libstdc++
tr1/tuple
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1 // class template tuple -*- C++ -*-
2 
3 // Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
4 //
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
15 
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
19 
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
24 
25 /** @file tr1/tuple
26 * This is a TR1 C++ Library header.
27 */
28 
29 // Chris Jefferson <chris@bubblescope.net>
30 // Variadic Templates support by Douglas Gregor <doug.gregor@gmail.com>
31 
32 #ifndef _GLIBCXX_TR1_TUPLE
33 #define _GLIBCXX_TR1_TUPLE 1
34 
35 #pragma GCC system_header
36 
37 #include <utility>
38 
39 namespace std
40 {
41 namespace tr1
42 {
43  // Adds a const reference to a non-reference type.
44  template<typename _Tp>
45  struct __add_c_ref
46  { typedef const _Tp& type; };
47 
48  template<typename _Tp>
49  struct __add_c_ref<_Tp&>
50  { typedef _Tp& type; };
51 
52  // Adds a reference to a non-reference type.
53  template<typename _Tp>
54  struct __add_ref
55  { typedef _Tp& type; };
56 
57  template<typename _Tp>
58  struct __add_ref<_Tp&>
59  { typedef _Tp& type; };
60 
61  /**
62  * Contains the actual implementation of the @c tuple template, stored
63  * as a recursive inheritance hierarchy from the first element (most
64  * derived class) to the last (least derived class). The @c Idx
65  * parameter gives the 0-based index of the element stored at this
66  * point in the hierarchy; we use it to implement a constant-time
67  * get() operation.
68  */
69  template<int _Idx, typename... _Elements>
70  struct _Tuple_impl;
71 
72  /**
73  * Zero-element tuple implementation. This is the basis case for the
74  * inheritance recursion.
75  */
76  template<int _Idx>
77  struct _Tuple_impl<_Idx> { };
78 
79  /**
80  * Recursive tuple implementation. Here we store the @c Head element
81  * and derive from a @c Tuple_impl containing the remaining elements
82  * (which contains the @c Tail).
83  */
84  template<int _Idx, typename _Head, typename... _Tail>
85  struct _Tuple_impl<_Idx, _Head, _Tail...>
86  : public _Tuple_impl<_Idx + 1, _Tail...>
87  {
88  typedef _Tuple_impl<_Idx + 1, _Tail...> _Inherited;
89 
90  _Head _M_head;
91 
92  _Inherited& _M_tail() { return *this; }
93  const _Inherited& _M_tail() const { return *this; }
94 
95  _Tuple_impl() : _Inherited(), _M_head() { }
96 
97  explicit
98  _Tuple_impl(typename __add_c_ref<_Head>::type __head,
99  typename __add_c_ref<_Tail>::type... __tail)
100  : _Inherited(__tail...), _M_head(__head) { }
101 
102  template<typename... _UElements>
104  : _Inherited(__in._M_tail()), _M_head(__in._M_head) { }
105 
106  _Tuple_impl(const _Tuple_impl& __in)
107  : _Inherited(__in._M_tail()), _M_head(__in._M_head) { }
108 
109  template<typename... _UElements>
110  _Tuple_impl&
111  operator=(const _Tuple_impl<_Idx, _UElements...>& __in)
112  {
113  _M_head = __in._M_head;
114  _M_tail() = __in._M_tail();
115  return *this;
116  }
117 
118  _Tuple_impl&
119  operator=(const _Tuple_impl& __in)
120  {
121  _M_head = __in._M_head;
122  _M_tail() = __in._M_tail();
123  return *this;
124  }
125  };
126 
127  template<typename... _Elements>
128  class tuple : public _Tuple_impl<0, _Elements...>
129  {
130  typedef _Tuple_impl<0, _Elements...> _Inherited;
131 
132  public:
133  tuple() : _Inherited() { }
134 
135  explicit
136  tuple(typename __add_c_ref<_Elements>::type... __elements)
137  : _Inherited(__elements...) { }
138 
139  template<typename... _UElements>
140  tuple(const tuple<_UElements...>& __in)
141  : _Inherited(__in) { }
142 
143  tuple(const tuple& __in)
144  : _Inherited(__in) { }
145 
146  template<typename... _UElements>
147  tuple&
148  operator=(const tuple<_UElements...>& __in)
149  {
150  static_cast<_Inherited&>(*this) = __in;
151  return *this;
152  }
153 
154  tuple&
155  operator=(const tuple& __in)
156  {
157  static_cast<_Inherited&>(*this) = __in;
158  return *this;
159  }
160  };
161 
162  template<> class tuple<> { };
163 
164  // 2-element tuple, with construction and assignment from a pair.
165  template<typename _T1, typename _T2>
166  class tuple<_T1, _T2> : public _Tuple_impl<0, _T1, _T2>
167  {
168  typedef _Tuple_impl<0, _T1, _T2> _Inherited;
169 
170  public:
171  tuple() : _Inherited() { }
172 
173  explicit
174  tuple(typename __add_c_ref<_T1>::type __a1,
175  typename __add_c_ref<_T2>::type __a2)
176  : _Inherited(__a1, __a2) { }
177 
178  template<typename _U1, typename _U2>
179  tuple(const tuple<_U1, _U2>& __in)
180  : _Inherited(__in) { }
181 
182  tuple(const tuple& __in)
183  : _Inherited(__in) { }
184 
185  template<typename _U1, typename _U2>
186  tuple(const pair<_U1, _U2>& __in)
187  : _Inherited(_Tuple_impl<0,
188  typename __add_c_ref<_U1>::type,
189  typename __add_c_ref<_U2>::type>(__in.first,
190  __in.second))
191  { }
192 
193  template<typename _U1, typename _U2>
194  tuple&
195  operator=(const tuple<_U1, _U2>& __in)
196  {
197  static_cast<_Inherited&>(*this) = __in;
198  return *this;
199  }
200 
201  tuple&
202  operator=(const tuple& __in)
203  {
204  static_cast<_Inherited&>(*this) = __in;
205  return *this;
206  }
207 
208  template<typename _U1, typename _U2>
209  tuple&
210  operator=(const pair<_U1, _U2>& __in)
211  {
212  this->_M_head = __in.first;
213  this->_M_tail()._M_head = __in.second;
214  return *this;
215  }
216  };
217 
218 
219  /// Gives the type of the ith element of a given tuple type.
220  template<int __i, typename _Tp>
222 
223  /**
224  * Recursive case for tuple_element: strip off the first element in
225  * the tuple and retrieve the (i-1)th element of the remaining tuple.
226  */
227  template<int __i, typename _Head, typename... _Tail>
228  struct tuple_element<__i, tuple<_Head, _Tail...> >
229  : tuple_element<__i - 1, tuple<_Tail...> > { };
230 
231  /**
232  * Basis case for tuple_element: The first element is the one we're seeking.
233  */
234  template<typename _Head, typename... _Tail>
235  struct tuple_element<0, tuple<_Head, _Tail...> >
236  {
237  typedef _Head type;
238  };
239 
240  /// Finds the size of a given tuple type.
241  template<typename _Tp>
242  struct tuple_size;
243 
244  /// class tuple_size
245  template<typename... _Elements>
246  struct tuple_size<tuple<_Elements...> >
247  {
248  static const int value = sizeof...(_Elements);
249  };
250 
251  template<typename... _Elements>
252  const int tuple_size<tuple<_Elements...> >::value;
253 
254  template<int __i, typename _Head, typename... _Tail>
255  inline typename __add_ref<_Head>::type
256  __get_helper(_Tuple_impl<__i, _Head, _Tail...>& __t)
257  {
258  return __t._M_head;
259  }
260 
261  template<int __i, typename _Head, typename... _Tail>
262  inline typename __add_c_ref<_Head>::type
263  __get_helper(const _Tuple_impl<__i, _Head, _Tail...>& __t)
264  {
265  return __t._M_head;
266  }
267 
268  // Return a reference (const reference) to the ith element of a tuple.
269  // Any const or non-const ref elements are returned with their original type.
270  template<int __i, typename... _Elements>
271  inline typename __add_ref<
272  typename tuple_element<__i, tuple<_Elements...> >::type
273  >::type
274  get(tuple<_Elements...>& __t)
275  {
276  return __get_helper<__i>(__t);
277  }
278 
279  template<int __i, typename... _Elements>
280  inline typename __add_c_ref<
281  typename tuple_element<__i, tuple<_Elements...> >::type
282  >::type
283  get(const tuple<_Elements...>& __t)
284  {
285  return __get_helper<__i>(__t);
286  }
287 
288  // This class helps construct the various comparison operations on tuples
289  template<int __check_equal_size, int __i, int __j,
290  typename _Tp, typename _Up>
291  struct __tuple_compare;
292 
293  template<int __i, int __j, typename _Tp, typename _Up>
294  struct __tuple_compare<0, __i, __j, _Tp, _Up>
295  {
296  static bool __eq(const _Tp& __t, const _Up& __u)
297  {
298  return (get<__i>(__t) == get<__i>(__u) &&
299  __tuple_compare<0, __i+1, __j, _Tp, _Up>::__eq(__t, __u));
300  }
301 
302  static bool __less(const _Tp& __t, const _Up& __u)
303  {
304  return ((get<__i>(__t) < get<__i>(__u))
305  || !(get<__i>(__u) < get<__i>(__t)) &&
306  __tuple_compare<0, __i+1, __j, _Tp, _Up>::__less(__t, __u));
307  }
308  };
309 
310  template<int __i, typename _Tp, typename _Up>
311  struct __tuple_compare<0, __i, __i, _Tp, _Up>
312  {
313  static bool __eq(const _Tp&, const _Up&)
314  { return true; }
315 
316  static bool __less(const _Tp&, const _Up&)
317  { return false; }
318  };
319 
320  template<typename... _TElements, typename... _UElements>
321  bool
322  operator==(const tuple<_TElements...>& __t,
323  const tuple<_UElements...>& __u)
324  {
325  typedef tuple<_TElements...> _Tp;
326  typedef tuple<_UElements...> _Up;
327  return (__tuple_compare<tuple_size<_Tp>::value - tuple_size<_Up>::value,
328  0, tuple_size<_Tp>::value, _Tp, _Up>::__eq(__t, __u));
329  }
330 
331  template<typename... _TElements, typename... _UElements>
332  bool
333  operator<(const tuple<_TElements...>& __t,
334  const tuple<_UElements...>& __u)
335  {
336  typedef tuple<_TElements...> _Tp;
337  typedef tuple<_UElements...> _Up;
338  return (__tuple_compare<tuple_size<_Tp>::value - tuple_size<_Up>::value,
339  0, tuple_size<_Tp>::value, _Tp, _Up>::__less(__t, __u));
340  }
341 
342  template<typename... _TElements, typename... _UElements>
343  inline bool
344  operator!=(const tuple<_TElements...>& __t,
345  const tuple<_UElements...>& __u)
346  { return !(__t == __u); }
347 
348  template<typename... _TElements, typename... _UElements>
349  inline bool
350  operator>(const tuple<_TElements...>& __t,
351  const tuple<_UElements...>& __u)
352  { return __u < __t; }
353 
354  template<typename... _TElements, typename... _UElements>
355  inline bool
356  operator<=(const tuple<_TElements...>& __t,
357  const tuple<_UElements...>& __u)
358  { return !(__u < __t); }
359 
360  template<typename... _TElements, typename... _UElements>
361  inline bool
362  operator>=(const tuple<_TElements...>& __t,
363  const tuple<_UElements...>& __u)
364  { return !(__t < __u); }
365 
366  template<typename _Tp>
367  class reference_wrapper;
368 
369  // Helper which adds a reference to a type when given a reference_wrapper
370  template<typename _Tp>
371  struct __strip_reference_wrapper
372  {
373  typedef _Tp __type;
374  };
375 
376  template<typename _Tp>
377  struct __strip_reference_wrapper<reference_wrapper<_Tp> >
378  {
379  typedef _Tp& __type;
380  };
381 
382  template<typename _Tp>
383  struct __strip_reference_wrapper<const reference_wrapper<_Tp> >
384  {
385  typedef _Tp& __type;
386  };
387 
388  template<typename... _Elements>
389  inline tuple<typename __strip_reference_wrapper<_Elements>::__type...>
390  make_tuple(_Elements... __args)
391  {
392  typedef tuple<typename __strip_reference_wrapper<_Elements>::__type...>
393  __result_type;
394  return __result_type(__args...);
395  }
396 
397  template<typename... _Elements>
398  inline tuple<_Elements&...>
399  tie(_Elements&... __args)
400  {
401  return tuple<_Elements&...>(__args...);
402  }
403 
404  // A class (and instance) which can be used in 'tie' when an element
405  // of a tuple is not required
406  struct _Swallow_assign
407  {
408  template<class _Tp>
409  _Swallow_assign&
410  operator=(const _Tp&)
411  { return *this; }
412  };
413 
414  // TODO: Put this in some kind of shared file.
415  namespace
416  {
417  _Swallow_assign ignore;
418  }; // anonymous namespace
419 }
420 }
421 
422 #endif // _GLIBCXX_TR1_TUPLE
Gives the type of the ith element of a given tuple type.
Definition: tr1/tuple:221
Finds the size of a given tuple type.
Definition: tr1/tuple:242
tuple
Definition: tuple:226