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https://github.com/RGBCube/serenity
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LibWeb: Make CSS 'An+B' parsing spec-compliant
Parsing this pattern from CSS tokens turns out to be slightly crazy, but thankfully well documented in the spec. The spec lists the cases in order of simple -> complicated, but this would cause problems in code, since `<n-dimension> <signed-.integer>` would never by reached, as `<n-dimension>` comes before. Instead, I have grouped them by their first token. Also renamed the NthChildPattern class to ANPlusBPattern, to match spec terminology.
This commit is contained in:
Sam Atkins
Andreas Kling
parent
8d0ff98eff
commit
6034fc0ee6
7 changed files with 333 additions and 92 deletions
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@ -6,6 +6,7 @@
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/CharacterTypes.h>
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#include <AK/Debug.h>
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#include <AK/NonnullRefPtrVector.h>
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#include <AK/SourceLocation.h>
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@ -603,7 +604,6 @@ Result<Selector::SimpleSelector, Parser::SelectorParsingResult> Parser::parse_si
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simple_selector.pseudo_class.nth_child_pattern = nth_child_pattern.value();
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} else {
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dbgln_if(CSS_PARSER_DEBUG, "!!! Invalid nth-child format");
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function_values.dump_all_tokens();
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return SelectorParsingResult::SyntaxError;
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}
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} else if (pseudo_function.name().equals_ignoring_case("nth-last-child")) {
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@ -611,11 +611,9 @@ Result<Selector::SimpleSelector, Parser::SelectorParsingResult> Parser::parse_si
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auto function_values = TokenStream<StyleComponentValueRule>(pseudo_function.values());
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auto nth_child_pattern = parse_a_n_plus_b_pattern(function_values);
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if (nth_child_pattern.has_value()) {
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dbgln("+++ Got An+B pattern: '{}'", nth_child_pattern.value().to_string());
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simple_selector.pseudo_class.nth_child_pattern = nth_child_pattern.value();
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} else {
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dbgln_if(CSS_PARSER_DEBUG, "!!! Invalid nth-child format");
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function_values.dump_all_tokens();
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return SelectorParsingResult::SyntaxError;
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}
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} else {
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@ -1491,7 +1489,7 @@ RefPtr<StyleValue> Parser::parse_numeric_value(ParsingContext const&, StyleCompo
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if (component_value.is(Token::Type::Number)) {
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auto number = component_value.token();
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if (number.m_number_type == Token::NumberType::Integer) {
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return NumericStyleValue::create(number.integer());
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return NumericStyleValue::create(number.to_integer());
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} else {
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auto float_value = try_parse_float(number.m_value.string_view());
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if (float_value.has_value())
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@ -1748,7 +1746,7 @@ RefPtr<StyleValue> Parser::parse_css_value(ParsingContext const& context, Proper
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if (takes_integer_value(property_id) && component_value.is(Token::Type::Number)) {
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auto number = component_value.token();
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if (number.m_number_type == Token::NumberType::Integer) {
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return LengthStyleValue::create(Length::make_px(number.integer()));
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return LengthStyleValue::create(Length::make_px(number.to_integer()));
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}
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}
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@ -1776,90 +1774,306 @@ RefPtr<StyleValue> Parser::parse_css_value(ParsingContext const& context, Proper
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return {};
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}
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Optional<Selector::SimpleSelector::NthChildPattern> Parser::parse_nth_child_pattern(TokenStream<StyleComponentValueRule>& values)
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Optional<Selector::SimpleSelector::ANPlusBPattern> Parser::parse_a_n_plus_b_pattern(TokenStream<StyleComponentValueRule>& values)
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{
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dbgln_if(CSS_PARSER_DEBUG, "Parser::parse_nth_child_pattern");
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dbgln_if(CSS_PARSER_DEBUG, "Parser::parse_a_n_plus_b_pattern");
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Selector::SimpleSelector::NthChildPattern pattern;
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int a = 0;
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int b = 0;
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auto current_value = values.next_token();
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if (current_value.is(Token::Type::Ident)) {
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auto ident = current_value.token().ident();
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if (ident.equals_ignoring_case("odd")) {
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pattern.step_size = 2;
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pattern.offset = 1;
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return pattern;
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} else if (ident.equals_ignoring_case("even")) {
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pattern.step_size = 2;
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return pattern;
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auto syntax_error = [&]() -> Optional<Selector::SimpleSelector::ANPlusBPattern> {
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if constexpr (CSS_PARSER_DEBUG) {
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dbgln("Invalid An+B value:");
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values.dump_all_tokens();
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}
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}
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// Try to match any of following patterns:
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// 1. An+B
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// 2. An
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// 3. B
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// ...where "A" is "step_size", "B" is "offset" and rest are literals.
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// "A" can be omitted, in that case "A" = 1.
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// "A" may have "+" or "-" sign, "B" always must be predated by sign for pattern (1).
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auto is_n = [](StyleComponentValueRule value) -> bool {
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return value.is(Token::Type::Ident) && value.token().ident().equals_ignoring_case("n");
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return {};
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};
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auto is_delim = [](StyleComponentValueRule value, StringView delim) -> bool {
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auto make_return_value = [&]() -> Optional<Selector::SimpleSelector::ANPlusBPattern> {
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// When we think we are done, but there are more non-whitespace tokens, then it's a parse error.
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values.skip_whitespace();
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if (values.has_next_token()) {
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if constexpr (CSS_PARSER_DEBUG) {
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dbgln("Extra tokens at end of An+B value:");
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values.dump_all_tokens();
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}
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return syntax_error();
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} else {
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return Selector::SimpleSelector::ANPlusBPattern { a, b };
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}
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};
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auto is_n = [](StyleComponentValueRule const& value) -> bool {
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return value.is(Token::Type::Ident) && value.token().ident().equals_ignoring_case("n"sv);
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};
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auto is_ndash = [](StyleComponentValueRule const& value) -> bool {
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return value.is(Token::Type::Ident) && value.token().ident().equals_ignoring_case("n-"sv);
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};
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auto is_dashn = [](StyleComponentValueRule const& value) -> bool {
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return value.is(Token::Type::Ident) && value.token().ident().equals_ignoring_case("-n"sv);
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};
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auto is_dashndash = [](StyleComponentValueRule const& value) -> bool {
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return value.is(Token::Type::Ident) && value.token().ident().equals_ignoring_case("-n-"sv);
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};
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auto is_delim = [](StyleComponentValueRule const& value, StringView const& delim) -> bool {
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return value.is(Token::Type::Delim) && value.token().delim().equals_ignoring_case(delim);
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};
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int step_size_or_offset = 0;
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// "When a=1, or a=-1, the 1 may be omitted from the rule."
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if (is_n(current_value)) {
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step_size_or_offset = +1;
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} else if (is_delim(current_value, "+"sv) && is_n(values.peek_token())) {
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step_size_or_offset = +1;
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values.next_token();
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} else if (is_delim(current_value, "-"sv) && is_n(values.peek_token())) {
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step_size_or_offset = -1;
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values.next_token();
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} else if (current_value.is(Token::Type::Number)) {
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step_size_or_offset = current_value.token().integer();
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} else {
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values.reconsume_current_input_token();
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}
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current_value = values.next_token();
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if (is_n(current_value)) {
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values.skip_whitespace();
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auto next_value = values.peek_token();
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if (is_delim(next_value, "+") || is_delim(next_value, "-")) {
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const auto sign = is_delim(next_value, "+") ? 1 : -1;
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values.next_token();
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values.skip_whitespace();
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// "An+B" pattern
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auto number = values.next_token();
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if (!number.is(Token::Type::Number))
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return {};
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pattern.step_size = step_size_or_offset;
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pattern.offset = sign * number.token().integer();
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} else {
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// "An" pattern
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pattern.step_size = step_size_or_offset;
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auto is_n_dimension = [](StyleComponentValueRule const& value) -> bool {
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if (!value.is(Token::Type::Dimension))
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return false;
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if (value.token().number_type() != Token::NumberType::Integer)
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return false;
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if (!value.token().dimension_unit().equals_ignoring_case("n"sv))
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return false;
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return true;
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};
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auto is_ndash_dimension = [](StyleComponentValueRule const& value) -> bool {
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if (!value.is(Token::Type::Dimension))
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return false;
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if (value.token().number_type() != Token::NumberType::Integer)
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return false;
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if (!value.token().dimension_unit().equals_ignoring_case("n-"sv))
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return false;
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return true;
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};
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auto is_ndashdigit_dimension = [](StyleComponentValueRule const& value) -> bool {
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if (!value.is(Token::Type::Dimension))
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return false;
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if (value.token().number_type() != Token::NumberType::Integer)
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return false;
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auto dimension_unit = value.token().dimension_unit();
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if (!dimension_unit.starts_with("n-"sv, CaseSensitivity::CaseInsensitive))
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return false;
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for (size_t i = 2; i < dimension_unit.length(); ++i) {
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if (!is_ascii_digit(dimension_unit[i]))
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return false;
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}
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} else {
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// "B" pattern
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pattern.offset = step_size_or_offset;
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return true;
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};
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auto is_ndashdigit_ident = [](StyleComponentValueRule const& value) -> bool {
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if (!value.is(Token::Type::Ident))
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return false;
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auto ident = value.token().ident();
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if (!ident.starts_with("n-"sv, CaseSensitivity::CaseInsensitive))
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return false;
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for (size_t i = 2; i < ident.length(); ++i) {
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if (!is_ascii_digit(ident[i]))
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return false;
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}
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return true;
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};
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auto is_dashndashdigit_ident = [](StyleComponentValueRule const& value) -> bool {
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if (!value.is(Token::Type::Ident))
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return false;
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auto ident = value.token().ident();
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if (!ident.starts_with("-n-"sv, CaseSensitivity::CaseInsensitive))
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return false;
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for (size_t i = 3; i < ident.length(); ++i) {
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if (!is_ascii_digit(ident[i]))
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return false;
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}
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return true;
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};
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auto is_integer = [](StyleComponentValueRule const& value) -> bool {
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return value.is(Token::Type::Number) && value.token().is(Token::NumberType::Integer);
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};
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auto is_signed_integer = [is_integer](StyleComponentValueRule const& value) -> bool {
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return is_integer(value) && value.token().is_integer_value_signed();
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};
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auto is_signless_integer = [is_integer](StyleComponentValueRule const& value) -> bool {
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return is_integer(value) && !value.token().is_integer_value_signed();
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};
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// https://www.w3.org/TR/css-syntax-3/#the-anb-type
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// Unfortunately these can't be in the same order as in the spec.
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values.skip_whitespace();
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auto& first_value = values.next_token();
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// odd | even
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if (first_value.is(Token::Type::Ident)) {
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auto ident = first_value.token().ident();
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if (ident.equals_ignoring_case("odd")) {
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a = 2;
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b = 1;
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return make_return_value();
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} else if (ident.equals_ignoring_case("even")) {
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a = 2;
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return make_return_value();
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}
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}
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// <integer>
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if (is_integer(first_value)) {
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b = first_value.token().to_integer();
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return make_return_value();
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}
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// <n-dimension>
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// <n-dimension> <signed-integer>
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// <n-dimension> ['+' | '-'] <signless-integer>
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if (is_n_dimension(first_value)) {
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a = first_value.token().dimension_value_int();
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values.skip_whitespace();
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auto& second_value = values.next_token();
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if (second_value.is(Token::Type::EndOfFile)) {
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// <n-dimension>
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return make_return_value();
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} else if (is_signed_integer(second_value)) {
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// <n-dimension> <signed-integer>
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b = second_value.token().to_integer();
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return make_return_value();
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}
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values.skip_whitespace();
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auto& third_value = values.next_token();
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if ((is_delim(second_value, "+"sv) || is_delim(second_value, "-"sv)) && is_signless_integer(third_value)) {
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// <n-dimension> ['+' | '-'] <signless-integer>
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b = third_value.token().to_integer() * (is_delim(second_value, "+"sv) ? 1 : -1);
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return make_return_value();
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}
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return syntax_error();
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}
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// <ndash-dimension> <signless-integer>
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if (is_ndash_dimension(first_value)) {
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values.skip_whitespace();
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auto& second_value = values.next_token();
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if (is_signless_integer(second_value)) {
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a = first_value.token().dimension_value_int();
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b = -second_value.token().to_integer();
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return make_return_value();
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}
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return syntax_error();
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}
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// <ndashdigit-dimension>
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if (is_ndashdigit_dimension(first_value)) {
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auto& dimension = first_value.token();
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a = dimension.dimension_value_int();
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auto maybe_b = dimension.dimension_unit().substring_view(1).to_int();
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if (maybe_b.has_value()) {
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b = maybe_b.value();
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return make_return_value();
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}
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return syntax_error();
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}
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// <dashndashdigit-ident>
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if (is_dashndashdigit_ident(first_value)) {
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a = -1;
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auto maybe_b = first_value.token().ident().substring_view(2).to_int();
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if (maybe_b.has_value()) {
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b = maybe_b.value();
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return make_return_value();
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}
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return syntax_error();
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}
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// -n
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// -n <signed-integer>
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// -n ['+' | '-'] <signless-integer>
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if (is_dashn(first_value)) {
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a = -1;
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values.skip_whitespace();
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auto& second_value = values.next_token();
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if (second_value.is(Token::Type::EndOfFile)) {
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// -n
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return make_return_value();
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} else if (is_signed_integer(second_value)) {
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// -n <signed-integer>
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b = second_value.token().to_integer();
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return make_return_value();
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}
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values.skip_whitespace();
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auto& third_value = values.next_token();
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if ((is_delim(second_value, "+"sv) || is_delim(second_value, "-"sv)) && is_signless_integer(third_value)) {
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// -n ['+' | '-'] <signless-integer>
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b = third_value.token().to_integer() * (is_delim(second_value, "+"sv) ? 1 : -1);
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return make_return_value();
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}
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return syntax_error();
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}
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// -n- <signless-integer>
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if (is_dashndash(first_value)) {
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values.skip_whitespace();
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auto& second_value = values.next_token();
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if (is_signless_integer(second_value)) {
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a = -1;
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b = -second_value.token().to_integer();
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return make_return_value();
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}
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return syntax_error();
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}
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if (values.has_next_token())
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return {};
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// All that's left now are these:
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// '+'?† n
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// '+'?† n <signed-integer>
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// '+'?† n ['+' | '-'] <signless-integer>
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// '+'?† n- <signless-integer>
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// '+'?† <ndashdigit-ident>
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// In all of these cases, the + is optional, and has no effect.
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// So, we just skip the +, and carry on.
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if (!is_delim(first_value, "+"sv)) {
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values.reconsume_current_input_token();
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// We do *not* skip whitespace here.
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}
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return pattern;
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auto& first_after_plus = values.next_token();
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// '+'?† n
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// '+'?† n <signed-integer>
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// '+'?† n ['+' | '-'] <signless-integer>
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if (is_n(first_after_plus)) {
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a = 1;
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values.skip_whitespace();
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auto& second_value = values.next_token();
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if (second_value.is(Token::Type::EndOfFile)) {
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// '+'?† n
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return make_return_value();
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} else if (is_signed_integer(second_value)) {
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// '+'?† n <signed-integer>
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b = second_value.token().to_integer();
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return make_return_value();
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}
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values.skip_whitespace();
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auto& third_value = values.next_token();
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if ((is_delim(second_value, "+"sv) || is_delim(second_value, "-"sv)) && is_signless_integer(third_value)) {
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// '+'?† n ['+' | '-'] <signless-integer>
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b = third_value.token().to_integer() * (is_delim(second_value, "+"sv) ? 1 : -1);
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return make_return_value();
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}
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return syntax_error();
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}
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// '+'?† n- <signless-integer>
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if (is_ndash(first_after_plus)) {
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values.skip_whitespace();
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auto& second_value = values.next_token();
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if (is_signless_integer(second_value)) {
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a = 1;
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b = -second_value.token().to_integer();
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return make_return_value();
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}
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return syntax_error();
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}
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// '+'?† <ndashdigit-ident>
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if (is_ndashdigit_ident(first_after_plus)) {
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a = 1;
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auto maybe_b = first_after_plus.token().ident().substring_view(1).to_int();
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if (maybe_b.has_value()) {
|
||||
b = maybe_b.value();
|
||||
return make_return_value();
|
||||
}
|
||||
|
||||
return syntax_error();
|
||||
}
|
||||
|
||||
return syntax_error();
|
||||
}
|
||||
}
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue