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Added documentation on scoped allocators

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[SVN r77679]
This commit is contained in:
Ion Gaztañaga
2012-03-31 20:57:45 +00:00
parent 7f1456c30f
commit 0098adea15
2 changed files with 66 additions and 22 deletions
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52
doc/container.qbk
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@@ -422,10 +422,9 @@ to suppose two allocators of the same type always compare equal (that means that
by one allocator object could be deallocated by another instance of the same type) and
allocators were not swapped when the container was swapped.
C++11 further improves stateful allocator support through the
[@http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2008/n2554.pdf
Scoped Allocators model]. [@http://en.cppreference.com/w/cpp/memory/allocator_traits
`std::allocator_traits`] is the protocol between a container and an allocator, and
C++11 further improves stateful allocator support through
[@http://en.cppreference.com/w/cpp/memory/allocator_traits `std::allocator_traits`].
`std::allocator_traits` is the protocol between a container and an allocator, and
an allocator writer can customize its behaviour (should the container propagate it in
move constructor, swap, etc.?) following `allocator_traits` requirements. [*Boost.Container]
not only supports this model with C++11 but also [*backports it to C++03].
@@ -437,6 +436,36 @@ not constructed on the fly when auxiliary memory is needed).
[endsect]
[section:scoped_allocator Scoped allocators]
C++11 improves stateful allocators with the introduction of
[@http://http://en.cppreference.com/w/cpp/memory/scoped_allocator_adaptor `std::scoped_allocator_adaptor`]
class template. `scoped_allocator_adaptor` is instantiated with one outer allocator and zero or more inner
allocators.
A scoped allocator is a mechanism to automatically propagate the state of the allocator to the subobjects
of a container in a controlled way. If instantiated with only one allocator type, the inner allocator
becomes the `scoped_allocator_adaptor` itself, thus using the same allocator
resource for the container and every element within the container and, if the elements themselves are
containers, each of their elements recursively. If instantiated with more than one allocator, the first allocator
is the outer allocator for use by the container, the second allocator is passed to the constructors of the
container's elements, and, if the elements themselves are containers, the third allocator is passed to the
elements' elements, and so on.
[*Boost.Container] implements its own `scoped_allocator_adaptor` class and [*backports this feature also
to C++03 compilers]. Due to C++03 limitations, in those compilers
the allocator propagation implemented by `scoped_allocator_adaptor::construct` functions
will be based on traits([classref boost::container::constructible_with_allocator_suffix constructible_with_allocator_suffix]
and [classref boost::container::constructible_with_allocator_prefix constructible_with_allocator_prefix])
proposed in [@http://www.open-std.org/jtc1/sc22/WG21/docs/papers/2008/n2554.pdf
N2554: The Scoped Allocator Model (Rev 2) proposal]. In conforming C++11 compilers or compilers supporting SFINAE
expressions (when `BOOST_NO_SFINAE_EXPR` is NOT defined), traits are ignored and C++11 rules
(`is_constructible<T, Args..., inner_allocator_type>::value` and
`is_constructible<T, allocator_arg_t, inner_allocator_type, Args...>::value`)
will be used to detect if the allocator must be propagated with suffix or prefix allocator arguments.
[endsect]
[section:initializer_lists Initializer lists]
[*Boost.Container] does not support initializer lists when constructing or assigning containers
@@ -585,6 +614,21 @@ use [*Boost.Container]? There are several reasons for that:
[section:release_notes Release Notes]
[section:release_notes_boost_1_50_00 Boost 1.50 Release]
* Added Scoped Allocator Model support.
* Fixed bugs
[@https://svn.boost.org/trac/boost/ticket/6566 #6566],
[@https://svn.boost.org/trac/boost/ticket/6575 #6575],
[@https://svn.boost.org/trac/boost/ticket/6606 #6606],
[@https://svn.boost.org/trac/boost/ticket/6615 #6615],
[@https://svn.boost.org/trac/boost/ticket/6533 #6533],
[@https://svn.boost.org/trac/boost/ticket/6536 #6536],
[endsect]
[section:release_notes_boost_1_49_00 Boost 1.49 Release]
* Fixed bugs

36
test/vector_test.cpp
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@@ -94,27 +94,27 @@ enum Test
};
int main()
{
const std::size_t positions_length = 10;
std::size_t positions[positions_length];
vector<int> vector_int;
vector<int> vector_int2(positions_length);
for(std::size_t i = 0; i != positions_length; ++i){
positions[i] = 0u;
}
for(std::size_t i = 0, max = vector_int2.size(); i != max; ++i){
vector_int2[i] = i;
}
{/*
{
const std::size_t positions_length = 10;
std::size_t positions[positions_length];
vector<int> vector_int;
vector<int> vector_int2(positions_length);
for(std::size_t i = 0; i != positions_length; ++i){
positions[i] = 0u;
}
for(std::size_t i = 0, max = vector_int2.size(); i != max; ++i){
vector_int2[i] = i;
}
vector_int.insert(vector_int.begin(), 999);
vector_int.insert(vector_int.begin(), 999);
//vector_int.insert_at_ordered_positions(positions, positions_length, vector_int2.end());
for(std::size_t i = 0, max = vector_int.size(); i != max; ++i){
std::cout << vector_int[i] << std::endl;
}
return 0;
vector_int.insert_ordered_at(positions_length, positions + positions_length, vector_int2.end());
for(std::size_t i = 0, max = vector_int.size(); i != max; ++i){
std::cout << vector_int[i] << std::endl;
}
}*/
recursive_vector_test();
{
//Now test move semantics