libstdc++-v3/include/std/tuple

   1 // <tuple> -*- C++ -*-
   2
   3 // Copyright (C) 2007 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 2, 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 // You should have received a copy of the GNU General Public License
  17 // along with this library; see the file COPYING.  If not, write to
  18 // the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  19 // Boston, MA 02110-1301, USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 /** @file include/tuple
  31  *  This is a Standard C++ Library header.
  32  */
  33
  34 #ifndef _GLIBCXX_CXX0X_TUPLE
  35 #define _GLIBCXX_CXX0X_TUPLE 1
  36
  37 #pragma GCC system_header
  38
  39 #ifndef __GXX_EXPERIMENTAL_CXX0X__
  40 # include <c++0x_warning.h>
  41 #endif
  42
  43 #include <utility>
  44
  45 namespace std
  46 {
  47   // Adds a const reference to a non-reference type.
  48   template<typename _Tp>
  49     struct __add_c_ref
  50     { typedef const _Tp& type; };
  51
  52   template<typename _Tp>
  53     struct __add_c_ref<_Tp&>
  54     { typedef _Tp& type; };
  55
  56   // Adds a reference to a non-reference type.
  57   template<typename _Tp>
  58     struct __add_ref
  59     { typedef _Tp& type; };
  60
  61   template<typename _Tp>
  62     struct __add_ref<_Tp&>
  63     { typedef _Tp& type; };
  64
  65   template<int _Idx, typename _Head, bool _IsEmpty>
  66     struct _Head_base;
  67
  68   template<int _Idx, typename _Head>
  69     struct _Head_base<_Idx, _Head, true>
  70     : public _Head
  71     {
  72       _Head_base()
  73       : _Head() { }
  74
  75       _Head_base(typename __add_c_ref<_Head>::type __h)
  76       : _Head(__h) { }
  77
  78       _Head_base(typename std::remove_reference<_Head>::type&& __h)
  79       : _Head(std::forward<_Head>(__h)) { }
  80
  81       _Head&       _M_head()       { return *this; }
  82       const _Head& _M_head() const { return *this; }
  83     };
  84
  85   template<int _Idx, typename _Head>
  86     struct _Head_base<_Idx, _Head, false>
  87     {
  88       _Head_base()
  89       : _M_head_impl() { }
  90
  91       _Head_base(typename __add_c_ref<_Head>::type __h)
  92       : _M_head_impl(__h) { }
  93
  94       _Head_base(typename std::remove_reference<_Head>::type&& __h)
  95       : _M_head_impl(std::move(__h)) { }
  96
  97       _Head&       _M_head()       { return _M_head_impl; }
  98       const _Head& _M_head() const { return _M_head_impl; }
  99
 100       _Head _M_head_impl;
 101     };
 102
 103   /**
 104    * @if maint
 105    * Contains the actual implementation of the @c tuple template, stored
 106    * as a recursive inheritance hierarchy from the first element (most
 107    * derived class) to the last (least derived class). The @c Idx
 108    * parameter gives the 0-based index of the element stored at this
 109    * point in the hierarchy; we use it to implement a constant-time
 110    * get() operation.
 111    * @endif
 112    */
 113   template<int _Idx, typename... _Elements>
 114     struct _Tuple_impl;
 115
 116   /**
 117    * @if maint
 118    * Zero-element tuple implementation. This is the basis case for the
 119    * inheritance recursion.
 120    * @endif maint
 121    */
 122   template<int _Idx>
 123     struct _Tuple_impl<_Idx> { };
 124
 125   /**
 126    * @if maint
 127    * Recursive tuple implementation. Here we store the @c Head element
 128    * and derive from a @c Tuple_impl containing the remaining elements
 129    * (which contains the @c Tail).
 130    * @endif
 131    */
 132   template<int _Idx, typename _Head, typename... _Tail>
 133     struct _Tuple_impl<_Idx, _Head, _Tail...>
 134     : public _Tuple_impl<_Idx + 1, _Tail...>,
 135       private _Head_base<_Idx, _Head, std::is_empty<_Head>::value>
 136     {
 137       typedef _Tuple_impl<_Idx + 1, _Tail...> _Inherited;
 138       typedef _Head_base<_Idx, _Head, std::is_empty<_Head>::value> _Base;
 139
 140       _Head&            _M_head()       { return _Base::_M_head(); }
 141       const _Head&      _M_head() const { return _Base::_M_head(); }
 142
 143       _Inherited&       _M_tail()       { return *this; }
 144       const _Inherited& _M_tail() const { return *this; }
 145
 146       _Tuple_impl()
 147       : _Inherited(), _Base() { }
 148
 149       explicit
 150       _Tuple_impl(typename __add_c_ref<_Head>::type __head,
 151                   typename __add_c_ref<_Tail>::type... __tail)
 152       : _Inherited(__tail...), _Base(__head) { }
 153
 154       template<typename... _UElements>
 155       _Tuple_impl(const _Tuple_impl<_Idx, _UElements...>& __in)
 156       : _Inherited(__in._M_tail()), _Base(__in._M_head()) { }
 157
 158       _Tuple_impl(const _Tuple_impl& __in)
 159       : _Inherited(__in._M_tail()), _Base(__in._M_head()) { }
 160
 161       template<typename... _UElements>
 162         _Tuple_impl&
 163         operator=(const _Tuple_impl<_Idx, _UElements...>& __in)
 164         {
 165           _M_head() = __in._M_head();
 166           _M_tail() = __in._M_tail();
 167           return *this;
 168         }
 169
 170       _Tuple_impl&
 171       operator=(const _Tuple_impl& __in)
 172       {
 173         _M_head() = __in._M_head();
 174         _M_tail() = __in._M_tail();
 175         return *this;
 176       }
 177     };
 178
 179   template<typename... _Elements>
 180     class tuple : public _Tuple_impl<0, _Elements...>
 181     {
 182       typedef _Tuple_impl<0, _Elements...> _Inherited;
 183
 184     public:
 185       tuple()
 186       : _Inherited() { }
 187
 188       explicit
 189       tuple(typename __add_c_ref<_Elements>::type... __elements)
 190       : _Inherited(__elements...) { }
 191
 192       template<typename... _UElements>
 193         tuple(const tuple<_UElements...>& __in)
 194         : _Inherited(__in) { }
 195
 196       tuple(const tuple& __in)
 197       : _Inherited(__in) { }
 198
 199       template<typename... _UElements>
 200         tuple&
 201         operator=(const tuple<_UElements...>& __in)
 202         {
 203           static_cast<_Inherited&>(*this) = __in;
 204           return *this;
 205         }
 206
 207       tuple&
 208       operator=(const tuple& __in)
 209       {
 210         static_cast<_Inherited&>(*this) = __in;
 211         return *this;
 212       }
 213     };
 214
 215   template<> class tuple<> { };
 216
 217   // 2-element tuple, with construction and assignment from a pair.
 218   template<typename _T1, typename _T2>
 219     class tuple<_T1, _T2> : public _Tuple_impl<0, _T1, _T2>
 220     {
 221       typedef _Tuple_impl<0, _T1, _T2> _Inherited;
 222
 223     public:
 224       tuple()
 225       : _Inherited() { }
 226
 227       explicit
 228       tuple(typename __add_c_ref<_T1>::type __a1,
 229             typename __add_c_ref<_T2>::type __a2)
 230       : _Inherited(__a1, __a2) { }
 231
 232       template<typename _U1, typename _U2>
 233         tuple(const tuple<_U1, _U2>& __in)
 234         : _Inherited(__in) { }
 235
 236       tuple(const tuple& __in)
 237       : _Inherited(__in) { }
 238
 239       template<typename _U1, typename _U2>
 240         tuple(const pair<_U1, _U2>& __in)
 241         : _Inherited(_Tuple_impl<0,
 242                      typename __add_c_ref<_U1>::type,
 243                      typename __add_c_ref<_U2>::type>(__in.first,
 244                                                       __in.second))
 245         { }
 246
 247       template<typename _U1, typename _U2>
 248         tuple&
 249         operator=(const tuple<_U1, _U2>& __in)
 250         {
 251           static_cast<_Inherited&>(*this) = __in;
 252           return *this;
 253         }
 254
 255       tuple&
 256       operator=(const tuple& __in)
 257       {
 258         static_cast<_Inherited&>(*this) = __in;
 259         return *this;
 260       }
 261
 262       template<typename _U1, typename _U2>
 263         tuple&
 264         operator=(const pair<_U1, _U2>& __in)
 265         {
 266           this->_M_head() = __in.first;
 267           this->_M_tail()._M_head() = __in.second;
 268           return *this;
 269         }
 270     };
 271
 272
 273   /// Gives the type of the ith element of a given tuple type.
 274   template<int __i, typename _Tp>
 275     struct tuple_element;
 276
 277   /**
 278    * @if maint
 279    * Recursive case for tuple_element: strip off the first element in
 280    * the tuple and retrieve the (i-1)th element of the remaining tuple.
 281    * @endif
 282    */
 283   template<int __i, typename _Head, typename... _Tail>
 284     struct tuple_element<__i, tuple<_Head, _Tail...> >
 285     : tuple_element<__i - 1, tuple<_Tail...> > { };
 286
 287   /**
 288    * @if maint
 289    * Basis case for tuple_element: The first element is the one we're seeking.
 290    * @endif
 291    */
 292   template<typename _Head, typename... _Tail>
 293     struct tuple_element<0, tuple<_Head, _Tail...> >
 294     {
 295       typedef _Head type;
 296     };
 297
 298   /// Finds the size of a given tuple type.
 299   template<typename _Tp>
 300     struct tuple_size;
 301
 302   /// @brief class tuple_size
 303   template<typename... _Elements>
 304     struct tuple_size<tuple<_Elements...> >
 305     {
 306       static const int value = sizeof...(_Elements);
 307     };
 308
 309   template<typename... _Elements>
 310     const int tuple_size<tuple<_Elements...> >::value;
 311
 312   template<int __i, typename _Head, typename... _Tail>
 313     inline typename __add_ref<_Head>::type
 314     __get_helper(_Tuple_impl<__i, _Head, _Tail...>& __t)
 315     { return __t._M_head(); }
 316
 317   template<int __i, typename _Head, typename... _Tail>
 318     inline typename __add_c_ref<_Head>::type
 319     __get_helper(const _Tuple_impl<__i, _Head, _Tail...>& __t)
 320     { return __t._M_head(); }
 321
 322   // Return a reference (const reference) to the ith element of a tuple.
 323   // Any const or non-const ref elements are returned with their original type.
 324   template<int __i, typename... _Elements>
 325     inline typename __add_ref<
 326                       typename tuple_element<__i, tuple<_Elements...> >::type
 327                     >::type
 328     get(tuple<_Elements...>& __t)
 329     { return __get_helper<__i>(__t); }
 330
 331   template<int __i, typename... _Elements>
 332     inline typename __add_c_ref<
 333                       typename tuple_element<__i, tuple<_Elements...> >::type
 334                     >::type
 335     get(const tuple<_Elements...>& __t)
 336     { return __get_helper<__i>(__t); }
 337
 338   // This class helps construct the various comparison operations on tuples
 339   template<int __check_equal_size, int __i, int __j,
 340            typename _Tp, typename _Up>
 341     struct __tuple_compare;
 342
 343   template<int __i, int __j, typename _Tp, typename _Up>
 344     struct __tuple_compare<0, __i, __j, _Tp, _Up>
 345     {
 346       static bool __eq(const _Tp& __t, const _Up& __u)
 347       {
 348         return (get<__i>(__t) == get<__i>(__u) &&
 349                 __tuple_compare<0, __i+1, __j, _Tp, _Up>::__eq(__t, __u));
 350       }
 351
 352       static bool __less(const _Tp& __t, const _Up& __u)
 353       {
 354         return ((get<__i>(__t) < get<__i>(__u))
 355                 || !(get<__i>(__u) < get<__i>(__t)) &&
 356                 __tuple_compare<0, __i+1, __j, _Tp, _Up>::__less(__t, __u));
 357       }
 358     };
 359
 360   template<int __i, typename _Tp, typename _Up>
 361     struct __tuple_compare<0, __i, __i, _Tp, _Up>
 362     {
 363       static bool __eq(const _Tp&, const _Up&)
 364       { return true; }
 365
 366       static bool __less(const _Tp&, const _Up&)
 367       { return false; }
 368     };
 369
 370   template<typename... _TElements, typename... _UElements>
 371     bool
 372     operator==(const tuple<_TElements...>& __t,
 373                const tuple<_UElements...>& __u)
 374     {
 375       typedef tuple<_TElements...> _Tp;
 376       typedef tuple<_UElements...> _Up;
 377       return (__tuple_compare<tuple_size<_Tp>::value - tuple_size<_Tp>::value,
 378               0, tuple_size<_Tp>::value, _Tp, _Up>::__eq(__t, __u));
 379     }
 380
 381   template<typename... _TElements, typename... _UElements>
 382     bool
 383     operator<(const tuple<_TElements...>& __t,
 384               const tuple<_UElements...>& __u)
 385     {
 386       typedef tuple<_TElements...> _Tp;
 387       typedef tuple<_UElements...> _Up;
 388       return (__tuple_compare<tuple_size<_Tp>::value - tuple_size<_Tp>::value,
 389               0, tuple_size<_Tp>::value, _Tp, _Up>::__less(__t, __u));
 390     }
 391
 392   template<typename... _TElements, typename... _UElements>
 393     inline bool
 394     operator!=(const tuple<_TElements...>& __t,
 395                const tuple<_UElements...>& __u)
 396     { return !(__t == __u); }
 397
 398   template<typename... _TElements, typename... _UElements>
 399     inline bool
 400     operator>(const tuple<_TElements...>& __t,
 401               const tuple<_UElements...>& __u)
 402     { return __u < __t; }
 403
 404   template<typename... _TElements, typename... _UElements>
 405     inline bool
 406     operator<=(const tuple<_TElements...>& __t,
 407                const tuple<_UElements...>& __u)
 408     { return !(__u < __t); }
 409
 410   template<typename... _TElements, typename... _UElements>
 411     inline bool
 412     operator>=(const tuple<_TElements...>& __t,
 413                const tuple<_UElements...>& __u)
 414     { return !(__t < __u); }
 415
 416   // NB: DR 705.
 417   template<typename... _Elements>
 418     inline tuple<typename __decay_and_strip<_Elements>::__type...>
 419     make_tuple(_Elements&&... __args)
 420     {
 421       typedef tuple<typename __decay_and_strip<_Elements>::__type...>
 422         __result_type;
 423       return __result_type(std::forward<_Elements>(__args)...);
 424     }
 425
 426   template<int...> struct __index_holder { };
 427
 428   template<int __i, typename _IdxHolder, typename... _Elements>
 429     struct __index_holder_impl;
 430
 431   template<int __i, int... _Indexes, typename _IdxHolder, typename... _Elements>
 432     struct __index_holder_impl<__i, __index_holder<_Indexes...>,
 433                                _IdxHolder, _Elements...>
 434     {
 435       typedef typename __index_holder_impl<__i + 1,
 436                                            __index_holder<_Indexes..., __i>,
 437                                            _Elements...>::type type;
 438     };
 439
 440   template<int __i, int... _Indexes>
 441     struct __index_holder_impl<__i, __index_holder<_Indexes...> >
 442     { typedef __index_holder<_Indexes...> type; };
 443
 444   template<typename... _Elements>
 445     struct __make_index_holder
 446     : __index_holder_impl<0, __index_holder<>, _Elements...> { };
 447
 448   template<typename... _TElements, int... _TIdx,
 449            typename... _UElements, int... _UIdx>
 450     inline tuple<_TElements..., _UElements...>
 451     __tuple_cat_helper(const tuple<_TElements...>& __t,
 452                        const __index_holder<_TIdx...>&,
 453                        const tuple<_UElements...>& __u,
 454                        const __index_holder<_UIdx...>&)
 455     { return tuple<_TElements..., _UElements...>(get<_TIdx>(__t)...,
 456                                                  get<_UIdx>(__u)...); }
 457
 458   template<typename... _TElements, int... _TIdx,
 459            typename... _UElements, int... _UIdx>
 460     inline tuple<_TElements..., _UElements...>
 461     __tuple_cat_helper(tuple<_TElements...>&& __t,
 462                        const __index_holder<_TIdx...>&,
 463                        const tuple<_UElements...>& __u,
 464                        const __index_holder<_UIdx...>&)
 465     { return tuple<_TElements..., _UElements...>(std::move(get<_TIdx>(__t))...,
 466                                                  get<_UIdx>(__u)...); }
 467
 468   template<typename... _TElements, int... _TIdx,
 469            typename... _UElements, int... _UIdx>
 470     inline tuple<_TElements..., _UElements...>
 471     __tuple_cat_helper(const tuple<_TElements...>& __t,
 472                        const __index_holder<_TIdx...>&,
 473                        tuple<_UElements...>&& __u,
 474                        const __index_holder<_UIdx...>&)
 475     { return tuple<_TElements..., _UElements...>(get<_TIdx>(__t)...,
 476                                                  std::move(get<_UIdx>(__u))...); }
 477
 478   template<typename... _TElements, int... _TIdx,
 479            typename... _UElements, int... _UIdx>
 480     inline tuple<_TElements..., _UElements...>
 481     __tuple_cat_helper(tuple<_TElements...>&& __t,
 482                        const __index_holder<_TIdx...>&,
 483                        tuple<_UElements...>&& __u,
 484                        const __index_holder<_UIdx...>&)
 485     { return tuple<_TElements..., _UElements...>(std::move(get<_TIdx>(__t))...,
 486                                                  std::move(get<_UIdx>(__u))...); }
 487
 488   template<typename... _TElements, typename... _UElements>
 489     inline tuple<_TElements..., _UElements...>
 490     tuple_cat(const tuple<_TElements...>& __t, const tuple<_UElements...>& __u)
 491     {
 492       return __tuple_cat_helper(__t, typename
 493                                 __make_index_holder<_TElements...>::type(),
 494                                 __u, typename
 495                                 __make_index_holder<_UElements...>::type());
 496     }
 497
 498   template<typename... _TElements, typename... _UElements>
 499     inline tuple<_TElements..., _UElements...>
 500     tuple_cat(tuple<_TElements...>&& __t, const tuple<_UElements...>& __u)
 501     {
 502       return __tuple_cat_helper(std::move(__t), typename
 503                                  __make_index_holder<_TElements...>::type(),
 504                                  __u, typename
 505                                  __make_index_holder<_UElements...>::type());
 506     }
 507
 508   template<typename... _TElements, typename... _UElements>
 509     inline tuple<_TElements..., _UElements...>
 510     tuple_cat(const tuple<_TElements...>& __t, tuple<_UElements...>&& __u)
 511     {
 512       return __tuple_cat_helper(__t, typename
 513                                 __make_index_holder<_TElements...>::type(),
 514                                 std::move(__u), typename
 515                                 __make_index_holder<_UElements...>::type());
 516     }
 517
 518   template<typename... _TElements, typename... _UElements>
 519     inline tuple<_TElements..., _UElements...>
 520     tuple_cat(tuple<_TElements...>&& __t, tuple<_UElements...>&& __u)
 521     {
 522       return __tuple_cat_helper(std::move(__t), typename
 523                                 __make_index_holder<_TElements...>::type(),
 524                                 std::move(__u), typename
 525                                 __make_index_holder<_UElements...>::type());
 526     }
 527
 528   template<typename... _TElements, typename... _UElements>
 529     tuple<_TElements..., _UElements...>
 530     operator+(tuple<_TElements...>&& __t, tuple<_UElements...>&& __u)
 531     { return tuple_cat(std::forward<decltype(__t)>(__t),
 532                        std::forward<decltype(__u)>(__u)); }
 533
 534   template<typename... _Elements>
 535     inline tuple<_Elements&...>
 536     tie(_Elements&... __args)
 537     { return tuple<_Elements&...>(__args...); }
 538
 539   // A class (and instance) which can be used in 'tie' when an element
 540   // of a tuple is not required
 541   struct _Swallow_assign
 542   {
 543     template<class _Tp>
 544       _Swallow_assign&
 545       operator=(const _Tp&)
 546       { return *this; }
 547   };
 548
 549   // TODO: Put this in some kind of shared file.
 550   namespace
 551   {
 552     _Swallow_assign ignore;
 553   }; // anonymous namespace
 554 }
 555
 556 #endif // _GLIBCXX_CXX0X_TUPLE