Method parse_spec

crates/common/src/format.rs:1293–1332

(text: &Wtf8)

    }

    fn parse_spec(text: &Wtf8) -> Result<(FormatPart, &Wtf8), FormatParseError> {
        let mut nested = false;
        let mut end_bracket_pos = None;
        let mut left = Wtf8Buf::new();

        // There may be one layer nesting brackets in spec
        for (idx, c) in text.code_point_indices() {
            if idx == 0 {
                if c != '{' {
                    return Err(FormatParseError::MissingStartBracket);
                }
            } else if c == '{' {
                if nested {
                    return Err(FormatParseError::InvalidFormatSpecifier);
                } else {
                    nested = true;
                    left.push(c);
                    continue;
                }
            } else if c == '}' {
                if nested {
                    nested = false;
                    left.push(c);
                    continue;
                } else {
                    end_bracket_pos = Some(idx);
                    break;
                }
            } else {
                left.push(c);
            }
        }
        if let Some(pos) = end_bracket_pos {
            let right = &text[pos..];
            let format_part = Self::parse_part_in_brackets(&left)?;
            Ok((format_part, &right[1..]))
        } else {
            Err(FormatParseError::UnmatchedBracket)
        }
    }
}

pub trait FromTemplate<'a>: Sized {