Method writeToStream

tutorials/external/catch.hpp:7644–7683

        }

        void writeToStream( std::ostream &os ) const {
            if (!m_exeName.name().empty()) {
                os << "usage:\n" << "  " << m_exeName.name() << " ";
                bool required = true, first = true;
                for( auto const &arg : m_args ) {
                    if (first)
                        first = false;
                    else
                        os << " ";
                    if( arg.isOptional() && required ) {
                        os << "[";
                        required = false;
                    }
                    os << "<" << arg.hint() << ">";
                    if( arg.cardinality() == 0 )
                        os << " ... ";
                }
                if( !required )
                    os << "]";
                if( !m_options.empty() )
                    os << " options";
                os << "\n\nwhere options are:" << std::endl;
            }

            auto rows = getHelpColumns();
            size_t consoleWidth = CATCH_CLARA_CONFIG_CONSOLE_WIDTH;
            size_t optWidth = 0;
            for( auto const &cols : rows )
                optWidth = (std::max)(optWidth, cols.left.size() + 2);

            optWidth = (std::min)(optWidth, consoleWidth/2);

            for( auto const &cols : rows ) {
                auto row =
                        TextFlow::Column( cols.left ).width( optWidth ).indent( 2 ) +
                        TextFlow::Spacer(4) +
                        TextFlow::Column( cols.right ).width( consoleWidth - 7 - optWidth );
                os << row << std::endl;
            }
        }

        friend auto operator<<( std::ostream &os, Parser const &parser ) -> std::ostream& {
            parser.writeToStream( os );