Ticket #5172: optional2.h

File optional2.h, 31.0 KB (added by nn-mail@…, 12 years ago)

Optional proposal file. In case links don't work.

Line 
1// Copyright (C) 2003, Fernando Luis Cacciola Carballal.
2//
3// Use, modification, and distribution is subject to the Boost Software
4// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
5// http://www.boost.org/LICENSE_1_0.txt)
6//
7// See http://www.boost.org/libs/optional for documentation.
8//
9// You are welcome to contact the author at:
10// fernando_cacciola@hotmail.com
11//
12#ifndef BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP
13#define BOOST_OPTIONAL_OPTIONAL_FLC_19NOV2002_HPP
14
15#include<new>
16#include<algorithm>
17#include <cstddef>
18
19#include "boost/config.hpp"
20#include "boost/assert.hpp"
21#include "boost/type.hpp"
22#include "boost/type_traits/alignment_of.hpp"
23#include "boost/type_traits/type_with_alignment.hpp"
24#include "boost/type_traits/remove_reference.hpp"
25#include "boost/type_traits/is_reference.hpp"
26#include "boost/mpl/if.hpp"
27#include "boost/mpl/bool.hpp"
28#include "boost/mpl/not.hpp"
29#include "boost/detail/reference_content.hpp"
30#include "boost/none.hpp"
31#include "boost/utility/compare_pointees.hpp"
32
33#include "boost/optional/optional_fwd.hpp"
34
35#if BOOST_WORKAROUND(BOOST_MSVC, == 1200)
36// VC6.0 has the following bug:
37// When a templated assignment operator exist, an implicit conversion
38// constructing an optional<T> is used when assigment of the form:
39// optional<T> opt ; opt = T(...);
40// is compiled.
41// However, optional's ctor is _explicit_ and the assignemt shouldn't compile.
42// Therefore, for VC6.0 templated assignment is disabled.
43//
44#define BOOST_OPTIONAL_NO_CONVERTING_ASSIGNMENT
45#endif
46
47#if BOOST_WORKAROUND(BOOST_MSVC, == 1300)
48// VC7.0 has the following bug:
49// When both a non-template and a template copy-ctor exist
50// and the templated version is made 'explicit', the explicit is also
51// given to the non-templated version, making the class non-implicitely-copyable.
52//
53#define BOOST_OPTIONAL_NO_CONVERTING_COPY_CTOR
54#endif
55
56#if BOOST_WORKAROUND(BOOST_MSVC, <= 1300) || BOOST_WORKAROUND(BOOST_INTEL_CXX_VERSION,<=700)
57// AFAICT only VC7.1 correctly resolves the overload set
58// that includes the in-place factory taking functions,
59// so for the other VC versions, in-place factory support
60// is disabled
61#define BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
62#endif
63
64#if BOOST_WORKAROUND(__BORLANDC__, <= 0x551)
65// BCB (5.5.1) cannot parse the nested template struct in an inplace factory.
66#define BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
67#endif
68
69#if !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) \
70 && BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581) )
71// BCB (up to 5.64) has the following bug:
72// If there is a member function/operator template of the form
73// template<class Expr> mfunc( Expr expr ) ;
74// some calls are resolved to this even if there are other better matches.
75// The effect of this bug is that calls to converting ctors and assignments
76// are incrorrectly sink to this general catch-all member function template as shown above.
77#define BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
78#endif
79
80// Daniel Wallin discovered that bind/apply.hpp badly interacts with the apply<>
81// member template of a factory as used in the optional<> implementation.
82// He proposed this simple fix which is to move the call to apply<> outside
83// namespace boost.
84namespace boost_optional_detail
85{
86 template <class T, class Factory>
87 void construct(Factory const& factory, void* address)
88 {
89 factory.BOOST_NESTED_TEMPLATE apply<T>(address);
90 }
91}
92
93
94namespace boost {
95
96 class in_place_factory_base ;
97 class typed_in_place_factory_base ;
98
99 namespace optional_detail {
100
101 // This local class is used instead of that in "aligned_storage.hpp"
102 // because I've found the 'official' class to ICE BCB5.5
103 // when some types are used with optional<>
104 // (due to sizeof() passed down as a non-type template parameter)
105 template <class T, std::size_t N>
106 class aligned_storage
107 {
108 // Borland ICEs if unnamed unions are used for this!
109 union dummy_u_helper
110 {
111 char data[ N ];
112 } dummy_helper ;
113
114 union dummy_u
115 {
116 char data[ N ];
117 BOOST_DEDUCED_TYPENAME type_with_alignment<
118 ::boost::alignment_of<dummy_u_helper>::value >::type aligner_;
119 } dummy_ ;
120
121
122
123 public:
124
125 void const* address() const { return &dummy_.data[0]; }
126 void * address() { return &dummy_.data[0]; }
127 } ;
128
129 // This local class is used instead of that in "aligned_storage.hpp"
130 // because I've found the 'official' class to ICE BCB5.5
131 // when some types are used with optional<>
132 // (due to sizeof() passed down as a non-type template parameter)
133 template <class T>
134 class aligned_storage<T, 0>
135 {
136 // Borland ICEs if unnamed unions are used for this!
137 union dummy_u
138 {
139 char data[ sizeof(T) ];
140 BOOST_DEDUCED_TYPENAME type_with_alignment<
141 ::boost::alignment_of<T>::value >::type aligner_;
142 } dummy_ ;
143
144
145 public:
146
147 void const* address() const { return &dummy_.data[0]; }
148 void * address() { return &dummy_.data[0]; }
149 } ;
150
151 template<class T>
152 struct types_when_isnt_ref
153 {
154 typedef T const& reference_const_type ;
155 typedef T & reference_type ;
156 typedef T const* pointer_const_type ;
157 typedef T * pointer_type ;
158 typedef T const& argument_type ;
159 } ;
160 template<class T>
161 struct types_when_is_ref
162 {
163 typedef BOOST_DEDUCED_TYPENAME remove_reference<T>::type raw_type ;
164
165 typedef raw_type& reference_const_type ;
166 typedef raw_type& reference_type ;
167 typedef raw_type* pointer_const_type ;
168 typedef raw_type* pointer_type ;
169 typedef raw_type& argument_type ;
170 } ;
171
172 struct optional_tag {} ;
173
174 template<class T, std::size_t N>
175 class optional2;
176
177 template<class T, std::size_t N>
178 class optional_base2 : public optional_tag
179 {
180 private :
181
182 typedef
183#if !BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x564))
184 BOOST_DEDUCED_TYPENAME
185#endif
186 ::boost::detail::make_reference_content<T>::type internal_type ;
187
188 typedef aligned_storage<internal_type, N> storage_type ;
189
190 typedef types_when_isnt_ref<T> types_when_not_ref ;
191 typedef types_when_is_ref<T> types_when_ref ;
192
193 typedef optional_base2<T, N> this_type ;
194
195 protected :
196
197 typedef T value_type ;
198
199 typedef mpl::true_ is_reference_tag ;
200 typedef mpl::false_ is_not_reference_tag ;
201
202 typedef BOOST_DEDUCED_TYPENAME is_reference<T>::type is_reference_predicate ;
203
204 public:
205 typedef BOOST_DEDUCED_TYPENAME mpl::if_<is_reference_predicate,types_when_ref,types_when_not_ref>::type types ;
206
207 protected:
208 typedef bool (this_type::*unspecified_bool_type)() const;
209
210 typedef BOOST_DEDUCED_TYPENAME types::reference_type reference_type ;
211 typedef BOOST_DEDUCED_TYPENAME types::reference_const_type reference_const_type ;
212 typedef BOOST_DEDUCED_TYPENAME types::pointer_type pointer_type ;
213 typedef BOOST_DEDUCED_TYPENAME types::pointer_const_type pointer_const_type ;
214 typedef BOOST_DEDUCED_TYPENAME types::argument_type argument_type ;
215
216 // Creates an optional<T> uninitialized.
217 // No-throw
218 optional_base2()
219 :
220 m_initialized(false) {}
221
222 // Creates an optional<T> uninitialized.
223 // No-throw
224 optional_base2 ( none_t )
225 :
226 m_initialized(false) {}
227
228 // Creates an optional<T> initialized with 'val'.
229 // Can throw if T::T(T const&) does
230 optional_base2 ( argument_type val )
231 :
232 m_initialized(false)
233 {
234 construct(val);
235 }
236
237 // Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialzed optional<T>.
238 // Can throw if T::T(T const&) does
239 optional_base2 ( bool cond, argument_type val )
240 :
241 m_initialized(false)
242 {
243 if ( cond )
244 construct(val);
245 }
246
247 // Creates a deep copy of another optional<T>
248 // Can throw if T::T(T const&) does
249 optional_base2 ( optional_base2 const& rhs )
250 :
251 m_initialized(false)
252 {
253 if ( rhs.is_initialized() )
254 construct(rhs.get_impl());
255 }
256
257
258 // This is used for both converting and in-place constructions.
259 // Derived classes use the 'tag' to select the appropriate
260 // implementation (the correct 'construct()' overload)
261 template<class Expr>
262 explicit optional_base2 ( Expr const& expr, Expr const* tag )
263 :
264 m_initialized(false)
265 {
266 construct(expr,tag);
267 }
268
269
270
271 // No-throw (assuming T::~T() doesn't)
272 ~optional_base2() { destroy() ; }
273
274 // Assigns from another optional<T> (deep-copies the rhs value)
275 void assign ( optional_base2 const& rhs )
276 {
277 if (is_initialized())
278 {
279 if ( rhs.is_initialized() )
280 assign_value(rhs.get_impl(), is_reference_predicate() );
281 else destroy();
282 }
283 else
284 {
285 if ( rhs.is_initialized() )
286 construct(rhs.get_impl());
287 }
288 }
289
290 // Assigns from another _convertible_ optional<U> (deep-copies the rhs value)
291 template<class U, std::size_t N2>
292 void assign ( optional2<U, N2> const& rhs )
293 {
294 if (is_initialized())
295 {
296 if ( rhs.is_initialized() )
297 assign_value(static_cast<value_type>(rhs.get()), is_reference_predicate() );
298 else destroy();
299 }
300 else
301 {
302 if ( rhs.is_initialized() )
303 construct(static_cast<value_type>(rhs.get()));
304 }
305 }
306
307 // Assigns from a T (deep-copies the rhs value)
308 void assign ( argument_type val )
309 {
310 if (is_initialized())
311 assign_value(val, is_reference_predicate() );
312 else construct(val);
313 }
314
315 // Assigns from "none", destroying the current value, if any, leaving this UNINITIALIZED
316 // No-throw (assuming T::~T() doesn't)
317 void assign ( none_t ) { destroy(); }
318
319#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
320 template<class Expr>
321 void assign_expr ( Expr const& expr, Expr const* tag )
322 {
323 if (is_initialized())
324 assign_expr_to_initialized(expr,tag);
325 else construct(expr,tag);
326 }
327#endif
328
329 public :
330
331 // Destroys the current value, if any, leaving this UNINITIALIZED
332 // No-throw (assuming T::~T() doesn't)
333 void reset() { destroy(); }
334
335 // Replaces the current value -if any- with 'val'
336 void reset ( argument_type val ) { assign(val); }
337
338 // Returns a pointer to the value if this is initialized, otherwise,
339 // returns NULL.
340 // No-throw
341 pointer_const_type get_ptr() const { return m_initialized ? get_ptr_impl() : 0 ; }
342 pointer_type get_ptr() { return m_initialized ? get_ptr_impl() : 0 ; }
343
344 bool is_initialized() const { return m_initialized ; }
345
346 protected :
347
348 void construct ( argument_type val )
349 {
350 new (m_storage.address()) internal_type(val) ;
351 m_initialized = true ;
352 }
353
354#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
355 // Constructs in-place using the given factory
356 template<class Expr>
357 void construct ( Expr const& factory, in_place_factory_base const* )
358 {
359 BOOST_STATIC_ASSERT ( ::boost::mpl::not_<is_reference_predicate>::value ) ;
360 boost_optional_detail::construct<value_type>(factory, m_storage.address());
361 m_initialized = true ;
362 }
363
364 // Constructs in-place using the given typed factory
365 template<class Expr>
366 void construct ( Expr const& factory, typed_in_place_factory_base const* )
367 {
368 BOOST_STATIC_ASSERT ( ::boost::mpl::not_<is_reference_predicate>::value ) ;
369 factory.apply(m_storage.address()) ;
370 m_initialized = true ;
371 }
372
373 template<class Expr>
374 void assign_expr_to_initialized ( Expr const& factory, in_place_factory_base const* tag )
375 {
376 destroy();
377 construct(factory,tag);
378 }
379
380 // Constructs in-place using the given typed factory
381 template<class Expr>
382 void assign_expr_to_initialized ( Expr const& factory, typed_in_place_factory_base const* tag )
383 {
384 destroy();
385 construct(factory,tag);
386 }
387#endif
388
389 // Constructs using any expression implicitely convertible to the single argument
390 // of a one-argument T constructor.
391 // Converting constructions of optional<T> from optional<U> uses this function with
392 // 'Expr' being of type 'U' and relying on a converting constructor of T from U.
393 template<class Expr>
394 void construct ( Expr const& expr, void const* )
395 {
396 new (m_storage.address()) internal_type(expr) ;
397 m_initialized = true ;
398 }
399
400 // Assigns using a form any expression implicitely convertible to the single argument
401 // of a T's assignment operator.
402 // Converting assignments of optional<T> from optional<U> uses this function with
403 // 'Expr' being of type 'U' and relying on a converting assignment of T from U.
404 template<class Expr>
405 void assign_expr_to_initialized ( Expr const& expr, void const* )
406 {
407 assign_value(expr, is_reference_predicate());
408 }
409
410#ifdef BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION
411 // BCB5.64 (and probably lower versions) workaround.
412 // The in-place factories are supported by means of catch-all constructors
413 // and assignment operators (the functions are parameterized in terms of
414 // an arbitrary 'Expr' type)
415 // This compiler incorrectly resolves the overload set and sinks optional<T> and optional<U>
416 // to the 'Expr'-taking functions even though explicit overloads are present for them.
417 // Thus, the following overload is needed to properly handle the case when the 'lhs'
418 // is another optional.
419 //
420 // For VC<=70 compilers this workaround dosen't work becasue the comnpiler issues and error
421 // instead of choosing the wrong overload
422 //
423 // Notice that 'Expr' will be optional<T> or optional<U> (but not optional_base<..>)
424 template<class Expr>
425 void construct ( Expr const& expr, optional_tag const* )
426 {
427 if ( expr.is_initialized() )
428 {
429 // An exception can be thrown here.
430 // It it happens, THIS will be left uninitialized.
431 new (m_storage.address()) internal_type(expr.get()) ;
432 m_initialized = true ;
433 }
434 }
435#endif
436
437 void assign_value ( argument_type val, is_not_reference_tag ) { get_impl() = val; }
438 void assign_value ( argument_type val, is_reference_tag ) { construct(val); }
439
440 void destroy()
441 {
442 if ( m_initialized )
443 destroy_impl(is_reference_predicate()) ;
444 }
445
446 unspecified_bool_type safe_bool() const { return m_initialized ? &this_type::is_initialized : 0 ; }
447
448 reference_const_type get_impl() const { return dereference(get_object(), is_reference_predicate() ) ; }
449 reference_type get_impl() { return dereference(get_object(), is_reference_predicate() ) ; }
450
451 pointer_const_type get_ptr_impl() const { return cast_ptr(get_object(), is_reference_predicate() ) ; }
452 pointer_type get_ptr_impl() { return cast_ptr(get_object(), is_reference_predicate() ) ; }
453
454 private :
455
456 // internal_type can be either T or reference_content<T>
457 internal_type const* get_object() const { return static_cast<internal_type const*>(m_storage.address()); }
458 internal_type * get_object() { return static_cast<internal_type *> (m_storage.address()); }
459
460 // reference_content<T> lacks an implicit conversion to T&, so the following is needed to obtain a proper reference.
461 reference_const_type dereference( internal_type const* p, is_not_reference_tag ) const { return *p ; }
462 reference_type dereference( internal_type* p, is_not_reference_tag ) { return *p ; }
463 reference_const_type dereference( internal_type const* p, is_reference_tag ) const { return p->get() ; }
464 reference_type dereference( internal_type* p, is_reference_tag ) { return p->get() ; }
465
466#if BOOST_WORKAROUND(__BORLANDC__, BOOST_TESTED_AT(0x581))
467 void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->internal_type::~internal_type() ; m_initialized = false ; }
468#else
469 void destroy_impl ( is_not_reference_tag ) { get_ptr_impl()->T::~T() ; m_initialized = false ; }
470#endif
471
472 void destroy_impl ( is_reference_tag ) { m_initialized = false ; }
473
474 // If T is of reference type, trying to get a pointer to the held value must result in a compile-time error.
475 // Decent compilers should disallow conversions from reference_content<T>* to T*, but just in case,
476 // the following olverloads are used to filter out the case and guarantee an error in case of T being a reference.
477 pointer_const_type cast_ptr( internal_type const* p, is_not_reference_tag ) const { return p ; }
478 pointer_type cast_ptr( internal_type * p, is_not_reference_tag ) { return p ; }
479 pointer_const_type cast_ptr( internal_type const* p, is_reference_tag ) const { return &p->get() ; }
480 pointer_type cast_ptr( internal_type * p, is_reference_tag ) { return &p->get() ; }
481
482 bool m_initialized ;
483 storage_type m_storage ;
484 } ;
485
486 } // namespace optional_detail
487
488 template<class T, std::size_t N = 0>
489 class optional2 : public optional_detail::optional_base2<T, N>
490 {
491 typedef optional_detail::optional_base2<T, N> base ;
492
493 typedef BOOST_DEDUCED_TYPENAME base::unspecified_bool_type unspecified_bool_type ;
494
495 public :
496
497 typedef optional2<T, N> this_type ;
498
499 typedef BOOST_DEDUCED_TYPENAME base::value_type value_type ;
500 typedef BOOST_DEDUCED_TYPENAME base::reference_type reference_type ;
501 typedef BOOST_DEDUCED_TYPENAME base::reference_const_type reference_const_type ;
502 typedef BOOST_DEDUCED_TYPENAME base::pointer_type pointer_type ;
503 typedef BOOST_DEDUCED_TYPENAME base::pointer_const_type pointer_const_type ;
504 typedef BOOST_DEDUCED_TYPENAME base::argument_type argument_type ;
505
506 // Creates an optional<T> uninitialized.
507 // No-throw
508 optional2() : base() {}
509
510 // Creates an optional<T> uninitialized.
511 // No-throw
512 optional2( none_t none_ ) : base(none_) {}
513
514 // Creates an optional<T> initialized with 'val'.
515 // Can throw if T::T(T const&) does
516 optional2 ( argument_type val ) : base(val) {}
517
518 // Creates an optional<T> initialized with 'val' IFF cond is true, otherwise creates an uninitialized optional.
519 // Can throw if T::T(T const&) does
520 optional2 ( bool cond, argument_type val ) : base(cond,val) {}
521
522#ifndef BOOST_OPTIONAL_NO_CONVERTING_COPY_CTOR
523 // NOTE: MSVC needs templated versions first
524
525 // Creates a deep copy of another convertible optional<U>
526 // Requires a valid conversion from U to T.
527 // Can throw if T::T(U const&) does
528 template<class U, std::size_t N2>
529 explicit optional2 ( optional2<U, N2> const& rhs )
530 :
531 base()
532 {
533 if ( rhs.is_initialized() )
534 this->construct(rhs.get());
535 }
536#endif
537
538#ifndef BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT
539 // Creates an optional<T> with an expression which can be either
540 // (a) An instance of InPlaceFactory (i.e. in_place(a,b,...,n);
541 // (b) An instance of TypedInPlaceFactory ( i.e. in_place<T>(a,b,...,n);
542 // (c) Any expression implicitely convertible to the single type
543 // of a one-argument T's constructor.
544 // (d*) Weak compilers (BCB) might also resolved Expr as optional<T> and optional<U>
545 // even though explicit overloads are present for these.
546 // Depending on the above some T ctor is called.
547 // Can throw is the resolved T ctor throws.
548 template<class Expr>
549 explicit optional2 ( Expr const& expr ) : base(expr,&expr) {}
550#endif
551
552 // Creates a deep copy of another optional<T>
553 // Can throw if T::T(T const&) does
554 optional2 ( optional2 const& rhs ) : base(rhs) {}
555
556 // No-throw (assuming T::~T() doesn't)
557 ~optional2() {}
558
559#if !defined(BOOST_OPTIONAL_NO_INPLACE_FACTORY_SUPPORT) && !defined(BOOST_OPTIONAL_WEAK_OVERLOAD_RESOLUTION)
560 // Assigns from an expression. See corresponding constructor.
561 // Basic Guarantee: If the resolved T ctor throws, this is left UNINITIALIZED
562 template<class Expr>
563 optional2& operator= ( Expr expr )
564 {
565 this->assign_expr(expr,&expr);
566 return *this ;
567 }
568#endif
569
570
571#ifndef BOOST_OPTIONAL_NO_CONVERTING_ASSIGNMENT
572 // Assigns from another convertible optional<U> (converts && deep-copies the rhs value)
573 // Requires a valid conversion from U to T.
574 // Basic Guarantee: If T::T( U const& ) throws, this is left UNINITIALIZED
575 template<class U, std::size_t N2>
576 optional2& operator= ( optional2<U, N2> const& rhs )
577 {
578 this->assign(rhs);
579 return *this ;
580 }
581#endif
582
583 // Assigns from another optional<T> (deep-copies the rhs value)
584 // Basic Guarantee: If T::T( T const& ) throws, this is left UNINITIALIZED
585 // (NOTE: On BCB, this operator is not actually called and left is left UNMODIFIED in case of a throw)
586 optional2& operator= ( optional2 const& rhs )
587 {
588 this->assign( rhs ) ;
589 return *this ;
590 }
591
592 // Assigns from a T (deep-copies the rhs value)
593 // Basic Guarantee: If T::( T const& ) throws, this is left UNINITIALIZED
594 optional2& operator= ( argument_type val )
595 {
596 this->assign( val ) ;
597 return *this ;
598 }
599
600 // Assigns from a "none"
601 // Which destroys the current value, if any, leaving this UNINITIALIZED
602 // No-throw (assuming T::~T() doesn't)
603 optional2& operator= ( none_t none_ )
604 {
605 this->assign( none_ ) ;
606 return *this ;
607 }
608
609 // Returns a reference to the value if this is initialized, otherwise,
610 // the behaviour is UNDEFINED
611 // No-throw
612 reference_const_type get() const { BOOST_ASSERT(this->is_initialized()) ; return this->get_impl(); }
613 reference_type get() { BOOST_ASSERT(this->is_initialized()) ; return this->get_impl(); }
614
615 // Returns a copy of the value if this is initialized, 'v' otherwise
616 reference_const_type get_value_or ( reference_const_type v ) const { return this->is_initialized() ? get() : v ; }
617 reference_type get_value_or ( reference_type v ) { return this->is_initialized() ? get() : v ; }
618
619 // Returns a pointer to the value if this is initialized, otherwise,
620 // the behaviour is UNDEFINED
621 // No-throw
622 pointer_const_type operator->() const { BOOST_ASSERT(this->is_initialized()) ; return this->get_ptr_impl() ; }
623 pointer_type operator->() { BOOST_ASSERT(this->is_initialized()) ; return this->get_ptr_impl() ; }
624
625 // Returns a reference to the value if this is initialized, otherwise,
626 // the behaviour is UNDEFINED
627 // No-throw
628 reference_const_type operator *() const { return this->get() ; }
629 reference_type operator *() { return this->get() ; }
630
631 // implicit conversion to "bool"
632 // No-throw
633 operator unspecified_bool_type() const { return this->safe_bool() ; }
634
635 // This is provided for those compilers which don't like the conversion to bool
636 // on some contexts.
637 bool operator!() const { return !this->is_initialized() ; }
638 } ;
639
640 // Returns optional<T>(v)
641 template<class T, std::size_t N>
642 inline
643 optional2<T, N> make_optional ( T const& v )
644 {
645 return optional2<T, N>(v);
646 }
647
648 // Returns optional<T>(cond,v)
649 template<class T, std::size_t N>
650 inline
651 optional2<T, N> make_optional ( bool cond, T const& v )
652 {
653 return optional2<T, N>(cond,v);
654 }
655
656 // Returns a reference to the value if this is initialized, otherwise, the behaviour is UNDEFINED.
657 // No-throw
658 template<class T, std::size_t N>
659 inline
660 BOOST_DEDUCED_TYPENAME optional2<T, N>::reference_const_type
661 get ( optional2<T, N> const& opt )
662 {
663 return opt.get() ;
664 }
665
666 template<class T, std::size_t N>
667 inline
668 BOOST_DEDUCED_TYPENAME optional2<T, N>::reference_type
669 get ( optional2<T, N>& opt )
670 {
671 return opt.get() ;
672 }
673
674 // Returns a pointer to the value if this is initialized, otherwise, returns NULL.
675 // No-throw
676 template<class T, std::size_t N>
677 inline
678 BOOST_DEDUCED_TYPENAME optional2<T, N>::pointer_const_type
679 get ( optional2<T, N> const* opt )
680 {
681 return opt->get_ptr() ;
682 }
683
684 template<class T, std::size_t N>
685 inline
686 BOOST_DEDUCED_TYPENAME optional2<T, N>::pointer_type
687 get ( optional2<T, N>* opt )
688 {
689 return opt->get_ptr() ;
690 }
691
692 // Returns a reference to the value if this is initialized, otherwise, the behaviour is UNDEFINED.
693 // No-throw
694 template<class T, std::size_t N>
695 inline
696 BOOST_DEDUCED_TYPENAME optional2<T, N>::reference_const_type
697 get_optional_value_or ( optional2<T, N> const& opt, BOOST_DEDUCED_TYPENAME optional2<T, N>::reference_const_type v )
698 {
699 return opt.get_value_or(v) ;
700 }
701
702 template<class T, std::size_t N>
703 inline
704 BOOST_DEDUCED_TYPENAME optional2<T, N>::reference_type
705 get_optional_value_or ( optional2<T, N>& opt, BOOST_DEDUCED_TYPENAME optional2<T, N>::reference_type v )
706 {
707 return opt.get_value_or(v) ;
708 }
709
710 // Returns a pointer to the value if this is initialized, otherwise, returns NULL.
711 // No-throw
712 template<class T, std::size_t N>
713 inline
714 BOOST_DEDUCED_TYPENAME optional2<T, N>::pointer_const_type
715 get_pointer ( optional2<T, N> const& opt )
716 {
717 return opt.get_ptr() ;
718 }
719
720 template<class T, std::size_t N>
721 inline
722 BOOST_DEDUCED_TYPENAME optional2<T, N>::pointer_type
723 get_pointer ( optional2<T, N>& opt )
724 {
725 return opt.get_ptr() ;
726 }
727
728 // optional's relational operators ( ==, !=, <, >, <=, >= ) have deep-semantics (compare values).
729 // WARNING: This is UNLIKE pointers. Use equal_pointees()/less_pointess() in generic code instead.
730
731
732 //
733 // optional<T> vs optional<T> cases
734 //
735
736 template<class T, std::size_t N2>
737 inline
738 bool operator == ( optional2<T, N2> const& x, optional2<T, N2> const& y )
739 { return equal_pointees(x,y); }
740
741 template<class T, std::size_t N2>
742 inline
743 bool operator < ( optional2<T, N2> const& x, optional2<T, N2> const& y )
744 { return less_pointees(x,y); }
745
746 template<class T, std::size_t N2>
747 inline
748 bool operator != ( optional2<T, N2> const& x, optional2<T, N2> const& y )
749 { return !( x == y ) ; }
750
751 template<class T, std::size_t N2>
752 inline
753 bool operator > ( optional2<T, N2> const& x, optional2<T, N2> const& y )
754 { return y < x ; }
755
756 template<class T, std::size_t N2>
757 inline
758 bool operator <= ( optional2<T, N2> const& x, optional2<T, N2> const& y )
759 { return !( y < x ) ; }
760
761 template<class T, std::size_t N2>
762 inline
763 bool operator >= ( optional2<T, N2> const& x, optional2<T, N2> const& y )
764 { return !( x < y ) ; }
765
766
767 //
768 // optional<T, N2> vs T cases
769 //
770 template<class T, std::size_t N2>
771 inline
772 bool operator == ( optional2<T, N2> const& x, T const& y )
773 { return equal_pointees(x, optional2<T, N2>(y)); }
774
775 template<class T, std::size_t N2>
776 inline
777 bool operator < ( optional2<T, N2> const& x, T const& y )
778 { return less_pointees(x, optional2<T, N2>(y)); }
779
780 template<class T, std::size_t N2>
781 inline
782 bool operator != ( optional2<T, N2> const& x, T const& y )
783 { return !( x == y ) ; }
784
785 template<class T, std::size_t N2>
786 inline
787 bool operator > ( optional2<T, N2> const& x, T const& y )
788 { return y < x ; }
789
790 template<class T, std::size_t N2>
791 inline
792 bool operator <= ( optional2<T, N2> const& x, T const& y )
793 { return !( y < x ) ; }
794
795 template<class T, std::size_t N2>
796 inline
797 bool operator >= ( optional2<T, N2> const& x, T const& y )
798 { return !( x < y ) ; }
799
800 //
801 // T vs optional<T, N2> cases
802 //
803
804 template<class T, std::size_t N2>
805 inline
806 bool operator == ( T const& x, optional2<T, N2> const& y )
807 { return equal_pointees( optional2<T, N2>(x), y ); }
808
809 template<class T, std::size_t N2>
810 inline
811 bool operator < ( T const& x, optional2<T, N2> const& y )
812 { return less_pointees( optional2<T, N2>(x), y ); }
813
814 template<class T, std::size_t N2>
815 inline
816 bool operator != ( T const& x, optional2<T, N2> const& y )
817 { return !( x == y ) ; }
818
819 template<class T, std::size_t N2>
820 inline
821 bool operator > ( T const& x, optional2<T, N2> const& y )
822 { return y < x ; }
823
824 template<class T, std::size_t N2>
825 inline
826 bool operator <= ( T const& x, optional2<T, N2> const& y )
827 { return !( y < x ) ; }
828
829 template<class T, std::size_t N2>
830 inline
831 bool operator >= ( T const& x, optional2<T, N2> const& y )
832 { return !( x < y ) ; }
833
834
835 //
836 // optional<T, N2> vs none cases
837 //
838
839 template<class T, std::size_t N2>
840 inline
841 bool operator == ( optional2<T, N2> const& x, none_t )
842 { return equal_pointees(x, optional2<T, N2>() ); }
843
844 template<class T, std::size_t N2>
845 inline
846 bool operator < ( optional2<T, N2> const& x, none_t )
847 { return less_pointees(x,optional2<T, N2>() ); }
848
849 template<class T, std::size_t N2>
850 inline
851 bool operator != ( optional2<T, N2> const& x, none_t y )
852 { return !( x == y ) ; }
853
854 template<class T, std::size_t N2>
855 inline
856 bool operator > ( optional2<T, N2> const& x, none_t y )
857 { return y < x ; }
858
859 template<class T, std::size_t N2>
860 inline
861 bool operator <= ( optional2<T, N2> const& x, none_t y )
862 { return !( y < x ) ; }
863
864 template<class T, std::size_t N2>
865 inline
866 bool operator >= ( optional2<T, N2> const& x, none_t y )
867 { return !( x < y ) ; }
868
869 //
870 // none vs optional<T, N2> cases
871 //
872
873 template<class T, std::size_t N2>
874 inline
875 bool operator == ( none_t x, optional2<T, N2> const& y )
876 { return equal_pointees(optional2<T, N2>() ,y); }
877
878 template<class T, std::size_t N2>
879 inline
880 bool operator < ( none_t x, optional2<T, N2> const& y )
881 { return less_pointees(optional2<T, N2>() ,y); }
882
883 template<class T, std::size_t N2>
884 inline
885 bool operator != ( none_t x, optional2<T, N2> const& y )
886 { return !( x == y ) ; }
887
888 template<class T, std::size_t N2>
889 inline
890 bool operator > ( none_t x, optional2<T, N2> const& y )
891 { return y < x ; }
892
893 template<class T, std::size_t N2>
894 inline
895 bool operator <= ( none_t x, optional2<T, N2> const& y )
896 { return !( y < x ) ; }
897
898 template<class T, std::size_t N2>
899 inline
900 bool operator >= ( none_t x, optional2<T, N2> const& y )
901 { return !( x < y ) ; }
902
903 //
904 // The following swap implementation follows the GCC workaround as found in
905 // "boost/detail/compressed_pair.hpp"
906 //
907 namespace optional_detail {
908
909 // GCC < 3.2 gets the using declaration at namespace scope (FLC, DWA)
910#if BOOST_WORKAROUND(__GNUC__, < 3) \
911 || BOOST_WORKAROUND(__GNUC__, == 3) && __GNUC_MINOR__ <= 2
912 using std::swap;
913#define BOOST_OPTIONAL_STD_SWAP_INTRODUCED_AT_NS_SCOPE
914#endif
915
916 // optional's swap:
917 // If both are initialized, calls swap(T&, T&). If this swap throws, both will remain initialized but their values are now unspecified.
918 // If only one is initialized, calls U.reset(*I), THEN I.reset().
919 // If U.reset(*I) throws, both are left UNCHANGED (U is kept uinitialized and I is never reset)
920 // If both are uninitialized, do nothing (no-throw)
921 template<class T, std::size_t N1, std::size_t N2>
922 inline
923 void optional_swap ( optional2<T, N1>& x, optional2<T, N2>& y )
924 {
925 if ( !x && !!y )
926 {
927 x.reset(*y);
928 y.reset();
929 }
930 else if ( !!x && !y )
931 {
932 y.reset(*x);
933 x.reset();
934 }
935 else if ( !!x && !!y )
936 {
937 // GCC > 3.2 and all other compilers have the using declaration at function scope (FLC)
938#ifndef BOOST_OPTIONAL_STD_SWAP_INTRODUCED_AT_NS_SCOPE
939 // allow for Koenig lookup
940 using std::swap ;
941#endif
942 swap(*x,*y);
943 }
944 }
945
946 } // namespace optional_detail
947
948 template<class T, std::size_t N1, std::size_t N2> inline void swap ( optional2<T, N1>& x, optional2<T, N2>& y )
949 {
950 optional_detail::optional_swap(x,y);
951 }
952
953
954} // namespace boost
955
956#endif
957