executable.h

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 * Copyright (c) 2015, 2024, Oracle and/or its affiliates.
 *
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 * published by the Free Software Foundation.
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 */
 
#ifndef MYSQLX_EXECUTABLE_H
#define MYSQLX_EXECUTABLE_H
 
#include "common.h"
#include "result.h"
#include "../common/op_if.h"
 
 
namespace mysqlx {
MYSQLX_ABI_BEGIN(2,0)
 
using std::ostream;
 
 
template <class Res, class Op>
class Executable
{
private:
  using Impl = common::Executable_if;
 
  std::unique_ptr<Impl> m_impl;
protected:
 
 
  Executable() = default;
 
  void reset(Impl *impl)
  {
    m_impl.reset(impl);
  }
 
  /*
    Copy semantics implementation: the current state of the other executable
    object (of its implementation, to be precise) is copied to this new
    instance. After that the two executables are independent objects describing
    the same operation.
  */
 
  void reset(const Executable &other)
  {
    if (m_impl.get() != other.m_impl.get()) m_impl.reset(other.m_impl->clone());
  }
 
  void reset(const Executable &&other)
  {
    m_impl.reset(other.m_impl->clone());
  }
 
  void check_if_valid() const
  {
    if (!m_impl)
      throw Error("Attempt to use invalid operation");
  }
 
  Impl* get_impl()
  {
    check_if_valid();
    return m_impl.get();
  }
 
public:
 
  Executable(const Executable &other)
  {
    operator=(other);
  }
 
  Executable(Executable &&other)
  {
    operator=(std::move(other));
  }
 
  virtual ~Executable() NOEXCEPT {}
 
 
  Executable& operator=(const Executable &other)
  {
    try {
      reset(other);
      return *this;
    }
    CATCH_AND_WRAP
  }
 
  Executable& operator=(Executable &&other)
  {
    try {
      reset(std::move(other));
      return *this;
    }
    CATCH_AND_WRAP
  }
 
 
 
  virtual Res execute()
  {
    try {
      check_if_valid();
      /*
        Note: The implementation object's execute() methods returns a reference
        to a common::Result_init object which provides information about
        the session and pending server reply. The returned Res instance should
        be constructible from such Result_init reference.
      */
      return m_impl->execute();
    }
    CATCH_AND_WRAP
  }
 
  struct Access;
  friend Access;
};
 
 
MYSQLX_ABI_END(2,0)
}  // mysqlx
 
#endif