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LibWeb/CSS: Parse media-feature values forgivingly
Instead of rejecting invalid media-feature values at parse time, we are expected to parse them, and then treat them as Unknown when evaluating their media query. To implement this, we first try to parse a valid value as before. If that fails, or we have any trailing tokens that could be part of a value, we then scoop up all the possible ComponentValues and treat that as an "unknown"-type MediaFeatureValue. This gets us 66 WPT passes.
This commit is contained in:
Sam Atkins
parent
72f50217b0
commit
9b8dc6b8d0
Notes:
github-actions[bot]
2025-05-23 09:19:18 +00:00
Author: https://github.com/AtkinsSJ
Commit: 9b8dc6b8d0
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4817
15 changed files with 228 additions and 146 deletions
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@ -1,7 +1,7 @@
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/*
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* Copyright (c) 2018-2022, Andreas Kling <andreas@ladybird.org>
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* Copyright (c) 2020-2021, the SerenityOS developers.
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* Copyright (c) 2021-2024, Sam Atkins <sam@ladybird.org>
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* Copyright (c) 2021-2025, Sam Atkins <sam@ladybird.org>
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* Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
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* Copyright (c) 2022, MacDue <macdue@dueutil.tech>
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*
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@ -314,7 +314,7 @@ OwnPtr<MediaFeature> Parser::parse_media_feature(TokenStream<ComponentValue>& to
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// `<mf-name> <mf-comparison> <mf-value>`
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// NOTE: We have to check for <mf-name> first, since all <mf-name>s will also parse as <mf-value>.
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if (auto maybe_name = parse_mf_name(tokens, false); maybe_name.has_value() && media_feature_type_is_range(maybe_name->id)) {
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if (auto maybe_name = parse_mf_name(tokens, false); maybe_name.has_value()) {
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tokens.discard_whitespace();
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if (auto maybe_comparison = parse_comparison(tokens); maybe_comparison.has_value()) {
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tokens.discard_whitespace();
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@ -352,7 +352,7 @@ OwnPtr<MediaFeature> Parser::parse_media_feature(TokenStream<ComponentValue>& to
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}
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// Now, we can parse the range properly.
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if (maybe_name.has_value() && media_feature_type_is_range(maybe_name->id)) {
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if (maybe_name.has_value()) {
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if (auto maybe_left_value = parse_media_feature_value(maybe_name->id, tokens); maybe_left_value.has_value()) {
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tokens.discard_whitespace();
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if (auto maybe_left_comparison = parse_comparison(tokens); maybe_left_comparison.has_value()) {
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@ -428,71 +428,148 @@ Optional<MediaQuery::MediaType> Parser::parse_media_type(TokenStream<ComponentVa
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};
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}
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static bool is_media_feature_value_token(ComponentValue const& component_value)
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{
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if (!component_value.is_token())
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return true;
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switch (component_value.token().type()) {
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case Token::Type::Ident:
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case Token::Type::Function:
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case Token::Type::AtKeyword:
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case Token::Type::Hash:
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case Token::Type::String:
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case Token::Type::BadString:
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case Token::Type::Url:
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case Token::Type::BadUrl:
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case Token::Type::Number:
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case Token::Type::Percentage:
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case Token::Type::Dimension:
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case Token::Type::Whitespace:
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case Token::Type::Comma:
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return true;
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case Token::Type::Delim:
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// FIXME: What list of delimiters should we actually allow here?
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return !first_is_one_of(component_value.token().delim(), static_cast<u32>('<'), static_cast<u32>('>'), static_cast<u32>('='));
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case Token::Type::Invalid:
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case Token::Type::EndOfFile:
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case Token::Type::CDO:
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case Token::Type::CDC:
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case Token::Type::Colon:
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case Token::Type::Semicolon:
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case Token::Type::OpenSquare:
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case Token::Type::CloseSquare:
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case Token::Type::OpenParen:
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case Token::Type::CloseParen:
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case Token::Type::OpenCurly:
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case Token::Type::CloseCurly:
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return false;
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}
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VERIFY_NOT_REACHED();
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}
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// `<mf-value>`, https://www.w3.org/TR/mediaqueries-4/#typedef-mf-value
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Optional<MediaFeatureValue> Parser::parse_media_feature_value(MediaFeatureID media_feature, TokenStream<ComponentValue>& tokens)
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{
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// Identifiers
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if (tokens.next_token().is(Token::Type::Ident)) {
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{
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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auto keyword = keyword_from_string(tokens.consume_a_token().token().ident());
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if (keyword.has_value() && media_feature_accepts_keyword(media_feature, keyword.value())) {
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transaction.commit();
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return MediaFeatureValue(keyword.value());
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}
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}
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auto value = [this](MediaFeatureID media_feature, TokenStream<ComponentValue>& tokens) -> Optional<MediaFeatureValue> {
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// One branch for each member of the MediaFeatureValueType enum:
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// Identifiers
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if (tokens.next_token().is(Token::Type::Ident)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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auto keyword = keyword_from_string(tokens.consume_a_token().token().ident());
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if (keyword.has_value() && media_feature_accepts_keyword(media_feature, keyword.value())) {
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transaction.commit();
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return MediaFeatureValue(keyword.value());
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}
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}
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// One branch for each member of the MediaFeatureValueType enum:
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// Boolean (<mq-boolean> in the spec: a 1 or 0)
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Boolean)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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if (auto integer = parse_integer(tokens); integer.has_value()) {
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if (integer.value().is_calculated() || integer->value() == 0 || integer->value() == 1) {
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transaction.commit();
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return MediaFeatureValue(integer.release_value());
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}
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}
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}
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// Boolean (<mq-boolean> in the spec: a 1 or 0)
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Boolean)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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if (auto integer = parse_integer(tokens); integer.has_value()) {
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if (integer.value().is_calculated() || integer->value() == 0 || integer->value() == 1) {
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// Integer
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Integer)) {
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auto transaction = tokens.begin_transaction();
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if (auto integer = parse_integer(tokens); integer.has_value()) {
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transaction.commit();
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return MediaFeatureValue(integer.release_value());
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}
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}
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// Length
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Length)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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if (auto length = parse_length(tokens); length.has_value()) {
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transaction.commit();
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return MediaFeatureValue(length.release_value());
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}
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}
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// Ratio
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Ratio)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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if (auto ratio = parse_ratio(tokens); ratio.has_value()) {
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transaction.commit();
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return MediaFeatureValue(ratio.release_value());
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}
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}
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// Resolution
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Resolution)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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if (auto resolution = parse_resolution(tokens); resolution.has_value()) {
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transaction.commit();
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return MediaFeatureValue(resolution.release_value());
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}
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}
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return {};
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}(media_feature, tokens);
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if (value.has_value()) {
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tokens.discard_whitespace();
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// Only returned the value if there are no trailing tokens.
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// Otherwise, the transaction gets reverted and we consume all the value tokens below.
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if (!is_media_feature_value_token(tokens.next_token())) {
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transaction.commit();
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return MediaFeatureValue(integer.release_value());
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return value.release_value();
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}
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}
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}
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// Integer
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Integer)) {
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auto transaction = tokens.begin_transaction();
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if (auto integer = parse_integer(tokens); integer.has_value()) {
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transaction.commit();
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return MediaFeatureValue(integer.release_value());
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// Parsing failed somehow, so wrap all the tokens into an "unknown" MediaFeatureValue if possible.
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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Vector<ComponentValue> unknown_tokens;
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// Consume any tokens that could be part of a value.
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while (tokens.has_next_token()) {
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if (is_media_feature_value_token(tokens.next_token())) {
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unknown_tokens.append(tokens.consume_a_token());
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} else {
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break;
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}
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}
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// Length
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Length)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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if (auto length = parse_length(tokens); length.has_value()) {
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transaction.commit();
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return MediaFeatureValue(length.release_value());
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}
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}
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// Ratio
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Ratio)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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if (auto ratio = parse_ratio(tokens); ratio.has_value()) {
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transaction.commit();
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return MediaFeatureValue(ratio.release_value());
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}
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}
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// Resolution
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if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Resolution)) {
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auto transaction = tokens.begin_transaction();
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tokens.discard_whitespace();
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if (auto resolution = parse_resolution(tokens); resolution.has_value()) {
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transaction.commit();
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return MediaFeatureValue(resolution.release_value());
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}
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if (!unknown_tokens.is_empty()) {
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transaction.commit();
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dbgln_if(CSS_PARSER_DEBUG, "Creating unknown media value: `{}`", String::join(""sv, unknown_tokens));
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return MediaFeatureValue(move(unknown_tokens));
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}
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return {};
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