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function_base.hpp:

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- Switch over to using is_reference_wrapper instead of homegrown is_ref
  - Identify stateless function objects

function_template.hpp:
  - Optimize away construction/allocator for stateless function objects.


[SVN r12559]
This commit is contained in:
Douglas Gregor
2002-01-30 01:59:49 +00:00
parent aaa7f61b9e
commit 11187bcf3a
2 changed files with 87 additions and 34 deletions
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43
include/boost/function/function_base.hpp
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@ -77,37 +77,6 @@ namespace boost {
typedef typename select::template Result<Then,Else>::type type;
};
// Determine if the incoming argument is a reference_wrapper
#ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
template<typename T>
struct is_ref
{
BOOST_STATIC_CONSTANT(bool, value = false);
};
template<typename T>
struct is_ref<reference_wrapper<T> >
{
BOOST_STATIC_CONSTANT(bool, value = true);
};
#else // no partial specialization
typedef char yes_type;
typedef double no_type;
no_type is_ref_tester(...);
template<typename T>
yes_type is_ref_tester(reference_wrapper<T>*);
template<typename T>
struct is_ref
{
static T* t;
BOOST_STATIC_CONSTANT(bool,
value = (sizeof(is_ref_tester(t)) == sizeof(yes_type)));
};
#endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
/**
* A union of a function pointer and a void pointer. This is necessary
* because 5.2.10/6 allows reinterpret_cast<> to safely cast between
@ -161,6 +130,7 @@ namespace boost {
struct function_obj_tag {};
struct member_ptr_tag {};
struct function_obj_ref_tag {};
struct stateless_function_obj_tag {};
template<typename F>
class get_function_tag
@ -172,10 +142,15 @@ namespace boost {
typedef typename IF<(is_member_pointer<F>::value),
member_ptr_tag,
ptr_or_obj_tag>::type ptr_or_obj_or_mem_tag;
public:
typedef typename IF<(is_ref<F>::value),
typedef typename IF<(is_reference_wrapper<F>::value),
function_obj_ref_tag,
ptr_or_obj_or_mem_tag>::type type;
ptr_or_obj_or_mem_tag>::type or_ref_tag;
public:
typedef typename IF<(is_stateless<F>::value),
stateless_function_obj_tag,
or_ref_tag>::type type;
};
// The trivial manager does nothing but return the same pointer (if we