Skip to content

core: minor refactoring of run_utf8_validation #108217

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

core: minor refactoring of run_utf8_validation #108217

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
55 changes: 24 additions & 31 deletions library/core/src/str/validations.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -125,34 +125,37 @@ const fn contains_nonascii(x: usize) -> bool {
#[inline(always)]
#[rustc_const_unstable(feature = "str_internals", issue = "none")]
pub(super) const fn run_utf8_validation(v: &[u8]) -> Result<(), Utf8Error> {
let mut index = 0;
let len = v.len();

let usize_bytes = mem::size_of::<usize>();
let ascii_block_size = 2 * usize_bytes;
let blocks_end = if len >= ascii_block_size { len - ascii_block_size + 1 } else { 0 };
let align = v.as_ptr().align_offset(usize_bytes);

while index < len {
let old_offset = index;
let mut index = 0;
while let Some(&first) = v.get(index) {
let valid_up_to = index;
macro_rules! err {
($error_len: expr) => {
return Err(Utf8Error { valid_up_to: old_offset, error_len: $error_len })
return Err(Utf8Error { valid_up_to, error_len: $error_len })
};
}

macro_rules! next {
() => {{
index += 1;
// we needed data, but there was none: error!
if index >= len {
err!(None)
macro_rules! get_byte {
($off:expr) => {
match v.get(index + $off) {
Some(&byte) => byte,
None => err!(None),
}
v[index]
}};
}
}
macro_rules! check_cont_byte {
($off:expr) => {
if !utf8_is_cont_byte(get_byte!($off)) {
err!(Some($off as u8))
}
}
}

let first = v[index];
if first >= 128 {
let w = utf8_char_width(first);
// 2-byte encoding is for codepoints \u{0080} to \u{07ff}
Expand All @@ -174,38 +177,28 @@ pub(super) const fn run_utf8_validation(v: &[u8]) -> Result<(), Utf8Error> {
// UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
// %xF4 %x80-8F 2( UTF8-tail )
match w {
2 => {
if next!() as i8 >= -64 {
err!(Some(1))
}
}
2 => check_cont_byte!(1),
3 => {
match (first, next!()) {
match (first, get_byte!(1)) {
(0xE0, 0xA0..=0xBF)
| (0xE1..=0xEC, 0x80..=0xBF)
| (0xED, 0x80..=0x9F)
| (0xEE..=0xEF, 0x80..=0xBF) => {}
_ => err!(Some(1)),
}
if next!() as i8 >= -64 {
err!(Some(2))
}
check_cont_byte!(2);
}
4 => {
match (first, next!()) {
match (first, get_byte!(1)) {
(0xF0, 0x90..=0xBF) | (0xF1..=0xF3, 0x80..=0xBF) | (0xF4, 0x80..=0x8F) => {}
_ => err!(Some(1)),
}
if next!() as i8 >= -64 {
err!(Some(2))
}
if next!() as i8 >= -64 {
err!(Some(3))
}
check_cont_byte!(2);
check_cont_byte!(3);
}
_ => err!(Some(1)),
}
index += 1;
index += w;
} else {
// Ascii case, try to skip forward quickly.
// When the pointer is aligned, read 2 words of data per iteration
Expand Down