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Make char and u8 methods const #82078

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merged 4 commits into from
Feb 25, 2021
Merged

Make char and u8 methods const #82078

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bcb1f06
Make char methods const
YenForYang Nov 30, 2020
6a72491
Remove const from iterator fns
lopopolo Feb 13, 2021
7b41ad1
Update since attributes for new const_ascii_methods_on_intrinsics to …
lopopolo Feb 13, 2021
1ed9dd4
Make ascii_change_case_unchecked const
lopopolo Feb 23, 2021
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17 changes: 11 additions & 6 deletions library/core/src/char/methods.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -569,8 +569,9 @@ impl char {
/// assert_eq!(len, tokyo.len());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_char_len_utf", since = "1.52.0")]
#[inline]
pub fn len_utf8(self) -> usize {
pub const fn len_utf8(self) -> usize {
len_utf8(self as u32)
}

Expand All @@ -594,8 +595,9 @@ impl char {
/// assert_eq!(len, 2);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_stable(feature = "const_char_len_utf", since = "1.52.0")]
#[inline]
pub fn len_utf16(self) -> usize {
pub const fn len_utf16(self) -> usize {
let ch = self as u32;
if (ch & 0xFFFF) == ch { 1 } else { 2 }
}
Expand Down Expand Up @@ -1086,8 +1088,9 @@ impl char {
/// [`make_ascii_uppercase()`]: #method.make_ascii_uppercase
/// [`to_uppercase()`]: #method.to_uppercase
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub fn to_ascii_uppercase(&self) -> char {
pub const fn to_ascii_uppercase(&self) -> char {
if self.is_ascii_lowercase() {
(*self as u8).ascii_change_case_unchecked() as char
} else {
Expand Down Expand Up @@ -1118,8 +1121,9 @@ impl char {
/// [`make_ascii_lowercase()`]: #method.make_ascii_lowercase
/// [`to_lowercase()`]: #method.to_lowercase
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub fn to_ascii_lowercase(&self) -> char {
pub const fn to_ascii_lowercase(&self) -> char {
if self.is_ascii_uppercase() {
(*self as u8).ascii_change_case_unchecked() as char
} else {
Expand All @@ -1143,8 +1147,9 @@ impl char {
/// assert!(!upper_a.eq_ignore_ascii_case(&lower_z));
/// ```
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub fn eq_ignore_ascii_case(&self, other: &char) -> bool {
pub const fn eq_ignore_ascii_case(&self, other: &char) -> bool {
self.to_ascii_lowercase() == other.to_ascii_lowercase()
}

Expand Down Expand Up @@ -1561,7 +1566,7 @@ impl char {
}

#[inline]
fn len_utf8(code: u32) -> usize {
const fn len_utf8(code: u32) -> usize {
if code < MAX_ONE_B {
1
} else if code < MAX_TWO_B {
Expand Down
11 changes: 7 additions & 4 deletions library/core/src/num/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -195,8 +195,9 @@ impl u8 {
///
/// [`make_ascii_uppercase`]: #method.make_ascii_uppercase
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub fn to_ascii_uppercase(&self) -> u8 {
pub const fn to_ascii_uppercase(&self) -> u8 {
// Unset the fifth bit if this is a lowercase letter
*self & !((self.is_ascii_lowercase() as u8) * ASCII_CASE_MASK)
}
Expand All @@ -218,15 +219,16 @@ impl u8 {
///
/// [`make_ascii_lowercase`]: #method.make_ascii_lowercase
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub fn to_ascii_lowercase(&self) -> u8 {
pub const fn to_ascii_lowercase(&self) -> u8 {
// Set the fifth bit if this is an uppercase letter
*self | (self.is_ascii_uppercase() as u8 * ASCII_CASE_MASK)
}

/// Assumes self is ascii
#[inline]
pub(crate) fn ascii_change_case_unchecked(&self) -> u8 {
pub(crate) const fn ascii_change_case_unchecked(&self) -> u8 {
*self ^ ASCII_CASE_MASK
}

Expand All @@ -243,8 +245,9 @@ impl u8 {
/// assert!(lowercase_a.eq_ignore_ascii_case(&uppercase_a));
/// ```
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub fn eq_ignore_ascii_case(&self, other: &u8) -> bool {
pub const fn eq_ignore_ascii_case(&self, other: &u8) -> bool {
self.to_ascii_lowercase() == other.to_ascii_lowercase()
}

Expand Down