boost/detail/ob_compressed_pair.hpp

   1 //  (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & John Maddock 2000.
   2 //  Use, modification and distribution are subject to the Boost Software License,
   3 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   4 //  http://www.boost.org/LICENSE_1_0.txt).
   5 //
   6 //  See http://www.boost.org/libs/utility for most recent version including documentation.
   7 //  see libs/utility/compressed_pair.hpp
   8 //
   9 /* Release notes:
  10    20 Jan 2001:
  11         Fixed obvious bugs (David Abrahams)
  12    07 Oct 2000:
  13       Added better single argument constructor support.
  14    03 Oct 2000:
  15       Added VC6 support (JM).
  16    23rd July 2000:
  17       Additional comments added. (JM)
  18    Jan 2000:
  19       Original version: this version crippled for use with crippled compilers
  20       - John Maddock Jan 2000.
  21 */
  22
  23
  24 #ifndef BOOST_OB_COMPRESSED_PAIR_HPP
  25 #define BOOST_OB_COMPRESSED_PAIR_HPP
  26
  27 #include <algorithm>
  28 #ifndef BOOST_OBJECT_TYPE_TRAITS_HPP
  29 #include <boost/type_traits/object_traits.hpp>
  30 #endif
  31 #ifndef BOOST_SAME_TRAITS_HPP
  32 #include <boost/type_traits/same_traits.hpp>
  33 #endif
  34 #ifndef BOOST_CALL_TRAITS_HPP
  35 #include <boost/call_traits.hpp>
  36 #endif
  37
  38 namespace boost
  39 {
  40 #ifdef BOOST_MSVC6_MEMBER_TEMPLATES
  41 //
  42 // use member templates to emulate
  43 // partial specialisation.  Note that due to
  44 // problems with overload resolution with VC6
  45 // each of the compressed_pair versions that follow
  46 // have one template single-argument constructor
  47 // in place of two specific constructors:
  48 //
  49
  50 template <class T1, class T2>
  51 class compressed_pair;
  52
  53 namespace detail{
  54
  55 template <class A, class T1, class T2>
  56 struct best_conversion_traits
  57 {
  58    typedef char one;
  59    typedef char (&two)[2];
  60    static A a;
  61    static one test(T1);
  62    static two test(T2);
  63
  64    enum { value = sizeof(test(a)) };
  65 };
  66
  67 template <int>
  68 struct init_one;
  69
  70 template <>
  71 struct init_one<1>
  72 {
  73    template <class A, class T1, class T2>
  74    static void init(const A& a, T1* p1, T2*)
  75    {
  76       *p1 = a;
  77    }
  78 };
  79
  80 template <>
  81 struct init_one<2>
  82 {
  83    template <class A, class T1, class T2>
  84    static void init(const A& a, T1*, T2* p2)
  85    {
  86       *p2 = a;
  87    }
  88 };
  89
  90
  91 // T1 != T2, both non-empty
  92 template <class T1, class T2>
  93 class compressed_pair_0
  94 {
  95 private:
  96    T1 _first;
  97    T2 _second;
  98 public:
  99    typedef T1                                                 first_type;
 100    typedef T2                                                 second_type;
 101    typedef typename call_traits<first_type>::param_type       first_param_type;
 102    typedef typename call_traits<second_type>::param_type      second_param_type;
 103    typedef typename call_traits<first_type>::reference        first_reference;
 104    typedef typename call_traits<second_type>::reference       second_reference;
 105    typedef typename call_traits<first_type>::const_reference  first_const_reference;
 106    typedef typename call_traits<second_type>::const_reference second_const_reference;
 107
 108             compressed_pair_0() : _first(), _second() {}
 109             compressed_pair_0(first_param_type x, second_param_type y) : _first(x), _second(y) {}
 110    template <class A>
 111    explicit compressed_pair_0(const A& val)
 112    {
 113       init_one<best_conversion_traits<A, T1, T2>::value>::init(val, &_first, &_second);
 114    }
 115    compressed_pair_0(const ::boost::compressed_pair<T1,T2>& x)
 116       : _first(x.first()), _second(x.second()) {}
 117
 118 #if 0
 119   compressed_pair_0& operator=(const compressed_pair_0& x) {
 120     cout << "assigning compressed pair 0" << endl;
 121     _first = x._first;
 122     _second = x._second;
 123     cout << "finished assigning compressed pair 0" << endl;
 124     return *this;
 125   }
 126 #endif
 127
 128    first_reference       first()       { return _first; }
 129    first_const_reference first() const { return _first; }
 130
 131    second_reference       second()       { return _second; }
 132    second_const_reference second() const { return _second; }
 133
 134    void swap(compressed_pair_0& y)
 135    {
 136       using std::swap;
 137       swap(_first, y._first);
 138       swap(_second, y._second);
 139    }
 140 };
 141
 142 // T1 != T2, T2 empty
 143 template <class T1, class T2>
 144 class compressed_pair_1 : T2
 145 {
 146 private:
 147    T1 _first;
 148 public:
 149    typedef T1                                                 first_type;
 150    typedef T2                                                 second_type;
 151    typedef typename call_traits<first_type>::param_type       first_param_type;
 152    typedef typename call_traits<second_type>::param_type      second_param_type;
 153    typedef typename call_traits<first_type>::reference        first_reference;
 154    typedef typename call_traits<second_type>::reference       second_reference;
 155    typedef typename call_traits<first_type>::const_reference  first_const_reference;
 156    typedef typename call_traits<second_type>::const_reference second_const_reference;
 157
 158             compressed_pair_1() : T2(), _first() {}
 159             compressed_pair_1(first_param_type x, second_param_type y) : T2(y), _first(x) {}
 160
 161    template <class A>
 162    explicit compressed_pair_1(const A& val)
 163    {
 164       init_one<best_conversion_traits<A, T1, T2>::value>::init(val, &_first, static_cast<T2*>(this));
 165    }
 166
 167    compressed_pair_1(const ::boost::compressed_pair<T1,T2>& x)
 168       : T2(x.second()), _first(x.first()) {}
 169
 170 #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
 171   // Total weirdness. If the assignment to _first is moved after
 172   // the call to the inherited operator=, then this breaks graph/test/graph.cpp
 173   // by way of iterator_adaptor.
 174   compressed_pair_1& operator=(const compressed_pair_1& x) {
 175     _first = x._first;
 176     T2::operator=(x);
 177     return *this;
 178   }
 179 #endif
 180
 181    first_reference       first()       { return _first; }
 182    first_const_reference first() const { return _first; }
 183
 184    second_reference       second()       { return *this; }
 185    second_const_reference second() const { return *this; }
 186
 187    void swap(compressed_pair_1& y)
 188    {
 189       // no need to swap empty base class:
 190       using std::swap;
 191       swap(_first, y._first);
 192    }
 193 };
 194
 195 // T1 != T2, T1 empty
 196 template <class T1, class T2>
 197 class compressed_pair_2 : T1
 198 {
 199 private:
 200    T2 _second;
 201 public:
 202    typedef T1                                                 first_type;
 203    typedef T2                                                 second_type;
 204    typedef typename call_traits<first_type>::param_type       first_param_type;
 205    typedef typename call_traits<second_type>::param_type      second_param_type;
 206    typedef typename call_traits<first_type>::reference        first_reference;
 207    typedef typename call_traits<second_type>::reference       second_reference;
 208    typedef typename call_traits<first_type>::const_reference  first_const_reference;
 209    typedef typename call_traits<second_type>::const_reference second_const_reference;
 210
 211             compressed_pair_2() : T1(), _second() {}
 212             compressed_pair_2(first_param_type x, second_param_type y) : T1(x), _second(y) {}
 213    template <class A>
 214    explicit compressed_pair_2(const A& val)
 215    {
 216       init_one<best_conversion_traits<A, T1, T2>::value>::init(val, static_cast<T1*>(this), &_second);
 217    }
 218    compressed_pair_2(const ::boost::compressed_pair<T1,T2>& x)
 219       : T1(x.first()), _second(x.second()) {}
 220
 221 #if 0
 222   compressed_pair_2& operator=(const compressed_pair_2& x) {
 223     cout << "assigning compressed pair 2" << endl;
 224     T1::operator=(x);
 225     _second = x._second;
 226     cout << "finished assigning compressed pair 2" << endl;
 227     return *this;
 228   }
 229 #endif
 230    first_reference       first()       { return *this; }
 231    first_const_reference first() const { return *this; }
 232
 233    second_reference       second()       { return _second; }
 234    second_const_reference second() const { return _second; }
 235
 236    void swap(compressed_pair_2& y)
 237    {
 238       // no need to swap empty base class:
 239       using std::swap;
 240       swap(_second, y._second);
 241    }
 242 };
 243
 244 // T1 != T2, both empty
 245 template <class T1, class T2>
 246 class compressed_pair_3 : T1, T2
 247 {
 248 public:
 249    typedef T1                                                 first_type;
 250    typedef T2                                                 second_type;
 251    typedef typename call_traits<first_type>::param_type       first_param_type;
 252    typedef typename call_traits<second_type>::param_type      second_param_type;
 253    typedef typename call_traits<first_type>::reference        first_reference;
 254    typedef typename call_traits<second_type>::reference       second_reference;
 255    typedef typename call_traits<first_type>::const_reference  first_const_reference;
 256    typedef typename call_traits<second_type>::const_reference second_const_reference;
 257
 258             compressed_pair_3() : T1(), T2() {}
 259             compressed_pair_3(first_param_type x, second_param_type y) : T1(x), T2(y) {}
 260    template <class A>
 261    explicit compressed_pair_3(const A& val)
 262    {
 263       init_one<best_conversion_traits<A, T1, T2>::value>::init(val, static_cast<T1*>(this), static_cast<T2*>(this));
 264    }
 265    compressed_pair_3(const ::boost::compressed_pair<T1,T2>& x)
 266       : T1(x.first()), T2(x.second()) {}
 267
 268    first_reference       first()       { return *this; }
 269    first_const_reference first() const { return *this; }
 270
 271    second_reference       second()       { return *this; }
 272    second_const_reference second() const { return *this; }
 273
 274    void swap(compressed_pair_3& y)
 275    {
 276       // no need to swap empty base classes:
 277    }
 278 };
 279
 280 // T1 == T2, and empty
 281 template <class T1, class T2>
 282 class compressed_pair_4 : T1
 283 {
 284 public:
 285    typedef T1                                                 first_type;
 286    typedef T2                                                 second_type;
 287    typedef typename call_traits<first_type>::param_type       first_param_type;
 288    typedef typename call_traits<second_type>::param_type      second_param_type;
 289    typedef typename call_traits<first_type>::reference        first_reference;
 290    typedef typename call_traits<second_type>::reference       second_reference;
 291    typedef typename call_traits<first_type>::const_reference  first_const_reference;
 292    typedef typename call_traits<second_type>::const_reference second_const_reference;
 293
 294             compressed_pair_4() : T1() {}
 295             compressed_pair_4(first_param_type x, second_param_type y) : T1(x), m_second(y) {}
 296    // only one single argument constructor since T1 == T2
 297    explicit compressed_pair_4(first_param_type x) : T1(x), m_second(x) {}
 298    compressed_pair_4(const ::boost::compressed_pair<T1,T2>& x)
 299       : T1(x.first()), m_second(x.second()) {}
 300
 301    first_reference       first()       { return *this; }
 302    first_const_reference first() const { return *this; }
 303
 304    second_reference       second()       { return m_second; }
 305    second_const_reference second() const { return m_second; }
 306
 307    void swap(compressed_pair_4& y)
 308    {
 309       // no need to swap empty base classes:
 310    }
 311 private:
 312    T2 m_second;
 313 };
 314
 315 // T1 == T2, not empty
 316 template <class T1, class T2>
 317 class compressed_pair_5
 318 {
 319 private:
 320    T1 _first;
 321    T2 _second;
 322 public:
 323    typedef T1                                                 first_type;
 324    typedef T2                                                 second_type;
 325    typedef typename call_traits<first_type>::param_type       first_param_type;
 326    typedef typename call_traits<second_type>::param_type      second_param_type;
 327    typedef typename call_traits<first_type>::reference        first_reference;
 328    typedef typename call_traits<second_type>::reference       second_reference;
 329    typedef typename call_traits<first_type>::const_reference  first_const_reference;
 330    typedef typename call_traits<second_type>::const_reference second_const_reference;
 331
 332             compressed_pair_5() : _first(), _second() {}
 333             compressed_pair_5(first_param_type x, second_param_type y) : _first(x), _second(y) {}
 334    // only one single argument constructor since T1 == T2
 335    explicit compressed_pair_5(first_param_type x) : _first(x), _second(x) {}
 336    compressed_pair_5(const ::boost::compressed_pair<T1,T2>& c)
 337       : _first(c.first()), _second(c.second()) {}
 338
 339    first_reference       first()       { return _first; }
 340    first_const_reference first() const { return _first; }
 341
 342    second_reference       second()       { return _second; }
 343    second_const_reference second() const { return _second; }
 344
 345    void swap(compressed_pair_5& y)
 346    {
 347       using std::swap;
 348       swap(_first, y._first);
 349       swap(_second, y._second);
 350    }
 351 };
 352
 353 template <bool e1, bool e2, bool same>
 354 struct compressed_pair_chooser
 355 {
 356    template <class T1, class T2>
 357    struct rebind
 358    {
 359       typedef compressed_pair_0<T1, T2> type;
 360    };
 361 };
 362
 363 template <>
 364 struct compressed_pair_chooser<false, true, false>
 365 {
 366    template <class T1, class T2>
 367    struct rebind
 368    {
 369       typedef compressed_pair_1<T1, T2> type;
 370    };
 371 };
 372
 373 template <>
 374 struct compressed_pair_chooser<true, false, false>
 375 {
 376    template <class T1, class T2>
 377    struct rebind
 378    {
 379       typedef compressed_pair_2<T1, T2> type;
 380    };
 381 };
 382
 383 template <>
 384 struct compressed_pair_chooser<true, true, false>
 385 {
 386    template <class T1, class T2>
 387    struct rebind
 388    {
 389       typedef compressed_pair_3<T1, T2> type;
 390    };
 391 };
 392
 393 template <>
 394 struct compressed_pair_chooser<true, true, true>
 395 {
 396    template <class T1, class T2>
 397    struct rebind
 398    {
 399       typedef compressed_pair_4<T1, T2> type;
 400    };
 401 };
 402
 403 template <>
 404 struct compressed_pair_chooser<false, false, true>
 405 {
 406    template <class T1, class T2>
 407    struct rebind
 408    {
 409       typedef compressed_pair_5<T1, T2> type;
 410    };
 411 };
 412
 413 template <class T1, class T2>
 414 struct compressed_pair_traits
 415 {
 416 private:
 417    typedef compressed_pair_chooser<is_empty<T1>::value, is_empty<T2>::value, is_same<T1,T2>::value> chooser;
 418    typedef typename chooser::template rebind<T1, T2> bound_type;
 419 public:
 420    typedef typename bound_type::type type;
 421 };
 422
 423 } // namespace detail
 424
 425 template <class T1, class T2>
 426 class compressed_pair : public detail::compressed_pair_traits<T1, T2>::type
 427 {
 428 private:
 429    typedef typename detail::compressed_pair_traits<T1, T2>::type base_type;
 430 public:
 431    typedef T1                                                 first_type;
 432    typedef T2                                                 second_type;
 433    typedef typename call_traits<first_type>::param_type       first_param_type;
 434    typedef typename call_traits<second_type>::param_type      second_param_type;
 435    typedef typename call_traits<first_type>::reference        first_reference;
 436    typedef typename call_traits<second_type>::reference       second_reference;
 437    typedef typename call_traits<first_type>::const_reference  first_const_reference;
 438    typedef typename call_traits<second_type>::const_reference second_const_reference;
 439
 440             compressed_pair() : base_type() {}
 441             compressed_pair(first_param_type x, second_param_type y) : base_type(x, y) {}
 442    template <class A>
 443    explicit compressed_pair(const A& x) : base_type(x){}
 444
 445    first_reference       first()       { return base_type::first(); }
 446    first_const_reference first() const { return base_type::first(); }
 447
 448    second_reference       second()       { return base_type::second(); }
 449    second_const_reference second() const { return base_type::second(); }
 450 };
 451
 452 template <class T1, class T2>
 453 inline void swap(compressed_pair<T1, T2>& x, compressed_pair<T1, T2>& y)
 454 {
 455    x.swap(y);
 456 }
 457
 458 #else
 459 // no partial specialisation, no member templates:
 460
 461 template <class T1, class T2>
 462 class compressed_pair
 463 {
 464 private:
 465    T1 _first;
 466    T2 _second;
 467 public:
 468    typedef T1                                                 first_type;
 469    typedef T2                                                 second_type;
 470    typedef typename call_traits<first_type>::param_type       first_param_type;
 471    typedef typename call_traits<second_type>::param_type      second_param_type;
 472    typedef typename call_traits<first_type>::reference        first_reference;
 473    typedef typename call_traits<second_type>::reference       second_reference;
 474    typedef typename call_traits<first_type>::const_reference  first_const_reference;
 475    typedef typename call_traits<second_type>::const_reference second_const_reference;
 476
 477             compressed_pair() : _first(), _second() {}
 478             compressed_pair(first_param_type x, second_param_type y) : _first(x), _second(y) {}
 479    explicit compressed_pair(first_param_type x) : _first(x), _second() {}
 480    // can't define this in case T1 == T2:
 481    // explicit compressed_pair(second_param_type y) : _first(), _second(y) {}
 482
 483    first_reference       first()       { return _first; }
 484    first_const_reference first() const { return _first; }
 485
 486    second_reference       second()       { return _second; }
 487    second_const_reference second() const { return _second; }
 488
 489    void swap(compressed_pair& y)
 490    {
 491       using std::swap;
 492       swap(_first, y._first);
 493       swap(_second, y._second);
 494    }
 495 };
 496
 497 template <class T1, class T2>
 498 inline void swap(compressed_pair<T1, T2>& x, compressed_pair<T1, T2>& y)
 499 {
 500    x.swap(y);
 501 }
 502
 503 #endif
 504
 505 } // boost
 506
 507 #endif // BOOST_OB_COMPRESSED_PAIR_HPP
 508
 509
 510