// file      : odb/lazy-ptr.hxx
// copyright : Copyright (c) 2009-2012 Code Synthesis Tools CC
// license   : GNU GPL v2; see accompanying LICENSE file

#ifndef ODB_LAZY_PTR_HXX
#define ODB_LAZY_PTR_HXX

#include <odb/pre.hxx>

#include <memory>  // std::auto_ptr, std::shared_ptr/weak_ptr
#include <utility> // std::move

#include <odb/forward.hxx>        // odb::database
#include <odb/traits.hxx>
#include <odb/lazy-ptr-impl.hxx>
#include <odb/details/config.hxx> // ODB_CXX11

namespace odb
{
  // Raw pointer lazy version.
  //
  template <class T>
  class lazy_ptr
  {
    // Pointer interface.
    //
  public:
    typedef T element_type;

    lazy_ptr ();
    template <class Y> lazy_ptr (Y*);

    lazy_ptr (const lazy_ptr&);
    template <class Y> lazy_ptr (const lazy_ptr<Y>&);

    lazy_ptr& operator= (const lazy_ptr&);
    template <class Y> lazy_ptr& operator= (Y*);
    template <class Y> lazy_ptr& operator= (const lazy_ptr<Y>&);

    void swap (lazy_ptr&);
    void reset ();
    template <class Y> void reset (Y*);

    T& operator* () const;
    T* operator-> () const;
    T* get () const;

    typedef T* lazy_ptr::*unspecified_bool_type;
    operator unspecified_bool_type () const
    {
      return (p_ || i_) ? &lazy_ptr::p_ : 0;
    }

    // Lazy loading interface.
    //
  public:
    typedef odb::database database_type;

    //  NULL      loaded()
    //
    //  true       true      NULL pointer to transient object
    //  false      true      valid pointer to persistent object
    //  true       false     unloaded pointer to persistent object
    //  false      false     valid pointer to transient object
    //
    bool loaded () const;

    T* load () const;

    // Unload the pointer. For transient objects this function is
    // equivalent to reset().
    //
    void unload () const;

    template <class ID> lazy_ptr (database_type&, const ID&);
    template <class Y> lazy_ptr (database_type&, Y*);

    template <class ID> void reset (database_type&, const ID&);
    template <class Y> void reset (database_type&, Y*);

#ifdef ODB_CXX11
    template <class O = T>
#else
    template <class O /* = T */>
#endif
    typename object_traits<O>::id_type object_id () const;

    database_type& database () const;

    // Helpers.
    //
  public:
    template <class Y> bool equal (const lazy_ptr<Y>&) const;

  private:
    template <class Y> friend class lazy_ptr;

    mutable T* p_;
    mutable lazy_ptr_impl<T> i_;
  };

  // operator< and operator<< are not provided.
  //
  template<class T, class Y>
  bool operator== (const lazy_ptr<T>&, const lazy_ptr<Y>&);

  template<class T, class Y>
  bool operator!= (const lazy_ptr<T>&, const lazy_ptr<Y>&);

  template<class T> void swap (lazy_ptr<T>&, lazy_ptr<T>&);

  // std::auto_ptr lazy version.
  //
  template <class T>
  struct lazy_auto_ptr_ref
  {
    explicit lazy_auto_ptr_ref (T*, const lazy_ptr_impl_ref&);

    T* p_;
    lazy_ptr_impl_ref i_;
  };

  template <class T>
  class lazy_auto_ptr
  {
    // Standard auto_ptr interface.
    //
  public:
    typedef T element_type;

    explicit lazy_auto_ptr (T* = 0);
    lazy_auto_ptr (lazy_auto_ptr&);
    template<class Y> lazy_auto_ptr (lazy_auto_ptr<Y>&);

    lazy_auto_ptr& operator= (lazy_auto_ptr&);
    template<class Y> lazy_auto_ptr& operator= (lazy_auto_ptr<Y>&);

    T& operator* () const;
    T* operator-> () const;
    T* get () const;
    T* release ();
    void reset (T* = 0);

    lazy_auto_ptr (const lazy_auto_ptr_ref<T>&);
    lazy_auto_ptr& operator= (const lazy_auto_ptr_ref<T>&);
    template<class Y> operator lazy_auto_ptr_ref<Y> ();
    template<class Y> operator lazy_auto_ptr<Y> ();

    // Extension: conversion to bool.
    //
  public:
    typedef std::auto_ptr<T> lazy_auto_ptr::*unspecified_bool_type;
    operator unspecified_bool_type () const
    {
      return (p_.get () != 0 || i_) ? &lazy_auto_ptr::p_ : 0;
    }

    // Initialization/assignment from auto_ptr.
    //
  public:
    template <class Y> lazy_auto_ptr (std::auto_ptr<Y>&);
    lazy_auto_ptr (std::auto_ptr_ref<T>);

    template <class Y> lazy_auto_ptr& operator= (std::auto_ptr<Y>&);
    lazy_auto_ptr& operator= (std::auto_ptr_ref<T>);

    // Lazy loading interface.
    //
  public:
    typedef odb::database database_type;

    //  NULL      loaded()
    //
    //  true       true      NULL pointer to transient object
    //  false      true      valid pointer to persistent object
    //  true       false     unloaded pointer to persistent object
    //  false      false     valid pointer to transient object
    //
    bool loaded () const;

    std::auto_ptr<T>& load () const;

    // Unload the pointer. For transient objects this function is
    // equivalent to reset().
    //
    void unload () const;

    template <class ID> lazy_auto_ptr (database_type&, const ID&);
    lazy_auto_ptr (database_type&, T*);
    template <class Y> lazy_auto_ptr (database_type&, std::auto_ptr<Y>&);

    template <class ID> void reset (database_type&, const ID&);
    void reset (database_type&, T*);
    template <class Y> void reset (database_type&, std::auto_ptr<Y>&);

#ifdef ODB_CXX11
    template <class O = T>
#else
    template <class O /* = T */>
#endif
    typename object_traits<O>::id_type object_id () const;

    database_type& database () const;

  private:
    template <class Y> friend class lazy_auto_ptr;

    // Note that it is possible to have a situation where p_ is NULL,
    // i_.id is NULL and i_.db is not NULL. This will happen if the
    // auto_ptr reference returned by load() is transferred to another
    // pointer or reset.
    //
    mutable std::auto_ptr<T> p_;
    mutable lazy_ptr_impl<T> i_;
  };

#ifdef ODB_CXX11

  // C++11 std::shared_ptr lazy version.
  //
  template <class T>
  class lazy_weak_ptr;

  template <class T>
  class lazy_shared_ptr
  {
    // The standard shared_ptr interface.
    //
  public:
    typedef T element_type;

    /*constexpr*/ lazy_shared_ptr () /*noexcept*/;
    /*constexpr*/ lazy_shared_ptr (std::nullptr_t) /*noexcept*/;
    template <class Y> explicit lazy_shared_ptr (Y*);
    template <class Y, class D> lazy_shared_ptr (Y*, D);
    template <class Y, class D, class A> lazy_shared_ptr (Y*, D, A);
    template <class D> lazy_shared_ptr (std::nullptr_t, D);
    template <class D, class A> lazy_shared_ptr (std::nullptr_t, D, A);
    template <class Y> lazy_shared_ptr (const lazy_shared_ptr<Y>&, T*) /*noexcept*/;

    lazy_shared_ptr (const lazy_shared_ptr&) /*noexcept*/;
    template <class Y> lazy_shared_ptr (const lazy_shared_ptr<Y>&) /*noexcept*/;
    lazy_shared_ptr (lazy_shared_ptr&&) /*noexcept*/;
    template <class Y> lazy_shared_ptr (lazy_shared_ptr<Y>&&) /*noexcept*/;
    template <class Y> explicit lazy_shared_ptr (const lazy_weak_ptr<Y>&);
    template <class Y> explicit lazy_shared_ptr (std::auto_ptr<Y>&&);
    template <class Y, class D> lazy_shared_ptr (std::unique_ptr<Y, D>&&);

    ~lazy_shared_ptr ();

    lazy_shared_ptr& operator= (const lazy_shared_ptr&) /*noexcept*/;
    template <class Y> lazy_shared_ptr& operator= (const lazy_shared_ptr<Y>&) /*noexcept*/;
    lazy_shared_ptr& operator= (lazy_shared_ptr&&) /*noexcept*/;
    template <class Y> lazy_shared_ptr& operator= (lazy_shared_ptr<Y>&&) /*noexcept*/;
    template <class Y> lazy_shared_ptr& operator= (std::auto_ptr<Y>&&);
    template <class Y, class D> lazy_shared_ptr& operator= (std::unique_ptr<Y, D>&&);

    void swap (lazy_shared_ptr&) /*noexcept*/;
    void reset () /*noexcept*/;
    template <class Y> void reset (Y*);
    template <class Y, class D> void reset (Y*, D);
    template <class Y, class D, class A> void reset (Y*, D, A);

    T* get () const /*noexcept*/;
    T& operator* () const /*noexcept*/;
    T* operator-> () const /*noexcept*/;
    long use_count () const /*noexcept*/;
    bool unique () const /*noexcept*/;

    explicit operator bool () const /*noexcept*/;

    // owner_before () is not provded.

    // Initialization/assignment from shared_ptr and weak_ptr.
    //
  public:
    template <class Y> lazy_shared_ptr (const std::shared_ptr<Y>&);
    template <class Y> lazy_shared_ptr (std::shared_ptr<Y>&&);
    template <class Y> explicit lazy_shared_ptr (const std::weak_ptr<Y>&);

    template <class Y> lazy_shared_ptr& operator= (const std::shared_ptr<Y>&);
    template <class Y> lazy_shared_ptr& operator= (std::shared_ptr<Y>&&);

    // Lazy loading interface.
    //
  public:
    typedef odb::database database_type;

    //  NULL      loaded()
    //
    //  true       true      NULL pointer to transient object
    //  false      true      valid pointer to persistent object
    //  true       false     unloaded pointer to persistent object
    //  false      false     valid pointer to transient object
    //
    bool loaded () const;

    std::shared_ptr<T> load () const;

    // Unload the pointer. For transient objects this function is
    // equivalent to reset().
    //
    void unload () const;

    template <class ID> lazy_shared_ptr (database_type&, const ID&);
    template <class Y> lazy_shared_ptr (database_type&, Y*);
    template <class Y, class D> lazy_shared_ptr (database_type&, Y*, D);
    template <class Y, class D, class A> lazy_shared_ptr (database_type&, Y*, D, A);
    template <class Y> lazy_shared_ptr (database_type&, std::auto_ptr<Y>&&);
    template <class Y> lazy_shared_ptr (database_type&, const std::shared_ptr<Y>&);
    template <class Y> lazy_shared_ptr (database_type&, std::shared_ptr<Y>&&);
    template <class Y> lazy_shared_ptr (database_type&, const std::weak_ptr<Y>&);

    template <class ID> void reset (database_type&, const ID&);
    template <class Y> void reset (database_type&, Y*);
    template <class Y, class D> void reset (database_type&, Y*, D);
    template <class Y, class D, class A> void reset (database_type&, Y*, D, A);
    template <class Y> void reset (database_type&, std::auto_ptr<Y>&&);
    template <class Y> void reset (database_type&, const std::shared_ptr<Y>&);
    template <class Y> void reset (database_type&, std::shared_ptr<Y>&&);

    template <class O = T>
    typename object_traits<O>::id_type object_id () const;

    database_type& database () const;

    // Helpers.
    //
  public:
    template <class Y> bool equal (const lazy_shared_ptr<Y>&) const;

  private:
    template <class Y> friend class lazy_shared_ptr;
    template <class Y> friend class lazy_weak_ptr;

    mutable std::shared_ptr<T> p_;
    mutable lazy_ptr_impl<T> i_;
  };

  template<class T> void swap (lazy_shared_ptr<T>&, lazy_shared_ptr<T>&) /*noexcept*/;

  template<class D, class T>
  D* get_deleter (const lazy_shared_ptr<T>&) /*noexcept*/;

  // operator< and operator<< are not provided.
  //
  template<class T, class Y>
  bool operator== (const lazy_shared_ptr<T>&, const lazy_shared_ptr<Y>&) /*noexcept*/;

  template<class T>
  bool operator== (const lazy_shared_ptr<T>&, std::nullptr_t) /*noexcept*/;

  template<class T>
  bool operator== (std::nullptr_t, const lazy_shared_ptr<T>&) /*noexcept*/;

  template<class T, class Y>
  bool operator!= (const lazy_shared_ptr<T>&, const lazy_shared_ptr<Y>&) /*noexcept*/;

  template<class T>
  bool operator!= (const lazy_shared_ptr<T>&, std::nullptr_t) /*noexcept*/;

  template<class T>
  bool operator!= (std::nullptr_t, const lazy_shared_ptr<T>&) /*noexcept*/;

  // C++11 std::weak_ptr lazy version.
  //
  template <class T>
  class lazy_weak_ptr
  {
    // The standard weak_ptr interface.
    //
  public:
    typedef T element_type;

    /*constexpr*/ lazy_weak_ptr () /*noexcept*/;
    template <class Y> lazy_weak_ptr (const lazy_shared_ptr<Y>&) /*noexcept*/;
    lazy_weak_ptr (const lazy_weak_ptr&) /*noexcept*/;
    template <class Y> lazy_weak_ptr (const lazy_weak_ptr<Y>&) /*noexcept*/;

    ~lazy_weak_ptr ();

    lazy_weak_ptr& operator= (const lazy_weak_ptr&) /*noexcept*/;
    template <class Y> lazy_weak_ptr& operator= (const lazy_weak_ptr<Y>&) /*noexcept*/;
    template <class Y> lazy_weak_ptr& operator= (const lazy_shared_ptr<Y>&) /*noexcept*/;

    void swap (lazy_weak_ptr<T>&) /*noexcept*/;
    void reset () /*noexcept*/;

    long use_count () const /*noexcept*/;
    bool expired () const /*noexcept*/;

    lazy_shared_ptr<T> lock () const /*noexcept*/;

    // owner_before () is not provded.

    // Initialization/assignment from shared_ptr and weak_ptr.
    //
  public:
    template <class Y> lazy_weak_ptr (const std::weak_ptr<Y>&);
    template <class Y> lazy_weak_ptr (const std::shared_ptr<Y>&);

    template <class Y> lazy_weak_ptr& operator= (const std::weak_ptr<Y>&);
    template <class Y> lazy_weak_ptr& operator= (const std::shared_ptr<Y>&);

    // Lazy loading interface.
    //
  public:
    typedef odb::database database_type;

    // expired()  loaded()
    //
    //  true       true      expired pointer to transient object
    //  false      true      valid pointer to persistent object
    //  true       false     expired pointer to persistent object
    //  false      false     valid pointer to transient object
    //
    bool loaded () const;

    // Performs both lock and load.
    //
    std::shared_ptr<T> load () const;

    // Unload the pointer. For transient objects this function is
    // equivalent to reset().
    //
    void unload () const;

    template <class ID> lazy_weak_ptr (database_type&, const ID&);
    template <class Y> lazy_weak_ptr (database_type&, const std::shared_ptr<Y>&);
    template <class Y> lazy_weak_ptr (database_type&, const std::weak_ptr<Y>&);

    template <class ID> void reset (database_type&, const ID&);
    template <class Y> void reset (database_type&, const std::shared_ptr<Y>&);
    template <class Y> void reset (database_type&, const std::weak_ptr<Y>&);

    // The object_id() function can only be called when the object is
    // persistent, or: expired() XOR loaded() (can use != for XOR).
    //
    template <class O = T>
    typename object_traits<O>::id_type object_id () const;

    database_type& database () const;

  private:
    template <class Y> friend class lazy_shared_ptr;
    template <class Y> friend class lazy_weak_ptr;

    mutable std::weak_ptr<T> p_;
    mutable lazy_ptr_impl<T> i_;
  };

  // operator< is not provided.
  //
  template<class T> void swap (lazy_weak_ptr<T>&, lazy_weak_ptr<T>&);

#endif // ODB_CXX11

  namespace core
  {
    using odb::lazy_ptr;
    using odb::lazy_auto_ptr;

#ifdef ODB_CXX11
    using odb::lazy_shared_ptr;
    using odb::lazy_weak_ptr;
#endif
  }
}

#include <odb/lazy-ptr.ixx>
#include <odb/lazy-ptr.txx>

#include <odb/lazy-pointer-traits.hxx>

#include <odb/post.hxx>

#endif // ODB_LAZY_PTR_HXX