fn next()

in starlark/src/values/types/string/interpolation.rs [340:396]

• 55 lines of code
• 7 McCabe index (conditional complexity)

    fn next(&mut self) -> anyhow::Result<Option<FormatToken<'a>>> {
        let mut i = 0;

        while i < self.rem_input.len() {
            match self.rem_input.as_bytes()[i] {
                b'{' | b'}' if i != 0 => {
                    let (text, rem) = self.rem_input.split_at(i);
                    self.rem_input = rem;
                    return Ok(Some(FormatToken::Text(text)));
                }
                b'{' => {
                    assert!(i == 0);
                    if self.rem_input.starts_with("{{") {
                        self.rem_input = &self.rem_input[2..];
                        return Ok(Some(FormatToken::Text("{")));
                    }
                    i = 1;
                    while i < self.rem_input.len() {
                        match self.rem_input.as_bytes()[i] {
                            b'}' => {
                                let capture = &self.rem_input[1..i];
                                self.rem_input = &self.rem_input[i + 1..];
                                return Ok(Some(FormatToken::Capture(capture)));
                            }
                            b'{' => {
                                break;
                            }
                            _ => i += 1,
                        }
                    }
                    return Err(anyhow!(
                        "Unmatched '{{' in format string `{}`",
                        self.format_str
                    ));
                }
                b'}' => {
                    assert!(i == 0);
                    if self.rem_input.starts_with("}}") {
                        self.rem_input = &self.rem_input[2..];
                        return Ok(Some(FormatToken::Text("}")));
                    }
                    return Err(anyhow!(
                        "Standalone '}}' in format string `{}`",
                        self.format_str
                    ));
                }
                _ => i += 1,
            }
        }

        if i == 0 {
            Ok(None)
        } else {
            let text = mem::take(&mut self.rem_input);
            Ok(Some(FormatToken::Text(text)))
        }
    }