ginac/container.h

   1 /** @file container.h
   2  *
   3  *  Wrapper template for making GiNaC classes out of STL containers. */
   4
   5 /*
   6  *  GiNaC Copyright (C) 1999-2003 Johannes Gutenberg University Mainz, Germany
   7  *
   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.
  12  *
  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.
  17  *
  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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  21  */
  22
  23 #ifndef __GINAC_CONTAINER_H__
  24 #define __GINAC_CONTAINER_H__
  25
  26 #include <iterator>
  27 #include <stdexcept>
  28 #include <algorithm>
  29 #include <vector>
  30 #include <list>
  31 #include <memory>
  32
  33 #include "ex.h"
  34 #include "print.h"
  35 #include "archive.h"
  36 #include "assertion.h"
  37
  38 namespace GiNaC {
  39
  40
  41 /** Helper template for encapsulating the reserve() mechanics of STL containers. */
  42 template <template <class> class C>
  43 class container_storage {
  44 protected:
  45         typedef C<ex> STLT;
  46
  47         container_storage() {}
  48         container_storage(size_t n, const ex & e) : seq(n, e) {}
  49
  50         template <class In>
  51         container_storage(In b, In e) : seq(b, e) {}
  52
  53         void reserve(size_t) {}
  54         static void reserve(STLT &, size_t) {}
  55
  56         STLT seq;
  57
  58         // disallow destruction of container through a container_storage*
  59 protected:
  60         ~container_storage() {}
  61 };
  62
  63 template <>
  64 inline void container_storage<std::vector>::reserve(size_t n) { seq.reserve(n); }
  65
  66 template <>
  67 inline void container_storage<std::vector>::reserve(std::vector<ex> & v, size_t n) { v.reserve(n); }
  68
  69
  70 /** Wrapper template for making GiNaC classes out of STL containers. */
  71 template <template <class> class C>
  72 class container : public basic, public container_storage<C> {
  73         GINAC_DECLARE_REGISTERED_CLASS(container, basic)
  74
  75         typedef typename container_storage<C>::STLT STLT;
  76
  77 public:
  78         typedef typename STLT::const_iterator const_iterator;
  79         typedef typename STLT::const_reverse_iterator const_reverse_iterator;
  80
  81 protected:
  82         // helpers
  83         static unsigned get_tinfo() { return TINFO_fail; }
  84         static char get_open_delim() { return '('; }
  85         static char get_close_delim() { return ')'; }
  86
  87         // constructors
  88 public:
  89         container(STLT const & s, bool discardable = false) : inherited(get_tinfo())
  90         {
  91                 if (discardable)
  92                         this->seq.swap(const_cast<STLT &>(s));
  93                 else
  94                         this->seq = s;
  95         }
  96
  97         explicit container(std::auto_ptr<STLT> vp) : inherited(get_tinfo())
  98         {
  99                 this->seq.swap(*vp);
 100         }
 101
 102         container(exvector::const_iterator b, exvector::const_iterator e)
 103          : inherited(get_tinfo()), container_storage<C>(b, e) {}
 104
 105         explicit container(const ex & p1)
 106          : inherited(get_tinfo()), container_storage<C>(1, p1) {}
 107
 108         container(const ex & p1, const ex & p2) : inherited(get_tinfo())
 109         {
 110                 reserve(this->seq, 2);
 111                 this->seq.push_back(p1); this->seq.push_back(p2);
 112         }
 113
 114         container(const ex & p1, const ex & p2, const ex & p3) : inherited(get_tinfo())
 115         {
 116                 reserve(this->seq, 3);
 117                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 118         }
 119
 120         container(const ex & p1, const ex & p2, const ex & p3,
 121                            const ex & p4) : inherited(get_tinfo())
 122         {
 123                 reserve(this->seq, 4);
 124                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 125                 this->seq.push_back(p4);
 126         }
 127
 128         container(const ex & p1, const ex & p2, const ex & p3,
 129                   const ex & p4, const ex & p5) : inherited(get_tinfo())
 130         {
 131                 reserve(this->seq, 5);
 132                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 133                 this->seq.push_back(p4); this->seq.push_back(p5);
 134         }
 135
 136         container(const ex & p1, const ex & p2, const ex & p3,
 137                   const ex & p4, const ex & p5, const ex & p6) : inherited(get_tinfo())
 138         {
 139                 reserve(this->seq, 6);
 140                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 141                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 142         }
 143
 144         container(const ex & p1, const ex & p2, const ex & p3,
 145                   const ex & p4, const ex & p5, const ex & p6,
 146                   const ex & p7) : inherited(get_tinfo())
 147         {
 148                 reserve(this->seq, 7);
 149                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 150                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 151                 this->seq.push_back(p7);
 152         }
 153
 154         container(const ex & p1, const ex & p2, const ex & p3,
 155                   const ex & p4, const ex & p5, const ex & p6,
 156                   const ex & p7, const ex & p8) : inherited(get_tinfo())
 157         {
 158                 reserve(this->seq, 8);
 159                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 160                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 161                 this->seq.push_back(p7); this->seq.push_back(p8);
 162         }
 163
 164         container(const ex & p1, const ex & p2, const ex & p3,
 165                   const ex & p4, const ex & p5, const ex & p6,
 166                   const ex & p7, const ex & p8, const ex & p9) : inherited(get_tinfo())
 167         {
 168                 reserve(this->seq, 9);
 169                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 170                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 171                 this->seq.push_back(p7); this->seq.push_back(p8); this->seq.push_back(p9);
 172         }
 173
 174         container(const ex & p1, const ex & p2, const ex & p3,
 175                   const ex & p4, const ex & p5, const ex & p6,
 176                   const ex & p7, const ex & p8, const ex & p9,
 177                   const ex & p10) : inherited(get_tinfo())
 178         {
 179                 reserve(this->seq, 10);
 180                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 181                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 182                 this->seq.push_back(p7); this->seq.push_back(p8); this->seq.push_back(p9);
 183                 this->seq.push_back(p10);
 184         }
 185
 186         container(const ex & p1, const ex & p2, const ex & p3,
 187                   const ex & p4, const ex & p5, const ex & p6,
 188                   const ex & p7, const ex & p8, const ex & p9,
 189                   const ex & p10, const ex & p11) : inherited(get_tinfo())
 190         {
 191                 reserve(this->seq, 11);
 192                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 193                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 194                 this->seq.push_back(p7); this->seq.push_back(p8); this->seq.push_back(p9);
 195                 this->seq.push_back(p10); this->seq.push_back(p11);
 196         }
 197
 198         container(const ex & p1, const ex & p2, const ex & p3,
 199                   const ex & p4, const ex & p5, const ex & p6,
 200                   const ex & p7, const ex & p8, const ex & p9,
 201                   const ex & p10, const ex & p11, const ex & p12) : inherited(get_tinfo())
 202         {
 203                 reserve(this->seq, 12);
 204                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 205                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 206                 this->seq.push_back(p7); this->seq.push_back(p8); this->seq.push_back(p9);
 207                 this->seq.push_back(p10); this->seq.push_back(p11); this->seq.push_back(p12);
 208         }
 209
 210         container(const ex & p1, const ex & p2, const ex & p3,
 211                   const ex & p4, const ex & p5, const ex & p6,
 212                   const ex & p7, const ex & p8, const ex & p9,
 213                   const ex & p10, const ex & p11, const ex & p12,
 214                   const ex & p13) : inherited(get_tinfo())
 215         {
 216                 reserve(this->seq, 13);
 217                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 218                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 219                 this->seq.push_back(p7); this->seq.push_back(p8); this->seq.push_back(p9);
 220                 this->seq.push_back(p10); this->seq.push_back(p11); this->seq.push_back(p12);
 221                 this->seq.push_back(p13);
 222         }
 223
 224         container(const ex & p1, const ex & p2, const ex & p3,
 225                   const ex & p4, const ex & p5, const ex & p6,
 226                   const ex & p7, const ex & p8, const ex & p9,
 227                   const ex & p10, const ex & p11, const ex & p12,
 228                   const ex & p13, const ex & p14) : inherited(get_tinfo())
 229         {
 230                 reserve(this->seq, 14);
 231                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 232                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 233                 this->seq.push_back(p7); this->seq.push_back(p8); this->seq.push_back(p9);
 234                 this->seq.push_back(p10); this->seq.push_back(p11); this->seq.push_back(p12);
 235                 this->seq.push_back(p13); this->seq.push_back(p14);
 236         }
 237
 238         container(const ex & p1, const ex & p2, const ex & p3,
 239                   const ex & p4, const ex & p5, const ex & p6,
 240                   const ex & p7, const ex & p8, const ex & p9,
 241                   const ex & p10, const ex & p11, const ex & p12,
 242                   const ex & p13, const ex & p14, const ex & p15) : inherited(get_tinfo())
 243         {
 244                 reserve(this->seq, 15);
 245                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 246                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 247                 this->seq.push_back(p7); this->seq.push_back(p8); this->seq.push_back(p9);
 248                 this->seq.push_back(p10); this->seq.push_back(p11); this->seq.push_back(p12);
 249                 this->seq.push_back(p13); this->seq.push_back(p14); this->seq.push_back(p15);
 250         }
 251
 252         container(const ex & p1, const ex & p2, const ex & p3,
 253                   const ex & p4, const ex & p5, const ex & p6,
 254                   const ex & p7, const ex & p8, const ex & p9,
 255                   const ex & p10, const ex & p11, const ex & p12,
 256                   const ex & p13, const ex & p14, const ex & p15,
 257                   const ex & p16) : inherited(get_tinfo())
 258         {
 259                 reserve(this->seq, 16);
 260                 this->seq.push_back(p1); this->seq.push_back(p2); this->seq.push_back(p3);
 261                 this->seq.push_back(p4); this->seq.push_back(p5); this->seq.push_back(p6);
 262                 this->seq.push_back(p7); this->seq.push_back(p8); this->seq.push_back(p9);
 263                 this->seq.push_back(p10); this->seq.push_back(p11); this->seq.push_back(p12);
 264                 this->seq.push_back(p13); this->seq.push_back(p14); this->seq.push_back(p15);
 265                 this->seq.push_back(p16);
 266         }
 267
 268         // functions overriding virtual functions from base classes
 269 public:
 270         bool info(unsigned inf) const { return inherited::info(inf); }
 271         unsigned precedence() const { return 10; }
 272         size_t nops() const { return this->seq.size(); }
 273         ex op(size_t i) const;
 274         ex & let_op(size_t i);
 275         ex eval(int level = 0) const;
 276         ex subs(const exmap & m, unsigned options = 0) const;
 277
 278 protected:
 279         bool is_equal_same_type(const basic & other) const;
 280
 281         // new virtual functions which can be overridden by derived classes
 282 protected:
 283         /** Similar to duplicate(), but with a preset sequence. Must be
 284          *  overridden by derived classes. */
 285         virtual ex thiscontainer(const STLT & v) const { return container(v); }
 286
 287         /** Similar to duplicate(), but with a preset sequence (which gets
 288          *  deleted). Must be overridden by derived classes. */
 289         virtual ex thiscontainer(std::auto_ptr<STLT> vp) const { return container(vp); }
 290
 291         virtual void printseq(const print_context & c, char openbracket, char delim,
 292                               char closebracket, unsigned this_precedence,
 293                               unsigned upper_precedence = 0) const;
 294
 295         // non-virtual functions in this class
 296 private:
 297         void sort_(std::random_access_iterator_tag)
 298         {
 299                 std::sort(this->seq.begin(), this->seq.end(), ex_is_less());
 300         }
 301
 302         void sort_(std::input_iterator_tag)
 303         {
 304                 this->seq.sort(ex_is_less());
 305         }
 306
 307         void unique_()
 308         {
 309                 typename STLT::iterator p = std::unique(this->seq.begin(), this->seq.end(), ex_is_equal());
 310                 this->seq.erase(p, this->seq.end());
 311         }
 312
 313 public:
 314         container & prepend(const ex & b);
 315         container & append(const ex & b);
 316         container & remove_first();
 317         container & remove_last();
 318         container & remove_all();
 319         container & sort();
 320         container & unique();
 321
 322         const_iterator begin() const {return this->seq.begin();}
 323         const_iterator end() const {return this->seq.end();}
 324         const_reverse_iterator rbegin() const {return this->seq.rbegin();}
 325         const_reverse_iterator rend() const {return this->seq.rend();}
 326
 327 protected:
 328         void do_print(const print_context & c, unsigned level) const;
 329         void do_print_tree(const print_tree & c, unsigned level) const;
 330         void do_print_python(const print_python & c, unsigned level) const;
 331         void do_print_python_repr(const print_python_repr & c, unsigned level) const;
 332         STLT evalchildren(int level) const;
 333         std::auto_ptr<STLT> subschildren(const exmap & m, unsigned options = 0) const;
 334 };
 335
 336 /** Default constructor */
 337 template <template <class> class C>
 338 container<C>::container() : inherited(get_tinfo()) {}
 339
 340 /** Construct object from archive_node. */
 341 template <template <class> class C>
 342 container<C>::container(const archive_node &n, lst &sym_lst) : inherited(n, sym_lst)
 343 {
 344         for (unsigned int i=0; true; i++) {
 345                 ex e;
 346                 if (n.find_ex("seq", e, sym_lst, i))
 347                         this->seq.push_back(e);
 348                 else
 349                         break;
 350         }
 351 }
 352
 353 /** Unarchive the object. */
 354 template <template <class> class C>
 355 ex container<C>::unarchive(const archive_node &n, lst &sym_lst)
 356 {
 357         return (new container(n, sym_lst))->setflag(status_flags::dynallocated);
 358 }
 359
 360 /** Archive the object. */
 361 template <template <class> class C>
 362 void container<C>::archive(archive_node &n) const
 363 {
 364         inherited::archive(n);
 365         const_iterator i = this->seq.begin(), end = this->seq.end();
 366         while (i != end) {
 367                 n.add_ex("seq", *i);
 368                 ++i;
 369         }
 370 }
 371
 372 template <template <class> class C>
 373 void container<C>::do_print(const print_context & c, unsigned level) const
 374 {
 375         // always print brackets around seq, ignore upper_precedence
 376         printseq(c, get_open_delim(), ',', get_close_delim(), precedence(), precedence()+1);
 377 }
 378
 379 template <template <class> class C>
 380 void container<C>::do_print_tree(const print_tree & c, unsigned level) const
 381 {
 382         c.s << std::string(level, ' ') << class_name()
 383             << std::hex << ", hash=0x" << hashvalue << ", flags=0x" << flags << std::dec
 384             << ", nops=" << nops()
 385             << std::endl;
 386         const_iterator i = this->seq.begin(), end = this->seq.end();
 387         while (i != end) {
 388                 i->print(c, level + c.delta_indent);
 389                 ++i;
 390         }
 391         c.s << std::string(level + c.delta_indent,' ') << "=====" << std::endl;
 392 }
 393
 394 template <template <class> class C>
 395 void container<C>::do_print_python(const print_python & c, unsigned level) const
 396 {
 397         printseq(c, '[', ',', ']', precedence(), precedence()+1);
 398 }
 399
 400 template <template <class> class C>
 401 void container<C>::do_print_python_repr(const print_python_repr & c, unsigned level) const
 402 {
 403         c.s << class_name();
 404         printseq(c, '(', ',', ')', precedence(), precedence()+1);
 405 }
 406
 407 template <template <class> class C>
 408 ex container<C>::op(size_t i) const
 409 {
 410         GINAC_ASSERT(i < nops());
 411
 412         const_iterator it = this->seq.begin();
 413         advance(it, i);
 414         return *it;
 415 }
 416
 417 template <template <class> class C>
 418 ex & container<C>::let_op(size_t i)
 419 {
 420         GINAC_ASSERT(i < nops());
 421
 422         ensure_if_modifiable();
 423         typename STLT::iterator it = this->seq.begin();
 424         advance(it, i);
 425         return *it;
 426 }
 427
 428 template <template <class> class C>
 429 ex container<C>::eval(int level) const
 430 {
 431         if (level == 1)
 432                 return hold();
 433         else
 434                 return thiscontainer(evalchildren(level));
 435 }
 436
 437 template <template <class> class C>
 438 ex container<C>::subs(const exmap & m, unsigned options) const
 439 {
 440         std::auto_ptr<STLT> vp = subschildren(m, options);
 441         if (vp.get())
 442                 return ex_to<basic>(thiscontainer(vp)).subs_one_level(m, options);
 443         else
 444                 return subs_one_level(m, options);
 445 }
 446
 447 /** Compare two containers of the same type. */
 448 template <template <class> class C>
 449 int container<C>::compare_same_type(const basic & other) const
 450 {
 451         GINAC_ASSERT(is_a<container>(other));
 452         const container & o = static_cast<const container &>(other);
 453
 454         const_iterator it1 = this->seq.begin(), it1end = this->seq.end(),
 455                        it2 = o.seq.begin(), it2end = o.seq.end();
 456
 457         while (it1 != it1end && it2 != it2end) {
 458                 int cmpval = it1->compare(*it2);
 459                 if (cmpval)
 460                         return cmpval;
 461                 ++it1; ++it2;
 462         }
 463
 464         return (it1 == it1end) ? (it2 == it2end ? 0 : -1) : 1;
 465 }
 466
 467 template <template <class> class C>
 468 bool container<C>::is_equal_same_type(const basic & other) const
 469 {
 470         GINAC_ASSERT(is_a<container>(other));
 471         const container & o = static_cast<const container &>(other);
 472
 473         if (this->seq.size() != o.seq.size())
 474                 return false;
 475
 476         const_iterator it1 = this->seq.begin(), it1end = this->seq.end(), it2 = o.seq.begin();
 477         while (it1 != it1end) {
 478                 if (!it1->is_equal(*it2))
 479                         return false;
 480                 ++it1; ++it2;
 481         }
 482
 483         return true;
 484 }
 485
 486 /** Add element at front. */
 487 template <template <class> class C>
 488 container<C> & container<C>::prepend(const ex & b)
 489 {
 490         ensure_if_modifiable();
 491         this->seq.push_front(b);
 492         return *this;
 493 }
 494
 495 /** Add element at back. */
 496 template <template <class> class C>
 497 container<C> & container<C>::append(const ex & b)
 498 {
 499         ensure_if_modifiable();
 500         this->seq.push_back(b);
 501         return *this;
 502 }
 503
 504 /** Remove first element. */
 505 template <template <class> class C>
 506 container<C> & container<C>::remove_first()
 507 {
 508         ensure_if_modifiable();
 509         this->seq.pop_front();
 510         return *this;
 511 }
 512
 513 /** Remove last element. */
 514 template <template <class> class C>
 515 container<C> & container<C>::remove_last()
 516 {
 517         ensure_if_modifiable();
 518         this->seq.pop_back();
 519         return *this;
 520 }
 521
 522 /** Remove all elements. */
 523 template <template <class> class C>
 524 container<C> & container<C>::remove_all()
 525 {
 526         ensure_if_modifiable();
 527         this->seq.clear();
 528         return *this;
 529 }
 530
 531 /** Sort elements. */
 532 template <template <class> class C>
 533 container<C> & container<C>::sort()
 534 {
 535         ensure_if_modifiable();
 536         sort_(typename std::iterator_traits<typename STLT::iterator>::iterator_category());
 537         return *this;
 538 }
 539
 540 /** Specialization of container::unique_() for std::list. */
 541 inline void container<std::list>::unique_()
 542 {
 543         this->seq.unique(ex_is_equal());
 544 }
 545
 546 /** Remove adjacent duplicate elements. */
 547 template <template <class> class C>
 548 container<C> & container<C>::unique()
 549 {
 550         ensure_if_modifiable();
 551         unique_();
 552         return *this;
 553 }
 554
 555 /** Print sequence of contained elements. */
 556 template <template <class> class C>
 557 void container<C>::printseq(const print_context & c, char openbracket, char delim,
 558                             char closebracket, unsigned this_precedence,
 559                             unsigned upper_precedence) const
 560 {
 561         if (this_precedence <= upper_precedence)
 562                 c.s << openbracket;
 563
 564         if (!this->seq.empty()) {
 565                 const_iterator it = this->seq.begin(), itend = this->seq.end();
 566                 --itend;
 567                 while (it != itend) {
 568                         it->print(c, this_precedence);
 569                         c.s << delim;
 570                         ++it;
 571                 }
 572                 it->print(c, this_precedence);
 573         }
 574
 575         if (this_precedence <= upper_precedence)
 576                 c.s << closebracket;
 577 }
 578
 579 template <template <class> class C>
 580 typename container<C>::STLT container<C>::evalchildren(int level) const
 581 {
 582         if (level == 1)
 583                 return this->seq;
 584         else if (level == -max_recursion_level)
 585                 throw std::runtime_error("max recursion level reached");
 586
 587         STLT s;
 588         reserve(s, this->seq.size());
 589
 590         --level;
 591         const_iterator it = this->seq.begin(), itend = this->seq.end();
 592         while (it != itend) {
 593                 s.push_back(it->eval(level));
 594                 ++it;
 595         }
 596
 597         return s;
 598 }
 599
 600 template <template <class> class C>
 601 std::auto_ptr<typename container<C>::STLT> container<C>::subschildren(const exmap & m, unsigned options) const
 602 {
 603         // returns a NULL pointer if nothing had to be substituted
 604         // returns a pointer to a newly created epvector otherwise
 605         // (and relinquishes responsibility for the epvector)
 606
 607         const_iterator cit = this->seq.begin(), end = this->seq.end();
 608         while (cit != end) {
 609                 const ex & subsed_ex = cit->subs(m, options);
 610                 if (!are_ex_trivially_equal(*cit, subsed_ex)) {
 611
 612                         // copy first part of seq which hasn't changed
 613                         std::auto_ptr<STLT> s(new STLT(this->seq.begin(), cit));
 614                         reserve(*s, this->seq.size());
 615
 616                         // insert changed element
 617                         s->push_back(subsed_ex);
 618                         ++cit;
 619
 620                         // copy rest
 621                         while (cit != end) {
 622                                 s->push_back(cit->subs(m, options));
 623                                 ++cit;
 624                         }
 625
 626                         return s;
 627                 }
 628
 629                 ++cit;
 630         }
 631
 632         return std::auto_ptr<STLT>(0); // nothing has changed
 633 }
 634
 635 } // namespace GiNaC
 636
 637 #endif // ndef __GINAC_CONTAINER_H__