3 * Interface to GiNaC's light-weight expression handles. */
6 * GiNaC Copyright (C) 1999-2005 Johannes Gutenberg University Mainz, Germany
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #ifndef __GINAC_EX_H__
24 #define __GINAC_EX_H__
37 /** Helper class to initialize the library. There must be one static object
38 * of this class in every object file that makes use of our flyweights in
39 * order to guarantee proper initialization. Hence we put it into this
40 * file which is included by every relevant file anyways. This is modeled
41 * after section 27.4.2.1.6 of the C++ standard, where cout and friends are
52 /** For construction of flyweights, etc. */
53 static library_init library_initializer;
56 class scalar_products;
58 class const_preorder_iterator;
59 class const_postorder_iterator;
62 /** Lightweight wrapper for GiNaC's symbolic objects. It holds a pointer to
63 * the other object in order to do garbage collection by the method of
64 * reference counting. I.e., it is a smart pointer. Also, the constructor
65 * ex::ex(const basic & other) calls the methods that do automatic
66 * evaluation. E.g., x-x turns automatically into 0. */
68 friend class archive_node;
69 friend inline bool are_ex_trivially_equal(const ex &, const ex &);
70 template<class T> friend inline const T &ex_to(const ex &);
71 template<class T> friend inline bool is_a(const ex &);
72 template<class T> friend inline bool is_exactly_a(const ex &);
74 // default constructor, copy constructor and assignment operator
77 #ifdef OBSCURE_CINT_HACK
79 ex & operator=(const ex & other);
84 ex(const basic & other);
91 /** Construct ex from string and a list of symbols. The input grammar is
92 * similar to the GiNaC output format. All symbols and indices to be used
93 * in the expression must be specified in a lst in the second argument.
94 * Undefined symbols and other parser errors will throw an exception. */
95 ex(const std::string &s, const ex &l);
98 // non-virtual functions in this class
100 /** Efficiently swap the contents of two expressions. */
101 void swap(ex & other) throw()
103 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
104 GINAC_ASSERT(other.bp->flags & status_flags::dynallocated);
109 const_iterator begin() const throw();
110 const_iterator end() const throw();
111 const_preorder_iterator preorder_begin() const;
112 const_preorder_iterator preorder_end() const throw();
113 const_postorder_iterator postorder_begin() const;
114 const_postorder_iterator postorder_end() const throw();
117 ex eval(int level = 0) const { return bp->eval(level); }
118 ex evalf(int level = 0) const { return bp->evalf(level); }
119 ex evalm() const { return bp->evalm(); }
120 ex eval_ncmul(const exvector & v) const { return bp->eval_ncmul(v); }
121 ex eval_integ() const { return bp->eval_integ(); }
124 void print(const print_context & c, unsigned level = 0) const;
125 void dbgprint() const;
126 void dbgprinttree() const;
129 bool info(unsigned inf) const { return bp->info(inf); }
132 size_t nops() const { return bp->nops(); }
133 ex op(size_t i) const { return bp->op(i); }
134 ex operator[](const ex & index) const { return (*bp)[index]; }
135 ex operator[](size_t i) const { return (*bp)[i]; }
136 ex & let_op(size_t i);
137 ex & operator[](const ex & index);
138 ex & operator[](size_t i);
142 // complex conjugation
143 ex conjugate() const { return bp->conjugate(); }
146 bool has(const ex & pattern) const { return bp->has(pattern); }
147 bool find(const ex & pattern, lst & found) const;
148 bool match(const ex & pattern) const;
149 bool match(const ex & pattern, lst & repl_lst) const { return bp->match(pattern, repl_lst); }
152 ex subs(const exmap & m, unsigned options = 0) const;
153 ex subs(const lst & ls, const lst & lr, unsigned options = 0) const;
154 ex subs(const ex & e, unsigned options = 0) const;
157 ex map(map_function & f) const { return bp->map(f); }
158 ex map(ex (*f)(const ex & e)) const;
160 // visitors and tree traversal
161 void accept(visitor & v) const { bp->accept(v); }
162 void traverse_preorder(visitor & v) const;
163 void traverse_postorder(visitor & v) const;
164 void traverse(visitor & v) const { traverse_preorder(v); }
167 int degree(const ex & s) const { return bp->degree(s); }
168 int ldegree(const ex & s) const { return bp->ldegree(s); }
169 ex coeff(const ex & s, int n = 1) const { return bp->coeff(s, n); }
170 ex lcoeff(const ex & s) const { return coeff(s, degree(s)); }
171 ex tcoeff(const ex & s) const { return coeff(s, ldegree(s)); }
174 ex expand(unsigned options=0) const;
175 ex collect(const ex & s, bool distributed = false) const { return bp->collect(s, distributed); }
177 // differentiation and series expansion
178 ex diff(const symbol & s, unsigned nth = 1) const;
179 ex series(const ex & r, int order, unsigned options = 0) const;
181 // rational functions
182 ex normal(int level = 0) const;
183 ex to_rational(exmap & repl) const;
184 ex to_rational(lst & repl_lst) const;
185 ex to_polynomial(exmap & repl) const;
186 ex to_polynomial(lst & repl_lst) const;
189 ex numer_denom() const;
191 // polynomial algorithms
192 ex unit(const ex &x) const;
193 ex content(const ex &x) const;
194 numeric integer_content() const;
195 ex primpart(const ex &x) const;
196 ex primpart(const ex &x, const ex &cont) const;
197 void unitcontprim(const ex &x, ex &u, ex &c, ex &p) const;
198 ex smod(const numeric &xi) const { return bp->smod(xi); }
199 numeric max_coefficient() const;
202 exvector get_free_indices() const { return bp->get_free_indices(); }
203 ex simplify_indexed(unsigned options = 0) const;
204 ex simplify_indexed(const scalar_products & sp, unsigned options = 0) const;
207 int compare(const ex & other) const;
208 bool is_equal(const ex & other) const;
209 bool is_zero() const { extern const ex _ex0; return is_equal(_ex0); }
212 ex symmetrize() const;
213 ex symmetrize(const lst & l) const;
214 ex antisymmetrize() const;
215 ex antisymmetrize(const lst & l) const;
216 ex symmetrize_cyclic() const;
217 ex symmetrize_cyclic(const lst & l) const;
220 unsigned return_type() const { return bp->return_type(); }
221 unsigned return_type_tinfo() const { return bp->return_type_tinfo(); }
223 unsigned gethash() const { return bp->gethash(); }
226 static ptr<basic> construct_from_basic(const basic & other);
227 static basic & construct_from_int(int i);
228 static basic & construct_from_uint(unsigned int i);
229 static basic & construct_from_long(long i);
230 static basic & construct_from_ulong(unsigned long i);
231 static basic & construct_from_double(double d);
232 static ptr<basic> construct_from_string_and_lst(const std::string &s, const ex &l);
233 void makewriteable();
234 void share(const ex & other) const;
236 #ifdef OBSCURE_CINT_HACK
238 static bool last_created_or_assigned_bp_can_be_converted_to_ex()
240 if (last_created_or_assigned_bp==0) return false;
241 if ((last_created_or_assigned_bp->flags &
242 status_flags::dynallocated)==0) return false;
243 if ((last_created_or_assigned_bp->flags &
244 status_flags::evaluated)==0) return false;
248 void update_last_created_or_assigned_bp()
250 last_created_or_assigned_bp = bp;
251 last_created_or_assigned_exp = (long)(void *)(this);
253 #endif // def OBSCURE_CINT_HACK
258 mutable ptr<basic> bp; ///< pointer to basic object managed by this
260 #ifdef OBSCURE_CINT_HACK
262 static ptr<basic> last_created_or_assigned_bp;
263 static basic * dummy_bp;
264 static long last_created_or_assigned_exp;
265 #endif // def OBSCURE_CINT_HACK
269 // performance-critical inlined method implementations
271 // This needs to be a basic* because we don't know that numeric is derived
272 // from basic and we need a basic& for the ex default constructor
273 extern const basic *_num0_bp;
276 ex::ex() throw() : bp(*const_cast<basic *>(_num0_bp))
278 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
279 #ifdef OBSCURE_CINT_HACK
280 update_last_created_or_assigned_bp();
281 #endif // def OBSCURE_CINT_HACK
284 #ifdef OBSCURE_CINT_HACK
286 ex::ex(const ex & other) : bp(other.bp)
288 GINAC_ASSERT((bp->flags) & status_flags::dynallocated);
289 update_last_created_or_assigned_bp();
293 ex & ex::operator=(const ex & other)
295 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
296 GINAC_ASSERT(other.bp->flags & status_flags::dynallocated);
298 update_last_created_or_assigned_bp();
301 #endif // def OBSCURE_CINT_HACK
304 ex::ex(const basic & other) : bp(construct_from_basic(other))
306 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
307 #ifdef OBSCURE_CINT_HACK
308 update_last_created_or_assigned_bp();
309 #endif // def OBSCURE_CINT_HACK
313 ex::ex(int i) : bp(construct_from_int(i))
315 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
316 #ifdef OBSCURE_CINT_HACK
317 update_last_created_or_assigned_bp();
318 #endif // def OBSCURE_CINT_HACK
322 ex::ex(unsigned int i) : bp(construct_from_uint(i))
324 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
325 #ifdef OBSCURE_CINT_HACK
326 update_last_created_or_assigned_bp();
327 #endif // def OBSCURE_CINT_HACK
331 ex::ex(long i) : bp(construct_from_long(i))
333 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
334 #ifdef OBSCURE_CINT_HACK
335 update_last_created_or_assigned_bp();
336 #endif // def OBSCURE_CINT_HACK
340 ex::ex(unsigned long i) : bp(construct_from_ulong(i))
342 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
343 #ifdef OBSCURE_CINT_HACK
344 update_last_created_or_assigned_bp();
345 #endif // def OBSCURE_CINT_HACK
349 ex::ex(double const d) : bp(construct_from_double(d))
351 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
352 #ifdef OBSCURE_CINT_HACK
353 update_last_created_or_assigned_bp();
354 #endif // def OBSCURE_CINT_HACK
358 ex::ex(const std::string &s, const ex &l) : bp(construct_from_string_and_lst(s, l))
360 GINAC_ASSERT(bp->flags & status_flags::dynallocated);
361 #ifdef OBSCURE_CINT_HACK
362 update_last_created_or_assigned_bp();
363 #endif // def OBSCURE_CINT_HACK
367 int ex::compare(const ex & other) const
369 #ifdef GINAC_COMPARE_STATISTICS
370 compare_statistics.total_compares++;
372 if (bp == other.bp) // trivial case: both expressions point to same basic
374 #ifdef GINAC_COMPARE_STATISTICS
375 compare_statistics.nontrivial_compares++;
377 const int cmpval = bp->compare(*other.bp);
380 // Expressions point to different, but equal, trees: conserve
381 // memory and make subsequent compare() operations faster by
382 // making both expressions point to the same tree.
390 bool ex::is_equal(const ex & other) const
392 #ifdef GINAC_COMPARE_STATISTICS
393 compare_statistics.total_is_equals++;
395 if (bp == other.bp) // trivial case: both expressions point to same basic
397 #ifdef GINAC_COMPARE_STATISTICS
398 compare_statistics.nontrivial_is_equals++;
400 const bool equal = bp->is_equal(*other.bp);
403 // Expressions point to different, but equal, trees: conserve
404 // memory and make subsequent compare() operations faster by
405 // making both expressions point to the same tree.
415 class const_iterator : public std::iterator<std::random_access_iterator_tag, ex, ptrdiff_t, const ex *, const ex &> {
417 friend class const_preorder_iterator;
418 friend class const_postorder_iterator;
421 const_iterator() throw() {}
424 const_iterator(const ex &e_, size_t i_) throw() : e(e_), i(i_) {}
427 // This should return an ex&, but that would be a reference to a
434 // This should return an ex*, but that would be a pointer to a
436 std::auto_ptr<ex> operator->() const
438 return std::auto_ptr<ex>(new ex(operator*()));
441 ex operator[](difference_type n) const
446 const_iterator &operator++() throw()
452 const_iterator operator++(int) throw()
454 const_iterator tmp = *this;
459 const_iterator &operator+=(difference_type n) throw()
465 const_iterator operator+(difference_type n) const throw()
467 return const_iterator(e, i + n);
470 inline friend const_iterator operator+(difference_type n, const const_iterator &it) throw()
472 return const_iterator(it.e, it.i + n);
475 const_iterator &operator--() throw()
481 const_iterator operator--(int) throw()
483 const_iterator tmp = *this;
488 const_iterator &operator-=(difference_type n) throw()
494 const_iterator operator-(difference_type n) const throw()
496 return const_iterator(e, i - n);
499 inline friend difference_type operator-(const const_iterator &lhs, const const_iterator &rhs) throw()
501 return lhs.i - rhs.i;
504 bool operator==(const const_iterator &other) const throw()
506 return are_ex_trivially_equal(e, other.e) && i == other.i;
509 bool operator!=(const const_iterator &other) const throw()
511 return !(*this == other);
514 bool operator<(const const_iterator &other) const throw()
519 bool operator>(const const_iterator &other) const throw()
521 return other < *this;
524 bool operator<=(const const_iterator &other) const throw()
526 return !(other < *this);
529 bool operator>=(const const_iterator &other) const throw()
531 return !(*this < other);
535 ex e; // this used to be a "const basic *", but in view of object fusion that wouldn't be safe
542 _iter_rep(const ex &e_, size_t i_, size_t i_end_) : e(e_), i(i_), i_end(i_end_) {}
544 bool operator==(const _iter_rep &other) const throw()
546 return are_ex_trivially_equal(e, other.e) && i == other.i;
549 bool operator!=(const _iter_rep &other) const throw()
551 return !(*this == other);
559 } // namespace internal
561 class const_preorder_iterator : public std::iterator<std::forward_iterator_tag, ex, ptrdiff_t, const ex *, const ex &> {
563 const_preorder_iterator() throw() {}
565 const_preorder_iterator(const ex &e, size_t n)
567 s.push(internal::_iter_rep(e, 0, n));
571 reference operator*() const
576 pointer operator->() const
581 const_preorder_iterator &operator++()
587 const_preorder_iterator operator++(int)
589 const_preorder_iterator tmp = *this;
594 bool operator==(const const_preorder_iterator &other) const throw()
599 bool operator!=(const const_preorder_iterator &other) const throw()
601 return !(*this == other);
605 std::stack<internal::_iter_rep, std::vector<internal::_iter_rep> > s;
609 while (!s.empty() && s.top().i == s.top().i_end) {
616 internal::_iter_rep & current = s.top();
618 if (current.i != current.i_end) {
619 const ex & child = current.e.op(current.i);
620 s.push(internal::_iter_rep(child, 0, child.nops()));
625 class const_postorder_iterator : public std::iterator<std::forward_iterator_tag, ex, ptrdiff_t, const ex *, const ex &> {
627 const_postorder_iterator() throw() {}
629 const_postorder_iterator(const ex &e, size_t n)
631 s.push(internal::_iter_rep(e, 0, n));
636 reference operator*() const
641 pointer operator->() const
646 const_postorder_iterator &operator++()
652 const_postorder_iterator operator++(int)
654 const_postorder_iterator tmp = *this;
659 bool operator==(const const_postorder_iterator &other) const throw()
664 bool operator!=(const const_postorder_iterator &other) const throw()
666 return !(*this == other);
670 std::stack<internal::_iter_rep, std::vector<internal::_iter_rep> > s;
674 while (s.top().i != s.top().i_end) {
675 internal::_iter_rep & current = s.top();
676 const ex & child = current.e.op(current.i);
677 s.push(internal::_iter_rep(child, 0, child.nops()));
683 if (s.top().i == s.top().i_end)
692 inline const_iterator ex::begin() const throw()
694 return const_iterator(*this, 0);
697 inline const_iterator ex::end() const throw()
699 return const_iterator(*this, nops());
702 inline const_preorder_iterator ex::preorder_begin() const
704 return const_preorder_iterator(*this, nops());
707 inline const_preorder_iterator ex::preorder_end() const throw()
709 return const_preorder_iterator();
712 inline const_postorder_iterator ex::postorder_begin() const
714 return const_postorder_iterator(*this, nops());
717 inline const_postorder_iterator ex::postorder_end() const throw()
719 return const_postorder_iterator();
725 /** Compare two objects of class quickly without doing a deep tree traversal.
726 * @return "true" if they are equal
727 * "false" if equality cannot be established quickly (e1 and e2 may
728 * still be equal, in this case. */
729 inline bool are_ex_trivially_equal(const ex &e1, const ex &e2)
731 return e1.bp == e2.bp;
734 /* Function objects for STL sort() etc. */
735 struct ex_is_less : public std::binary_function<ex, ex, bool> {
736 bool operator() (const ex &lh, const ex &rh) const { return lh.compare(rh) < 0; }
739 struct ex_is_equal : public std::binary_function<ex, ex, bool> {
740 bool operator() (const ex &lh, const ex &rh) const { return lh.is_equal(rh); }
743 struct op0_is_equal : public std::binary_function<ex, ex, bool> {
744 bool operator() (const ex &lh, const ex &rh) const { return lh.op(0).is_equal(rh.op(0)); }
747 struct ex_swap : public std::binary_function<ex, ex, void> {
748 void operator() (ex &lh, ex &rh) const { lh.swap(rh); }
751 // wrapper functions around member functions
752 inline size_t nops(const ex & thisex)
753 { return thisex.nops(); }
755 inline ex expand(const ex & thisex, unsigned options = 0)
756 { return thisex.expand(options); }
758 inline ex conjugate(const ex & thisex)
759 { return thisex.conjugate(); }
761 inline bool has(const ex & thisex, const ex & pattern)
762 { return thisex.has(pattern); }
764 inline bool find(const ex & thisex, const ex & pattern, lst & found)
765 { return thisex.find(pattern, found); }
767 inline int degree(const ex & thisex, const ex & s)
768 { return thisex.degree(s); }
770 inline int ldegree(const ex & thisex, const ex & s)
771 { return thisex.ldegree(s); }
773 inline ex coeff(const ex & thisex, const ex & s, int n=1)
774 { return thisex.coeff(s, n); }
776 inline ex numer(const ex & thisex)
777 { return thisex.numer(); }
779 inline ex denom(const ex & thisex)
780 { return thisex.denom(); }
782 inline ex numer_denom(const ex & thisex)
783 { return thisex.numer_denom(); }
785 inline ex normal(const ex & thisex, int level=0)
786 { return thisex.normal(level); }
788 inline ex to_rational(const ex & thisex, lst & repl_lst)
789 { return thisex.to_rational(repl_lst); }
791 inline ex to_rational(const ex & thisex, exmap & repl)
792 { return thisex.to_rational(repl); }
794 inline ex to_polynomial(const ex & thisex, exmap & repl)
795 { return thisex.to_polynomial(repl); }
797 inline ex to_polynomial(const ex & thisex, lst & repl_lst)
798 { return thisex.to_polynomial(repl_lst); }
800 inline ex collect(const ex & thisex, const ex & s, bool distributed = false)
801 { return thisex.collect(s, distributed); }
803 inline ex eval(const ex & thisex, int level = 0)
804 { return thisex.eval(level); }
806 inline ex evalf(const ex & thisex, int level = 0)
807 { return thisex.evalf(level); }
809 inline ex evalm(const ex & thisex)
810 { return thisex.evalm(); }
812 inline ex eval_integ(const ex & thisex)
813 { return thisex.eval_integ(); }
815 inline ex diff(const ex & thisex, const symbol & s, unsigned nth = 1)
816 { return thisex.diff(s, nth); }
818 inline ex series(const ex & thisex, const ex & r, int order, unsigned options = 0)
819 { return thisex.series(r, order, options); }
821 inline bool match(const ex & thisex, const ex & pattern, lst & repl_lst)
822 { return thisex.match(pattern, repl_lst); }
824 inline ex simplify_indexed(const ex & thisex, unsigned options = 0)
825 { return thisex.simplify_indexed(options); }
827 inline ex simplify_indexed(const ex & thisex, const scalar_products & sp, unsigned options = 0)
828 { return thisex.simplify_indexed(sp, options); }
830 inline ex symmetrize(const ex & thisex)
831 { return thisex.symmetrize(); }
833 inline ex symmetrize(const ex & thisex, const lst & l)
834 { return thisex.symmetrize(l); }
836 inline ex antisymmetrize(const ex & thisex)
837 { return thisex.antisymmetrize(); }
839 inline ex antisymmetrize(const ex & thisex, const lst & l)
840 { return thisex.antisymmetrize(l); }
842 inline ex symmetrize_cyclic(const ex & thisex)
843 { return thisex.symmetrize_cyclic(); }
845 inline ex symmetrize_cyclic(const ex & thisex, const lst & l)
846 { return thisex.symmetrize_cyclic(l); }
848 inline ex op(const ex & thisex, size_t i)
849 { return thisex.op(i); }
851 inline ex lhs(const ex & thisex)
852 { return thisex.lhs(); }
854 inline ex rhs(const ex & thisex)
855 { return thisex.rhs(); }
857 inline bool is_zero(const ex & thisex)
858 { return thisex.is_zero(); }
860 inline void swap(ex & e1, ex & e2)
863 inline ex ex::subs(const exmap & m, unsigned options) const
865 return bp->subs(m, options);
868 inline ex subs(const ex & thisex, const exmap & m, unsigned options = 0)
869 { return thisex.subs(m, options); }
871 inline ex subs(const ex & thisex, const lst & ls, const lst & lr, unsigned options = 0)
872 { return thisex.subs(ls, lr, options); }
874 inline ex subs(const ex & thisex, const ex & e, unsigned options = 0)
875 { return thisex.subs(e, options); }
878 /* Convert function pointer to function object suitable for map(). */
879 class pointer_to_map_function : public map_function {
881 ex (*ptr)(const ex &);
883 explicit pointer_to_map_function(ex x(const ex &)) : ptr(x) {}
884 ex operator()(const ex & e) { return ptr(e); }
888 class pointer_to_map_function_1arg : public map_function {
890 ex (*ptr)(const ex &, T1);
893 explicit pointer_to_map_function_1arg(ex x(const ex &, T1), T1 a1) : ptr(x), arg1(a1) {}
894 ex operator()(const ex & e) { return ptr(e, arg1); }
897 template<class T1, class T2>
898 class pointer_to_map_function_2args : public map_function {
900 ex (*ptr)(const ex &, T1, T2);
904 explicit pointer_to_map_function_2args(ex x(const ex &, T1, T2), T1 a1, T2 a2) : ptr(x), arg1(a1), arg2(a2) {}
905 ex operator()(const ex & e) { return ptr(e, arg1, arg2); }
908 template<class T1, class T2, class T3>
909 class pointer_to_map_function_3args : public map_function {
911 ex (*ptr)(const ex &, T1, T2, T3);
916 explicit pointer_to_map_function_3args(ex x(const ex &, T1, T2, T3), T1 a1, T2 a2, T3 a3) : ptr(x), arg1(a1), arg2(a2), arg3(a3) {}
917 ex operator()(const ex & e) { return ptr(e, arg1, arg2, arg3); }
920 inline ex ex::map(ex f(const ex &)) const
922 pointer_to_map_function fcn(f);
926 // convenience type checker template functions
928 /** Check if ex is a handle to a T, including base classes. */
930 inline bool is_a(const ex &obj)
932 return is_a<T>(*obj.bp);
935 /** Check if ex is a handle to a T, not including base classes. */
937 inline bool is_exactly_a(const ex &obj)
939 return is_exactly_a<T>(*obj.bp);
942 /** Return a reference to the basic-derived class T object embedded in an
943 * expression. This is fast but unsafe: the result is undefined if the
944 * expression does not contain a T object at its top level. Hence, you
945 * should generally check the type of e first. Also, you shouldn't cache
946 * the returned reference because GiNaC's garbage collector may destroy
947 * the referenced object any time it's used in another expression.
949 * @param e expression
950 * @return reference to object of class T
951 * @see is_exactly_a<class T>() */
953 inline const T &ex_to(const ex &e)
955 GINAC_ASSERT(is_a<T>(e));
956 return static_cast<const T &>(*e.bp);
962 // Specializations of Standard Library algorithms
965 /** Specialization of std::swap() for ex objects. */
967 inline void swap(GiNaC::ex &a, GiNaC::ex &b)
972 /** Specialization of std::iter_swap() for vector<ex> iterators. */
974 inline void iter_swap(vector<GiNaC::ex>::iterator i1, vector<GiNaC::ex>::iterator i2)
979 /** Specialization of std::iter_swap() for list<ex> iterators. */
981 inline void iter_swap(list<GiNaC::ex>::iterator i1, list<GiNaC::ex>::iterator i2)
988 #endif // ndef __GINAC_EX_H__