mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2025-09-12 04:22:28 +00:00
LibWeb: Implement HTML spec-compliant rules for floating-point parsing
Attempt to implement HTML specs for parsing floating-point number https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#rules-for-parsing-floating-point-number-values
This commit is contained in:
Khaled Lakehal
Andreas Kling
parent
ba71cb1ca4
commit
14e1e55319
Notes:
github-actions[bot]
2024-10-30 09:48:30 +00:00
Author: https://github.com/khaledev
Commit: 14e1e55319
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1962
3 changed files with 329 additions and 5 deletions
|
|
@ -83,13 +83,204 @@ Optional<u32> parse_non_negative_integer(StringView string)
|
|||
// https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#rules-for-parsing-floating-point-number-values
|
||||
Optional<double> parse_floating_point_number(StringView string)
|
||||
{
|
||||
// FIXME: Implement spec compliant floating point number parsing
|
||||
auto maybe_double = string.to_number<double>(TrimWhitespace::Yes);
|
||||
if (!maybe_double.has_value())
|
||||
// 1. Let input be the string being parsed.
|
||||
// 2. Let position be a pointer into input, initially pointing at the start of the string.
|
||||
GenericLexer lexer { string };
|
||||
|
||||
// 3. Let value have the value 1.
|
||||
double value = 1;
|
||||
|
||||
// 4. Let divisor have the value 1.
|
||||
double divisor = 1;
|
||||
|
||||
// 5. Let exponent have the value 1.
|
||||
i16 exponent = 1;
|
||||
|
||||
// 6. Skip ASCII whitespace within input given position.
|
||||
lexer.ignore_while(Web::Infra::is_ascii_whitespace);
|
||||
|
||||
// 7. If position is past the end of input, return an error.
|
||||
if (lexer.is_eof()) {
|
||||
return {};
|
||||
if (!isfinite(maybe_double.value()))
|
||||
}
|
||||
|
||||
// 8. If the character indicated by position is a U+002D HYPHEN-MINUS character (-):
|
||||
if (lexer.next_is('-')) {
|
||||
// 8.1. Change value and divisor to −1.
|
||||
value = -1;
|
||||
divisor = -1;
|
||||
|
||||
// 8.2. Advance position to the next character.
|
||||
lexer.consume();
|
||||
|
||||
// 8.3. If position is past the end of input, return an error.
|
||||
if (lexer.is_eof()) {
|
||||
return {};
|
||||
}
|
||||
}
|
||||
// Otherwise, if the character indicated by position (the first character) is a U+002B PLUS SIGN character (+):
|
||||
else if (lexer.next_is('+')) {
|
||||
// 8.1. Advance position to the next character. (The "+" is ignored, but it is not conforming.)
|
||||
lexer.consume();
|
||||
|
||||
// 8.2. If position is past the end of input, return an error.
|
||||
if (lexer.is_eof()) {
|
||||
return {};
|
||||
}
|
||||
}
|
||||
|
||||
// 9. If the character indicated by position is a U+002E FULL STOP (.),
|
||||
// and that is not the last character in input,
|
||||
// and the character after the character indicated by position is an ASCII digit,
|
||||
// then set value to zero and jump to the step labeled fraction.
|
||||
if (lexer.next_is('.') && (lexer.tell_remaining() > 1) && is_ascii_digit(lexer.peek(1))) {
|
||||
value = 0;
|
||||
goto fraction;
|
||||
}
|
||||
|
||||
// 10. If the character indicated by position is not an ASCII digit, then return an error.
|
||||
if (!lexer.next_is(is_ascii_digit)) {
|
||||
return {};
|
||||
return maybe_double.value();
|
||||
}
|
||||
|
||||
// 11. Collect a sequence of code points that are ASCII digits from input given position, and interpret the resulting sequence as a base-ten integer.
|
||||
// Multiply value by that integer.
|
||||
{
|
||||
size_t start_index = lexer.tell();
|
||||
lexer.consume_while(is_ascii_digit);
|
||||
size_t end_index = lexer.tell();
|
||||
auto digits = lexer.input().substring_view(start_index, end_index - start_index);
|
||||
auto optional_value = AK::StringUtils::convert_to_int<i32>(digits);
|
||||
value *= optional_value.value();
|
||||
}
|
||||
|
||||
// 12. If position is past the end of input, jump to the step labeled conversion.
|
||||
if (lexer.is_eof()) {
|
||||
goto conversion;
|
||||
}
|
||||
|
||||
fraction: {
|
||||
// 13. Fraction: If the character indicated by position is a U+002E FULL STOP (.), run these substeps:
|
||||
if (lexer.next_is('.')) {
|
||||
// 13.1. Advance position to the next character.
|
||||
lexer.consume();
|
||||
|
||||
// 13.2. If position is past the end of input,
|
||||
// or if the character indicated by position is not an ASCII digit,
|
||||
// U+0065 LATIN SMALL LETTER E (e), or U+0045 LATIN CAPITAL LETTER E (E),
|
||||
// then jump to the step labeled conversion.
|
||||
if (lexer.is_eof() || (!lexer.next_is(is_ascii_digit) && !lexer.next_is('e') && !lexer.next_is('E'))) {
|
||||
goto conversion;
|
||||
}
|
||||
|
||||
// 13.3. If the character indicated by position is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E),
|
||||
// skip the remainder of these substeps.
|
||||
if (lexer.next_is('e') || lexer.next_is('E')) {
|
||||
goto fraction_exit;
|
||||
}
|
||||
|
||||
// fraction_loop:
|
||||
while (true) {
|
||||
// 13.4. Fraction loop: Multiply divisor by ten.
|
||||
divisor *= 10;
|
||||
|
||||
// 13.5. Add the value of the character indicated by position, interpreted as a base-ten digit (0..9) and divided by divisor, to value.
|
||||
value += (lexer.peek() - '0') / divisor;
|
||||
|
||||
// 13.6. Advance position to the next character.
|
||||
lexer.consume();
|
||||
|
||||
// 13.7. If position is past the end of input, then jump to the step labeled conversion.
|
||||
if (lexer.is_eof()) {
|
||||
goto conversion;
|
||||
}
|
||||
|
||||
// 13.8. If the character indicated by position is an ASCII digit, jump back to the step labeled fraction loop in these substeps.
|
||||
if (!lexer.next_is(is_ascii_digit)) {
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fraction_exit:
|
||||
}
|
||||
|
||||
// 14. If the character indicated by position is U+0065 (e) or a U+0045 (E), then:
|
||||
if (lexer.next_is('e') || lexer.next_is('E')) {
|
||||
// 14.1. Advance position to the next character.
|
||||
lexer.consume();
|
||||
|
||||
// 14.2. If position is past the end of input, then jump to the step labeled conversion.
|
||||
if (lexer.is_eof()) {
|
||||
goto conversion;
|
||||
}
|
||||
|
||||
// 14.3. If the character indicated by position is a U+002D HYPHEN-MINUS character (-):
|
||||
if (lexer.next_is('-')) {
|
||||
// 14.3.1. Change exponent to −1.
|
||||
exponent = -1;
|
||||
|
||||
// 14.3.2. Advance position to the next character.
|
||||
lexer.consume();
|
||||
|
||||
// 14.3.3. If position is past the end of input, then jump to the step labeled conversion.
|
||||
if (lexer.is_eof()) {
|
||||
goto conversion;
|
||||
}
|
||||
}
|
||||
// Otherwise, if the character indicated by position is a U+002B PLUS SIGN character (+):
|
||||
else if (lexer.next_is('+')) {
|
||||
// 14.3.1. Advance position to the next character.
|
||||
lexer.consume();
|
||||
|
||||
// 14.3.2. If position is past the end of input, then jump to the step labeled conversion.
|
||||
if (lexer.is_eof()) {
|
||||
goto conversion;
|
||||
}
|
||||
}
|
||||
|
||||
// 14.4. If the character indicated by position is not an ASCII digit, then jump to the step labeled conversion.
|
||||
if (!lexer.next_is(is_ascii_digit)) {
|
||||
goto conversion;
|
||||
}
|
||||
|
||||
// 14.5. Collect a sequence of code points that are ASCII digits from input given position, and interpret the resulting sequence as a base-ten integer.
|
||||
// Multiply exponent by that integer.
|
||||
{
|
||||
size_t start_index = lexer.tell();
|
||||
lexer.consume_while(is_ascii_digit);
|
||||
size_t end_index = lexer.tell();
|
||||
auto digits = lexer.input().substring_view(start_index, end_index - start_index);
|
||||
auto optional_value = AK::StringUtils::convert_to_int<i32>(digits);
|
||||
exponent *= optional_value.value();
|
||||
}
|
||||
|
||||
// 14.6. Multiply value by ten raised to the exponentth power.
|
||||
value *= std::pow(10, exponent);
|
||||
}
|
||||
|
||||
conversion: {
|
||||
// 15. Conversion: Let S be the set of finite IEEE 754 double-precision floating-point values except −0,
|
||||
// but with two special values added: 2^1024 and −2^1024.
|
||||
if (!std::isfinite(value)) {
|
||||
return {};
|
||||
}
|
||||
if ((value == 0) && std::signbit(value)) {
|
||||
return 0;
|
||||
}
|
||||
|
||||
// 16. Let rounded-value be the number in S that is closest to value, selecting the number with an even significand if there are two equally close values.
|
||||
// (The two special values 2^1024 and −2^1024 are considered to have even significands for this purpose.)
|
||||
double rounded_value = value;
|
||||
|
||||
// 17. If rounded-value is 2^1024 or −2^1024, return an error.
|
||||
if (std::abs(rounded_value) >= std::pow(2, 1024)) {
|
||||
return {};
|
||||
}
|
||||
|
||||
// 18. Return rounded-value.
|
||||
return rounded_value;
|
||||
}
|
||||
}
|
||||
|
||||
// https://html.spec.whatwg.org/multipage/common-microsyntaxes.html#valid-floating-point-number
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue