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LibWeb: Parse grid track placements closer to spec

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This brings parsing of grid-row-* and grid-column-* properties (and
their associated shorthands) more inline with spec.

Changes:
- Only set omitted properties for combined-value shorthands (e.g.
  `grid-row: a` rather than `grid-row: a / b`) if the single value is
  `<custom-ident>`.

- `[ [ <integer [-∞,-1]> | <integer [1,∞]> ] && <custom-ident>? ]`:
  - Properly resolve `calc`s for `<integer>` that rely on compute-time
    information.

- `[ span && [ <integer [1,∞]> || <custom-ident> ] ]`
  - Allow `calc`s for `<integer>`
  - Allow `<custom-ident>`

There is still work to be done to properly use these parsed values.

Gains us 46 WPT tests.
This commit is contained in:
Callum Law 2025-07-08 14:31:40 +12:00 • committed by Tim Ledbetter
parent a424a06d45
commit 36e2d25efa
Notes: github-actions[bot] 2025-07-08 16:27:31 +00:00
12 changed files with 153 additions and 171 deletions
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120
Libraries/LibWeb/CSS/Parser/ValueParsing.cpp
View file

@ -3647,108 +3647,72 @@ GridTrackSizeList Parser::parse_explicit_track_list(TokenStream<ComponentValue>&
RefPtr<GridTrackPlacementStyleValue const> Parser::parse_grid_track_placement(TokenStream<ComponentValue>& tokens)
{
// FIXME: This shouldn't be needed. Right now, the below code returns a CSSStyleValue even if no tokens are consumed!
if (!tokens.has_next_token())
return nullptr;
if (tokens.remaining_token_count() > 3)
return nullptr;
// https://www.w3.org/TR/css-grid-2/#line-placement
// Line-based Placement: the grid-row-start, grid-column-start, grid-row-end, and grid-column-end properties
// <grid-line> =
// auto |
// <custom-ident> |
// [ <integer> && <custom-ident>? ] |
// [ span && [ <integer> || <custom-ident> ] ]
auto is_valid_integer = [](auto& token) -> bool {
// An <integer> value of zero makes the declaration invalid.
if (token.is(Token::Type::Number) && token.token().number().is_integer() && token.token().number_value() != 0)
return true;
return false;
};
auto parse_custom_ident = [this](auto& tokens) {
// The <custom-ident> additionally excludes the keywords span and auto.
return parse_custom_ident_value(tokens, { { "span"sv, "auto"sv } });
};
// [ [ <integer [-∞,-1]> | <integer [1,∞]> ] && <custom-ident>? ] |
// [ span && [ <integer [1,∞]> || <custom-ident> ] ]
bool is_span = false;
Optional<String> parsed_custom_ident;
Optional<IntegerOrCalculated> parsed_integer;
auto transaction = tokens.begin_transaction();
// FIXME: Handle the single-token case inside the loop instead, so that we can more easily call this from
// `parse_grid_area_shorthand_value()` using a single TokenStream.
if (tokens.remaining_token_count() == 1) {
if (auto custom_ident = parse_custom_ident(tokens)) {
transaction.commit();
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_line({}, custom_ident->custom_ident().to_string()));
}
auto const& token = tokens.consume_a_token();
if (auto maybe_calculated = parse_calculated_value(token)) {
if (maybe_calculated->is_number()) {
transaction.commit();
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_line(static_cast<int>(maybe_calculated->as_number().number()), {}));
}
if (maybe_calculated->is_calculated() && maybe_calculated->as_calculated().resolves_to_number()) {
transaction.commit();
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_line(static_cast<int>(maybe_calculated->as_calculated().resolve_integer({}).value()), {}));
}
}
if (token.is_ident("auto"sv)) {
transaction.commit();
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_auto());
}
if (is_valid_integer(token)) {
transaction.commit();
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_line(static_cast<int>(token.token().number_value()), {}));
}
return nullptr;
if (tokens.remaining_token_count() == 1 && tokens.next_token().is_ident("auto"sv)) {
tokens.discard_a_token();
transaction.commit();
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_auto());
}
auto span_value = false;
auto span_or_position_value = 0;
String identifier_value;
while (tokens.has_next_token()) {
auto const& token = tokens.next_token();
if (token.is_ident("auto"sv))
return nullptr;
if (token.is_ident("span"sv)) {
if (span_value)
if (tokens.next_token().is_ident("span"sv)) {
if (is_span)
return nullptr;
tokens.discard_a_token(); // span
if (tokens.has_next_token() && ((span_or_position_value != 0 && identifier_value.is_empty()) || (span_or_position_value == 0 && !identifier_value.is_empty())))
tokens.discard_a_token();
// NOTE: "span" must not appear in between <custom-ident> and <integer>
if (tokens.has_next_token() && (parsed_custom_ident.has_value() || parsed_integer.has_value()))
return nullptr;
span_value = true;
is_span = true;
continue;
}
if (is_valid_integer(token)) {
if (span_or_position_value != 0)
if (auto maybe_parsed_custom_ident = parse_custom_ident(tokens, { { "auto"sv } }); maybe_parsed_custom_ident.has_value()) {
if (parsed_custom_ident.has_value())
return nullptr;
span_or_position_value = static_cast<int>(tokens.consume_a_token().token().to_integer());
parsed_custom_ident = maybe_parsed_custom_ident->to_string();
continue;
}
if (auto custom_ident = parse_custom_ident(tokens)) {
if (!identifier_value.is_empty())
if (auto maybe_parsed_integer = parse_integer(tokens); maybe_parsed_integer.has_value()) {
if (parsed_integer.has_value())
return nullptr;
identifier_value = custom_ident->custom_ident().to_string();
parsed_integer = maybe_parsed_integer;
continue;
}
break;
return nullptr;
}
if (tokens.has_next_token())
return nullptr;
// Negative integers or zero are invalid.
if (span_value && span_or_position_value < 1)
return nullptr;
// If the <integer> is omitted, it defaults to 1.
if (span_or_position_value == 0)
span_or_position_value = 1;
transaction.commit();
if (!identifier_value.is_empty())
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_line(span_or_position_value, identifier_value));
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_span(span_or_position_value));
// <custom-ident>
// [ [ <integer [-∞,-1]> | <integer [1,∞]> ] && <custom-ident>? ]
if (!is_span && (parsed_integer.has_value() || parsed_custom_ident.has_value()) && (!parsed_integer.has_value() || parsed_integer.value().is_calculated() || parsed_integer.value().value() != 0))
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_line(parsed_integer, parsed_custom_ident));
// [ span && [ <integer [1,∞]> || <custom-ident> ] ]
if (is_span && (parsed_integer.has_value() || parsed_custom_ident.has_value()) && (!parsed_integer.has_value() || parsed_integer.value().is_calculated() || parsed_integer.value().value() > 0))
// If the <integer> is omitted, it defaults to 1.
return GridTrackPlacementStyleValue::create(GridTrackPlacement::make_span(parsed_integer.value_or(1), parsed_custom_ident));
return nullptr;
}
RefPtr<CSSStyleValue const> Parser::parse_calculated_value(ComponentValue const& component_value)