example-tuple.cpp revision 03414b98caba86771622c35b1fa70d13de0c14ba 
1// RUN: %clang_cc1 -std=c++0x -fsyntax-only -verify %s
2
3// Example tuple implementation from the variadic templates proposal,
4// ISO C++ committee document nmber N2080.
5
6// Helper type traits
7template<typename T>
8struct add_reference {
9  typedef T &type;
10};
11
12template<typename T>
13struct add_reference<T&> {
14  typedef T &type;
15};
16
17template<typename T>
18struct add_const_reference {
19  typedef T const &type;
20};
21
22template<typename T>
23struct add_const_reference<T&> {
24  typedef T &type;
25};
26
27template<typename T, typename U>
28struct is_same {
29  static const bool value = false;
30};
31
32template<typename T>
33struct is_same<T, T> {
34  static const bool value = true;
35};
36
37template<typename T>
38class reference_wrapper {
39  T *ptr;
40
41public:
42  reference_wrapper(T& t) : ptr(&t) { }
43  operator T&() const { return *ptr; }
44};
45
46template<typename T> reference_wrapper<T> ref(T& t) {
47  return reference_wrapper<T>(t);
48}
49template<typename T> reference_wrapper<const T> cref(const T& t) {
50  return reference_wrapper<const T>(t);
51}
52
53template<typename... Values> class tuple;
54
55// Basis case: zero-length tuple
56template<> class tuple<> { };
57
58template<typename Head, typename... Tail>
59class tuple<Head, Tail...> : private tuple<Tail...> {
60  typedef tuple<Tail...> inherited;
61
62public:
63  tuple() { }
64  // implicit copy-constructor is okay
65
66  // Construct tuple from separate arguments.
67  tuple(typename add_const_reference<Head>::type v,
68        typename add_const_reference<Tail>::type... vtail)
69    : m_head(v), inherited(vtail...) { }
70
71  // Construct tuple from another tuple.
72  template<typename... VValues> tuple(const tuple<VValues...>& other)
73    : m_head(other.head()), inherited(other.tail()) { }
74
75  template<typename... VValues> tuple&
76  operator=(const tuple<VValues...>& other) {
77    m_head = other.head();
78    tail() = other.tail();
79    return *this;
80  }
81
82  typename add_reference<Head>::type head() { return m_head; }
83  typename add_reference<const Head>::type head() const { return m_head; }
84  inherited& tail() { return *this; }
85  const inherited& tail() const { return *this; }
86
87protected:
88  Head m_head;
89};
90
91void test_tuple() {
92  tuple<> t0a;
93  tuple<> t0b(t0a);
94  t0a = t0b;
95
96  tuple<int> t1a;
97  tuple<int> t1b(17);
98  tuple<int> t1c(t1b);
99  t1a = t1b;
100
101  tuple<float> t1d(3.14159);
102  tuple<float> t1e(t1d);
103  t1d = t1e;
104
105  int i;
106  float f;
107  double d;
108  tuple<int*, float*, double*> t3a(&i, &f, &d);
109}
110
111// Creation functions
112template<typename T>
113struct make_tuple_result {
114  typedef T type;
115};
116
117template<typename T>
118struct make_tuple_result<reference_wrapper<T> > {
119  typedef T& type;
120};
121
122template<typename... Values>
123tuple<typename make_tuple_result<Values>::type...>
124make_tuple(const Values&... values) {
125  return tuple<typename make_tuple_result<Values>::type...>(values...);
126}
127
128template<typename... Values>
129tuple<Values&...> tie(Values&... values) {
130  return tuple<Values&...>(values...);
131}
132
133template<typename T> const T *addr(const T& ref) { return &ref; }
134void test_creation_functions() {
135  int i;
136  float f;
137  double d;
138  const tuple<int, float&, const double&> *t3p = addr(make_tuple(i, ref(f), cref(d)));
139  const tuple<int&, float&, double&> *t3q = addr(tie(i, f, d));
140}
141
142// Helper classes
143template<typename Tuple> struct tuple_size;
144
145template<typename... Values> struct tuple_size<tuple<Values...> > {
146  static const int value = sizeof...(Values);
147};
148
149int check_tuple_size_0[tuple_size<tuple<> >::value == 0? 1 : -1];
150int check_tuple_size_1[tuple_size<tuple<int>>::value == 1? 1 : -1];
151int check_tuple_size_2[tuple_size<tuple<float, double>>::value == 2? 1 : -1];
152int check_tuple_size_3[tuple_size<tuple<char, unsigned char, signed char>>::value == 3? 1 : -1];
153
154template<int I, typename Tuple> struct tuple_element;
155
156template<int I, typename Head, typename... Tail>
157struct tuple_element<I, tuple<Head, Tail...> > {
158  typedef typename tuple_element<I-1, tuple<Tail...> >::type type;
159};
160
161template<typename Head, typename... Tail>
162struct tuple_element<0, tuple<Head, Tail...> > {
163  typedef Head type;
164};
165
166int check_tuple_element_0[is_same<tuple_element<0, tuple<int&, float, double>>::type,
167                                  int&>::value? 1 : -1];
168
169int check_tuple_element_1[is_same<tuple_element<1, tuple<int&, float, double>>::type,
170                                  float>::value? 1 : -1];
171
172int check_tuple_element_2[is_same<tuple_element<2, tuple<int&, float, double>>::type,
173                                  double>::value? 1 : -1];
174
175// Element access
176template<int I, typename Tuple> class get_impl;
177template<int I, typename Head, typename... Values>
178class get_impl<I, tuple<Head, Values...> > {
179  typedef typename tuple_element<I-1, tuple<Values...> >::type Element;
180  typedef typename add_reference<Element>::type RJ;
181  typedef typename add_const_reference<Element>::type PJ;
182  typedef get_impl<I-1, tuple<Values...> > Next;
183public:
184  static RJ get(tuple<Head, Values...>& t) { return Next::get(t.tail()); }
185  static PJ get(const tuple<Head, Values...>& t) { return Next::get(t.tail()); }
186};
187
188template<typename Head, typename... Values>
189class get_impl<0, tuple<Head, Values...> > {
190  typedef typename add_reference<Head>::type RJ;
191  typedef typename add_const_reference<Head>::type PJ;
192public:
193  static RJ get(tuple<Head, Values...>& t) { return t.head(); }
194  static PJ get(const tuple<Head, Values...>& t) { return t.head(); }
195};
196
197template<int I, typename... Values> typename add_reference<
198typename tuple_element<I, tuple<Values...> >::type >::type
199get(tuple<Values...>& t) {
200  return get_impl<I, tuple<Values...> >::get(t);
201}
202
203template<int I, typename... Values> typename add_const_reference<
204typename tuple_element<I, tuple<Values...> >::type >::type
205get(const tuple<Values...>& t) {
206  return get_impl<I, tuple<Values...> >::get(t);
207}
208
209#if 0
210// FIXME: Not yet functional, because we aren't currently able to
211// extend a partially-explicitly-specified parameter pack.
212void test_element_access(tuple<int*, float*, double*&> t3) {
213  int i;
214  float f;
215  double d;
216  get<0>(t3) = &i;
217  get<1>(t3) = &f;
218  get<2>(t3) = &d;
219}
220#endif
221
222// Relational operators
223inline bool operator==(const tuple<>&, const tuple<>&) { return true; }
224
225template<typename T, typename... TTail, typename U, typename... UTail>
226bool operator==(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) {
227  return t.head() == u.head() && t.tail() == u.tail();
228}
229
230template<typename... TValues, typename... UValues>
231bool operator!=(const tuple<TValues...>& t, const tuple<UValues...>& u) {
232  return !(t == u);
233}
234
235inline bool operator<(const tuple<>&, const tuple<>&) { return false; }
236
237template<typename T, typename... TTail, typename U, typename... UTail>
238bool operator<(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u) {
239  return (t.head() < u.head() || (!(t.head() < u.head()) && t.tail() < u.tail()));
240}
241
242template<typename... TValues, typename... UValues>
243bool operator>(const tuple<TValues...>& t, const tuple<UValues...>& u) {
244  return u < t;
245}
246
247template<typename... TValues, typename... UValues>
248bool operator<=(const tuple<TValues...>& t, const tuple<UValues...>& u) {
249  return !(u < t);
250}
251
252template<typename... TValues, typename... UValues>
253bool operator>=(const tuple<TValues...>& t, const tuple<UValues...>& u) {
254  return !(t < u);
255}
256
257void test_relational_operators(tuple<int*, float*, double*> t3) {
258  (void)(t3 == t3);
259  (void)(t3 != t3);
260  (void)(t3 < t3);
261  (void)(t3 <= t3);
262  (void)(t3 >= t3);
263  (void)(t3 > t3);
264};
265