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LibJS: Rewrite parseInt to be more specification-compliant

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Idan Horowitz 2022-01-16 20:35:26 +02:00 committed by Linus Groh
parent 877ae85017
commit de2f5bb5a7
1 changed files with 45 additions and 15 deletions
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60
Userland/Libraries/LibJS/Runtime/GlobalObject.cpp
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@ -387,37 +387,63 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::parse_float)
// 19.2.5 parseInt ( string, radix ), https://tc39.es/ecma262/#sec-parseint-string-radix
JS_DEFINE_NATIVE_FUNCTION(GlobalObject::parse_int)
{
// 1. Let inputString be ? ToString(string).
auto input_string = TRY(vm.argument(0).to_string(global_object));
// FIXME: There's a bunch of unnecessary string copying here.
double sign = 1;
auto s = input_string.trim_whitespace(TrimMode::Left);
if (!s.is_empty() && s[0] == '-')
sign = -1;
if (!s.is_empty() && (s[0] == '+' || s[0] == '-'))
s = s.substring(1, s.length() - 1);
// 2. Let S be ! TrimString(inputString, start).
auto string = MUST(trim_string(global_object, js_string(vm, input_string), TrimMode::Left));
// 3. Let sign be 1.
auto sign = 1;
// 4. If S is not empty and the first code unit of S is the code unit 0x002D (HYPHEN-MINUS), set sign to -1.
if (!string.is_empty() && string[0] == 0x2D)
sign = -1;
// 5. If S is not empty and the first code unit of S is the code unit 0x002B (PLUS SIGN) or the code unit 0x002D (HYPHEN-MINUS), remove the first code unit from S.
auto trimmed_view = string.view();
if (!string.is_empty() && (string[0] == 0x2B || string[0] == 0x2D))
trimmed_view = trimmed_view.substring_view(1);
// 6. Let R be ℝ(? ToInt32(radix)).
auto radix = TRY(vm.argument(1).to_i32(global_object));
bool strip_prefix = true;
// 7. Let stripPrefix be true.
auto strip_prefix = true;
// 8. If R ≠ 0, then
if (radix != 0) {
// a. If R < 2 or R > 36, return NaN.
if (radix < 2 || radix > 36)
return js_nan();
// b. If R ≠ 16, set stripPrefix to false.
if (radix != 16)
strip_prefix = false;
} else {
}
// 9. Else,
else {
// a. Set R to 10.
radix = 10;
}
// 10. If stripPrefix is true, then
if (strip_prefix) {
if (s.length() >= 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) {
s = s.substring(2, s.length() - 2);
// a. If the length of S is at least 2 and the first two code units of S are either "0x" or "0X", then
if (trimmed_view.length() >= 2 && trimmed_view.substring_view(0, 2).equals_ignoring_case("0x"sv)) {
// i. Remove the first two code units from S.
trimmed_view = trimmed_view.substring_view(2);
// ii. Set R to 16.
radix = 16;
}
}
auto parse_digit = [&](u32 code_point, i32 radix) -> Optional<i32> {
if (!is_ascii_alphanumeric(code_point) || radix <= 0)
// 11. If S contains a code unit that is not a radix-R digit, let end be the index within S of the first such code unit; otherwise, let end be the length of S.
// 12. Let Z be the substring of S from 0 to end.
// 13. If Z is empty, return NaN.
// 14. Let mathInt be the integer value that is represented by Z in radix-R notation, using the letters A-Z and a-z for digits with values 10 through 35. (However, if R is 10 and Z contains more than 20 significant digits, every significant digit after the 20th may be replaced by a 0 digit, at the option of the implementation; and if R is not 2, 4, 8, 10, 16, or 32, then mathInt may be an implementation-approximated integer representing the integer value denoted by Z in radix-R notation.)
auto parse_digit = [&](u32 code_point) -> Optional<u32> {
if (!is_ascii_alphanumeric(code_point))
return {};
auto digit = parse_ascii_base36_digit(code_point);
if (digit >= (u32)radix)
@ -427,8 +453,8 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::parse_int)
bool had_digits = false;
double number = 0;
for (auto code_point : Utf8View(s)) {
auto digit = parse_digit(code_point, radix);
for (auto code_point : Utf8View(trimmed_view)) {
auto digit = parse_digit(code_point);
if (!digit.has_value())
break;
had_digits = true;
@ -439,6 +465,10 @@ JS_DEFINE_NATIVE_FUNCTION(GlobalObject::parse_int)
if (!had_digits)
return js_nan();
// 15. If mathInt = 0, then
// a. If sign = -1, return -0𝔽.
// b. Return +0𝔽.
// 16. Return 𝔽(sign × mathInt).
return Value(sign * number);
}