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LibWeb: Support range syntax for media queries

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This means you can now do queries like:

```css
@media (400px <= width < 800px) { }
```

Chromium and Firefox which I tested with both don't support this yet, so
that's cool. :^)
This commit is contained in:
Sam Atkins 2022-01-01 16:24:43 +00:00 • committed by Andreas Kling
parent c3bf9e5b79
commit 416033a660
4 changed files with 366 additions and 43 deletions
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154
Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
View file

@ -869,9 +869,23 @@ Optional<MediaFeature> Parser::parse_media_feature(TokenStream<StyleComponentVal
tokens.skip_whitespace();
// `<mf-name> = <ident>`
auto parse_mf_name = [](StyleComponentValueRule const& token) -> Optional<String> {
if (token.is(Token::Type::Ident))
return token.token().ident();
auto parse_mf_name = [](auto& tokens, bool allow_min_max_prefix) -> Optional<String> {
auto& token = tokens.peek_token();
if (token.is(Token::Type::Ident)) {
auto name = token.token().ident();
if (is_media_feature_name(name)) {
tokens.next_token();
return name;
}
if (allow_min_max_prefix && (name.starts_with("min-", CaseSensitivity::CaseInsensitive) || name.starts_with("max-", CaseSensitivity::CaseInsensitive))) {
auto adjusted_name = name.substring_view(4);
if (is_media_feature_name(adjusted_name)) {
tokens.next_token();
return name;
}
}
}
return {};
};
@ -880,7 +894,7 @@ Optional<MediaFeature> Parser::parse_media_feature(TokenStream<StyleComponentVal
auto position = tokens.position();
tokens.skip_whitespace();
auto maybe_name = parse_mf_name(tokens.next_token());
auto maybe_name = parse_mf_name(tokens, false);
if (maybe_name.has_value()) {
tokens.skip_whitespace();
if (!tokens.has_next_token())
@ -896,7 +910,7 @@ Optional<MediaFeature> Parser::parse_media_feature(TokenStream<StyleComponentVal
auto position = tokens.position();
tokens.skip_whitespace();
if (auto maybe_name = parse_mf_name(tokens.next_token()); maybe_name.has_value()) {
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();
@ -912,13 +926,141 @@ Optional<MediaFeature> Parser::parse_media_feature(TokenStream<StyleComponentVal
return {};
};
// `<mf-lt> = '<' '='?
// <mf-gt> = '>' '='?
// <mf-eq> = '='
// <mf-comparison> = <mf-lt> | <mf-gt> | <mf-eq>`
auto parse_comparison = [](auto& tokens) -> Optional<MediaFeature::Comparison> {
auto position = tokens.position();
tokens.skip_whitespace();
auto& first = tokens.next_token();
if (first.is(Token::Type::Delim)) {
auto first_delim = first.token().delim();
if (first_delim == "="sv)
return MediaFeature::Comparison::Equal;
if (first_delim == "<"sv) {
auto& second = tokens.peek_token();
if (second.is(Token::Type::Delim) && second.token().delim() == "="sv) {
tokens.next_token();
return MediaFeature::Comparison::LessThanOrEqual;
}
return MediaFeature::Comparison::LessThan;
}
if (first_delim == ">"sv) {
auto& second = tokens.peek_token();
if (second.is(Token::Type::Delim) && second.token().delim() == "="sv) {
tokens.next_token();
return MediaFeature::Comparison::GreaterThanOrEqual;
}
return MediaFeature::Comparison::GreaterThan;
}
}
tokens.rewind_to_position(position);
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 position = tokens.position();
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()) {
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(tokens); maybe_value.has_value()) {
tokens.skip_whitespace();
if (!tokens.has_next_token() && !maybe_value->is_ident())
return MediaFeature::half_range(maybe_value.release_value(), flip(maybe_comparison.release_value()), maybe_name.release_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>`
if (auto maybe_left_value = parse_media_feature_value(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();
if (auto maybe_name = parse_mf_name(tokens, false); maybe_name.has_value()) {
tokens.skip_whitespace();
if (!tokens.has_next_token())
return MediaFeature::half_range(maybe_left_value.release_value(), maybe_left_comparison.release_value(), maybe_name.release_value());
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(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()) {
return MediaFeature::range(maybe_left_value.release_value(), left_comparison, maybe_name.release_value(), right_comparison, maybe_right_value.release_value());
}
}
}
}
}
}
tokens.rewind_to_position(position);
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();
// FIXME: Implement range syntax
if (auto maybe_mf_range = parse_mf_range(tokens); maybe_mf_range.has_value())
return maybe_mf_range.release_value();
tokens.rewind_to_position(position);
return {};