Method formatQueryImpl

src/Parsers/ASTExplainQuery.h:137–179

protected:
    void formatQueryImpl(WriteBuffer & ostr, const FormatSettings & settings, FormatState & state, FormatStateStacked frame) const override
    {
        ostr << toString(kind);

        if (ast_settings)
        {
            ostr << ' ';
            ast_settings->format(ostr, settings, state, frame);
        }

        if (query)
        {
            ostr << settings.nl_or_ws;

            /// When trailing output options (SETTINGS, FORMAT, etc.) follow the EXPLAIN body,
            /// and the inner query is not an ASTQueryWithOutput (e.g. a bare SELECT or UNION),
            /// we must wrap it in parentheses. Otherwise the trailing SETTINGS clause would be
            /// consumed by the inner SELECT during re-parsing.
            /// For inner ASTQueryWithOutput queries (like CREATE TABLE), the flag propagates
            /// through the frame and is handled by each query's own `formatQueryImpl`.
            /// INSERT queries also don't need wrapping: wrapping INSERT in parens would
            /// produce `(INSERT ...)` which cannot be parsed back.
            bool need_parens = frame.has_trailing_output_options
                && !dynamic_cast<const ASTQueryWithOutput *>(query.get())
                && query->getQueryKind() != QueryKind::Insert
                && query->getQueryKind() != QueryKind::AsyncInsertFlush;
            if (need_parens)
                ostr << "(";
            query->format(ostr, settings, state, frame);
            if (need_parens)
                ostr << ")";
        }
        if (table_function)
        {
            ostr << settings.nl_or_ws;
            table_function->format(ostr, settings, state, frame);
        }
        if (table_override)
        {
            ostr << settings.nl_or_ws;
            table_override->format(ostr, settings, state, frame);
        }
    }

private:
    ExplainKind kind;