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//
// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/boostorg/json
//
#include <boost/json/monotonic_resource.hpp>
#include <boost/json/static_resource.hpp>
#include <boost/json/value.hpp>
#include <boost/container/pmr/vector.hpp>
#include <vector>
#include "test_suite.hpp"
#ifdef assert
#undef assert
#endif
#define assert BOOST_TEST
namespace boost {
namespace json {
namespace doc_background {
namespace background {
template<class T>
using vector = boost::container::pmr::vector<T>;
} // background
//----------------------------------------------------------
namespace std {
template<class T>
using allocator = ::std::allocator<T>;
} // std
// tag::doc_background_1[]
namespace std {
template< class T, class Allocator = std::allocator< T > >
class vector;
} // namespace std
// end::doc_background_1[]
//----------------------------------------------------------
// tag::doc_background_2[]
namespace std {
template< class T, class Allocator >
class vector
{
public:
explicit vector( Allocator const& alloc );
//...
// end::doc_background_2[]
};
template<class T, class A>
vector<T,A>::vector(A const&){}
}
//----------------------------------------------------------
// tag::doc_background_3[]
namespace std {
namespace pmr {
class memory_resource
{
public:
virtual ~memory_resource();
void* allocate ( size_t bytes, size_t alignment );
void deallocate( void* p, size_t bytes, size_t alignment );
bool is_equal ( const memory_resource& other ) const;
protected:
virtual void* do_allocate ( size_t bytes, size_t alignment ) = 0;
virtual void do_deallocate( void* p, size_t bytes, size_t alignment ) = 0;
virtual bool do_is_equal ( memory_resource const& other ) const noexcept = 0;
};
} // namespace pmr
} // namespace std
// end::doc_background_3[]
//----------------------------------------------------------
// tag::doc_background_4[]
namespace std {
namespace pmr {
template< class T >
using vector = std::vector< T, boost::container::pmr::polymorphic_allocator< T > >;
} // namespace pmr
} // namespace std
// end::doc_background_4[]
//----------------------------------------------------------
static void set1() {
using namespace background;
//----------------------------------------------------------
{
struct T {};
// tag::doc_background_5[]
// A type of memory resource
monotonic_resource mr;
// Construct a vector using the monotonic buffer resource
vector< T > v1(( boost::container::pmr::polymorphic_allocator< T >(&mr) ));
// Or this way, since construction from memory_resource* is implicit:
vector< T > v2( &mr );
// end::doc_background_5[]
}
//----------------------------------------------------------
{
// tag::doc_background_6[]
{
// A type of memory resource which uses a stack buffer
unsigned char temp[4096];
static_resource mr( temp, sizeof(temp) );
// Construct a vector using the static buffer resource
vector< value > v( &mr );
// The vector will allocate from `temp` first, and then the heap.
}
// end::doc_background_6[]
}
//----------------------------------------------------------
} // set1
//----------------------------------------------------------
struct my_resource : container::pmr::memory_resource
{
void* do_allocate ( size_t, size_t ) override { return 0; }
void do_deallocate( void*, size_t, size_t ) override {}
bool do_is_equal ( memory_resource const& ) const noexcept override { return true; }
};
// tag::doc_background_7[]
namespace my_library {
std::pmr::vector<char> get_chars1()
{
// This leaks memory because `v` does not own the memory resource
std::pmr::vector<char> v( new my_resource );
return v;
}
} // my_library
// end::doc_background_7[]
//----------------------------------------------------------
// tag::doc_background_8[]
namespace my_library {
std::pmr::vector<char> get_chars2()
{
// Declare a local memory resource
my_resource mr;
// Construct a vector that uses our resource
std::pmr::vector<char> v( &mr );
// Undefined behavior, `mr` goes out of scope!
return v;
}
} // my_library
// end::doc_background_8[]
//----------------------------------------------------------
} // doc_background
class doc_background_test
{
public:
void
run()
{
using namespace doc_background;
(void)&set1;
BOOST_TEST_PASS();
}
};
TEST_SUITE(doc_background_test, "boost.json.doc_background");
} // namespace json
} // namespace boost
|
