From bbcc71fec42b991c638e0917be874c01107faf53 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Tue, 1 Dec 2020 15:40:20 +0100
Subject: [PATCH] LibWeb: Parse :before and :after pseudo-elements

Note that this is the old CSS2 syntax, we don't support the CSS3 syntax
just yet. Also we don't actually implement the pseudo-elements, this is
really just to make the selectors distinct from the same ones without
these pseudo-elements.
---
 Libraries/LibWeb/CSS/Parser/CSSParser.cpp | 6 ++++++
 Libraries/LibWeb/CSS/Selector.h           | 7 +++++++
 Libraries/LibWeb/CSS/SelectorEngine.cpp   | 8 ++++++++
 3 files changed, 21 insertions(+)

diff --git a/Libraries/LibWeb/CSS/Parser/CSSParser.cpp b/Libraries/LibWeb/CSS/Parser/CSSParser.cpp
index e5c024d768..ef1884e720 100644
--- a/Libraries/LibWeb/CSS/Parser/CSSParser.cpp
+++ b/Libraries/LibWeb/CSS/Parser/CSSParser.cpp
@@ -502,6 +502,7 @@ public:
             return CSS::Selector::SimpleSelector {
                 type,
                 CSS::Selector::SimpleSelector::PseudoClass::None,
+                CSS::Selector::SimpleSelector::PseudoElement::None,
                 String(),
                 CSS::Selector::SimpleSelector::AttributeMatchType::None,
                 String(),
@@ -537,6 +538,7 @@ public:
         CSS::Selector::SimpleSelector simple_selector {
             type,
             CSS::Selector::SimpleSelector::PseudoClass::None,
+            CSS::Selector::SimpleSelector::PseudoElement::None,
             value,
             CSS::Selector::SimpleSelector::AttributeMatchType::None,
             String(),
@@ -639,6 +641,10 @@ public:
                 simple_selector.pseudo_class = CSS::Selector::SimpleSelector::PseudoClass::Empty;
             else if (pseudo_name.equals_ignoring_case("root"))
                 simple_selector.pseudo_class = CSS::Selector::SimpleSelector::PseudoClass::Root;
+            else if (pseudo_name.equals_ignoring_case("before"))
+                simple_selector.pseudo_element = CSS::Selector::SimpleSelector::PseudoElement::Before;
+            else if (pseudo_name.equals_ignoring_case("after"))
+                simple_selector.pseudo_element = CSS::Selector::SimpleSelector::PseudoElement::After;
         }
 
         if (index == index_at_start) {
diff --git a/Libraries/LibWeb/CSS/Selector.h b/Libraries/LibWeb/CSS/Selector.h
index 463aa013eb..d5dae94f98 100644
--- a/Libraries/LibWeb/CSS/Selector.h
+++ b/Libraries/LibWeb/CSS/Selector.h
@@ -57,6 +57,13 @@ public:
         };
         PseudoClass pseudo_class { PseudoClass::None };
 
+        enum class PseudoElement {
+            None,
+            Before,
+            After,
+        };
+        PseudoElement pseudo_element { PseudoElement::None };
+
         FlyString value;
 
         enum class AttributeMatchType {
diff --git a/Libraries/LibWeb/CSS/SelectorEngine.cpp b/Libraries/LibWeb/CSS/SelectorEngine.cpp
index 942fccf0cd..306356ff57 100644
--- a/Libraries/LibWeb/CSS/SelectorEngine.cpp
+++ b/Libraries/LibWeb/CSS/SelectorEngine.cpp
@@ -44,6 +44,14 @@ static bool matches_hover_pseudo_class(const DOM::Element& element)
 
 static bool matches(const CSS::Selector::SimpleSelector& component, const DOM::Element& element)
 {
+    switch (component.pseudo_element) {
+    case CSS::Selector::SimpleSelector::PseudoElement::None:
+        break;
+    default:
+        // FIXME: Implement pseudo-elements.
+        return false;
+    }
+
     switch (component.pseudo_class) {
     case CSS::Selector::SimpleSelector::PseudoClass::None:
         break;