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/** Common implementation for statement parameter lists.
*
* These are used for both prepared statements and parameterized statements.
*
* DO NOT INCLUDE THIS FILE DIRECTLY. Other headers include it for you.
*
* 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.
*/
#ifndef PQXX_H_STATEMENT_PARAMETER
#define PQXX_H_STATEMENT_PARAMETER
#include "pqxx/compiler-public.hxx"
#include "pqxx/compiler-internal-pre.hxx"
#include <cstring>
#include <iterator>
#include <string>
#include <vector>
#include "pqxx/binarystring"
#include "pqxx/strconv"
#include "pqxx/util"
#include "pqxx/internal/type_utils.hxx"
namespace pqxx
{
namespace internal
{
/// Marker type: pass a dynamically-determined number of statement parameters.
/** Normally when invoking a prepared or parameterised statement, the number
* of parameters is known at compile time. For instance,
* @c t.exec_prepared("foo", 1, "x"); executes statement @c foo with two
* parameters, an @c int and a C string.
*
* But sometimes you may want to pass a number of parameters known only at run
* time. In those cases, a @c dynamic_params encodes a dynamically
* determined number of parameters.
*/
template<typename IT> class dynamic_params
{
public:
/// Wrap a sequence of pointers or iterators.
dynamic_params(IT begin, IT end) : m_begin(begin), m_end(end) {}
/// Wrap a container.
template<typename C> explicit dynamic_params(const C &container) :
m_begin(std::begin(container)),
m_end(std::end(container))
{}
IT begin() const { return m_begin; }
IT end() const { return m_end; }
private:
const IT m_begin, m_end;
};
class PQXX_LIBEXPORT statement_parameters
{
protected:
statement_parameters() =default;
statement_parameters &operator=(const statement_parameters &) =delete;
void add_param() { this->add_checked_param("", false, false); }
template<typename T> void add_param(const T &v, bool nonnull)
{
nonnull = (nonnull && not pqxx::string_traits<T>::is_null(v));
this->add_checked_param(
(nonnull ? pqxx::to_string(v) : ""),
nonnull,
false);
}
void add_binary_param(const binarystring &b, bool nonnull)
{ this->add_checked_param(b.str(), nonnull, true); }
/// Marshall parameter values into C-compatible arrays for passing to libpq.
int marshall(
std::vector<const char *> &values,
std::vector<int> &lengths,
std::vector<int> &binaries) const;
private:
void add_checked_param(const std::string &value, bool nonnull, bool binary);
std::vector<std::string> m_values;
std::vector<bool> m_nonnull;
std::vector<bool> m_binary;
};
/// Internal type: encode statement parameters.
/** Compiles arguments for prepared statements and parameterised queries into
* a format that can be passed into libpq.
*
* Objects of this type are meant to be short-lived. If you pass in a non-null
* pointer as a parameter, it may simply use that pointer as a parameter value.
*/
struct params
{
/// Construct directly from a series of statement arguments.
/** The arrays all default to zero, null, and empty strings.
*/
template<typename ...Args> params(Args && ... args)
{
strings.reserve(sizeof...(args));
lengths.reserve(sizeof...(args));
nonnulls.reserve(sizeof...(args));
binaries.reserve(sizeof...(args));
// Start recursively storing parameters.
add_fields(std::forward<Args>(args)...);
}
/// Compose a vector of pointers to parameter string values.
std::vector<const char *> get_pointers() const
{
const std::size_t num_fields = lengths.size();
std::size_t cur_string = 0, cur_bin_string = 0;
std::vector<const char *> pointers(num_fields);
for (std::size_t index = 0; index < num_fields; index++)
{
const char *value;
if (binaries[index])
{
value = bin_strings[cur_bin_string].get();
cur_bin_string++;
}
else if (nonnulls[index])
{
value = strings[cur_string].c_str();
cur_string++;
}
else
{
value = nullptr;
}
pointers[index] = value;
}
return pointers;
}
/// String values, for string parameters.
std::vector<std::string> strings;
/// As used by libpq: lengths of non-null arguments, in bytes.
std::vector<int> lengths;
/// As used by libpq: boolean "is this parameter non-null?"
std::vector<int> nonnulls;
/// As used by libpq: boolean "is this parameter in binary format?"
std::vector<int> binaries;
/// Binary string values, for binary parameters.
std::vector<pqxx::binarystring> bin_strings;
private:
/// Add a non-null string field.
void add_field(std::string str)
{
lengths.push_back(int(str.size()));
nonnulls.push_back(1);
binaries.push_back(0);
strings.emplace_back(std::move(str));
}
/// Compile one argument (specialised for null pointer, a null value).
void add_field(std::nullptr_t)
{
lengths.push_back(0);
nonnulls.push_back(0);
binaries.push_back(0);
}
/// Compile one argument (specialised for binarystring).
void add_field(const binarystring &arg)
{
lengths.push_back(int(arg.size()));
nonnulls.push_back(1);
binaries.push_back(1);
bin_strings.push_back(arg);
}
/// Compile one argument (default, generic implementation).
/** Uses string_traits to represent the argument as a std::string.
*/
template<typename Arg> void add_field(const Arg &arg)
{
if (string_traits<Arg>::is_null(arg)) add_field(nullptr);
else add_field(to_string(arg));
}
/// Compile a dynamic_params object into a dynamic number of parameters.
template<typename IT> void add_field(const dynamic_params<IT> ¶meters)
{
for (auto param: parameters) add_field(param);
}
/// Compile argument list.
/** This recursively "peels off" the next remaining element, compiles its
* information into its final form, and calls itself for the rest of the
* list.
*
* @param arg Current argument to be compiled.
* @param args Optional remaining arguments, to be compiled recursively.
*/
template<typename Arg, typename ...More>
void add_fields(Arg &&arg, More && ... args)
{
add_field(std::forward<Arg>(arg));
// Compile remaining arguments, if any.
add_fields(std::forward<More>(args)...);
}
/// Terminating version of add_fields, at the end of the list.
/** Recursion in add_fields ends with this call.
*/
void add_fields() {}
};
} // namespace pqxx::internal
} // namespace pqxx
#include "pqxx/compiler-internal-post.hxx"
#endif
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