ydb/contrib/libs/libpqxx/include/pqxx/internal/statement_parameters.hxx

/** 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> &parameters)
  {
    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