;
+    GC::Ptr<HTML::HTMLBaseElement const> m_first_base_element_with_target_in_tree_order;
 
     // https://html.spec.whatwg.org/multipage/images.html#list-of-available-images
     GC::Ptr<HTML::ListOfAvailableImages> m_list_of_available_images;

Libraries/LibWeb/HTML/HTMLElement.cpp

@@ -948,8 +948,10 @@ String HTMLElement::get_an_elements_target(Optional<String> target) const
         if (auto maybe_target = attribute(AttributeNames::target); maybe_target.has_value()) {
             target = maybe_target.release_value();
         }
-        // FIXME: 2. Otherwise, if element's node document contains a base element with a target attribute,
+        // 2. Otherwise, if element's node document contains a base element with a target attribute,
         //    set target to the value of the target attribute of the first such base element.
+        if (auto base_element = document().first_base_element_with_target_in_tree_order())
+            target = base_element->attribute(AttributeNames::target);
     }
 
     // 2. If target is not null, and contains an ASCII tab or newline and a U+003C (<), then set target to "_blank".

Tests/LibWeb/Text/data/base/a-element-target-sub-alt.html

@@ -0,0 +1,2 @@
+<!DOCTYPE html>
+SUCCESS!

Tests/LibWeb/Text/data/base/a-element-target-sub-sub.html

@@ -0,0 +1,3 @@
+<!DOCTYPE html>
+<base target="_parent">
+<a id="a" href="a-element-target-sub-alt.html">Click me!</a>

Tests/LibWeb/Text/data/base/a-element-target-sub.html

@@ -0,0 +1,2 @@
+<!DOCTYPE html>
+<iframe id="frame" src="a-element-target-sub-sub.html"></iframe>

Tests/LibWeb/Text/expected/base/a-element-target.txt

@@ -0,0 +1 @@
+Parent frame navigated successfully!

Tests/LibWeb/Text/input/base/a-element-target.html

@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<script src="../include.js"></script>
+<iframe id="frame" src="../../data/base/a-element-target-sub.html"></iframe>
+<script>
+    asyncTest(done => {
+        window.onload = () => {
+            frame.onload = () => {
+                frame.onload = () => {
+                    println(frame.contentDocument.location.href.includes("a-element-target-sub-alt.html")? "Parent frame navigated successfully!" : "Parent frame incorrectly navigated to " + frame.contentDocument.location.href);
+                    done();
+                }
+            }
+            frame.contentDocument.getElementById("frame").contentDocument.getElementById("a").click();
+        };
+    });
+</script>