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Diffstat (limited to 'libodb/odb/wrapper-traits.hxx')
| -rw-r--r-- | libodb/odb/wrapper-traits.hxx | 276 |
1 files changed, 276 insertions, 0 deletions
diff --git a/libodb/odb/wrapper-traits.hxx b/libodb/odb/wrapper-traits.hxx new file mode 100644 index 0000000..d31425d --- /dev/null +++ b/libodb/odb/wrapper-traits.hxx @@ -0,0 +1,276 @@ +// file : odb/wrapper-traits.hxx +// license : GNU GPL v2; see accompanying LICENSE file + +#ifndef ODB_WRAPPER_TRAITS_HXX +#define ODB_WRAPPER_TRAITS_HXX + +#include <odb/pre.hxx> + +#include <memory> // std::auto_ptr, std::unique_ptr, std::shared_ptr/weak_ptr + +#include <odb/nullable.hxx> + +#include <odb/details/config.hxx> // ODB_CXX11 +#include <odb/details/meta/remove-const.hxx> + +namespace odb +{ + template <typename T> + class wrapper_traits; + + // Sample specialization for raw pointers. It is not enabled by default + // since it makes many assumptions that may not always hold true (such + // as that instances are allocated with new and freed with delete). + // This makes it too dangerous to be enabled unconditionally. If you + // need this functionality, you can copy the below code into your + // application. Also consider changing it to only specialize for + // specific types instead of for any pointer (it will almost always + // do the wrong thing for char*). + // +#if 0 + template <typename T> + class wrapper_traits<T*> + { + public: + typedef T wrapped_type; + typedef T* wrapper_type; + + // T can be const. + // + typedef + typename details::meta::remove_const<T>::result + unrestricted_wrapped_type; + + static const bool null_handler = true; + static const bool null_default = false; + + static bool + get_null (const wrapper_type& p) + { + return p == 0; + } + + static void + set_null (wrapper_type& p) + { + delete p; + p = 0; + } + + static const wrapped_type& + get_ref (const wrapper_type& p) + { + return *p; + } + + static unrestricted_wrapped_type& + set_ref (wrapper_type& p) + { + if (p == 0) + p = new unrestricted_wrapped_type; + + return const_cast<unrestricted_wrapped_type&> (*p); + } + }; +#endif + + // Specialization for std::auto_ptr. + // +#ifndef ODB_CXX11 + template <typename T> + class wrapper_traits< std::auto_ptr<T> > + { + public: + // T can be const. + // + typedef T wrapped_type; + typedef std::auto_ptr<T> wrapper_type; + + // T can be const. + // + typedef + typename odb::details::meta::remove_const<T>::result + unrestricted_wrapped_type; + + static const bool null_handler = true; + static const bool null_default = false; + + static bool + get_null (const wrapper_type& p) + { + return p.get () == 0; + } + + static void + set_null (wrapper_type& p) + { + p.reset (); + } + + static const wrapped_type& + get_ref (const wrapper_type& p) + { + return *p; + } + + static unrestricted_wrapped_type& + set_ref (wrapper_type& p) + { + if (p.get () == 0) + p.reset (new unrestricted_wrapped_type ()); + + return const_cast<unrestricted_wrapped_type&> (*p); + } + }; +#endif + +#ifdef ODB_CXX11 + + // Specialization for C++11 std::unique_ptr. + // + template <typename T, typename D> + class wrapper_traits<std::unique_ptr<T, D>> + { + public: + // T can be const. + // + typedef T wrapped_type; + typedef std::unique_ptr<T, D> wrapper_type; + + // T can be const. + // + typedef + typename odb::details::meta::remove_const<T>::result + unrestricted_wrapped_type; + + static const bool null_handler = true; + static const bool null_default = false; + + static bool + get_null (const wrapper_type& p) + { + return !p; + } + + static void + set_null (wrapper_type& p) + { + p.reset (); + } + + static const wrapped_type& + get_ref (const wrapper_type& p) + { + return *p; + } + + static unrestricted_wrapped_type& + set_ref (wrapper_type& p) + { + if (!p) + p.reset (new unrestricted_wrapped_type ()); + + return const_cast<unrestricted_wrapped_type&> (*p); + } + }; + + // Specialization for C++11 std::shared_ptr. + // + template <typename T> + class wrapper_traits<std::shared_ptr<T>> + { + public: + typedef T wrapped_type; + typedef std::shared_ptr<T> wrapper_type; + + // T can be const. + // + typedef + typename odb::details::meta::remove_const<T>::result + unrestricted_wrapped_type; + + static const bool null_handler = true; + static const bool null_default = false; + + static bool + get_null (const wrapper_type& p) + { + return !p; + } + + static void + set_null (wrapper_type& p) + { + p.reset (); + } + + static const wrapped_type& + get_ref (const wrapper_type& p) + { + return *p; + } + + static unrestricted_wrapped_type& + set_ref (wrapper_type& p) + { + if (!p) + p.reset (new unrestricted_wrapped_type); + + return const_cast<unrestricted_wrapped_type&> (*p); + } + }; + +#endif // ODB_CXX11 + + // Specialization for odb::nullable. + // + template <typename T> + class wrapper_traits< nullable<T> > + { + public: + // T can be const. + // + typedef T wrapped_type; + typedef nullable<T> wrapper_type; + + // T can be const. + // + typedef + typename odb::details::meta::remove_const<T>::result + unrestricted_wrapped_type; + + static const bool null_handler = true; + static const bool null_default = true; + + static bool + get_null (const wrapper_type& n) + { + return n.null (); + } + + static void + set_null (wrapper_type& n) + { + n.reset (); + } + + static const wrapped_type& + get_ref (const wrapper_type& n) + { + return *n; + } + + static unrestricted_wrapped_type& + set_ref (wrapper_type& n) + { + if (n.null ()) + n = unrestricted_wrapped_type (); + + return const_cast<unrestricted_wrapped_type&> (*n); + } + }; +} + +#include <odb/post.hxx> + +#endif // ODB_WRAPPER_TRAITS_HXX |