From 0578bec65572ef77b88c2651a83e48e2c70600b8 Mon Sep 17 00:00:00 2001
From: Sam Atkins <atkinssj@serenityos.org>
Date: Fri, 8 Dec 2023 17:06:04 +0000
Subject: [PATCH] LibWeb: Parse math-depth property using TokenStream

We don't need to skip whitespace at the top level because that's already
done before we're called. But we do still have to skip it inside the
`add()` function
---
 .../Libraries/LibWeb/CSS/Parser/Parser.cpp    | 20 +++++++++++--------
 Userland/Libraries/LibWeb/CSS/Parser/Parser.h |  2 +-
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index 6da4b4496d..b075c8b4a7 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -4443,21 +4443,21 @@ RefPtr<StyleValue> Parser::parse_list_style_value(TokenStream<ComponentValue>& t
         { list_position.release_nonnull(), list_image.release_nonnull(), list_type.release_nonnull() });
 }
 
-RefPtr<StyleValue> Parser::parse_math_depth_value(Vector<ComponentValue> const& component_values)
+RefPtr<StyleValue> Parser::parse_math_depth_value(TokenStream<ComponentValue>& tokens)
 {
     // https://w3c.github.io/mathml-core/#propdef-math-depth
     // auto-add | add(<integer>) | <integer>
-    auto tokens = TokenStream { component_values };
+    auto transaction = tokens.begin_transaction();
 
-    tokens.skip_whitespace();
     auto token = tokens.next_token();
-    tokens.skip_whitespace();
     if (tokens.has_next_token())
         return nullptr;
 
     // auto-add
-    if (token.is_ident("auto-add"sv))
+    if (token.is_ident("auto-add"sv)) {
+        transaction.commit();
         return MathDepthStyleValue::create_auto_add();
+    }
 
     // FIXME: Make it easier to parse "thing that might be <bar> or literally anything that resolves to it" and get rid of this
     auto parse_something_that_resolves_to_integer = [this](ComponentValue& token) -> RefPtr<StyleValue> {
@@ -4476,14 +4476,18 @@ RefPtr<StyleValue> Parser::parse_math_depth_value(Vector<ComponentValue> const&
         add_tokens.skip_whitespace();
         if (add_tokens.has_next_token())
             return nullptr;
-        if (auto integer_value = parse_something_that_resolves_to_integer(integer_token))
+        if (auto integer_value = parse_something_that_resolves_to_integer(integer_token)) {
+            transaction.commit();
             return MathDepthStyleValue::create_add(integer_value.release_nonnull());
+        }
         return nullptr;
     }
 
     // <integer>
-    if (auto integer_value = parse_something_that_resolves_to_integer(token))
+    if (auto integer_value = parse_something_that_resolves_to_integer(token)) {
+        transaction.commit();
         return MathDepthStyleValue::create_integer(integer_value.release_nonnull());
+    }
 
     return nullptr;
 }
@@ -5907,7 +5911,7 @@ Parser::ParseErrorOr<NonnullRefPtr<StyleValue>> Parser::parse_css_value(Property
             return parsed_value.release_nonnull();
         return ParseError::SyntaxError;
     case PropertyID::MathDepth:
-        if (auto parsed_value = parse_math_depth_value(component_values))
+        if (auto parsed_value = parse_math_depth_value(tokens); parsed_value && !tokens.has_next_token())
             return parsed_value.release_nonnull();
         return ParseError::SyntaxError;
     case PropertyID::Overflow:
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.h b/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
index c1e02b5870..c088924b56 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
@@ -241,7 +241,7 @@ private:
     RefPtr<StyleValue> parse_font_value(TokenStream<ComponentValue>&);
     RefPtr<StyleValue> parse_font_family_value(TokenStream<ComponentValue>&);
     RefPtr<StyleValue> parse_list_style_value(TokenStream<ComponentValue>&);
-    RefPtr<StyleValue> parse_math_depth_value(Vector<ComponentValue> const&);
+    RefPtr<StyleValue> parse_math_depth_value(TokenStream<ComponentValue>&);
     RefPtr<StyleValue> parse_overflow_value(Vector<ComponentValue> const&);
     RefPtr<StyleValue> parse_place_content_value(Vector<ComponentValue> const&);
     RefPtr<StyleValue> parse_place_items_value(Vector<ComponentValue> const&);