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optimize put_back_char

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Always encode the char directly into the buffer.
Only shift the buffer content if there isn't enough room in the front.
This commit is contained in:
Skgland
2026-04-26 13:43:04 +02:00
parent b2dad66270
commit af54fb2aba
1 changed files with 10 additions and 9 deletions
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19
src/parser/char_reader.rs
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@@ -235,16 +235,17 @@ impl<R: Read> CharRead for CharReader<R> {
#[inline(always)]
fn put_back_char(&mut self, c: char) {
let c_len = c.len_utf8();
if c_len <= self.pos {
self.pos -= c_len;
} else {
self.buf.insert_from_slice(
0,
&[0u8; 4/* char::MAX_LEN_UTF8 once msrv reached 1.93 */][..c_len - self.pos],
);
self.pos = 0;
}
let mut shifted_slice = SmallVec::<[u8; 32]>::new();
shifted_slice.extend_from_slice(&self.buf[self.pos..]);
self.buf.clear();
self.buf.resize(c_len, 0);
c.encode_utf8(&mut self.buf[..c_len]);
self.buf.extend_from_slice(&shifted_slice);
self.pos = 0;
c.encode_utf8(&mut self.buf[self.pos..]);
}
#[inline(always)]