This file is indexed.

/usr/include/CGAL/Polychain_2.h is in libcgal-dev 4.7-4.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
// Copyright (c) 2015  Università della Svizzera italiana.
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org).
// You can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation,
// either version 3 of the License, or (at your option) any later version.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
// 
//
// Author(s)     : Panagiotis Cheilaris, Sandeep Kumar Dey, Evanthia Papadopoulou
//philaris@gmail.com, sandeep.kr.dey@gmail.com, evanthia.papadopoulou@usi.ch

#ifndef CGAL_POLYCHAIN_2_H
#define CGAL_POLYCHAIN_2_H

#include <CGAL/basic.h>
#include <CGAL/Polygon_2.h>
#include <CGAL/intersections.h>


// Polychainsegment_2

namespace CGAL {

namespace Qt {
  template <typename K> class PainterOstream;
}

template <class Traits_P, class Container_P
        = std::vector<typename Traits_P::Point_2> >
class Polychainsegment_2 : public Polygon_2<Traits_P, Container_P> {

  public:
    typedef Traits_P Traits;
    typedef Polygon_2<Traits_P, Container_P> Base;

    // constructors

    Polychainsegment_2() : Base() {}

    Polychainsegment_2(
        const Polychainsegment_2<Traits_P,Container_P>& pc)
      : Base((Base) pc) {}

    template <class InputIterator>
    Polychainsegment_2(InputIterator first, InputIterator last,
                       Traits p_traits = Traits())
        : Base(first, last, p_traits)  {}


    template< class K >
    void draw(CGAL::Qt::PainterOstream<K>& stream) const {
      typedef typename K::Segment_2 K_Segment_2;
      typedef typename Polychainsegment_2<
                        Traits_P,Container_P>::Vertex_const_iterator
              VI;

      if (this->size() > 1) {
        VI source = this->vertices_begin();
        VI target = source+1;
        for( ; target!=this->vertices_end(); ++source, ++target)
        {
          stream << K_Segment_2(*source, *target);
        }
      }
    }

    template< class Stream >
    void draw(Stream & str) const
    {
      typedef typename Traits_P::Segment_2 Segment_2;
      typedef typename Polychainsegment_2<
                        Traits_P,Container_P>::Vertex_const_iterator
              VI;
      if (this->size() > 1) {
        VI source = this->vertices_begin();
        VI target = source+1;
        for( ; target!=this->vertices_end(); ++source, ++target)
        {
          str << Segment_2(*source, *target);
        }
      }
    }

} ;




template <class Traits_P, class Container_P>
std::ostream&
operator<<(std::ostream &os,
           const Polychainsegment_2<Traits_P,Container_P>& p)
{
  typename Polychainsegment_2<Traits_P,Container_P>
              ::Vertex_const_iterator
           i;

  switch(os.iword(IO::mode)) {
    case IO::ASCII :
      os << p.size() << ' ';
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << *i << ' ';
      }
      return os;

    case IO::BINARY :
      os << p.size();
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << *i;
      }
      return os;

    default:
      os << "Polychainsegment_2(" << std::endl;
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << "  " << *i << std::endl;
      }
      os << ")" << std::endl;
      return os;
  }
}





/* the following not allowed in some compilers: */
/*
template< class Stream,
          class Traits_P,
          class Container_P = std::vector<typename Traits_P::Point_2>
        >
inline
Stream& operator<<(Stream &s,
                   const Polychainsegment_2 <Traits_P, Container_P> &P)
{
  P.draw(s);
  return s;
}
*/


/* instead, we use overloading */

/*
template< class Stream,
          class Traits_P
        >
inline
Stream& operator<<(Stream &s,
                   const Polychainsegment_2 <Traits_P> &P)
{
  P.draw(s);
  return s;
}


template< class Stream,
          class Traits_P,
          class Container_P
        >
inline
Stream& operator<<(Stream &s,
                   const Polychainsegment_2 <Traits_P, Container_P> &P)
{
  P.draw(s);
  return s;
}
*/



// Polychainray_2

template <class Traits_P, class Container_P
        = std::vector<typename Traits_P::Point_2> >
class Polychainray_2 :
  public Polychainsegment_2<Traits_P, Container_P> {

public:
    typedef Traits_P Traits;

private:
    typedef typename Traits_P::Direction_2 OutgoingDirection;
    typedef Polychainsegment_2<Traits_P, Container_P> Base;

    OutgoingDirection outgoing;

public:

    // constructors

    Polychainray_2(): Base(), outgoing() {}

    Polychainray_2(const Polychainray_2<Traits_P,Container_P>& pcr)
      : Base((Base) pcr), outgoing(pcr.outgoing) {}

    template <class InputIterator>
    Polychainray_2(InputIterator first, InputIterator last,
	           OutgoingDirection d,
              Traits p_traits = Traits())
        : Base(first, last, p_traits), outgoing(d)
    {
    }


    // get_outgoing

    OutgoingDirection get_outgoing() const {
	return outgoing;
    }


    // drawing

    template< class K >
    void draw(CGAL::Qt::PainterOstream<K>& stream) const {
      typedef typename K::Segment_2 K_Segment_2;
      typedef typename K::Ray_2 K_Ray_2;
      typedef typename
	  Polychainray_2<Traits_P,Container_P>::Vertex_const_iterator VI;

      CGAL_assertion( this->size() > 0 );

      VI source = this->vertices_begin();
      if (this->size() > 1) {
        VI target = source+1;
        for( ; target!=this->vertices_end(); ++source, ++target)
        {
          stream << K_Segment_2(*source, *target);
        }
      }
      // now source contains the last point;
      // draw outgoing ray from this point
      stream << K_Ray_2(*source, this->get_outgoing());
    }

    template< class Stream >
    void draw(Stream & stream) const {
      typedef typename Traits_P::Segment_2 Segment_2;
      typedef typename Traits_P::Ray_2 Ray_2;
      typedef typename
	  Polychainray_2<Traits_P,Container_P>::Vertex_const_iterator VI;

      CGAL_assertion( this->size() > 0 );

      VI source = this->vertices_begin();
      if (this->size() > 1) {
        VI target = source+1;
        for( ; target!=this->vertices_end(); ++source, ++target)
        {
          stream << Segment_2(*source, *target);
        }
      }
      // now source contains the last point;
      // draw outgoing ray from this point
      stream << Ray_2(*source, this->get_outgoing());
    }


} ;


template <class Traits_P, class Container_P>
std::ostream&
operator<<(std::ostream &os,
           const Polychainray_2<Traits_P,Container_P>& p)
{
  typename Polychainray_2<Traits_P,Container_P>::Vertex_const_iterator i;

  switch(os.iword(IO::mode)) {
    case IO::ASCII :
      os << p.size() << ' ';
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << *i << ' ';
      }
      os << ", dout=" << p.get_outgoing() << ' ';
      return os;

    case IO::BINARY :
      os << p.size();
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << *i;
      }
      os << p.get_outgoing();
      return os;

    default:
      os << "Polychainray_2(" << std::endl;
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << "  " << *i << std::endl;
      }
      os << "dout=" << p.get_outgoing() << std::endl;
      os << ")" << std::endl;
      return os;
  }
}





/*
template< class Stream,
          class Traits_P
        >
inline
Stream& operator<<(Stream &s,
                   const Polychainray_2 <Traits_P> &P)
{
  P.draw(s);
  return s;
}


template< class Stream,
          class Traits_P,
          class Container_P
        >
inline
Stream& operator<<(Stream &s,
                   const Polychainray_2 <Traits_P, Container_P> &P)
{
  P.draw(s);
  return s;
}
*/



// Polychainline_2

template <class Traits_P, class Container_P
        = std::vector<typename Traits_P::Point_2> >
class Polychainline_2 : public Polychainray_2<Traits_P, Container_P> {

public:

private:
    typedef Traits_P Traits;
    typedef typename Traits_P::Direction_2 IncomingDirection;
    typedef typename Traits_P::Direction_2 OutgoingDirection;
    typedef typename Traits_P::Line_2      Line_2;
    typedef typename Traits_P::Ray_2       Ray_2;
    typedef typename Traits_P::Segment_2   Segment_2;
    typedef typename Traits_P::Point_2     Point_2;
    typedef Polychainray_2<Traits_P, Container_P>  Base;
    typedef Polychainline_2<Traits_P, Container_P> Self;

    IncomingDirection incoming;
    bool is_line_optimization;

public:

    // constructors

    Polychainline_2() : Base(), incoming(),
      is_line_optimization(false)
    {}

    Polychainline_2(const Self& pcl)
      : Base((Base) pcl), incoming(pcl.incoming),
        is_line_optimization(pcl.is_line_optimization)
    {}

    template <class InputIterator>
    Polychainline_2(IncomingDirection dinc,
	            InputIterator first, InputIterator last,
	            OutgoingDirection dout,
                    Traits p_traits = Traits())
        : Base(first, last, dout, p_traits), incoming(dinc),
          is_line_optimization(false)
    {
    }

    void set_line_optimization() {
      CGAL_assertion(this->size() == 1);
      CGAL_assertion(this->incoming == - this->get_outgoing());
      is_line_optimization = true;
    }

    // get_incoming

    IncomingDirection get_incoming() const {
	return incoming;
    }


    // unary minus operator
    // that reverses the orientation of the polychainline

    Self
    operator-() const {
      // first reverse list of points of polychainline

      std::vector<typename Traits_P::Point_2> reverse;

      unsigned int npts = this->size();

      CGAL_SDG_DEBUG(std::cout << "pcl_reverse npts="
          << npts << std::endl;);

      reverse.resize(npts);

      //std::reverse_copy(this->vertices_begin(),
      //                  this->vertices_end(),
      //                  reverse);

      typedef typename Polychainline_2<
                        Traits_P,Container_P>::Vertex_const_iterator
              VI;

      unsigned int i = npts - 1;

      for (VI vi = this->vertices_begin();
              vi != this->vertices_end();
              ++vi)
      {
        //CGAL_SDG_DEBUG(std::cout << "debug pcl_reverse setting at " << i
        //          << " value " << *vi << std::endl;);
        reverse[i] = *vi;
        --i;
      }


      // then also swap incoming and outgoing directions

      //return Self(this->get_outgoing(),
      //            reverse.begin(),
      //            reverse.end(),
      //            this->get_incoming());

      Self pclreverse(this->get_outgoing(),
                      reverse.begin(),
                      reverse.end(),
                      this->get_incoming());

      if (is_line_optimization) {
        pclreverse.set_line_optimization();
      }

      return pclreverse;
    }

    // line_first_intersection_point_with
    typename Traits_P::Point_2
    line_first_intersection_point_with(
        const Polychainline_2<Traits_P,Container_P>& pcl)
    {
      CGAL_assertion(is_line_optimization);
      Line_2 line((*this)[0], this->get_outgoing());

      typedef typename
	  Polychainline_2<Traits_P,Container_P>::
                     Vertex_const_iterator
          VI;

      CGAL::Object result;

      VI sourcepcl  = pcl.vertices_begin();
      Ray_2 rayincpcl (*sourcepcl,  pcl.get_incoming());
      result = CGAL::intersection(line, rayincpcl);
      if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
        return *ipoint;
      }

      if (pcl.size() > 1) {
        VI targetpcl = sourcepcl+1;
        for( ;
            targetpcl != pcl.vertices_end();
            ++sourcepcl, ++targetpcl)
        {
          Segment_2 testseg(*sourcepcl, *targetpcl);
          result = CGAL::intersection(line, testseg);
          if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
            return *ipoint;
          }
        }
      }
      Ray_2 rayoutpcl(*sourcepcl, pcl.get_outgoing());
      result = CGAL::intersection(line, rayoutpcl);
      if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
        return *ipoint;
      }

      CGAL_SDG_DEBUG(std::cout
          << "debug error: no intersection found for "
          << "this=" << *this << " pcl=" << pcl << std::endl;);

      CGAL_assertion(false);

      return Point_2();

    } // end of line_first_intersection_point_with

    // first_intersection_point_with
    typename Traits_P::Point_2
    first_intersection_point_with(
        const Polychainline_2<Traits_P,Container_P>& pcl)
    {
      // for every piece of object,
      // try intersecting with every piece of pcl

      CGAL_SDG_DEBUG(std::cout
          << "debug first_intersection entering this="
          << *this << " pcl=" << pcl << std::endl;);

      typedef typename
	  Polychainline_2<Traits_P,Container_P>::
                     Vertex_const_iterator
          VI;

      typedef typename std::vector<typename Traits_P::Segment_2>::
               const_iterator SI;

      CGAL_assertion( this->size() > 0 );
      CGAL_assertion( pcl.size() > 0 );

      if (this->is_line_optimization) {
        return line_first_intersection_point_with(pcl);
      }

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
          << "creating empty vectors" << std::endl;);
#endif

      // create two empty vectors for storing the segments
      std::vector<Segment_2> segmentsthis;
      std::vector<Segment_2> segmentspcl;

      VI sourcethis = this->vertices_begin();
      Ray_2 rayincthis(*sourcethis, this->get_incoming());
      if (this->size() > 1) {
        VI targetthis = sourcethis+1;
        for( ;
            targetthis != this->vertices_end();
            ++sourcethis, ++targetthis)
        {
          segmentsthis.push_back(Segment_2(*sourcethis, *targetthis));
        }
      }
      Ray_2 rayoutthis(*sourcethis, this->get_outgoing());

      CGAL_assertion(this->size() == (segmentsthis.size() + 1));

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                     << "segmentsthis computed" << std::endl;);
#endif


      VI sourcepcl  = pcl.vertices_begin();
      Ray_2 rayincpcl (*sourcepcl,  pcl.get_incoming());
      if (pcl.size() > 1) {
        VI targetpcl = sourcepcl+1;
        for( ;
            targetpcl != pcl.vertices_end();
            ++sourcepcl, ++targetpcl)
        {
          segmentspcl.push_back(Segment_2(*sourcepcl, *targetpcl));
        }
      }
      Ray_2 rayoutpcl(*sourcepcl, pcl.get_outgoing());

      CGAL_assertion(pcl.size() == (segmentspcl.size() + 1));

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                     << "segmentspcl computed" << std::endl;);
#endif


      CGAL::Object result;

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                    << "trying rayincthis with pcl" << std::endl;);
#endif

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                << "trying ray " << rayincthis
                     << " with ray " << rayincpcl << std::endl;);
#endif

      result = CGAL::intersection(rayincthis, rayincpcl);
      if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
        return *ipoint;
      }

      for (SI sipcl = segmentspcl.begin();
              sipcl != segmentspcl.end();
              ++sipcl) {
#if 0
        CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                << "trying ray " << rayincthis
                       << " with segment " << *sipcl << std::endl;);
#endif

        result = CGAL::intersection(rayincthis, *sipcl);
        if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
          return *ipoint;
        }
      }

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                << "trying ray " << rayincthis
                     << " with ray " << rayoutpcl << std::endl;);
#endif

      result = CGAL::intersection(rayincthis, rayoutpcl);
      if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
        return *ipoint;
      }

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                     << "trying segmentsthis with pcl" << std::endl;);
#endif

      for (SI sithis = segmentsthis.begin();
              sithis != segmentsthis.end();
              ++sithis) {

#if 0
        CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                << "trying segment " << *sithis
                       << " with ray " << rayincpcl << std::endl;);
#endif

        result = CGAL::intersection(*sithis, rayincpcl);
        if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
          return *ipoint;
        }

        for (SI sipcl = segmentspcl.begin();
            sipcl != segmentspcl.end();
            ++sipcl) {
#if 0
          CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                << "trying segment " << *sithis
                         << " with segment " << *sipcl << std::endl;);
#endif

          result = CGAL::intersection(*sithis, *sipcl);
          if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result))
          {
            return *ipoint;
          }
        }

#if 0
        CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
            << "trying segment " << *sithis
            << " with ray " << rayoutpcl << std::endl;);
#endif

        result = CGAL::intersection(*sithis, rayoutpcl);
        if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
          return *ipoint;
        }

      }

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                     << "trying rayoutthis with pcl" << std::endl;);
#endif

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                << "trying ray " << rayoutthis
                     << " with ray " << rayincpcl << std::endl;);
#endif

      result = CGAL::intersection(rayoutthis, rayincpcl);
      if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
        return *ipoint;
      }

      for (SI sipcl = segmentspcl.begin();
              sipcl != segmentspcl.end();
              ++sipcl) {
#if 0
        CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                << "trying ray " << rayoutthis
                       << " with segment " << *sipcl << std::endl;);
#endif

        result = CGAL::intersection(rayoutthis, *sipcl);
        if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
          return *ipoint;
        }
      }

#if 0
      CGAL_SDG_DEBUG(std::cout << "debug first_intersection "
                << "trying ray " << rayoutthis
                     << " with ray " << rayoutpcl << std::endl;);
#endif

      result = CGAL::intersection(rayoutthis, rayoutpcl);
      if (const Point_2 *ipoint = CGAL::object_cast<Point_2>(&result)) {
        return *ipoint;
      }

      CGAL_SDG_DEBUG(std::cout
          << "debug error: no intersection found for "
          << "this=" << *this << " pcl=" << pcl << std::endl;);

      CGAL_assertion(false);

      // philaris: added to avoid complaining from some compilers

      return Point_2();

    }


    // drawing

    template< class K >
    void draw(CGAL::Qt::PainterOstream<K>& stream) const {
      typedef typename K::Segment_2 K_Segment_2;
      typedef typename K::Ray_2 K_Ray_2;
      typedef typename
	  Polychainline_2<Traits_P,Container_P>::Vertex_const_iterator VI;

      CGAL_assertion( this->size() > 0 );

      VI source = this->vertices_begin();

      // draw outgoing ray from first point
      stream << K_Ray_2(*source, this->get_incoming());

      if (this->size() > 1) {
        VI target = source+1;
        for( ; target!=this->vertices_end(); ++source, ++target)
        {
          stream << K_Segment_2(*source, *target);
        }
      }

      // now source contains the last point;
      // draw outgoing ray from this point
      stream << K_Ray_2(*source, this->get_outgoing());
    }

    template< class Stream >
    void draw(Stream & stream) const {
      typedef typename
	  Polychainline_2<Traits_P,Container_P>::Vertex_const_iterator VI;

      CGAL_assertion( this->size() > 0 );

      VI source = this->vertices_begin();

      // draw outgoing ray from first point
      stream << Ray_2(*source, this->get_incoming());

      if (this->size() > 1) {
        VI target = source+1;
        for( ; target!=this->vertices_end(); ++source, ++target)
        {
          stream << Segment_2(*source, *target);
        }
      }

      // now source contains the last point;
      // draw outgoing ray from this point
      stream << Ray_2(*source, this->get_outgoing());
    }

} ;



template <class Traits_P, class Container_P>
std::ostream&
operator<<(std::ostream &os,
           const Polychainline_2<Traits_P,Container_P>& p)
{
  typename Polychainline_2<Traits_P,Container_P>::Vertex_const_iterator i;

  switch(os.iword(IO::mode)) {
    case IO::ASCII :
      os << p.size() << ' ';
      os << ", dinc=" << p.get_incoming() << ", ";
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << *i << ' ';
      }
      os << ", dout=" << p.get_outgoing() << ' ';
      return os;

    case IO::BINARY :
      os << p.size();
      os << p.get_incoming();
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << *i;
      }
      os << p.get_outgoing();
      return os;

    default:
      os << "Polychainline_2(" << std::endl;
      os << "dinc=" << p.get_incoming() << std::endl;
      for (i = p.vertices_begin(); i != p.vertices_end(); ++i) {
        os << "  " << *i << std::endl;
      }
      os << "dout=" << p.get_outgoing() << std::endl;
      os << ")" << std::endl;
      return os;
  }
}


/*
template< class Stream,
          class Traits_P
        >
inline
Stream& operator<<(Stream &s,
                   const Polychainline_2 <Traits_P> &P)
{
  P.draw(s);
  return s;
}


template< class Stream,
          class Traits_P,
          class Container_P
        >
inline
Stream& operator<<(Stream &s,
                   const Polychainline_2 <Traits_P, Container_P> &P)
{
  P.draw(s);
  return s;
}
*/



} //namespace CGAL

#endif // CGAL_POLYCHAIN_2_H