Method add_code_line

crates/ruff_python_formatter/src/string/docstring.rs:908–942

Looks for a valid doctest PS2 prompt in the line given. If one is found, it is added to this code example and ownership of the example is returned to the caller. In this case, callers should continue trying to add PS2 prompt lines. But if one isn't found, then the given line is not part of the code example and ownership of this example is not returned. In either case, relevant actions will be ad

(
        mut self,
        original: InputDocstringLine<'src>,
        queue: &mut VecDeque<CodeExampleAddAction<'src>>,
    )

    /// In either case, relevant actions will be added to the given queue to
    /// process.
    fn add_code_line(
        mut self,
        original: InputDocstringLine<'src>,
        queue: &mut VecDeque<CodeExampleAddAction<'src>>,
    ) -> Option<CodeExampleDoctest<'src>> {
        let Some((ps2_indent, ps2_after)) = original.line.split_once("...") else {
            queue.push_back(self.into_format_action());
            return None;
        };
        // PS2 prompts must have the same indentation as their
        // corresponding PS1 prompt.[1] While the 'doctest' Python
        // module will error in this case, we just treat this line as a
        // non-doctest line.
        //
        // [1]: https://github.com/python/cpython/blob/0ff6368519ed7542ad8b443de01108690102420a/Lib/doctest.py#L733
        if self.ps1_indent != ps2_indent {
            queue.push_back(self.into_format_action());
            return None;
        }
        // PS2 prompts must be followed by an ASCII space character unless
        // it's an otherwise empty line[1].
        //
        // [1]: https://github.com/python/cpython/blob/0ff6368519ed7542ad8b443de01108690102420a/Lib/doctest.py#L809-L812
        let code = match ps2_after.strip_prefix(' ') {
            None if ps2_after.is_empty() => "",
            None => {
                queue.push_back(self.into_format_action());
                return None;
            }
            Some(code) => code,
        };
        self.lines.push(CodeExampleLine { original, code });
        queue.push_back(CodeExampleAddAction::Kept);
        Some(self)
    }

    /// Consume this doctest and turn it into a formatting action.
    fn into_format_action(self) -> CodeExampleAddAction<'src> {