1 //===----------------------------------------------------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #ifndef STACK_ALLOCATOR_H
11 #define STACK_ALLOCATOR_H
12 
13 #include <cstddef>
14 #include <new>
15 
16 template <class T, std::size_t N>
17 class stack_allocator
18 {
19     char buf_[sizeof(T)*N];
20     char* ptr_;
21 public:
22     typedef T                 value_type;
23     typedef value_type*       pointer;
24     typedef const value_type* const_pointer;
25     typedef value_type&       reference;
26     typedef const value_type& const_reference;
27     typedef std::size_t       size_type;
28     typedef std::ptrdiff_t    difference_type;
29 
30     template <class U> struct rebind {typedef stack_allocator<U, N> other;};
31 
stack_allocator()32     stack_allocator() : ptr_(buf_) {}
33 
34 private:
35     stack_allocator(const stack_allocator&);// = delete;
36     stack_allocator& operator=(const stack_allocator&);// = delete;
37 
38 public:
39     pointer allocate(size_type n, const void* = 0)
40     {
41         if (n > N - (ptr_ - buf_) / sizeof(value_type)) {
42 #ifndef _LIBCPP_NO_EXCEPTIONS
43             throw std::bad_alloc();
44 #else
45             std::terminate();
46 #endif
47         }
48         pointer r = (T*)ptr_;
49         ptr_ += n * sizeof(T);
50         return r;
51     }
deallocate(pointer p,size_type n)52     void deallocate(pointer p, size_type n)
53     {
54         if ((char*)(p + n) == ptr_)
55             ptr_ = (char*)p;
56     }
57 
max_size()58     size_type max_size() const {return N;}
59 };
60 
61 template <class T, std::size_t N>
62 inline
63 void
swap(stack_allocator<T,N> & x,stack_allocator<T,N> & y)64 swap(stack_allocator<T, N>& x, stack_allocator<T, N>& y) {}
65 
66 #endif  // STACK_ALLOCATOR_H
67