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

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/*
* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2020-2021, the SerenityOS developers.
* Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.org>
* Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
* Copyright (c) 2022, MacDue <macdue@dueutil.tech>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Debug.h>
#include <LibWeb/CSS/CSSMediaRule.h>
#include <LibWeb/CSS/CalculatedOr.h>
#include <LibWeb/CSS/MediaList.h>
#include <LibWeb/CSS/MediaQuery.h>
#include <LibWeb/CSS/Parser/Parser.h>
namespace Web::CSS::Parser {
Vector<NonnullRefPtr<MediaQuery>> Parser::parse_as_media_query_list()
{
return parse_a_media_query_list(m_token_stream);
}
template<typename T>
Vector<NonnullRefPtr<MediaQuery>> Parser::parse_a_media_query_list(TokenStream<T>& tokens)
{
// https://www.w3.org/TR/mediaqueries-4/#mq-list
auto comma_separated_lists = parse_a_comma_separated_list_of_component_values(tokens);
AK::Vector<NonnullRefPtr<MediaQuery>> media_queries;
for (auto& media_query_parts : comma_separated_lists) {
auto stream = TokenStream(media_query_parts);
media_queries.append(parse_media_query(stream));
}
return media_queries;
}
RefPtr<MediaQuery> Parser::parse_as_media_query()
{
// https://www.w3.org/TR/cssom-1/#parse-a-media-query
auto media_query_list = parse_as_media_query_list();
if (media_query_list.is_empty())
return MediaQuery::create_not_all();
if (media_query_list.size() == 1)
return media_query_list.first();
return nullptr;
}
// `<media-query>`, https://www.w3.org/TR/mediaqueries-4/#typedef-media-query
NonnullRefPtr<MediaQuery> Parser::parse_media_query(TokenStream<ComponentValue>& tokens)
{
// `<media-query> = <media-condition>
// | [ not | only ]? <media-type> [ and <media-condition-without-or> ]?`
// `[ not | only ]?`, Returns whether to negate the query
auto parse_initial_modifier = [](auto& tokens) -> Optional<bool> {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
auto& token = tokens.next_token();
if (!token.is(Token::Type::Ident))
return {};
auto ident = token.token().ident();
if (ident.equals_ignoring_ascii_case("not"sv)) {
transaction.commit();
return true;
}
if (ident.equals_ignoring_ascii_case("only"sv)) {
transaction.commit();
return false;
}
return {};
};
auto invalid_media_query = [&]() {
// "A media query that does not match the grammar in the previous section must be replaced by `not all`
// during parsing." - https://www.w3.org/TR/mediaqueries-5/#error-handling
if constexpr (CSS_PARSER_DEBUG) {
dbgln("Invalid media query:");
tokens.dump_all_tokens();
}
return MediaQuery::create_not_all();
};
auto media_query = MediaQuery::create();
tokens.skip_whitespace();
// `<media-condition>`
if (auto media_condition = parse_media_condition(tokens, MediaCondition::AllowOr::Yes)) {
tokens.skip_whitespace();
if (tokens.has_next_token())
return invalid_media_query();
media_query->m_media_condition = move(media_condition);
return media_query;
}
// `[ not | only ]?`
if (auto modifier = parse_initial_modifier(tokens); modifier.has_value()) {
media_query->m_negated = modifier.value();
tokens.skip_whitespace();
}
// `<media-type>`
if (auto media_type = parse_media_type(tokens); media_type.has_value()) {
media_query->m_media_type = media_type.value();
tokens.skip_whitespace();
} else {
return invalid_media_query();
}
if (!tokens.has_next_token())
return media_query;
// `[ and <media-condition-without-or> ]?`
if (auto maybe_and = tokens.next_token(); maybe_and.is_ident("and"sv)) {
if (auto media_condition = parse_media_condition(tokens, MediaCondition::AllowOr::No)) {
tokens.skip_whitespace();
if (tokens.has_next_token())
return invalid_media_query();
media_query->m_media_condition = move(media_condition);
return media_query;
}
return invalid_media_query();
}
return invalid_media_query();
}
// `<media-condition>`, https://www.w3.org/TR/mediaqueries-4/#typedef-media-condition
// `<media-condition-widthout-or>`, https://www.w3.org/TR/mediaqueries-4/#typedef-media-condition-without-or
// (We distinguish between these two with the `allow_or` parameter.)
OwnPtr<MediaCondition> Parser::parse_media_condition(TokenStream<ComponentValue>& tokens, MediaCondition::AllowOr allow_or)
{
// `<media-not> | <media-in-parens> [ <media-and>* | <media-or>* ]`
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
// `<media-not> = not <media-in-parens>`
auto parse_media_not = [&](auto& tokens) -> OwnPtr<MediaCondition> {
auto local_transaction = tokens.begin_transaction();
tokens.skip_whitespace();
auto& first_token = tokens.next_token();
if (first_token.is_ident("not"sv)) {
if (auto child_condition = parse_media_condition(tokens, MediaCondition::AllowOr::Yes)) {
local_transaction.commit();
return MediaCondition::from_not(child_condition.release_nonnull());
}
}
return {};
};
auto parse_media_with_combinator = [&](auto& tokens, StringView combinator) -> OwnPtr<MediaCondition> {
auto local_transaction = tokens.begin_transaction();
tokens.skip_whitespace();
auto& first = tokens.next_token();
if (first.is_ident(combinator)) {
tokens.skip_whitespace();
if (auto media_in_parens = parse_media_in_parens(tokens)) {
local_transaction.commit();
return media_in_parens;
}
}
return {};
};
// `<media-and> = and <media-in-parens>`
auto parse_media_and = [&](auto& tokens) { return parse_media_with_combinator(tokens, "and"sv); };
// `<media-or> = or <media-in-parens>`
auto parse_media_or = [&](auto& tokens) { return parse_media_with_combinator(tokens, "or"sv); };
// `<media-not>`
if (auto maybe_media_not = parse_media_not(tokens)) {
transaction.commit();
return maybe_media_not.release_nonnull();
}
// `<media-in-parens> [ <media-and>* | <media-or>* ]`
if (auto maybe_media_in_parens = parse_media_in_parens(tokens)) {
tokens.skip_whitespace();
// Only `<media-in-parens>`
if (!tokens.has_next_token()) {
transaction.commit();
return maybe_media_in_parens.release_nonnull();
}
Vector<NonnullOwnPtr<MediaCondition>> child_conditions;
child_conditions.append(maybe_media_in_parens.release_nonnull());
// `<media-and>*`
if (auto media_and = parse_media_and(tokens)) {
child_conditions.append(media_and.release_nonnull());
tokens.skip_whitespace();
while (tokens.has_next_token()) {
if (auto next_media_and = parse_media_and(tokens)) {
child_conditions.append(next_media_and.release_nonnull());
tokens.skip_whitespace();
continue;
}
// We failed - invalid syntax!
return {};
}
transaction.commit();
return MediaCondition::from_and_list(move(child_conditions));
}
// `<media-or>*`
if (allow_or == MediaCondition::AllowOr::Yes) {
if (auto media_or = parse_media_or(tokens)) {
child_conditions.append(media_or.release_nonnull());
tokens.skip_whitespace();
while (tokens.has_next_token()) {
if (auto next_media_or = parse_media_or(tokens)) {
child_conditions.append(next_media_or.release_nonnull());
tokens.skip_whitespace();
continue;
}
// We failed - invalid syntax!
return {};
}
transaction.commit();
return MediaCondition::from_or_list(move(child_conditions));
}
}
}
return {};
}
// `<media-feature>`, https://www.w3.org/TR/mediaqueries-4/#typedef-media-feature
Optional<MediaFeature> Parser::parse_media_feature(TokenStream<ComponentValue>& tokens)
{
// `[ <mf-plain> | <mf-boolean> | <mf-range> ]`
tokens.skip_whitespace();
// `<mf-name> = <ident>`
struct MediaFeatureName {
enum Type {
Normal,
Min,
Max
} type;
MediaFeatureID id;
};
auto parse_mf_name = [](auto& tokens, bool allow_min_max_prefix) -> Optional<MediaFeatureName> {
auto transaction = tokens.begin_transaction();
auto& token = tokens.next_token();
if (token.is(Token::Type::Ident)) {
auto name = token.token().ident();
if (auto id = media_feature_id_from_string(name); id.has_value()) {
transaction.commit();
return MediaFeatureName { MediaFeatureName::Type::Normal, id.value() };
}
if (allow_min_max_prefix && (name.starts_with_bytes("min-"sv, CaseSensitivity::CaseInsensitive) || name.starts_with_bytes("max-"sv, CaseSensitivity::CaseInsensitive))) {
auto adjusted_name = name.bytes_as_string_view().substring_view(4);
if (auto id = media_feature_id_from_string(adjusted_name); id.has_value() && media_feature_type_is_range(id.value())) {
transaction.commit();
return MediaFeatureName {
name.starts_with_bytes("min-"sv, CaseSensitivity::CaseInsensitive) ? MediaFeatureName::Type::Min : MediaFeatureName::Type::Max,
id.value()
};
}
}
}
return {};
};
// `<mf-boolean> = <mf-name>`
auto parse_mf_boolean = [&](auto& tokens) -> Optional<MediaFeature> {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
if (auto maybe_name = parse_mf_name(tokens, false); maybe_name.has_value()) {
tokens.skip_whitespace();
if (!tokens.has_next_token()) {
transaction.commit();
return MediaFeature::boolean(maybe_name->id);
}
}
return {};
};
// `<mf-plain> = <mf-name> : <mf-value>`
auto parse_mf_plain = [&](auto& tokens) -> Optional<MediaFeature> {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
if (auto maybe_name = parse_mf_name(tokens, true); maybe_name.has_value()) {
tokens.skip_whitespace();
if (tokens.next_token().is(Token::Type::Colon)) {
tokens.skip_whitespace();
if (auto maybe_value = parse_media_feature_value(maybe_name->id, tokens); maybe_value.has_value()) {
tokens.skip_whitespace();
if (!tokens.has_next_token()) {
transaction.commit();
switch (maybe_name->type) {
case MediaFeatureName::Type::Normal:
return MediaFeature::plain(maybe_name->id, maybe_value.release_value());
case MediaFeatureName::Type::Min:
return MediaFeature::min(maybe_name->id, maybe_value.release_value());
case MediaFeatureName::Type::Max:
return MediaFeature::max(maybe_name->id, maybe_value.release_value());
}
VERIFY_NOT_REACHED();
}
}
}
}
return {};
};
// `<mf-lt> = '<' '='?
// <mf-gt> = '>' '='?
// <mf-eq> = '='
// <mf-comparison> = <mf-lt> | <mf-gt> | <mf-eq>`
auto parse_comparison = [](auto& tokens) -> Optional<MediaFeature::Comparison> {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
auto& first = tokens.next_token();
if (first.is(Token::Type::Delim)) {
auto first_delim = first.token().delim();
if (first_delim == '=') {
transaction.commit();
return MediaFeature::Comparison::Equal;
}
if (first_delim == '<') {
auto& second = tokens.peek_token();
if (second.is_delim('=')) {
tokens.next_token();
transaction.commit();
return MediaFeature::Comparison::LessThanOrEqual;
}
transaction.commit();
return MediaFeature::Comparison::LessThan;
}
if (first_delim == '>') {
auto& second = tokens.peek_token();
if (second.is_delim('=')) {
tokens.next_token();
transaction.commit();
return MediaFeature::Comparison::GreaterThanOrEqual;
}
transaction.commit();
return MediaFeature::Comparison::GreaterThan;
}
}
return {};
};
auto flip = [](MediaFeature::Comparison comparison) {
switch (comparison) {
case MediaFeature::Comparison::Equal:
return MediaFeature::Comparison::Equal;
case MediaFeature::Comparison::LessThan:
return MediaFeature::Comparison::GreaterThan;
case MediaFeature::Comparison::LessThanOrEqual:
return MediaFeature::Comparison::GreaterThanOrEqual;
case MediaFeature::Comparison::GreaterThan:
return MediaFeature::Comparison::LessThan;
case MediaFeature::Comparison::GreaterThanOrEqual:
return MediaFeature::Comparison::LessThanOrEqual;
}
VERIFY_NOT_REACHED();
};
auto comparisons_match = [](MediaFeature::Comparison a, MediaFeature::Comparison b) -> bool {
switch (a) {
case MediaFeature::Comparison::Equal:
return b == MediaFeature::Comparison::Equal;
case MediaFeature::Comparison::LessThan:
case MediaFeature::Comparison::LessThanOrEqual:
return b == MediaFeature::Comparison::LessThan || b == MediaFeature::Comparison::LessThanOrEqual;
case MediaFeature::Comparison::GreaterThan:
case MediaFeature::Comparison::GreaterThanOrEqual:
return b == MediaFeature::Comparison::GreaterThan || b == MediaFeature::Comparison::GreaterThanOrEqual;
}
VERIFY_NOT_REACHED();
};
// `<mf-range> = <mf-name> <mf-comparison> <mf-value>
// | <mf-value> <mf-comparison> <mf-name>
// | <mf-value> <mf-lt> <mf-name> <mf-lt> <mf-value>
// | <mf-value> <mf-gt> <mf-name> <mf-gt> <mf-value>`
auto parse_mf_range = [&](auto& tokens) -> Optional<MediaFeature> {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
// `<mf-name> <mf-comparison> <mf-value>`
// NOTE: We have to check for <mf-name> first, since all <mf-name>s will also parse as <mf-value>.
if (auto maybe_name = parse_mf_name(tokens, false); maybe_name.has_value() && media_feature_type_is_range(maybe_name->id)) {
tokens.skip_whitespace();
if (auto maybe_comparison = parse_comparison(tokens); maybe_comparison.has_value()) {
tokens.skip_whitespace();
if (auto maybe_value = parse_media_feature_value(maybe_name->id, tokens); maybe_value.has_value()) {
tokens.skip_whitespace();
if (!tokens.has_next_token() && !maybe_value->is_ident()) {
transaction.commit();
return MediaFeature::half_range(maybe_value.release_value(), flip(maybe_comparison.release_value()), maybe_name->id);
}
}
}
}
// `<mf-value> <mf-comparison> <mf-name>
// | <mf-value> <mf-lt> <mf-name> <mf-lt> <mf-value>
// | <mf-value> <mf-gt> <mf-name> <mf-gt> <mf-value>`
// NOTE: To parse the first value, we need to first find and parse the <mf-name> so we know what value types to parse.
// To allow for <mf-value> to be any number of tokens long, we scan forward until we find a comparison, and then
// treat the next non-whitespace token as the <mf-name>, which should be correct as long as they don't add a value
// type that can include a comparison in it. :^)
Optional<MediaFeatureName> maybe_name;
{
// This transaction is never committed, we just use it to rewind automatically.
auto temp_transaction = tokens.begin_transaction();
while (tokens.has_next_token() && !maybe_name.has_value()) {
if (auto maybe_comparison = parse_comparison(tokens); maybe_comparison.has_value()) {
// We found a comparison, so the next non-whitespace token should be the <mf-name>
tokens.skip_whitespace();
maybe_name = parse_mf_name(tokens, false);
break;
}
tokens.next_token();
tokens.skip_whitespace();
}
}
// Now, we can parse the range properly.
if (maybe_name.has_value() && media_feature_type_is_range(maybe_name->id)) {
if (auto maybe_left_value = parse_media_feature_value(maybe_name->id, tokens); maybe_left_value.has_value()) {
tokens.skip_whitespace();
if (auto maybe_left_comparison = parse_comparison(tokens); maybe_left_comparison.has_value()) {
tokens.skip_whitespace();
tokens.next_token(); // The <mf-name> which we already parsed above.
tokens.skip_whitespace();
if (!tokens.has_next_token()) {
transaction.commit();
return MediaFeature::half_range(maybe_left_value.release_value(), maybe_left_comparison.release_value(), maybe_name->id);
}
if (auto maybe_right_comparison = parse_comparison(tokens); maybe_right_comparison.has_value()) {
tokens.skip_whitespace();
if (auto maybe_right_value = parse_media_feature_value(maybe_name->id, tokens); maybe_right_value.has_value()) {
tokens.skip_whitespace();
// For this to be valid, the following must be true:
// - Comparisons must either both be >/>= or both be </<=.
// - Neither comparison can be `=`.
// - Neither value can be an ident.
auto left_comparison = maybe_left_comparison.release_value();
auto right_comparison = maybe_right_comparison.release_value();
if (!tokens.has_next_token()
&& comparisons_match(left_comparison, right_comparison)
&& left_comparison != MediaFeature::Comparison::Equal
&& !maybe_left_value->is_ident() && !maybe_right_value->is_ident()) {
transaction.commit();
return MediaFeature::range(maybe_left_value.release_value(), left_comparison, maybe_name->id, right_comparison, maybe_right_value.release_value());
}
}
}
}
}
}
return {};
};
if (auto maybe_mf_boolean = parse_mf_boolean(tokens); maybe_mf_boolean.has_value())
return maybe_mf_boolean.release_value();
if (auto maybe_mf_plain = parse_mf_plain(tokens); maybe_mf_plain.has_value())
return maybe_mf_plain.release_value();
if (auto maybe_mf_range = parse_mf_range(tokens); maybe_mf_range.has_value())
return maybe_mf_range.release_value();
return {};
}
Optional<MediaQuery::MediaType> Parser::parse_media_type(TokenStream<ComponentValue>& tokens)
{
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
auto const& token = tokens.next_token();
if (!token.is(Token::Type::Ident))
return {};
transaction.commit();
auto ident = token.token().ident();
return media_type_from_string(ident);
}
// `<media-in-parens>`, https://www.w3.org/TR/mediaqueries-4/#typedef-media-in-parens
OwnPtr<MediaCondition> Parser::parse_media_in_parens(TokenStream<ComponentValue>& tokens)
{
// `<media-in-parens> = ( <media-condition> ) | ( <media-feature> ) | <general-enclosed>`
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
// `( <media-condition> ) | ( <media-feature> )`
auto const& first_token = tokens.peek_token();
if (first_token.is_block() && first_token.block().is_paren()) {
TokenStream inner_token_stream { first_token.block().values() };
if (auto maybe_media_condition = parse_media_condition(inner_token_stream, MediaCondition::AllowOr::Yes)) {
tokens.next_token();
transaction.commit();
return maybe_media_condition.release_nonnull();
}
if (auto maybe_media_feature = parse_media_feature(inner_token_stream); maybe_media_feature.has_value()) {
tokens.next_token();
transaction.commit();
return MediaCondition::from_feature(maybe_media_feature.release_value());
}
}
// `<general-enclosed>`
// FIXME: We should only be taking this branch if the grammar doesn't match the above options.
// Currently we take it if the above fail to parse, which is different.
// eg, `@media (min-width: 76yaks)` is valid grammar, but does not parse because `yaks` isn't a unit.
if (auto maybe_general_enclosed = parse_general_enclosed(tokens); maybe_general_enclosed.has_value()) {
transaction.commit();
return MediaCondition::from_general_enclosed(maybe_general_enclosed.release_value());
}
return {};
}
// `<mf-value>`, https://www.w3.org/TR/mediaqueries-4/#typedef-mf-value
Optional<MediaFeatureValue> Parser::parse_media_feature_value(MediaFeatureID media_feature, TokenStream<ComponentValue>& tokens)
{
// NOTE: Calculations are not allowed for media feature values, at least in the current spec, so we reject them.
// Identifiers
if (tokens.peek_token().is(Token::Type::Ident)) {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
auto ident = value_id_from_string(tokens.next_token().token().ident());
if (ident.has_value() && media_feature_accepts_identifier(media_feature, ident.value())) {
transaction.commit();
return MediaFeatureValue(ident.value());
}
}
// One branch for each member of the MediaFeatureValueType enum:
// Boolean (<mq-boolean> in the spec: a 1 or 0)
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Boolean)) {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
if (auto integer = parse_integer(tokens); integer.has_value() && !integer->is_calculated()) {
auto integer_value = integer->value();
if (integer_value == 0 || integer_value == 1) {
transaction.commit();
return MediaFeatureValue(integer_value);
}
}
}
// Integer
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Integer)) {
auto transaction = tokens.begin_transaction();
if (auto integer = parse_integer(tokens); integer.has_value() && !integer->is_calculated()) {
transaction.commit();
return MediaFeatureValue(integer->value());
}
}
// Length
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Length)) {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
if (auto length = parse_length(tokens); length.has_value() && !length->is_calculated()) {
transaction.commit();
return MediaFeatureValue(length->value());
}
}
// Ratio
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Ratio)) {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
if (auto ratio = parse_ratio(tokens); ratio.has_value()) {
transaction.commit();
return MediaFeatureValue(ratio.release_value());
}
}
// Resolution
if (media_feature_accepts_type(media_feature, MediaFeatureValueType::Resolution)) {
auto transaction = tokens.begin_transaction();
tokens.skip_whitespace();
if (auto resolution = parse_resolution(tokens); resolution.has_value() && !resolution->is_calculated()) {
transaction.commit();
return MediaFeatureValue(resolution->value());
}
}
return {};
}
CSSMediaRule* Parser::convert_to_media_rule(NonnullRefPtr<Web::CSS::Parser::Rule> rule)
{
auto media_query_tokens = TokenStream { rule->prelude() };
auto media_query_list = parse_a_media_query_list(media_query_tokens);
if (media_query_list.is_empty() || !rule->block())
return {};
auto child_tokens = TokenStream { rule->block()->values() };
auto parser_rules = parse_a_list_of_rules(child_tokens);
JS::MarkedVector<CSSRule*> child_rules(m_context.realm().heap());
for (auto& raw_rule : parser_rules) {
if (auto* child_rule = convert_to_rule(raw_rule))
child_rules.append(child_rule);
}
auto media_list = MediaList::create(m_context.realm(), move(media_query_list));
auto rule_list = CSSRuleList::create(m_context.realm(), child_rules);
return CSSMediaRule::create(m_context.realm(), media_list, rule_list);
}
}
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