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Diffstat (limited to 'libodb/odb/pointer-traits.hxx')
| -rw-r--r-- | libodb/odb/pointer-traits.hxx | 405 |
1 files changed, 405 insertions, 0 deletions
diff --git a/libodb/odb/pointer-traits.hxx b/libodb/odb/pointer-traits.hxx new file mode 100644 index 0000000..a0baa21 --- /dev/null +++ b/libodb/odb/pointer-traits.hxx @@ -0,0 +1,405 @@ +// file : odb/pointer-traits.hxx +// license : GNU GPL v2; see accompanying LICENSE file + +#ifndef ODB_POINTER_TRAITS_HXX +#define ODB_POINTER_TRAITS_HXX + +#include <odb/pre.hxx> + +#include <new> // operators new/delete +#include <memory> // std::auto_ptr, std::unique_ptr, std::shared_ptr/weak_ptr +#include <cstddef> // std::size_t + +#include <odb/details/config.hxx> // ODB_CXX11 +#include <odb/details/meta/remove-const.hxx> + +namespace odb +{ + enum pointer_kind + { + pk_raw, // Raw pointer or equivalent (i.e., unmanaged). + pk_unique, // Smart pointer that doesn't support sharing. + pk_shared, // Smart pointer that supports sharing. + pk_weak // Weak counterpart for shared pointer. + }; + + template <typename P> + class pointer_traits; + + // + // Standard pointer guards. + // + + // Raw pointer guard. + // + template <typename P> + class raw_ptr_guard + { + public: + ~raw_ptr_guard () {delete p_;} + raw_ptr_guard (): p_ (0) {} + + explicit + raw_ptr_guard (P p): p_ (p) {} + + void + release () {p_ = 0;} + + void + reset (P p = 0) {delete p_; p_ = p;} + + private: + P p_; + }; + + // No-op pointer guard for smart pointers. + // + template <typename P> + class smart_ptr_guard + { + public: + smart_ptr_guard () {} + + explicit + smart_ptr_guard (const P&) {} + + void + release () {} + + void + reset () {} + + void + reset (const P&) {} + }; + + // Specialization for raw pointers. + // + template <typename T> + class pointer_traits<T*> + { + public: + static const pointer_kind kind = pk_raw; + static const bool lazy = false; + + typedef T element_type; + typedef T* pointer_type; + typedef const T* const_pointer_type; + typedef typename odb::details::meta::remove_const<T>::result* + unrestricted_pointer_type; + typedef raw_ptr_guard<pointer_type> guard; + + // Return raw pointer to the pointed-to element, including NULL. + // + static element_type* + get_ptr (pointer_type p) + { + return p; + } + + // Return reference to the pointed-to element. + // + static element_type& + get_ref (pointer_type p) + { + return *p; + } + + // Return true if the pointer is NULL. + // + static bool + null_ptr (pointer_type p) + { + return p == 0; + } + + // Casts. + // + static unrestricted_pointer_type + const_pointer_cast (pointer_type p) + { + return const_cast<unrestricted_pointer_type> (p); + } + + template <typename T1> + static T1* + static_pointer_cast (pointer_type p) + { + return static_cast<T1*> (p); + } + + template <typename T1> + static T1* + dynamic_pointer_cast (pointer_type p) + { + return dynamic_cast<T1*> (p); + } + + public: + // Allocate memory for an element that will be managed by this + // pointer. + // + static void* + allocate (std::size_t n) + { + return operator new (n); + } + + // Free memory allocated for an element. This functions is only + // called if the constructor of the element being created fails. + // Otherwise, the pointer (or guard) is used to delete the object + // and free the memory. This behavior is identical to the one + // used by operator delete overloading. + // + static void + free (void* p) + { + operator delete (p); + } + }; + + // Specialization for std::auto_ptr. + // +#ifndef ODB_CXX11 + template <typename T> + class pointer_traits< std::auto_ptr<T> > + { + public: + static const pointer_kind kind = pk_unique; + static const bool lazy = false; + + typedef T element_type; + typedef std::auto_ptr<element_type> pointer_type; + typedef std::auto_ptr<const element_type> const_pointer_type; + typedef smart_ptr_guard<pointer_type> guard; + + static element_type* + get_ptr (const pointer_type& p) + { + return p.get (); + } + + static element_type& + get_ref (const pointer_type& p) + { + return *p; + } + + static bool + null_ptr (const pointer_type& p) + { + return p.get () == 0; + } + + // const_pointer_cast() is not provided. + // + + // Note: transfers ownership. + // + template <typename T1> + static std::auto_ptr<T1> + static_pointer_cast (pointer_type& p) + { + return std::auto_ptr<T1> (static_cast<T1*> (p.release ())); + } + + // Note: transfers ownership if successful. + // + template <typename T1> + static std::auto_ptr<T1> + dynamic_pointer_cast (pointer_type& p) + { + T1* p1 (dynamic_cast<T1*> (p.get ())); + + if (p1 != 0) + p.release (); + + return std::auto_ptr<T1> (p1); + } + + public: + static void* + allocate (std::size_t n) + { + return operator new (n); + } + + static void + free (void* p) + { + operator delete (p); + } + }; +#endif + +#ifdef ODB_CXX11 + + // Specialization for C++11 std::unique_ptr. + // + template <typename T, template <typename> class D> + class pointer_traits<std::unique_ptr<T, D<T>>> + { + public: + static const pointer_kind kind = pk_unique; + static const bool lazy = false; + + typedef T element_type; + typedef std::unique_ptr<T, D<T>> pointer_type; + typedef std::unique_ptr<const T, D<const T>> const_pointer_type; + typedef smart_ptr_guard<pointer_type> guard; + + static element_type* + get_ptr (const pointer_type& p) + { + return p.get (); + } + + static element_type& + get_ref (const pointer_type& p) + { + return *p; + } + + static bool + null_ptr (const pointer_type& p) + { + return !p; + } + + // const_pointer_cast() is not provided. + // + + // Note: transfers ownership. + // + template <typename T1> + static std::unique_ptr<T1, D<T1>> + static_pointer_cast (pointer_type& p) + { + return std::unique_ptr<T1, D<T1>> (static_cast<T1*> (p.release ())); + } + + // Note: transfers ownership if successful. + // + template <typename T1> + static std::unique_ptr<T1, D<T1>> + dynamic_pointer_cast (pointer_type& p) + { + T1* p1 (dynamic_cast<T1*> (p.get ())); + + if (p1 != 0) + p.release (); + + return std::unique_ptr<T1, D<T1>> (p1); + } + + public: + static void* + allocate (std::size_t n) + { + return operator new (n); + } + + static void + free (void* p) + { + operator delete (p); + } + }; + + // Specialization for C++11 std::shared_ptr. + // + template <typename T> + class pointer_traits<std::shared_ptr<T>> + { + public: + static const pointer_kind kind = pk_shared; + static const bool lazy = false; + + typedef T element_type; + typedef std::shared_ptr<element_type> pointer_type; + typedef std::shared_ptr<const element_type> const_pointer_type; + typedef typename odb::details::meta::remove_const<element_type>::result + unrestricted_element_type; + typedef std::shared_ptr<unrestricted_element_type> + unrestricted_pointer_type; + typedef smart_ptr_guard<pointer_type> guard; + + static element_type* + get_ptr (const pointer_type& p) + { + return p.get (); + } + + static element_type& + get_ref (const pointer_type& p) + { + return *p; + } + + static bool + null_ptr (const pointer_type& p) + { + return !p; + } + + static unrestricted_pointer_type + const_pointer_cast (const pointer_type& p) + { + return std::const_pointer_cast<unrestricted_element_type> (p); + } + + template <typename T1> + static std::shared_ptr<T1> + static_pointer_cast (const pointer_type& p) + { + return std::static_pointer_cast<T1> (p); + } + + template <typename T1> + static std::shared_ptr<T1> + dynamic_pointer_cast (const pointer_type& p) + { + return std::dynamic_pointer_cast<T1> (p); + } + + public: + static void* + allocate (std::size_t n) + { + return operator new (n); + } + + static void + free (void* p) + { + operator delete (p); + } + }; + + // Specialization for C++11 std::weak_ptr. + // + template <typename T> + class pointer_traits<std::weak_ptr<T>> + { + public: + static const pointer_kind kind = pk_weak; + static const bool lazy = false; + + typedef T element_type; + typedef std::weak_ptr<element_type> pointer_type; + typedef std::shared_ptr<element_type> strong_pointer_type; + + static strong_pointer_type + lock (const pointer_type& p) + { + return p.lock (); + } + }; + +#endif // ODB_CXX11 + +} + +#include <odb/post.hxx> + +#endif // ODB_POINTER_TRAITS_HXX |