//! impl char {}
+use crate::intrinsics::likely;
use crate::slice;
use crate::str::from_utf8_unchecked_mut;
use crate::unicode::printable::is_printable;
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn to_digit(self, radix: u32) -> Option<u32> {
+ assert!(radix <= 36, "to_digit: radix is too high (maximum 36)");
+ const ASCII_DIGIT_MASK: u32 = 0b11_0000;
// the code is split up here to improve execution speed for cases where
// the `radix` is constant and 10 or smaller
- let val = if radix <= 10 {
- match self {
- '0'..='9' => self as u32 - '0' as u32,
- _ => return None,
- }
+ let val = if likely(radix <= 10) {
+ // If not a digit, a number greater than radix will be created.
+ self as u32 ^ ASCII_DIGIT_MASK
} else {
- assert!(radix <= 36, "to_digit: radix is too high (maximum 36)");
-
match self {
'0'..='9' => self as u32 - '0' as u32,
'a'..='z' => self as u32 - 'a' as u32 + 10,