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 COUNTER_H
11 #define COUNTER_H
12 
13 #include <functional> // for std::hash
14 
15 struct Counter_base { static int gConstructed; };
16 
17 template <typename T>
18 class Counter : public Counter_base
19 {
20 public:
Counter()21     Counter() : data_()                             { ++gConstructed; }
Counter(const T & data)22     Counter(const T &data) : data_(data)            { ++gConstructed; }
Counter(const Counter & rhs)23     Counter(const Counter& rhs) : data_(rhs.data_)  { ++gConstructed; }
24     Counter& operator=(const Counter& rhs)          { ++gConstructed; data_ = rhs.data_; return *this; }
25 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
Counter(Counter && rhs)26     Counter(Counter&& rhs) : data_(std::move(rhs.data_))  { ++gConstructed; }
27     Counter& operator=(Counter&& rhs) { ++gConstructed; data_ = std::move(rhs.data_); return *this; }
28 #endif
~Counter()29     ~Counter() { --gConstructed; }
30 
get()31     const T& get() const {return data_;}
32 
33     bool operator==(const Counter& x) const {return data_ == x.data_;}
34     bool operator< (const Counter& x) const {return data_ <  x.data_;}
35 
36 private:
37     T data_;
38 };
39 
40 int Counter_base::gConstructed = 0;
41 
42 namespace std {
43 
44 template <class T>
45 struct hash<Counter<T> >
46     : public std::unary_function<Counter<T>, std::size_t>
47 {
48     std::size_t operator()(const Counter<T>& x) const {return std::hash<T>(x.get());}
49 };
50 }
51 
52 #endif
53