Method add_first_line

crates/ruff_python_formatter/src/string/docstring.rs:1198–1232

Looks for the first line in a literal or code block. If a first line is found, then this returns true. Otherwise, an empty line has been found and the caller should pass it through to the docstring unchanged. (Empty lines are allowed to precede a block. And there must be at least one of them.) If the given line is invalid for a reStructuredText block (i.e., no empty lines seen between the openin

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

    /// Callers must only call this when the first indentation has not yet been
    /// found. If it has, then this panics.
    fn add_first_line(
        mut self,
        original: InputDocstringLine<'src>,
        queue: &mut VecDeque<CodeExampleAddAction<'src>>,
    ) -> Option<CodeExampleRst<'src>> {
        assert!(self.min_indent.is_none());

        // While the rst spec isn't completely clear on this point, through
        // experimentation, I found that multiple empty lines before the first
        // non-empty line are ignored.
        let (indent, rest) = indent_with_suffix(original.line);
        if rest.is_empty() {
            queue.push_back(CodeExampleAddAction::Print { original });
            return Some(self);
        }
        // Ignore parameters in field lists. These can only occur in
        // directives, not literal blocks.
        if self.is_directive && is_rst_option(rest) {
            queue.push_back(CodeExampleAddAction::Print { original });
            return Some(self);
        }
        let min_indent = Indentation::from_str(indent);
        // At this point, we found a non-empty line. The only thing we require
        // is that its indentation is strictly greater than the indentation of
        // the line containing the `::`. Otherwise, we treat this as an invalid
        // block and bail.
        if min_indent <= self.opening_indent {
            queue.push_back(self.into_reset_action());
            return None;
        }
        self.min_indent = Some(min_indent);
        self.push(original);
        queue.push_back(CodeExampleAddAction::Kept);
        Some(self)
    }

    /// Pushes the given line as part of this code example.
    fn push(&mut self, original: InputDocstringLine<'src>) {