LibWeb/CSS: Make CSS Parser::create() infallible

Now that `Tokenizer::tokenize()` just returns a String, there are no
errors to propagate, and we can simplify the user code a bit.

Userland/Libraries/LibWeb/Animations/AnimationEffect.cpp

@@ -594,11 +594,9 @@ Optional<double> AnimationEffect::transformed_progress() const
 
 RefPtr<CSS::StyleValue const> AnimationEffect::parse_easing_string(JS::Realm& realm, StringView value)
 {
-    auto maybe_parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), value);
-    if (maybe_parser.is_error())
-        return {};
+    auto parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), value);
 
-    if (auto style_value = maybe_parser.release_value().parse_as_css_value(CSS::PropertyID::AnimationTimingFunction)) {
+    if (auto style_value = parser.parse_as_css_value(CSS::PropertyID::AnimationTimingFunction)) {
         if (style_value->is_easing())
             return style_value;
     }

Userland/Libraries/LibWeb/Animations/KeyframeEffect.cpp

@@ -540,11 +540,9 @@ static WebIDL::ExceptionOr<Vector<BaseKeyframe>> process_a_keyframes_argument(JS
             if (!property_id.has_value())
                 continue;
 
-            auto maybe_parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), value_string);
-            if (maybe_parser.is_error())
-                continue;
+            auto parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), value_string);
 
-            if (auto style_value = maybe_parser.release_value().parse_as_css_value(*property_id)) {
+            if (auto style_value = parser.parse_as_css_value(*property_id)) {
                 // Handle 'initial' here so we don't have to get the default value of the property every frame in StyleComputer
                 if (style_value->is_initial())
                     style_value = CSS::property_initial_value(realm, *property_id);

Userland/Libraries/LibWeb/CSS/FontFace.cpp

@@ -61,11 +61,8 @@ JS_DEFINE_ALLOCATOR(FontFace);
 template<CSS::PropertyID PropertyID>
 RefPtr<CSS::StyleValue const> parse_property_string(JS::Realm& realm, StringView value)
 {
-    auto maybe_parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), value);
-    if (maybe_parser.is_error())
-        return {};
-
-    return maybe_parser.release_value().parse_as_css_value(PropertyID);
+    auto parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), value);
+    return parser.parse_as_css_value(PropertyID);
 }
 
 // https://drafts.csswg.org/css-font-loading/#font-face-constructor
@@ -92,15 +89,10 @@ JS::NonnullGCPtr<FontFace> FontFace::construct_impl(JS::Realm& realm, String fam
     Vector<CSS::ParsedFontFace::Source> sources;
     ByteBuffer buffer;
     if (auto* string = source.get_pointer<String>()) {
-        auto maybe_parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm, base_url), *string);
-        if (maybe_parser.is_error()) {
+        auto parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm, base_url), *string);
+        sources = parser.parse_as_font_face_src();
+        if (sources.is_empty())
             WebIDL::reject_promise(realm, promise, WebIDL::SyntaxError::create(realm, "FontFace constructor: Invalid source string"_fly_string));
-        } else {
-            auto parser = maybe_parser.release_value();
-            sources = parser.parse_as_font_face_src();
-            if (sources.is_empty())
-                WebIDL::reject_promise(realm, promise, WebIDL::SyntaxError::create(realm, "FontFace constructor: Invalid source string"_fly_string));
-        }
     } else {
         auto buffer_source = source.get<JS::Handle<WebIDL::BufferSource>>();
         auto maybe_buffer = WebIDL::get_buffer_source_copy(buffer_source->raw_object());

Userland/Libraries/LibWeb/CSS/Parser/Helpers.cpp

@@ -22,64 +22,55 @@ CSS::CSSStyleSheet* parse_css_stylesheet(CSS::Parser::ParsingContext const& cont
         auto media_list = CSS::MediaList::create(context.realm(), {});
         return CSS::CSSStyleSheet::create(context.realm(), rule_list, media_list, location);
     }
-    auto parser = CSS::Parser::Parser::create(context, css).release_value_but_fixme_should_propagate_errors();
-    return parser.parse_as_css_stylesheet(location);
+    return CSS::Parser::Parser::create(context, css).parse_as_css_stylesheet(location);
 }
 
 CSS::ElementInlineCSSStyleDeclaration* parse_css_style_attribute(CSS::Parser::ParsingContext const& context, StringView css, DOM::Element& element)
 {
     if (css.is_empty())
         return CSS::ElementInlineCSSStyleDeclaration::create(element, {}, {});
-    auto parser = CSS::Parser::Parser::create(context, css).release_value_but_fixme_should_propagate_errors();
-    return parser.parse_as_style_attribute(element);
+    return CSS::Parser::Parser::create(context, css).parse_as_style_attribute(element);
 }
 
 RefPtr<CSS::StyleValue> parse_css_value(CSS::Parser::ParsingContext const& context, StringView string, CSS::PropertyID property_id)
 {
     if (string.is_empty())
         return nullptr;
-    auto parser = MUST(CSS::Parser::Parser::create(context, string));
-    return parser.parse_as_css_value(property_id);
+    return CSS::Parser::Parser::create(context, string).parse_as_css_value(property_id);
 }
 
 CSS::CSSRule* parse_css_rule(CSS::Parser::ParsingContext const& context, StringView css_text)
 {
-    auto parser = CSS::Parser::Parser::create(context, css_text).release_value_but_fixme_should_propagate_errors();
-    return parser.parse_as_css_rule();
+    return CSS::Parser::Parser::create(context, css_text).parse_as_css_rule();
 }
 
 Optional<CSS::SelectorList> parse_selector(CSS::Parser::ParsingContext const& context, StringView selector_text)
 {
-    auto parser = CSS::Parser::Parser::create(context, selector_text).release_value_but_fixme_should_propagate_errors();
-    return parser.parse_as_selector();
+    return CSS::Parser::Parser::create(context, selector_text).parse_as_selector();
 }
 
 RefPtr<CSS::MediaQuery> parse_media_query(CSS::Parser::ParsingContext const& context, StringView string)
 {
-    auto parser = CSS::Parser::Parser::create(context, string).release_value_but_fixme_should_propagate_errors();
-    return parser.parse_as_media_query();
+    return CSS::Parser::Parser::create(context, string).parse_as_media_query();
 }
 
 Vector<NonnullRefPtr<CSS::MediaQuery>> parse_media_query_list(CSS::Parser::ParsingContext const& context, StringView string)
 {
-    auto parser = CSS::Parser::Parser::create(context, string).release_value_but_fixme_should_propagate_errors();
-    return parser.parse_as_media_query_list();
+    return CSS::Parser::Parser::create(context, string).parse_as_media_query_list();
 }
 
 RefPtr<CSS::Supports> parse_css_supports(CSS::Parser::ParsingContext const& context, StringView string)
 {
     if (string.is_empty())
         return {};
-    auto parser = CSS::Parser::Parser::create(context, string).release_value_but_fixme_should_propagate_errors();
-    return parser.parse_as_supports();
+    return CSS::Parser::Parser::create(context, string).parse_as_supports();
 }
 
 Optional<CSS::StyleProperty> parse_css_supports_condition(CSS::Parser::ParsingContext const& context, StringView string)
 {
     if (string.is_empty())
         return {};
-    auto parser = CSS::Parser::Parser::create(context, string).release_value_but_fixme_should_propagate_errors();
-    return parser.parse_as_supports_condition();
+    return CSS::Parser::Parser::create(context, string).parse_as_supports_condition();
 }
 
 }

Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp

@@ -93,7 +93,7 @@ static void log_parse_error(SourceLocation const& location = SourceLocation::cur
 
 namespace Web::CSS::Parser {
 
-ErrorOr<Parser> Parser::create(ParsingContext const& context, StringView input, StringView encoding)
+Parser Parser::create(ParsingContext const& context, StringView input, StringView encoding)
 {
     auto tokens = Tokenizer::tokenize(input, encoding);
     return Parser { context, move(tokens) };
@@ -7788,7 +7788,7 @@ NonnullRefPtr<StyleValue> Parser::resolve_unresolved_style_value(ParsingContext
 
     // If the value is invalid, we fall back to `unset`: https://www.w3.org/TR/css-variables-1/#invalid-at-computed-value-time
 
-    auto parser = MUST(Parser::create(context, ""sv));
+    auto parser = Parser::create(context, ""sv);
     return parser.resolve_unresolved_style_value(element, pseudo_element, property_id, unresolved);
 }
 
@@ -8072,7 +8072,7 @@ bool Parser::substitute_attr_function(DOM::Element& element, FlyString const& pr
         auto attribute_value = element.get_attribute_value(attribute_name);
         if (attribute_type.equals_ignoring_ascii_case("angle"_fly_string)) {
             // Parse a component value from the attribute’s value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             // If the result is a <dimension-token> whose unit matches the given type, the result is the substitution value.
             // Otherwise, there is no substitution value.
             if (component_value.has_value() && component_value->is(Token::Type::Dimension)) {
@@ -8085,7 +8085,7 @@ bool Parser::substitute_attr_function(DOM::Element& element, FlyString const& pr
             // Parse a component value from the attribute’s value.
             // If the result is a <hex-color> or a named color ident, the substitution value is that result as a <color>.
             // Otherwise there is no substitution value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             if (component_value.has_value()) {
                 if ((component_value->is(Token::Type::Hash)
                         && Color::from_string(MUST(String::formatted("#{}", component_value->token().hash_value()))).has_value())
@@ -8097,7 +8097,7 @@ bool Parser::substitute_attr_function(DOM::Element& element, FlyString const& pr
             }
         } else if (attribute_type.equals_ignoring_ascii_case("flex"_fly_string)) {
             // Parse a component value from the attribute’s value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             // If the result is a <dimension-token> whose unit matches the given type, the result is the substitution value.
             // Otherwise, there is no substitution value.
             if (component_value.has_value() && component_value->is(Token::Type::Dimension)) {
@@ -8108,7 +8108,7 @@ bool Parser::substitute_attr_function(DOM::Element& element, FlyString const& pr
             }
         } else if (attribute_type.equals_ignoring_ascii_case("frequency"_fly_string)) {
             // Parse a component value from the attribute’s value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             // If the result is a <dimension-token> whose unit matches the given type, the result is the substitution value.
             // Otherwise, there is no substitution value.
             if (component_value.has_value() && component_value->is(Token::Type::Dimension)) {
@@ -8131,7 +8131,7 @@ bool Parser::substitute_attr_function(DOM::Element& element, FlyString const& pr
             }
         } else if (attribute_type.equals_ignoring_ascii_case("length"_fly_string)) {
             // Parse a component value from the attribute’s value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             // If the result is a <dimension-token> whose unit matches the given type, the result is the substitution value.
             // Otherwise, there is no substitution value.
             if (component_value.has_value() && component_value->is(Token::Type::Dimension)) {
@@ -8144,14 +8144,14 @@ bool Parser::substitute_attr_function(DOM::Element& element, FlyString const& pr
             // Parse a component value from the attribute’s value.
             // If the result is a <number-token>, the result is the substitution value.
             // Otherwise, there is no substitution value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             if (component_value.has_value() && component_value->is(Token::Type::Number)) {
                 dest.append(component_value.release_value());
                 return true;
             }
         } else if (attribute_type.equals_ignoring_ascii_case("percentage"_fly_string)) {
             // Parse a component value from the attribute’s value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             // If the result is a <percentage-token>, the result is the substitution value.
             // Otherwise, there is no substitution value.
             if (component_value.has_value() && component_value->is(Token::Type::Percentage)) {
@@ -8166,7 +8166,7 @@ bool Parser::substitute_attr_function(DOM::Element& element, FlyString const& pr
             return true;
         } else if (attribute_type.equals_ignoring_ascii_case("time"_fly_string)) {
             // Parse a component value from the attribute’s value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             // If the result is a <dimension-token> whose unit matches the given type, the result is the substitution value.
             // Otherwise, there is no substitution value.
             if (component_value.has_value() && component_value->is(Token::Type::Dimension)) {
@@ -8186,7 +8186,7 @@ bool Parser::substitute_attr_function(DOM::Element& element, FlyString const& pr
             // Parse a component value from the attribute’s value.
             // If the result is a <number-token>, the substitution value is a dimension with the result’s value, and the given unit.
             // Otherwise, there is no substitution value.
-            auto component_value = MUST(Parser::Parser::create(m_context, attribute_value)).parse_as_component_value();
+            auto component_value = Parser::Parser::create(m_context, attribute_value).parse_as_component_value();
             if (component_value.has_value() && component_value->is(Token::Type::Number)) {
                 if (attribute_value == "%"sv) {
                     dest.empend(Token::create_dimension(component_value->token().number_value(), attribute_type));

Userland/Libraries/LibWeb/CSS/Parser/Parser.h

@@ -40,7 +40,7 @@ class PropertyDependencyNode;
 
 class Parser {
 public:
-    static ErrorOr<Parser> create(ParsingContext const&, StringView input, StringView encoding = "utf-8"sv);
+    static Parser create(ParsingContext const&, StringView input, StringView encoding = "utf-8"sv);
 
     Parser(Parser&&);
 

Userland/Libraries/LibWeb/HTML/Canvas/CanvasFillStrokeStyles.h

@@ -33,12 +33,7 @@ public:
             // 1. If the given value is a string, then:
             [&](String const& string) {
                 // 1. Let context be this's canvas attribute's value, if that is an element; otherwise null.
-                auto maybe_parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), string);
-                if (maybe_parser.is_error()) {
-                    dbgln_if(CANVAS_RENDERING_CONTEXT_2D_DEBUG, "CanvasFillStrokeStyles: Failed to create CSS parser.");
-                    return;
-                }
-                auto parser = maybe_parser.release_value();
+                auto parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), string);
 
                 // 2. Let parsedValue be the result of parsing the given value with context if non-null.
                 // FIXME: Parse a color value
@@ -80,12 +75,7 @@ public:
             // 1. If the given value is a string, then:
             [&](String const& string) {
                 // 1. Let context be this's canvas attribute's value, if that is an element; otherwise null.
-                auto maybe_parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), string);
-                if (maybe_parser.is_error()) {
-                    dbgln_if(CANVAS_RENDERING_CONTEXT_2D_DEBUG, "CanvasFillStrokeStyles: Failed to create CSS parser.");
-                    return;
-                }
-                auto parser = maybe_parser.release_value();
+                auto parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext(realm), string);
 
                 // 2. Let parsedValue be the result of parsing the given value with context if non-null.
                 // FIXME: Parse a color value

Userland/Libraries/LibWeb/HTML/SourceSet.cpp

@@ -341,7 +341,7 @@ descriptor_parser:
 // https://html.spec.whatwg.org/multipage/images.html#parse-a-sizes-attribute
 CSS::LengthOrCalculated parse_a_sizes_attribute(DOM::Document const& document, StringView sizes)
 {
-    auto css_parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext { document }, sizes).release_value_but_fixme_should_propagate_errors();
+    auto css_parser = CSS::Parser::Parser::create(CSS::Parser::ParsingContext { document }, sizes);
     return css_parser.parse_as_sizes_attribute();
 }