diff options
author | Michael Shepanski <michael@codesynthesis.com> | 2014-10-30 15:21:32 +1100 |
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committer | Michael Shepanski <michael@codesynthesis.com> | 2014-10-31 08:39:49 +1100 |
commit | 1f217e38f7507758da1d33d46e675e801621aa38 (patch) | |
tree | bad382ee315a820ec08bd2a83eaece12ac8169e3 /odb/details | |
parent | 31af5a488f2be9f4059e159492d4fe62f25a895a (diff) |
Allow lambdas & std::functions as query factories with C++-98 builds of libodb
Diffstat (limited to 'odb/details')
-rw-r--r-- | odb/details/function-wrapper.hxx | 83 | ||||
-rw-r--r-- | odb/details/function-wrapper.ixx | 47 | ||||
-rw-r--r-- | odb/details/function-wrapper.txx | 87 |
3 files changed, 217 insertions, 0 deletions
diff --git a/odb/details/function-wrapper.hxx b/odb/details/function-wrapper.hxx new file mode 100644 index 0000000..5615fca --- /dev/null +++ b/odb/details/function-wrapper.hxx @@ -0,0 +1,83 @@ +// file : odb/details/function-wrapper.hxx +// copyright : Copyright (c) 2009-2014 Code Synthesis Tools CC +// license : GNU GPL v2; see accompanying LICENSE file + +#ifndef ODB_DETAILS_FUNCTION_WRAPPER_HXX +#define ODB_DETAILS_FUNCTION_WRAPPER_HXX + +#include <odb/pre.hxx> + +#include <odb/details/config.hxx> // ODB_CXX11 + +#ifdef ODB_CXX11 +# include <functional> // std::function +# include <type_traits> // std::enable_if, std::is_convertible +#endif + +namespace odb +{ + namespace details + { + // Low-level 'callable object' wrapper similar to std::function but + // that works in both C++98 and 11. In particular, the call site can + // be compiled in C++98 and the registration site in C++11 and it + // will work. + // + template <typename F> + struct function_wrapper + { + ~function_wrapper (); + + explicit + function_wrapper (F* = 0); + +#ifdef ODB_CXX11 + typedef typename std::function<F> std_function_type; + + // This overload accepts lambdas and std::functions, but when the + // argument is convertible to F*, then we disable it in favor of the + // other overload (above), which is more efficient. + // + // Subtlety alert: if you're thinking of changing this to accept a + // std::function<F> argument, stop. That creates an overload ambiguity + // when the actual parameter is a lambda, which is convertible to either + // std::function<F> or F*. + // + template <typename F1> + function_wrapper(F1, + typename std::enable_if< + !std::is_convertible<F1, F*>::value>::type* = 0); +#endif + + // Destructive copy construction and assignment (aka move). These + // should really only be called by containers when they need to + // reallocate the underlying buffer and move the elements. + // + function_wrapper (const function_wrapper<F>&); + function_wrapper& + operator= (const function_wrapper<F>&); + + void swap (function_wrapper<F>&); + + // Conversion to bool. + // + public: + typedef void (function_wrapper<F>::*bool_convertible) (); + void true_value () {} + + operator bool_convertible () const; + + public: + F* function; + void (*deleter) (const void*); + const void* std_function; + }; + } +} + +#include <odb/details/function-wrapper.ixx> +#include <odb/details/function-wrapper.txx> + +#include <odb/post.hxx> + +#endif // ODB_DETAILS_FUNCTION_WRAPPER_HXX diff --git a/odb/details/function-wrapper.ixx b/odb/details/function-wrapper.ixx new file mode 100644 index 0000000..58ede04 --- /dev/null +++ b/odb/details/function-wrapper.ixx @@ -0,0 +1,47 @@ +// file : odb/details/function-wrapper.ixx +// copyright : Copyright (c) 2009-2014 Code Synthesis Tools CC +// license : GNU GPL v2; see accompanying LICENSE file + +namespace odb +{ + namespace details + { + template <typename F> + inline function_wrapper<F>:: + ~function_wrapper () + { + if (deleter != 0) + deleter (std_function); + } + + template <typename F> + inline function_wrapper<F>:: + function_wrapper (F* f) + : function (f), deleter (0), std_function (0) + { + } + + template <typename F> + inline function_wrapper<F>:: + function_wrapper (const function_wrapper<F>& x) + : function (0), deleter (0), std_function (0) + { + swap (const_cast<function_wrapper<F>&> (x)); + } + + template <typename F> + inline function_wrapper<F>& function_wrapper<F>:: + operator= (const function_wrapper<F>& x) + { + swap (const_cast<function_wrapper<F>&> (x)); + return *this; + } + + template <typename F> + inline function_wrapper<F>:: + operator bool_convertible () const + { + return function != 0 ? &function_wrapper<F>::true_value : 0; + } + } +} diff --git a/odb/details/function-wrapper.txx b/odb/details/function-wrapper.txx new file mode 100644 index 0000000..70dcb0f --- /dev/null +++ b/odb/details/function-wrapper.txx @@ -0,0 +1,87 @@ +// file : odb/details/function-wrapper.txx +// copyright : Copyright (c) 2009-2014 Code Synthesis Tools CC +// license : GNU GPL v2; see accompanying LICENSE file + +#include <utility> // std::swap, std::move + +namespace odb +{ + namespace details + { +#ifdef ODB_CXX11 + template <typename F> + struct caller_impl; + +#ifdef ODB_CXX11_VARIADIC_TEMPLATE + template <typename R, typename... A> + struct caller_impl<R (A...)> + { + static R + function (const void* f, A... a) + { + return (*static_cast<const std::function<R (A...)>*> (f)) (a...); + } + }; +#else + template <typename R, typename A1> + struct caller_impl<R (A1)> + { + static R + function (const void* f, A1 a1) + { + return (*static_cast<const std::function<R (A1)>*> (f)) (a1); + } + }; + + template <typename R, typename A1, typename A2> + struct caller_impl<R (A1, A2)> + { + static R + function (const void* f, A1 a1, A2 a2) + { + return (*static_cast<const std::function<R (A1, A2)>*> (f)) (a1, a2); + } + }; +#endif + + template <typename F> + void + deleter_impl (const void* f) + { + delete static_cast<const std::function<F>*> (f); + } + + template <typename F> + template <typename F1> + function_wrapper<F>:: + function_wrapper ( + F1 f, + typename std::enable_if<!std::is_convertible<F1, F*>::value>::type*) + { + std_function_type sf (std::move (f)); + + if (F* const* const f = sf.template target<F*> ()) + { + function = *f; + deleter = 0; + std_function = 0; + } + else + { + function = reinterpret_cast<F*> (&caller_impl<F>::function); + deleter = &deleter_impl<F>; + std_function = new std_function_type (std::move (sf)); + } + } +#endif + + template <typename F> + void function_wrapper<F>:: + swap (function_wrapper<F>& x) + { + std::swap (function, x.function); + std::swap (deleter, x.deleter); + std::swap (std_function, x.std_function); + } + } +} |