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use oxc_syntax::{identifier::is_white_space, line_terminator::is_line_terminator};
pub trait StringToNumber {
fn string_to_number(&self) -> f64;
}
/// `StringToNumber`
///
/// <https://tc39.es/ecma262/#sec-stringtonumber>
impl StringToNumber for &str {
fn string_to_number(&self) -> f64 {
let s = self.trim_start_matches(is_str_white_space_char);
match s {
"" => return 0.0,
"-Infinity" => return f64::NEG_INFINITY,
"Infinity" | "+Infinity" => return f64::INFINITY,
_ => {
// Make sure that no further variants of "infinity" are parsed by `f64::parse`.
// Note that alphabetical characters are not case-sensitive.
// <https://doc.rust-lang.org/std/primitive.f64.html#method.from_str>
let mut bytes = s.trim_start_matches(['-', '+']).bytes();
if bytes
.next()
.filter(|c| c.eq_ignore_ascii_case(&b'i'))
.and_then(|_| bytes.next().filter(|c| c.eq_ignore_ascii_case(&b'n')))
.and_then(|_| bytes.next().filter(|c| c.eq_ignore_ascii_case(&b'f')))
.is_some()
{
return f64::NAN;
}
}
}
let mut bytes = s.bytes();
if s.len() > 2 && bytes.next() == Some(b'0') {
// `| 32` converts upper case ASCII letters to lower case.
// A bit more efficient than testing for `b'x' | b'X'`.
// https://godbolt.org/z/Korrhd4TE
let radix: u32 = match bytes.next().unwrap() | 32 {
b'x' => 16,
b'o' => 8,
b'b' => 2,
_ => 0,
};
if radix != 0 {
let s = &s[2..];
// Fast path
if let Ok(value) = u32::from_str_radix(s, radix) {
return f64::from(value);
}
// Slow path
let mut value: f64 = 0.0;
for c in bytes {
if let Some(digit) = char::from(c).to_digit(radix) {
value = value.mul_add(f64::from(radix), f64::from(digit));
} else {
return f64::NAN;
}
}
return value;
}
}
s.parse::<f64>().unwrap_or(f64::NAN)
}
}
/// whether the char is a StrWhiteSpaceChar
/// <https://tc39.es/ecma262/#sec-tonumber-applied-to-the-string-type>
fn is_str_white_space_char(c: char) -> bool {
is_white_space(c) || is_line_terminator(c)
}