From d72ce7b989362801bbc236e391c68902d1dc189f Mon Sep 17 00:00:00 2001
From: Sam Atkins <atkinssj@gmail.com>
Date: Wed, 14 Jul 2021 16:20:06 +0100
Subject: [PATCH] LibWeb: Generate a ValueListStyleValue when parsing CSS
 values

We skip whitespace tokens while doing this. As far as I can tell,
whitespace is not useful once we get to this point, and it legally
may or may not appear between any two tokens. By not including it
in the ValueListStyleValue, we make the "if it has 3 parts"-type
checks a lot more straightforward.
---
 .../Libraries/LibWeb/CSS/Parser/Parser.cpp    | 80 ++++++++++++-------
 Userland/Libraries/LibWeb/CSS/Parser/Parser.h |  2 +
 2 files changed, 53 insertions(+), 29 deletions(-)

diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
index 679d28cfc6..beb13f4560 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
@@ -1271,10 +1271,9 @@ Optional<float> Parser::try_parse_float(StringView string)
     return is_negative ? -value : value;
 }
 
-RefPtr<StyleValue> Parser::parse_css_value(PropertyID property_id, TokenStream<StyleComponentValueRule>& tokens)
+RefPtr<StyleValue> Parser::parse_single_css_value(PropertyID property_id, StyleComponentValueRule const& component_value)
 {
-    dbgln_if(CSS_PARSER_TRACE, "Parser::parse_css_value");
-
+    dbgln_if(CSS_PARSER_TRACE, "Parser::parse_single_css_value '{}'", component_value.to_debug_string());
     // FIXME: This is mostly copied from the old, deprecated parser. It is probably not to spec.
 
     auto takes_integer_value = [](PropertyID property_id) -> bool {
@@ -1287,11 +1286,9 @@ RefPtr<StyleValue> Parser::parse_css_value(PropertyID property_id, TokenStream<S
         Length::Type type = Length::Type::Undefined;
         Optional<float> numeric_value;
 
-        auto token = tokens.next_token();
-
-        if (token.is(Token::Type::Dimension)) {
-            auto length_string = token.token().m_value.string_view();
-            auto unit_string = token.token().m_unit.string_view();
+        if (component_value.is(Token::Type::Dimension)) {
+            auto length_string = component_value.token().m_value.string_view();
+            auto unit_string = component_value.token().m_unit.string_view();
 
             if (unit_string.equals_ignoring_case("%")) {
                 type = Length::Type::Percentage;
@@ -1328,8 +1325,8 @@ RefPtr<StyleValue> Parser::parse_css_value(PropertyID property_id, TokenStream<S
             }
 
             numeric_value = try_parse_float(length_string);
-        } else if (token.is(Token::Type::Number)) {
-            auto value_string = token.token().m_value.string_view();
+        } else if (component_value.is(Token::Type::Number)) {
+            auto value_string = component_value.token().m_value.string_view();
             if (value_string == "0") {
                 type = Length::Type::Px;
                 numeric_value = 0;
@@ -1345,31 +1342,27 @@ RefPtr<StyleValue> Parser::parse_css_value(PropertyID property_id, TokenStream<S
         return Length(numeric_value.value(), type);
     };
 
-    auto token = tokens.next_token();
-
-    if (takes_integer_value(property_id) && token.is(Token::Type::Number)) {
-        auto number = token.token();
+    if (takes_integer_value(property_id) && component_value.is(Token::Type::Number)) {
+        auto number = component_value.token();
         if (number.m_number_type == Token::NumberType::Integer) {
             return LengthStyleValue::create(Length::make_px(number.integer()));
         }
     }
 
-    if (token.is(Token::Type::Dimension) || token.is(Token::Type::Number)) {
-        tokens.reconsume_current_input_token();
-
+    if (component_value.is(Token::Type::Dimension) || component_value.is(Token::Type::Number)) {
         auto length = parse_length();
         if (length.has_value())
             return LengthStyleValue::create(length.value());
 
-        auto value_string = token.token().m_value.string_view();
+        auto value_string = component_value.token().m_value.string_view();
         auto float_number = try_parse_float(value_string);
         if (float_number.has_value())
             return NumericStyleValue::create(float_number.value());
         return nullptr;
     }
 
-    if (token.is(Token::Type::Ident)) {
-        auto ident = token.token().ident();
+    if (component_value.is(Token::Type::Ident)) {
+        auto ident = component_value.token().ident();
         if (ident.equals_ignoring_case("inherit"))
             return InheritStyleValue::create();
         if (ident.equals_ignoring_case("initial"))
@@ -1378,11 +1371,11 @@ RefPtr<StyleValue> Parser::parse_css_value(PropertyID property_id, TokenStream<S
             return LengthStyleValue::create(Length::make_auto());
     }
 
-    if (token.is_function() && token.function().name().equals_ignoring_case("var")) {
+    if (component_value.is_function() && component_value.function().name().equals_ignoring_case("var")) {
         // FIXME: Handle fallback value as second parameter
         // https://www.w3.org/TR/css-variables-1/#using-variables
-        if (!token.function().values().is_empty()) {
-            auto& property_name_token = token.function().values().first();
+        if (!component_value.function().values().is_empty()) {
+            auto& property_name_token = component_value.function().values().first();
             if (property_name_token.is(Token::Type::Ident))
                 return CustomStyleValue::create(property_name_token.token().ident());
             else
@@ -1390,21 +1383,21 @@ RefPtr<StyleValue> Parser::parse_css_value(PropertyID property_id, TokenStream<S
         }
     }
 
-    if (token.is(Token::Type::Ident)) {
-        auto value_id = value_id_from_string(token.token().ident());
+    if (component_value.is(Token::Type::Ident)) {
+        auto value_id = value_id_from_string(component_value.token().ident());
         if (value_id != ValueID::Invalid)
             return IdentifierStyleValue::create(value_id);
     }
 
     auto parse_css_color = [&]() -> Optional<Color> {
-        if (token.is(Token::Type::Ident) && token.token().ident().equals_ignoring_case("transparent"))
+        if (component_value.is(Token::Type::Ident) && component_value.token().ident().equals_ignoring_case("transparent"))
             return Color::from_rgba(0x00000000);
 
         // FIXME: Handle all the different color notations.
         // https://www.w3.org/TR/css-color-3/
         // Right now, this uses non-CSS-specific parsing, and assumes the whole color value is one token,
         // which is isn't if it's a function-style syntax.
-        auto color = Color::from_string(token.token().m_value.to_string().to_lowercase());
+        auto color = Color::from_string(component_value.token().m_value.to_string().to_lowercase());
         if (color.has_value())
             return color;
 
@@ -1415,12 +1408,41 @@ RefPtr<StyleValue> Parser::parse_css_value(PropertyID property_id, TokenStream<S
     if (color.has_value())
         return ColorStyleValue::create(color.value());
 
-    if (token.is(Token::Type::String))
-        return StringStyleValue::create(token.token().string());
+    if (component_value.is(Token::Type::String))
+        return StringStyleValue::create(component_value.token().string());
 
     return {};
 }
 
+RefPtr<StyleValue> Parser::parse_css_value(PropertyID property_id, TokenStream<StyleComponentValueRule>& tokens)
+{
+    dbgln_if(CSS_PARSER_TRACE, "Parser::parse_css_value");
+
+    Vector<StyleComponentValueRule> component_values;
+
+    while (tokens.has_next_token()) {
+        auto& token = tokens.next_token();
+
+        if (token.is(Token::Type::Semicolon)) {
+            tokens.reconsume_current_input_token();
+            break;
+        }
+
+        if (token.is(Token::Type::Whitespace))
+            continue;
+
+        component_values.append(token);
+    }
+
+    if (component_values.is_empty())
+        return {};
+
+    if (component_values.size() == 1)
+        return parse_single_css_value(property_id, component_values.first());
+
+    return ValueListStyleValue::create(move(component_values));
+}
+
 Optional<Selector::SimpleSelector::NthChildPattern> Parser::parse_nth_child_pattern(TokenStream<StyleComponentValueRule>& values)
 {
     dbgln_if(CSS_PARSER_TRACE, "Parser::parse_nth_child_pattern");
diff --git a/Userland/Libraries/LibWeb/CSS/Parser/Parser.h b/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
index 3e46103f51..6e8b82e927 100644
--- a/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
+++ b/Userland/Libraries/LibWeb/CSS/Parser/Parser.h
@@ -177,6 +177,8 @@ private:
 
     static Optional<float> try_parse_float(StringView string);
 
+    RefPtr<StyleValue> parse_single_css_value(PropertyID, StyleComponentValueRule const&);
+
     ParsingContext m_context;
 
     Tokenizer m_tokenizer;