针对C++容器类的一个简陋的allocator
作者:互联网
参考:
https://en.cppreference.com/w/cpp/named_req/Allocator
http://www.josuttis.com/libbook/memory/myalloc.hpp.html
template <class T> class MyAlloc { public: // type definitions typedef T value_type; typedef T* pointer; typedef const T* const_pointer; typedef T& reference; typedef const T& const_reference; typedef std::size_t size_type; typedef std::ptrdiff_t difference_type; // rebind allocator to type U template <class U> struct rebind { typedef MyAlloc<U> other; }; // return address of values pointer address (reference value) const { return &value; } const_pointer address (const_reference value) const { return &value; } /* constructors and destructor * - nothing to do because the allocator has no state */ MyAlloc() throw() { } MyAlloc(const MyAlloc&) throw() { } template <class U> MyAlloc (const MyAlloc<U>&) throw() { } ~MyAlloc() throw() { } // return maximum number of elements that can be allocated size_type max_size () const throw() { return std::numeric_limits<std::size_t>::max() / sizeof(T); } // allocate but don't initialize num elements of type T pointer allocate (size_type num, const void* = 0) { // print message and allocate memory with global new pointer ret = (pointer)(malloc(num*sizeof(T))); return ret; } // initialize elements of allocated storage p with value value void construct (pointer p, const T& value) { // initialize memory with placement new new((void*)p)T(value); } // destroy elements of initialized storage p void destroy (pointer p) { // destroy objects by calling their destructor p->~T(); } // deallocate storage p of deleted elements void deallocate (pointer p, size_type num) { free((void*)p); } }; // return that all specializations of this allocator are interchangeable template <class T1, class T2> bool operator== (const MyAlloc<T1>&, const MyAlloc<T2>&) throw() { return true; } template <class T1, class T2> bool operator!= (const MyAlloc<T1>&, const MyAlloc<T2>&) throw() { return false; }
标签:value,const,简陋,C++,MyAlloc,type,return,pointer,allocator 来源: https://www.cnblogs.com/eaglexmw/p/11583360.html