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Optimize is_ascii_digit() and is_ascii_hexdigit() #67143

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Optimize is_ascii_digit() and is_ascii_hexdigit() #67143

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9fae8a9
Optimize is_ascii_digit() and is_ascii_hexdigit()
DarkKirb Dec 8, 2019
c2434c0
fix: fixed typo in is_ascii_hexdigit()
DarkKirb Dec 8, 2019
34f89fd
fix: fix compilation error in is_ascii_hexdigit()
DarkKirb Dec 8, 2019
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11 changes: 9 additions & 2 deletions src/libcore/char/methods.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1210,7 +1210,7 @@ impl char {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_digit(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_digit()
self.is_digit(10)
}

/// Checks if the value is an ASCII hexadecimal digit:
Expand Down Expand Up @@ -1245,7 +1245,14 @@ impl char {
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[inline]
pub fn is_ascii_hexdigit(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_hexdigit()
if !self.is_ascii() {
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Why not change this like is_ascii_digit to self.is_digit(16)? Does that end up with worse codegen?

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yes, currently is_digit(x) checks two separate alphabetic ranges instead of one bit-manipulated one, but i could change that if desired

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Yeah, seems like it'd be best to fix is_digit.

return false;
}
if self.is_digit(10) {
return true;
}
let code = (*self as u8) & !0x20; // 0x20 is the case bit
code >= b'A' && code <= b'F'
}

/// Checks if the value is an ASCII punctuation character:
Expand Down