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Improve char::is_ascii_* code
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These methods explicitly check if a char is in a specific ASCII range,
therefore the `is_ascii()` check is not needed, but LLVM seems to be
unable to remove it.

WARNING: this change improves the performance on ASCII `char`s, but
complex checks such as `is_ascii_punctuation` become slower on
non-ASCII `char`s.
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ranma42 committed Feb 11, 2020
1 parent dc4242d commit 4e7aeaf
Showing 1 changed file with 40 additions and 10 deletions.
50 changes: 40 additions & 10 deletions src/libcore/char/methods.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1075,7 +1075,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_alphabetic(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_alphabetic()
match *self {
'A'..='Z' | 'a'..='z' => true,
_ => false,
}
}

/// Checks if the value is an ASCII uppercase character:
Expand Down Expand Up @@ -1108,7 +1111,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_uppercase(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_uppercase()
match *self {
'A'..='Z' => true,
_ => false,
}
}

/// Checks if the value is an ASCII lowercase character:
Expand Down Expand Up @@ -1141,7 +1147,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_lowercase(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_lowercase()
match *self {
'a'..='z' => true,
_ => false,
}
}

/// Checks if the value is an ASCII alphanumeric character:
Expand Down Expand Up @@ -1177,7 +1186,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_alphanumeric(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_alphanumeric()
match *self {
'0'..='9' | 'A'..='Z' | 'a'..='z' => true,
_ => false,
}
}

/// Checks if the value is an ASCII decimal digit:
Expand Down Expand Up @@ -1210,7 +1222,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_digit(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_digit()
match *self {
'0'..='9' => true,
_ => false,
}
}

/// Checks if the value is an ASCII hexadecimal digit:
Expand Down Expand Up @@ -1246,7 +1261,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_hexdigit(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_hexdigit()
match *self {
'0'..='9' | 'A'..='F' | 'a'..='f' => true,
_ => false,
}
}

/// Checks if the value is an ASCII punctuation character:
Expand Down Expand Up @@ -1283,7 +1301,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_punctuation(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_punctuation()
match *self {
'!'..='/' | ':'..='@' | '['..='`' | '{'..='~' => true,
_ => false,
}
}

/// Checks if the value is an ASCII graphic character:
Expand Down Expand Up @@ -1316,7 +1337,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_graphic(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_graphic()
match *self {
'!'..='~' => true,
_ => false,
}
}

/// Checks if the value is an ASCII whitespace character:
Expand Down Expand Up @@ -1366,7 +1390,10 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_whitespace(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_whitespace()
match *self {
'\t' | '\n' | '\x0C' | '\r' | ' ' => true,
_ => false,
}
}

/// Checks if the value is an ASCII control character:
Expand Down Expand Up @@ -1401,6 +1428,9 @@ impl char {
#[rustc_const_unstable(feature = "const_ascii_ctype_on_intrinsics", issue = "68983")]
#[inline]
pub const fn is_ascii_control(&self) -> bool {
self.is_ascii() && (*self as u8).is_ascii_control()
match *self {
'\0'..='\x1F' | '\x7F' => true,
_ => false,
}
}
}

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