3 * This file is a part of LEMON, a generic C++ optimization library
5 * Copyright (C) 2003-2008
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
19 #ifndef LEMON_BITS_VARIANT_H
20 #define LEMON_BITS_VARIANT_H
22 #include <lemon/assert.h>
25 /// \brief Variant types
29 namespace _variant_bits {
31 template <int left, int right>
33 static const int value = left < right ? right : left;
39 /// \brief Simple Variant type for two types
41 /// Simple Variant type for two types. The Variant type is a type
42 /// safe union. The C++ has strong limitations for using unions, by
43 /// example we can not store type with non default constructor or
44 /// destructor in an union. This class always knowns the current
45 /// state of the variant and it cares for the proper construction
47 template <typename _First, typename _Second>
51 /// \brief The \c First type.
53 /// \brief The \c Second type.
54 typedef _Second Second;
56 /// \brief Constructor
58 /// This constructor initalizes to the default value of the \c First
62 new(reinterpret_cast<First*>(data)) First();
65 /// \brief Constructor
67 /// This constructor initalizes to the given value of the \c First
69 BiVariant(const First& f) {
71 new(reinterpret_cast<First*>(data)) First(f);
74 /// \brief Constructor
76 /// This constructor initalizes to the given value of the \c
78 BiVariant(const Second& s) {
80 new(reinterpret_cast<Second*>(data)) Second(s);
83 /// \brief Copy constructor
86 BiVariant(const BiVariant& bivariant) {
87 flag = bivariant.flag;
89 new(reinterpret_cast<First*>(data)) First(bivariant.first());
91 new(reinterpret_cast<Second*>(data)) Second(bivariant.second());
102 /// \brief Set to the default value of the \c First type.
104 /// This function sets the variant to the default value of the \c
106 BiVariant& setFirst() {
109 new(reinterpret_cast<First*>(data)) First();
113 /// \brief Set to the given value of the \c First type.
115 /// This function sets the variant to the given value of the \c
117 BiVariant& setFirst(const First& f) {
120 new(reinterpret_cast<First*>(data)) First(f);
124 /// \brief Set to the default value of the \c Second type.
126 /// This function sets the variant to the default value of the \c
128 BiVariant& setSecond() {
131 new(reinterpret_cast<Second*>(data)) Second();
135 /// \brief Set to the given value of the \c Second type.
137 /// This function sets the variant to the given value of the \c
139 BiVariant& setSecond(const Second& s) {
142 new(reinterpret_cast<Second*>(data)) Second(s);
146 /// \brief Operator form of the \c setFirst()
147 BiVariant& operator=(const First& f) {
151 /// \brief Operator form of the \c setSecond()
152 BiVariant& operator=(const Second& s) {
156 /// \brief Assign operator
157 BiVariant& operator=(const BiVariant& bivariant) {
158 if (this == &bivariant) return *this;
160 flag = bivariant.flag;
162 new(reinterpret_cast<First*>(data)) First(bivariant.first());
164 new(reinterpret_cast<Second*>(data)) Second(bivariant.second());
169 /// \brief Reference to the value
171 /// Reference to the value of the \c First type.
172 /// \pre The BiVariant should store value of \c First type.
174 LEMON_DEBUG(flag, "Variant wrong state");
175 return *reinterpret_cast<First*>(data);
178 /// \brief Const reference to the value
180 /// Const reference to the value of the \c First type.
181 /// \pre The BiVariant should store value of \c First type.
182 const First& first() const {
183 LEMON_DEBUG(flag, "Variant wrong state");
184 return *reinterpret_cast<const First*>(data);
187 /// \brief Operator form of the \c first()
188 operator First&() { return first(); }
189 /// \brief Operator form of the const \c first()
190 operator const First&() const { return first(); }
192 /// \brief Reference to the value
194 /// Reference to the value of the \c Second type.
195 /// \pre The BiVariant should store value of \c Second type.
197 LEMON_DEBUG(!flag, "Variant wrong state");
198 return *reinterpret_cast<Second*>(data);
201 /// \brief Const reference to the value
203 /// Const reference to the value of the \c Second type.
204 /// \pre The BiVariant should store value of \c Second type.
205 const Second& second() const {
206 LEMON_DEBUG(!flag, "Variant wrong state");
207 return *reinterpret_cast<const Second*>(data);
210 /// \brief Operator form of the \c second()
211 operator Second&() { return second(); }
212 /// \brief Operator form of the const \c second()
213 operator const Second&() const { return second(); }
215 /// \brief %True when the variant is in the first state
217 /// %True when the variant stores value of the \c First type.
218 bool firstState() const { return flag; }
220 /// \brief %True when the variant is in the second state
222 /// %True when the variant stores value of the \c Second type.
223 bool secondState() const { return !flag; }
229 reinterpret_cast<First*>(data)->~First();
231 reinterpret_cast<Second*>(data)->~Second();
235 char data[_variant_bits::CTMax<sizeof(First), sizeof(Second)>::value];
239 namespace _variant_bits {
241 template <int _idx, typename _TypeMap>
244 typedef typename _TypeMap::template Map<_idx>::Type Current;
246 static void destroy(int index, char* place) {
248 reinterpret_cast<Current*>(place)->~Current();
250 Memory<_idx - 1, _TypeMap>::destroy(index, place);
254 static void copy(int index, char* to, const char* from) {
256 new (reinterpret_cast<Current*>(to))
257 Current(reinterpret_cast<const Current*>(from));
259 Memory<_idx - 1, _TypeMap>::copy(index, to, from);
265 template <typename _TypeMap>
266 struct Memory<-1, _TypeMap> {
268 static void destroy(int, char*) {
269 LEMON_DEBUG(false, "Variant wrong index.");
272 static void copy(int, char*, const char*) {
273 LEMON_DEBUG(false, "Variant wrong index.");
277 template <int _idx, typename _TypeMap>
279 static const int value =
280 CTMax<sizeof(typename _TypeMap::template Map<_idx>::Type),
281 Size<_idx - 1, _TypeMap>::value>::value;
284 template <typename _TypeMap>
285 struct Size<0, _TypeMap> {
286 static const int value =
287 sizeof(typename _TypeMap::template Map<0>::Type);
292 /// \brief Variant type
294 /// Simple Variant type. The Variant type is a type safe union. The
295 /// C++ has strong limitations for using unions, for example we
296 /// cannot store type with non default constructor or destructor in
297 /// a union. This class always knowns the current state of the
298 /// variant and it cares for the proper construction and
301 /// \param _num The number of the types which can be stored in the
303 /// \param _TypeMap This class describes the types of the Variant. The
304 /// _TypeMap::Map<index>::Type should be a valid type for each index
305 /// in the range {0, 1, ..., _num - 1}. The \c VariantTypeMap is helper
306 /// class to define such type mappings up to 10 types.
308 /// And the usage of the class:
310 /// typedef Variant<3, VariantTypeMap<int, std::string, double> > MyVariant;
313 /// std::cout << var.get<0>() << std::endl;
314 /// var.set<1>("alpha");
315 /// std::cout << var.get<1>() << std::endl;
316 /// var.set<2>(0.75);
317 /// std::cout << var.get<2>() << std::endl;
320 /// The result of course:
326 template <int _num, typename _TypeMap>
330 static const int num = _num;
332 typedef _TypeMap TypeMap;
334 /// \brief Constructor
336 /// This constructor initalizes to the default value of the \c type
340 new(reinterpret_cast<typename TypeMap::template Map<0>::Type*>(data))
341 typename TypeMap::template Map<0>::Type();
345 /// \brief Copy constructor
348 Variant(const Variant& variant) {
350 _variant_bits::Memory<num - 1, TypeMap>::copy(flag, data, variant.data);
353 /// \brief Assign operator
356 Variant& operator=(const Variant& variant) {
357 if (this == &variant) return *this;
358 _variant_bits::Memory<num - 1, TypeMap>::
361 _variant_bits::Memory<num - 1, TypeMap>::
362 copy(flag, data, variant.data);
366 /// \brief Destrcutor
370 _variant_bits::Memory<num - 1, TypeMap>::destroy(flag, data);
373 /// \brief Set to the default value of the type with \c _idx index.
375 /// This function sets the variant to the default value of the
376 /// type with \c _idx index.
379 _variant_bits::Memory<num - 1, TypeMap>::destroy(flag, data);
381 new(reinterpret_cast<typename TypeMap::template Map<_idx>::Type*>(data))
382 typename TypeMap::template Map<_idx>::Type();
386 /// \brief Set to the given value of the type with \c _idx index.
388 /// This function sets the variant to the given value of the type
389 /// with \c _idx index.
391 Variant& set(const typename _TypeMap::template Map<_idx>::Type& init) {
392 _variant_bits::Memory<num - 1, TypeMap>::destroy(flag, data);
394 new(reinterpret_cast<typename TypeMap::template Map<_idx>::Type*>(data))
395 typename TypeMap::template Map<_idx>::Type(init);
399 /// \brief Gets the current value of the type with \c _idx index.
401 /// Gets the current value of the type with \c _idx index.
403 const typename TypeMap::template Map<_idx>::Type& get() const {
404 LEMON_DEBUG(_idx == flag, "Variant wrong index");
405 return *reinterpret_cast<const typename TypeMap::
406 template Map<_idx>::Type*>(data);
409 /// \brief Gets the current value of the type with \c _idx index.
411 /// Gets the current value of the type with \c _idx index.
413 typename _TypeMap::template Map<_idx>::Type& get() {
414 LEMON_DEBUG(_idx == flag, "Variant wrong index");
415 return *reinterpret_cast<typename TypeMap::template Map<_idx>::Type*>
419 /// \brief Returns the current state of the variant.
421 /// Returns the current state of the variant.
428 char data[_variant_bits::Size<num - 1, TypeMap>::value];
432 namespace _variant_bits {
434 template <int _index, typename _List>
436 typedef typename Get<_index - 1, typename _List::Next>::Type Type;
439 template <typename _List>
440 struct Get<0, _List> {
441 typedef typename _List::Type Type;
446 template <typename _Type, typename _List>
452 template <int _idx, typename _T0, typename _T1, typename _T2,
453 typename _T3, typename _T5, typename _T4, typename _T6,
454 typename _T7, typename _T8, typename _T9>
457 typedef Insert<_T9, L10> L9;
458 typedef Insert<_T8, L9> L8;
459 typedef Insert<_T7, L8> L7;
460 typedef Insert<_T6, L7> L6;
461 typedef Insert<_T5, L6> L5;
462 typedef Insert<_T4, L5> L4;
463 typedef Insert<_T3, L4> L3;
464 typedef Insert<_T2, L3> L2;
465 typedef Insert<_T1, L2> L1;
466 typedef Insert<_T0, L1> L0;
467 typedef typename Get<_idx, L0>::Type Type;
472 /// \brief Helper class for Variant
474 /// Helper class to define type mappings for Variant. This class
475 /// converts the template parameters to be mappable by integer.
479 typename _T1 = void, typename _T2 = void, typename _T3 = void,
480 typename _T5 = void, typename _T4 = void, typename _T6 = void,
481 typename _T7 = void, typename _T8 = void, typename _T9 = void>
482 struct VariantTypeMap {
485 typedef typename _variant_bits::
486 Mapper<_idx, _T0, _T1, _T2, _T3, _T4, _T5, _T6, _T7, _T8, _T9>::Type