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/** Implementation of the pqxx::tablereader class.
*
* pqxx::tablereader 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/tablereader"
#include "pqxx/transaction"
#include "pqxx/internal/gates/transaction-tablereader.hxx"
using namespace pqxx::internal;
pqxx::tablereader::tablereader(
transaction_base &T,
const std::string &Name,
const std::string &Null) :
namedclass{"tablereader", Name},
tablestream(T, Null),
m_done{true}
{
set_up(T, Name);
}
void pqxx::tablereader::set_up(
transaction_base &T,
const std::string &Name,
const std::string &Columns)
{
gate::transaction_tablereader{T}.BeginCopyRead(Name, Columns);
register_me();
m_done = false;
}
pqxx::tablereader::~tablereader() noexcept
{
try
{
reader_close();
}
catch (const std::exception &e)
{
reg_pending_error(e.what());
}
}
bool pqxx::tablereader::get_raw_line(std::string &Line)
{
if (not m_done) try
{
m_done = not gate::transaction_tablereader{m_trans}.read_copy_line(Line);
}
catch (const std::exception &)
{
m_done = true;
throw;
}
return not m_done;
}
void pqxx::tablereader::complete()
{
reader_close();
}
void pqxx::tablereader::reader_close()
{
if (not is_finished())
{
base_close();
// If any lines remain to be read, consume them to not confuse PQendcopy()
if (not m_done)
{
try
{
std::string Dummy;
while (get_raw_line(Dummy)) ;
}
catch (const broken_connection &)
{
try { base_close(); } catch (const std::exception &) {}
throw;
}
catch (const std::exception &e)
{
reg_pending_error(e.what());
}
}
}
}
namespace
{
inline 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 findtab(
const std::string &Line,
std::string::size_type start)
{
// TODO: Fix for multibyte encodings?
const auto here = Line.find('\t', start);
return (here == std::string::npos) ? Line.size() : here;
}
} // namespace
std::string pqxx::tablereader::extract_field(
const std::string &Line,
std::string::size_type &i) const
{
// TODO: Pick better exception types
std::string R;
bool isnull=false;
auto stop = findtab(Line, i);
for (; i < stop; ++i)
{
const char c = Line[i];
switch (c)
{
case '\n': // End of row
// Shouldn't happen, but we may get old-style, newline-terminated lines
i = stop;
break;
case '\\': // Escape sequence
{
const char n = Line[++i];
if (i >= Line.size())
throw failure{"Row ends in backslash."};
switch (n)
{
case 'N': // Null value
if (not R.empty())
throw failure{"Null sequence found in nonempty field."};
R = NullStr();
isnull = true;
break;
case '0': // Octal sequence (3 digits)
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
{
if ((i+2) >= Line.size())
throw failure{"Row ends in middle of octal value."};
const char n1 = Line[++i];
const char n2 = Line[++i];
if (not is_octalchar(n1) or not is_octalchar(n2))
throw failure{"Invalid octal in encoded table stream."};
R += char(
(digit_to_number(n)<<6) |
(digit_to_number(n1)<<3) |
digit_to_number(n2));
}
break;
case 'b':
// TODO: Escape code?
R += char(8);
break; // Backspace
case 'v':
// TODO: Escape code?
R += char(11);
break; // Vertical tab
case 'f':
// TODO: Escape code?
R += char(12);
break; // Form feed
case 'n':
R += '\n';
break; // Newline
case 't':
R += '\t';
break; // Tab
case 'r':
R += '\r';
break; // Carriage return;
default: // Self-escaped character
R += n;
// This may be a self-escaped tab that we thought was a terminator...
if (i == stop)
{
if ((i+1) >= Line.size())
throw internal_error{"COPY line ends in backslash."};
stop = findtab(Line, i+1);
}
break;
}
}
break;
default:
R += c;
break;
}
}
++i;
if (isnull and (R.size() != NullStr().size()))
throw failure{"Field contains data behind null sequence."};
return R;
}
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