13 #ifndef PQXX_H_STREAM_TO
14 #define PQXX_H_STREAM_TO
16 #include "pqxx/compiler-public.hxx"
17 #include "pqxx/internal/compiler-internal-pre.hxx"
19 #include "pqxx/separated_list.hxx"
20 #include "pqxx/transaction_base.hxx"
74 class PQXX_LIBEXPORT
stream_to : internal::transactionfocus
88 template<
typename Columns>
93 template<
typename Iter>
101 [[nodiscard]]
operator bool() const noexcept {
return not m_finished; }
103 [[nodiscard]]
bool operator!() const noexcept {
return m_finished; }
156 fill_buffer(fields...);
161 bool m_finished =
false;
164 std::string m_buffer;
167 std::string m_field_buf;
170 void write_raw_line(std::string_view);
178 static constexpr std::string_view null_field{
"\\N\t"};
182 static std::enable_if_t<nullness<T>::always_null, std::size_t>
183 estimate_buffer(T
const &)
185 return std::size(null_field);
193 static std::enable_if_t<not nullness<T>::always_null, std::size_t>
194 estimate_buffer(T
const &field)
200 void escape_field_to_buffer(std::string_view);
209 template<
typename Field>
210 std::enable_if_t<not nullness<Field>::always_null>
211 append_to_buffer(Field
const &f)
219 m_buffer.append(null_field);
225 using traits = string_traits<Field>;
226 auto const budget{estimate_buffer(f)};
227 auto const offset{std::size(m_buffer)};
229 if constexpr (std::is_arithmetic_v<Field>)
237 auto const total{offset + budget};
238 m_buffer.resize(total);
239 char *
const end{traits::into_buf(
240 m_buffer.data() + offset, m_buffer.data() + total, f)};
243 m_buffer.resize(
static_cast<std::size_t
>(end - m_buffer.data()));
250 m_field_buf.resize(budget);
251 escape_field_to_buffer(traits::to_buf(
252 m_field_buf.data(), m_field_buf.data() + std::size(m_field_buf), f));
264 template<
typename Field>
265 std::enable_if_t<nullness<Field>::always_null>
266 append_to_buffer(Field
const &)
268 m_buffer.append(null_field);
272 template<
typename Container>
void fill_buffer(Container
const &c)
277 std::size_t budget{0};
278 for (
auto const &f : c) budget += estimate_buffer(f);
279 m_buffer.reserve(budget);
280 for (
auto const &f : c) append_to_buffer(f);
284 template<
typename Tuple, std::size_t... indexes>
286 budget_tuple(Tuple
const &t, std::index_sequence<indexes...>)
288 return (estimate_buffer(std::get<indexes>(t)) + ...);
292 template<
typename Tuple, std::size_t... indexes>
293 void append_tuple(Tuple
const &t, std::index_sequence<indexes...>)
295 (append_to_buffer(std::get<indexes>(t)), ...);
299 template<
typename... Elts>
void fill_buffer(std::tuple<Elts...>
const &t)
301 using indexes = std::make_index_sequence<
sizeof...(Elts)>;
303 m_buffer.reserve(budget_tuple(t, indexes{}));
304 append_tuple(t, indexes{});
307 void set_up(transaction_base &, std::string_view table_name);
309 transaction_base &, std::string_view table_name, std::string_view columns);
312 template<
typename... Ts>
void fill_buffer(
const Ts &...fields)
314 (..., append_to_buffer(fields));
317 constexpr
static std::string_view s_classname{
"stream_to"};
321 template<
typename Columns>
323 transaction_base &tb, std::string_view table_name, Columns
const &columns) :
324 stream_to{tb, table_name, std::begin(columns), std::end(columns)}
328 template<
typename Iter>
332 internal::transactionfocus{tb, s_classname, table_name}
334 set_up(tb, table_name,
separated_list(
",", columns_begin, columns_end));
338 #include "pqxx/internal/compiler-internal-post.hxx"
The home of all libpqxx classes, functions, templates, etc.
Definition: array.hxx:26
std::string separated_list(std::string_view sep, ITER begin, ITER end, ACCESS access)
Represent sequence of values as a string, joined by a given separator.
Definition: separated_list.hxx:40
std::size_t size_buffer(TYPE const &...value) noexcept
Estimate how much buffer space is needed to represent values as a string.
Definition: strconv.hxx:364
std::basic_ostream< CHAR > & operator<<(std::basic_ostream< CHAR > &s, field const &value)
Write a result field to any type of stream.
Definition: field.hxx:480
bool is_null(TYPE const &value) noexcept
Is value null?
Definition: strconv.hxx:353
Reference to one row in a result.
Definition: row.hxx:46
Stream data from the database.
Definition: stream_from.hxx:68
Efficiently write data directly to a database table.
Definition: stream_to.hxx:75
stream_to & operator<<(Row const &row)
Insert a row of data.
Definition: stream_to.hxx:124
void write_values(const Ts &...fields)
Insert values as a row.
Definition: stream_to.hxx:154
stream_to(transaction_base &, std::string_view table_name)
Create a stream, without specifying columns.
Definition: stream_to.cxx:36
void write_row(Row const &row)
Insert a row of data, given in the form of a std::tuple or container.
Definition: stream_to.hxx:144
bool operator!() const noexcept
Has this stream been through its concluding complete()?
Definition: stream_to.hxx:103
Interface definition (and common code) for "transaction" classes.
Definition: transaction_base.hxx:72