Method parse_ascii_lower

crates/css_lexer/src/source_cursor.rs:654–711

Parse the cursor's content to ASCII lowercase using any allocator that implements the Allocator trait.

(&self, allocator: A)

	/// Parse the cursor's content to ASCII lowercase using any allocator that implements the Allocator trait.
	pub fn parse_ascii_lower<A: Allocator + Clone + 'a>(&self, allocator: A) -> CowStr<'a, A> {
		debug_assert!(self.token() != Kind::Delim);
		let start = self.token().leading_len() as usize;
		let end = self.source.len() - self.token().trailing_len() as usize;
		if !self.token().contains_escape_chars() && self.token().is_lower_case() {
			return CowStr::Borrowed(&self.source[start..end]);
		}
		let mut chars = self.source[start..end].chars().peekable();
		let mut i = 0;
		let mut vec: Vec<u8, A> = Vec::new_in(allocator.clone());
		while let Some(c) = chars.next() {
			if c == '\0' {
				let mut buf = [0; 4];
				let bytes = REPLACEMENT_CHARACTER.encode_utf8(&mut buf).as_bytes();
				vec.extend_from_slice(bytes);
				i += 1;
			} else if c == '\\' {
				// String has special rules
				// https://drafts.csswg.org/css-syntax-3/#consume-string-cursor
				if self.token().kind_bits() == Kind::String as u8 {
					// When the token is a string, escaped EOF points are not consumed
					// U+005C REVERSE SOLIDUS (\)
					//   If the next input code point is EOF, do nothing.
					//   Otherwise, if the next input code point is a newline, consume it.
					let c = chars.peek();
					if let Some(c) = c {
						if is_newline(*c) {
							chars.next();
							if chars.peek() == Some(&'\n') {
								i += 1;
							}
							i += 2;
							chars = self.source[(start + i)..end].chars().peekable();
							continue;
						}
					} else {
						break;
					}
				}
				i += 1;
				let (ch, n) = self.source[(start + i)..].chars().parse_escape_sequence();
				let char_to_push = if ch == '\0' { REPLACEMENT_CHARACTER } else { ch.to_ascii_lowercase() };
				let mut buf = [0; 4];
				let bytes = char_to_push.encode_utf8(&mut buf).as_bytes();
				vec.extend_from_slice(bytes);
				i += n as usize;
				chars = self.source[(start + i)..end].chars().peekable();
			} else {
				let mut buf = [0; 4];
				let bytes = c.to_ascii_lowercase().encode_utf8(&mut buf).as_bytes();
				vec.extend_from_slice(bytes);
				i += c.len_utf8();
			}
		}
		let boxed_slice = vec.into_boxed_slice();
		// SAFETY: The source is valid UTF-8, so the slice is valid UTF-8
		unsafe { CowStr::Owned(Box::from_raw_in(Box::into_raw(boxed_slice) as *mut str, allocator)) }
	}