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/** Implementation of the pqxx::stream_from class.
*
* pqxx::stream_from enables optimized batch reads from a database table.
*
* Copyright (c) 2000-2019, Jeroen T. Vermeulen.
*
* See COPYING for copyright license. If you did not receive a file called
* COPYING with this source code, please notify the distributor of this mistake,
* or contact the author.
*/
#include "pqxx/compiler-internal.hxx"
#include "pqxx/stream_from"
#include "pqxx/internal/encodings.hxx"
#include "pqxx/internal/gates/transaction-stream_from.hxx"
namespace
{
// bool is_octalchar(char o) noexcept
// {
// return (o>='0') and (o<='7');
// }
/// Find first tab character at or after start position in string
/** If not found, returns line.size() rather than string::npos.
*/
std::string::size_type find_tab(
pqxx::internal::encoding_group enc,
const std::string &line,
std::string::size_type start
)
{
auto here = pqxx::internal::find_with_encoding(enc, line, '\t', start);
return (here == std::string::npos) ? line.size() : here;
}
} // namespace
pqxx::stream_from::stream_from(
transaction_base &tb,
const std::string &table_name
) :
namedclass{"stream_from", table_name},
stream_base{tb},
m_retry_line{false}
{
set_up(tb, table_name);
}
pqxx::stream_from::~stream_from() noexcept
{
try
{
complete();
}
catch (const std::exception &e)
{
reg_pending_error(e.what());
}
}
void pqxx::stream_from::complete()
{
close();
}
bool pqxx::stream_from::get_raw_line(std::string &line)
{
internal::gate::transaction_stream_from gate{m_trans};
if (*this)
try
{
if (not gate.read_copy_line(line)) close();
}
catch (const std::exception &)
{
close();
throw;
}
return *this;
}
void pqxx::stream_from::set_up(
transaction_base &tb,
const std::string &table_name
)
{
set_up(tb, table_name, "");
}
void pqxx::stream_from::set_up(
transaction_base &tb,
const std::string &table_name,
const std::string &columns
)
{
// Get the encoding before starting the COPY, otherwise reading the the
// variable will interrupt it
m_copy_encoding = internal::enc_group(m_trans.conn().encoding_id());
internal::gate::transaction_stream_from{tb}.BeginCopyRead(
table_name,
columns
);
register_me();
}
void pqxx::stream_from::close()
{
pqxx::stream_base::close();
try
{
// Flush any remaining lines
std::string s;
while (get_raw_line(s));
}
catch (const broken_connection &)
{
try
{
pqxx::stream_base::close();
}
catch (const std::exception &) {}
throw;
}
catch (const std::exception &e)
{
reg_pending_error(e.what());
}
}
bool pqxx::stream_from::extract_field(
const std::string &line,
std::string::size_type &i,
std::string &s
) const
{
using namespace pqxx::internal;
const auto next_seq = get_glyph_scanner(m_copy_encoding);
s.clear();
bool is_null{false};
auto stop = find_tab(m_copy_encoding, line, i);
while (i < stop)
{
auto glyph_end = next_seq(line.c_str(), line.size(), i);
auto seq_len = glyph_end - i;
if (seq_len == 1)
{
switch (line[i])
{
case '\n':
// End-of-row; shouldn't happen, but we may get old-style
// newline-terminated lines.
i = stop;
break;
case '\\':
{
// Escape sequence.
if (glyph_end >= line.size())
throw failure{"Row ends in backslash"};
char n = line[glyph_end++];
/*
* "Presently, COPY TO will never emit an octal or hex-digits
* backslash sequence [...]"
* - https://www.postgresql.org/docs/10/sql-copy.html
*/
// if (is_octalchar(n))
// {
// if (here.end_byte+2 >= line.size())
// throw failure{"Row ends in middle of octal value"};
// char n1 = line[here.end_byte++];
// char n2 = line[here.end_byte++];
// if (not is_octalchar(n1) or not is_octalchar(n2))
// throw failure{
// "Invalid octal in encoded table stream"
// };
// s += (
// (digit_to_number(n)<<6) |
// (digit_to_number(n1)<<3) |
// digit_to_number(n2)
// );
// break;
// }
// else
switch (n)
{
case 'N':
// Null value
if (not s.empty())
throw failure{
"Null sequence found in nonempty field"
};
is_null = true;
break;
case 'b': // Backspace
s += '\b'; break;
case 'f': // Vertical tab
s += '\f'; break;
case 'n': // Form feed
s += '\n'; break;
case 'r': // Newline
s += '\r'; break;
case 't': // Tab
s += '\t'; break;
case 'v': // Carriage return
s += '\v'; break;
default:
// Self-escaped character
s += n;
break;
}
}
break;
default:
s += line[i];
break;
}
}
else
{
// Multi-byte sequence; never treated specially, so just append
s.insert(s.size(), line.c_str() + i, seq_len);
}
i = glyph_end;
}
// Skip field separator
i += 1;
return not is_null;
}
template<> void pqxx::stream_from::extract_value<std::nullptr_t>(
const std::string &line,
std::nullptr_t&,
std::string::size_type &here,
std::string &workspace
) const
{
if (extract_field(line, here, workspace))
throw pqxx::conversion_error{
"Attempt to convert non-null '"
+ workspace
+ "' to null"
};
}
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