This file is indexed.

/usr/include/libabigail/abg-diff-utils.h is in libabigail-dev 1.0~rc6-1.

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
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
// -*- Mode: C++ -*-
//
// Copyright (C) 2013-2015 Red Hat, Inc.
//
// This file is part of the GNU Application Binary Interface Generic
// Analysis and Instrumentation Library (libabigail).  This library is
// free software; you can redistribute it and/or modify it under the
// terms of the GNU Lesser General Public License as published by the
// Free Software Foundation; either version 3, or (at your option) any
// later version.

// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Lesser Public License for more details.

// You should have received a copy of the GNU Lesser General Public
// License along with this program; see the file COPYING-LGPLV3.  If
// not, see <http://www.gnu.org/licenses/>.

/// @file
///
/// This file declares types and operations implementing the "O(ND)
/// Difference Algorithm" (aka diff2) from Eugene W. Myers, to compute
/// the difference between two sequences.
///
/// To understand what is going on here, one must read the paper at
/// http://www.xmailserver.org/diff2.pdf.  Throughout this file, that
/// paper is referred to as "the paper".
///
/// The implementations goes as far as calculating the shortest edit
/// script (the set of insertions and deletions) for transforming a
/// sequence into another.  The main entry point for that is the
/// compute_diff() function.

#ifndef __ABG_DIFF_UTILS_H__
#define __ABG_DIFF_UTILS_H__

#include <stdexcept>
#include <cassert>
#include <cstdlib>
#include <ostream>
#include <string>
#include <vector>
#include <sstream>
#include <tr1/memory>

namespace abigail
{

/// @brief Libabigail's core diffing algorithms
///
/// This is the namespace defining the core diffing algorithm used by
/// libabigail @ref comparison tools.  This based on the diff
/// algorithm from Eugene Myers.
namespace diff_utils
{

using std::tr1::shared_ptr;

// Inject the names from std:: below into this namespace
using std::string;
using std::ostream;
using std::vector;
using std::abs;
using std::ostringstream;

/// A class representing a vertex in an edit graph, as explained in
/// the paper.  A vertex is a basically a pair of coordinates
/// (abscissa and ordinate).
class point
{
  int x_;
  int y_;
  bool empty_;

public:

  point()
    : x_(-1), y_(-1),empty_(true)
  {}

  point(int x, int y)
    : x_(x), y_(y), empty_(false)
  {}

  point(const point& p)
    : x_(p.x()), y_(p.y()), empty_(p.is_empty())
  {}

  int
  x() const
  {return x_;}

  void
  x(int x)
  {
    x_ = x;
    empty_ = false;
  }

  int
  y() const
  {return y_;}

  void
  y(int y)
  {
    y_ = y;
    empty_ = false;
  }

  void
  set(int x, int y)
  {
    x_ = x;
    y_ = y;
    empty_ = false;
  }

  void
  set(int x, int y, bool empty)
  {
    x_ = x;
    y_ = y;
    empty_ = empty;
  }

  void
  add(int ax, int ay)
  {set (x() + ax, y() + ay);}

  bool
  operator!=(const point& o) const
  {return (x() != o.x() || y() != o.y() || is_empty() != o.is_empty());}

  bool
  operator==(const point& o) const
  {return !(operator!=(o));}

  bool
  operator<(const point& o) const
  {return (x() < o.x() && y() < o.y());}

  bool
  operator>(const point& o) const
  {return (x() > o.x() && y() > o.y());}

  bool
  operator<=(const point& o) const
  {return (x() <= o.x() && y() <= o.y());}

  bool
  operator>=(const point& o) const
  {return (x() >= o.x() && y() >= o.y());}

  point
  operator+(int val) const
  {return point(x() + val, y() + val);}

  point
  operator-(int val) const
  {return point(x() - val, y() - val);}

  point&
  operator+= (int val)
  {
    set(x_ + val, y_ + val);
    return *this;
  }

  point&
  operator-= (int val)
  {return (*this) += (-val);}

  point&
  operator--()
  {return (*this) -= 1;}

  point&
  operator++()
  {return (*this) += 1;}

  point
  operator--(int)
  {
    point tmp(*this);
    (*this)--;
    return tmp;
  }

  point
  operator++(int)
  {
    point tmp(*this);
    (*this)++;
    return tmp;
  }

  point&
  operator=(int val)
  {
    set(val, val);
    return *this;
  }

  point&
  operator=(const point& p)
  {
    set(p.x(), p.y(), p.is_empty());
    return *this;
  }

  bool
  is_empty() const
  {return empty_;}

  operator bool () const
  {return !is_empty();}

  bool
  operator!() const
  {return is_empty();}

  void
  clear()
  {
    x_ = -1;
    y_ = -1;
    empty_ = true;
  }
};// end point

/// The abstraction of the Snake concept, from the paper.
///
/// In a given path from the edit graph, a snake is a non-diagonal
/// edge followed by zero or more diagonal edges.
///
/// The starting poing of the non-diagonal edge is the beginning of
/// the snake.  This is given by the snake::begin() method.  This point
/// is not explicitely referenced in the paper, but we need it for
/// some grunt implementation details of the algorithm.
///
/// The end point of the non-diagonal edge is the intermediate point
/// of the snake; it's given by the snake::intermediate() method.
/// This point is what is referred to as "the begining of the snake"
/// in the paper.
///
/// The end point of the first diagonal edge is given by the
/// snake::diagonal_start() method.
///
/// The end point of the last diagonal edge is given by the
/// snake::end() method.  Note that when the snake contains no
/// diagonal edge, snake::intermediate(), and snake::end() return the
/// same point; snake::diagonal_start() contains an empty point (i.e,
/// a point for which point::is_empty() returns true).
class snake
{
  point begin_, intermediate_, diagonal_start_, end_;
  bool forward_;

public:

  /// Default constructor for snake.
  snake()
    : forward_(false)
  {}

  /// Constructor from the beginning, intermediate and end points.
  ///
  /// @param b the beginning point of the snake.  That is, the
  /// starting point of the non-diagonal edge.
  ///
  /// @param i the intermediate point of the snake.  That is, the end
  /// point of the non-diagonal edge.
  ///
  /// @param e the end point of the snake.  That is the end point of
  /// the last diagonal edge.
  snake(const point& b,
	const point& i,
	const point& e)
    : begin_(b), intermediate_(i),
      end_(e), forward_(false)
  {}

  /// Constructor from the beginning, intermediate and end points.
  ///
  /// @param b the beginning point of the snake.  That is, the
  /// starting point of the non-diagonal edge.
  ///
  /// @param i the intermediate point of the snake.  That is, the end
  /// point of the non-diagonal edge.
  ///
  /// @param d the beginning of the diagonal edge.  That is the end of
  /// the first diagonal edge of the snake.
  ///
  /// @param e the end point of the snake.  That is the end point of
  /// the last diagonal edge.
  snake(const point& b,
	const point& i,
	const point& d,
	const point& e)
    : begin_(b), intermediate_(i),
      diagonal_start_(d), end_(e),
      forward_(false)
  {}

  /// Getter for the starting point of the non-diagonal edge of the
  /// snake.
  ///
  /// @return the starting point of the non-diagonal edge of the snake
  const point&
  begin() const
  {return begin_;}

  /// Getter for the starting point of the non-diagonal edge of the
  /// snake, aka begin point.
  ///
  ///@param p the new begin point.
  void
  begin(const point& p)
  {begin_ = p;}

  /// Getter for the end point of the non-diagonal edge of the snake.
  ///
  /// @return the end point of the non-diagonal edge of the snake
  const point&
  intermediate() const
  {return intermediate_;}

  /// Setter for the end point of the non-diagonal edge of the snake,
  /// aka intermediate point.
  ///
  /// @param p the new intermediate point.
  void
  intermediate(const point& p)
  {intermediate_ = p;}

  /// Getter for the end point of the first diagonal edge, aka
  /// diagonal start point.  Note that if the snake has no diagonal
  /// edge, this point is empty.
  ///
  /// @return the end point of the first diagonal edge.
  const point&
  diagonal_start() const
  {return diagonal_start_;}

  /// Setter for the end point of the first diagonal edge, aka
  /// diagonal start point.
  ///
  /// @param p the new diagonal start.d
  void
  diagonal_start(const point& p)
  {diagonal_start_ = p;}

  /// Getter for the end point of the last diagonal edge, aka snake
  /// end point.  Note that if the snake has no diagonal edge, this
  /// point is equal to the intermediate point.
  ///
  /// @return the end point of the last diagonal edge
  const point&
  end() const
  {return end_;}

  /// Setter for the end point of the last diagonal edge, aka snake
  /// end point.  Note that if the snake has no diagonal edge, this
  /// point is equal to the intermediate point.
  void
  end(const point& p)
  {end_ = p;}

  /// Setter for the begin, intermediate and end points of the snake.
  ///
  /// @param b the new snake begin point
  ///
  /// @param i the new snake intermediate point
  ///
  /// @param e the new snake end point
  void
  set(const point& b, const point&i, const point&e)
  {
    begin(b);
    intermediate(i);
    end(e);
  }

  /// Setter for the begin, intermediate, diagonal start and end points
  /// of the snake.
  ///
  /// @param b the new snake begin point
  ///
  /// @param i the new snake intermediate point
  ///
  /// @param d the new diagonal start point
  ///
  /// @param e the new snake end point
  void
  set(const point& b, const point&i, const point& d, const point&e)
  {
    begin(b);
    intermediate(i);
    diagonal_start(d);
    end(e);
  }

  /// @return true iff the snake is a forward snake.  That is, if it
  /// was built while walking the edit graph going forward (from the
  /// top left corner to the right bottom corner.
  bool
  is_forward() const
  {return forward_;}

  /// Set to true if the snake is a forward snake; that is, if it was
  /// built while walking the edit graph going forward (from the top
  /// left corner to the right bottom corner.  Set to false otherwise.
  ///
  /// @param f whether the snake is a forward snake or not.
  void
  set_forward(bool f)
  {forward_ = f;}

  /// Add an offset to the abscissas of the points of the snake, and
  /// add another offset to the ordinates of these same points.
  ///
  /// @param x_offset the offset to add to the abscissas of all the
  /// points of the snake.
  ///
  /// @param y_offset the offset to add to the ordinates of all the
  /// points of the snake.
  void
  add(int x_offset, int y_offset)
  {
    if (is_empty())
      return;

    begin_.add(x_offset, y_offset);
    intermediate_.add(x_offset, y_offset);
    if (diagonal_start_)
      diagonal_start_.add(x_offset, y_offset);
    end_.add(x_offset, y_offset);
  }

  /// @return true iff the snake has at least one diagonal edge.
  bool
  has_diagonal_edge() const
  {return !diagonal_start().is_empty();}

  /// @return true iff the non-diagonal edge is horizontal.
  bool
  has_horizontal_edge() const
  {return (begin().y() == intermediate().y());}

  /// @return true iff the non-diagonal edge is vertical.
  bool
  has_vertical_edge() const
  {return (begin().x() == intermediate().x());}

  /// @return true iff the snake is empty, that is, if all the points
  /// it contains are empty.
  bool is_empty() const
  {return begin().is_empty() && intermediate().is_empty() && end().is_empty();}
};// end class snake

/// The array containing the furthest D-path end-points, for each value
/// of K.  MAX_D is the maximum value of the D-Path.  That is, M+N if
/// M is the size of the first input string, and N is the size of the
/// second.
class d_path_vec : public std::vector<int>
{
private:

  unsigned a_size_;
  unsigned b_size_;

  /// Forbid vector size modifications
  void
  push_back(const vector<int>::value_type&);

  /// Forbid default constructor.
  d_path_vec();

  bool
  over_bounds(long long index) const
  {return  (index + offset()) >= (long long) size();}

  void
  check_index_against_bound(int index) const
  {
    if (over_bounds(index))
      {
	ostringstream o;
	o << "index '" << index
	  << "' out of range [-" << max_d() << ", " << max_d() << "]";
	throw std::out_of_range(o.str());
      }
  }

public:

  /// Constructor of the d_path_vec.
  ///
  /// For forward vectors, the underlying vector allocates 2 *
  /// [MAX_D+1].
  /// space, so that one can address elements in the index range
  /// [-MAX_D, MAX_D].  And MAX_D is the sum of the two sequence
  /// sizes. delta is the difference.
  ///
  /// For reverse vectors, note that we need to be able to address
  /// [-MAX_D - delta, MAX_D + delta], with delta being the (signed)
  /// difference between the size of the two sequences.  We consider
  /// delta being bounded by MAX_D itself; so we say we need to be
  /// able to address [-2MAX_D, 2MAX_D].
  ///
  /// @param size1 the size of the first sequence we are interested
  /// in.
  ///
  /// @param size2 the size of the second sequence we are interested
  /// in.
  d_path_vec(unsigned size1, unsigned size2)
    : vector<int>(2 * (size1 + size2 + 1 + (size1 + size2)) + 1, 0),
      a_size_(size1), b_size_(size2)
  {
  }

  std::vector<int>::const_reference
  operator[](int index) const
  {return at(index);}

  std::vector<int>::reference
  operator[](int index)
  {return at(index);}

  std::vector<int>::reference
  at(long long index)
  {
    //check_index_against_bound(index);
    long long i = index + offset();
    return vector<int>::operator[](i);
  }

  std::vector<int>::const_reference
  at(long long index) const
  {
    check_index_against_bound(index);
    long long i = offset() + index;
    return static_cast<const vector<int>* >(this)->at(i);
  }

  unsigned
  a_size() const
  {return a_size_;}

  unsigned
  b_size() const
  {return b_size_;}

  unsigned
  max_d() const
  {return a_size_ + b_size_;}

  unsigned
  offset() const
  {return max_d() + abs((long long) a_size() - (long long) b_size());}
}; // end class d_path_vec

/// The abstration of an insertion of elements of a sequence B into a
/// sequence A.  This is used to represent the edit script for
/// transforming a sequence A into a sequence B.
///
/// And insertion mainly encapsulates two components:
///
///   - An insertion point: this is the index (starting at 0) of the
///     element of the sequence A after which the insertion occurs.
///
///   - Inserted elements: this is a vector of indexes of elements of
///     sequence B (starting at 0) that got inserted into sequence A,
///     after the insertion point.
class insertion
{
  int			insertion_point_;
  vector<unsigned>	inserted_;

public:

  insertion(int insertion_point,
	    const vector<unsigned>& inserted_indexes)
    : insertion_point_(insertion_point),
      inserted_(inserted_indexes)
  {}

    insertion(int insertion_point = 0)
      : insertion_point_(insertion_point)
  {}

  int
  insertion_point_index() const
  {return insertion_point_;}

  void
  insertion_point_index(int i)
  {insertion_point_ = i;}

  const vector<unsigned>&
  inserted_indexes() const
  {return inserted_;}

  vector<unsigned>&
  inserted_indexes()
  {return inserted_;}
};// end class insertion

/// The abstraction of the deletion of one element of a sequence A.
///
/// This encapsulates the index of the element A that got deleted.
class deletion
{
  int index_;

public:

  deletion(int i)
    : index_(i)
  {}

  int
  index() const
  {return index_;}

  void
  index(int i)
  {index_ = i;}
};// end class deletion

/// The abstraction of an edit script for transforming a sequence A
/// into a sequence B.
///
/// It encapsulates the insertions and deletions for transforming A
/// into B.
class edit_script
{
  vector<insertion>	insertions_;
  vector<deletion>	deletions_;

public:

  edit_script()
  {}

  const vector<insertion>&
  insertions() const
  {return insertions_;}

  vector<insertion>&
  insertions()
  {return insertions_;}

  const vector<deletion>&
  deletions() const
  {return deletions_;}

  vector<deletion>&
  deletions()
  {return deletions_;}

  void
  append(const edit_script& es)
  {
    insertions().insert(insertions().end(),
			es.insertions().begin(),
			es.insertions().end());
    deletions().insert(deletions().end(),
		       es.deletions().begin(),
		       es.deletions().end());
  }

  void
  prepend(const edit_script& es)
  {
    insertions().insert(insertions().begin(),
			es.insertions().begin(),
			es.insertions().end());
    deletions().insert(deletions().begin(),
		       es.deletions().begin(),
		       es.deletions().end());
  }

  void
  clear()
  {
    insertions().clear();
    deletions().clear();
  }

  bool
  is_empty() const
  {return insertions().empty() && deletions().empty();}

  operator bool() const
  {return !is_empty();}

  int
  num_insertions() const
  {
    int l = 0;
    for (vector<insertion>::const_iterator i = insertions().begin();
	 i != insertions().end();
	 ++i)
      l += i->inserted_indexes().size();
    return l;
  }

  int
  num_deletions() const
  {return deletions().size();}

  int
  length() const
  {return num_insertions() + num_deletions();}
};//end class edit_script

bool
point_is_valid_in_graph(point& p,
			unsigned a_size,
			unsigned b_size);

bool
ends_of_furthest_d_paths_overlap(const point& forward_d_path_end,
				 const point& reverse_d_path_end);

/// The default equality functor used by the core diffing algorithms.
struct default_eq_functor
{
  /// This equality operator uses the default "==" to compare its
  /// arguments.
  ///
  /// @param a the first comparison argument.
  ///
  /// @param b the second comparison argument.
  ///
  /// @return true if the two arguments are equal, false otherwise.
  template<typename T>
  bool
  operator()(const T a, const T b) const
  {return a == b;}
};


/// An equality functor to deeply compare pointers.
struct deep_ptr_eq_functor
{
  /// This equality operator compares pointers by comparing the
  /// pointed-to objects.
  ///
  /// @param first the first comparison argument.
  ///
  /// @param second the second comparison argument.
  ///
  /// @return true if the objects pointed to by the pointers are
  /// equal, false otherwise.
  template<typename T>
  bool
  operator()(const T* first,
	     const T* second) const
  {
    if (!!first != !!second)
      return false;

    if (!first)
      return true;

    return *first == *second;
  }

  template<typename T>
  bool
  operator()(const shared_ptr<T> first,
	     const shared_ptr<T> second) const
  {return operator()(first.get(), second.get());}
};

/// Find the end of the furthest reaching d-path on diagonal k, for
/// two sequences.  In the paper This is referred to as "the basic
/// algorithm".
///
/// Unlike in the paper, the coordinates of the edit graph start at
/// (-1,-1), rather than (0,0), and they end at (M-1, N-1), rather
/// than (M,N).
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param k the number of the diagonal on which we want to find the
/// end of the furthest reaching D-path.
///
/// @param d the D in D-Path.  That's the number of insertions/deletions
/// (the number of changes, in other words) in the changeset.  That is
/// also the number of non-diagonals in the D-Path.
///
/// @param a_begin an iterator to the beginning of the first sequence
///
/// @param a_end an iterator that points right after the last element
/// of the second sequence to consider.
///
/// @param b_begin an iterator to the beginning of the second sequence.
///
/// @param b_end an iterator that points right after the last element
/// of the second sequence to consider.
///
/// @param v the vector of furthest end points of d_paths, at (d-1).
/// It contains the abscissas of the furthest end points for different
/// values of k, at (d-1).  That is, for k in [-D + 1, -D + 3, -D + 5,
/// ..., D - 1], v[k] is the abscissa of the end of the furthest
/// reaching (D-1)-path on diagonal k.
///
/// @param snak the last snake of the furthest path found.  The end
/// point of the snake is the end point of the furthest path.
///
/// @return true if the end of the furthest reaching path that was
/// found was inside the boundaries of the edit graph, false
/// otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
bool
end_of_fr_d_path_in_k(int k, int d,
		      RandomAccessOutputIterator a_begin,
		      RandomAccessOutputIterator a_end,
		      RandomAccessOutputIterator b_start,
		      RandomAccessOutputIterator b_end,
		      d_path_vec& v, snake& snak)
{
  int x = -1, y = -1;
  point begin, intermediate, diag_start, end;
  snake s;
  EqualityFunctor eq;

  // Let's pick the end point of the furthest reaching
  // (D-1)-path.  It's either v[k-1] or v[k+1]; the word
  // "furthest" means we choose the one which abscissa is the
  // greatest (that is, furthest from abscissa zero).
  if (k == -d || ((k != d) && (v[k-1] < v[k + 1])))
    // So, the abscissa of the end point of the furthest
    // reaching (D-1)-path is v[k+1].  That is a diagonal that
    // is above the current (k) diagonal, and on the right.
    // To move to the current k diagonal, one has to move
    // "down" from the diagonal k+1.  So the abscissa won't
    // change.  Only the ordinate will.  It will be given by y
    // = x - k (a bit below); as k has changed from k - 1 (it
    // has increased), y is going to be the new y that is
    // 'down' from the previous y in k - 1.
    {
      x = v[k+1];
      begin.set(x, x - (k + 1));
    }
  else
    {
      // So the abscissa of the end point of the furthest
      // (D-1)-path is v[k-1].  That is on the left of the
      // current k diagonal.  To move to the current k diagonal,
      // one has to move "right" from diagonal k - 1.  That is,
      // the y stays constant and x is incremented.
      x = v[k-1];
      begin.set(x, x - (k - 1));
      ++x;
    }

  // Now get the value of y from the equation k = x -y.
  // This is the point where we first touch K, when we move
  // from the end of the furthest reaching (D-1)-path.
  y = x - k;

  intermediate.x(x);
  intermediate.y(y);

  int last_x_index = a_end - a_begin - 1;
  int last_y_index = b_end - b_start - 1;
  // Now, follow the snake (aka, zero or more consecutive
  // diagonals).  Note that we stay on the k diagonal when we
  // do this.
  while ((x < last_x_index) && (y < last_y_index))
    if (eq(a_begin[x + 1], b_start[y + 1]))
      {
	x = x + 1;
	y = y + 1;
	if (!diag_start)
	  diag_start.set(x, y);
      }
    else
      break;

  end.x(x);
  end.y(y);

  // Note the point that we store in v here might be outside the
  // bounds of the edit graph.  But we store it at this step (for a
  // given D) anyway, because out of bound or not, we need this value
  // at this step to be able to compute the value of the point on the
  // "next" diagonal for the next D.
  v[k] = x;

  if (x >= (int) v.a_size()
      || y >= (int) v.b_size()
      || x < -1 || y < -1)
    return false;

  s.set(begin, intermediate, diag_start, end);
  s.set_forward(true);
  snak = s;

  return true;
}

/// Find the end of the furthest reaching reverse d-path on diagonal k
/// + delta.  Delta is abs(M - N), with M being the size of a and N
/// being the size of b.  This is the "basic algorithm", run backward.
/// That is, starting from the point (M,N) of the edit graph.
///
/// Unlike in the paper, the coordinates of the edit graph start at
/// (-1,-1), rather than (0,0), and they end at (M-1, N-1), rather
/// than (M,N).
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param k the number of the diagonal on which we want to find the
/// end of the furthest reaching reverse D-path.  Actually, we want to
/// find the end of the furthest reaching reverse D-path on diagonal (k
/// - delta).
///
/// @param d the D in D-path.  That's the number of insertions/deletions
/// (the number of changes, in other words) in the changeset.  That is
/// also the number of non-diagonals in the D-Path.
///
/// @param a_begin an iterator to the beginning of the first sequence
///
/// @param a_end an iterator that points right after the last element
/// of the second sequence to consider.
///
/// @param b_begin an iterator to the beginning of the second sequence.
///
/// @param b_end an iterator that points right after the last element
/// of the second sequence to consider.
///
/// @param v the vector of furthest end points of d_paths, at (d-1).
/// It contains the abscissae of the furthest end points for different
/// values of k - delta, at (d-1).  That is, for k in [-D + 1, -D + 3,
/// -D + 5, ..., D - 1], v[k - delta] is the abscissa of the end of the
/// furthest reaching (D-1)-path on diagonal k - delta.
///
/// @param snak the last snake of the furthest path found.  The end
/// point of the snake is the end point of the furthest path.
///
/// @return true iff the end of the furthest reaching path that was
/// found was inside the boundaries of the edit graph, false
/// otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
bool
end_of_frr_d_path_in_k_plus_delta (int k, int d,
				   RandomAccessOutputIterator a_begin,
				   RandomAccessOutputIterator a_end,
				   RandomAccessOutputIterator b_begin,
				   RandomAccessOutputIterator b_end,
				   d_path_vec& v, snake& snak)
{
  int a_size = a_end - a_begin;
  int b_size = b_end - b_begin;
  int delta = a_size - b_size;
  int k_plus_delta = k + delta;
  int x = -1, y = -1;
  point begin, intermediate, diag_start, end;
  snake s;
  EqualityFunctor eq;

  // Let's pick the end point of the furthest reaching (D-1)-path and
  // move from there to reach the current k_plus_delta-line.  That end
  // point of the furthest reaching (D-1)-path is either on
  // v[k_plus_delta-1] or on v[k_plus_delta+1]; the word "furthest"
  // means we choose the one which abscissa is the lowest (that is,
  // furthest from abscissa M).
  if (k_plus_delta == -d + delta
      || ((k_plus_delta != d + delta)
	  && (v[k_plus_delta + 1] <= v[k_plus_delta - 1])))
    {
      // We move left, that means ordinate won't change ...
      x = v[k_plus_delta + 1];
      y = x - (k_plus_delta + 1);
      begin.set(x, y);
      // ... and abscissa decreases.
      x = x - 1;
    }
  else
    {
      // So the furthest end point is on the k_plus_delta - 1
      // diagonal.  That is a diagonal that is 'below' the
      // k_plus_delta current diagonal.  So to join the current
      // diagonal from the k_plus_delta - 1 one, we need to move up.

      // So moving up means abscissa won't change ...
      x = v[k_plus_delta - 1];
      begin.set(x, x - (k_plus_delta - 1));
      // ... and that ordinate decreases.
      y = x - (k_plus_delta - 1) - 1;
    }

  intermediate.set(x, y);

  // Now, follow the snake.  Note that we stay on the k_plus_delta
  // diagonal when we do this.
  while (x >= 0 && y >= 0)
    if (eq(a_begin[x], b_begin[y]))
      {
	if (!diag_start)
	  diag_start.set(x, y);
	x = x - 1;
	y = y - 1;
      }
    else
      break;

  end.set(x, y);

  // Note the point that we store in v here might be outside the
  // bounds of the edit graph.  But we store it at this step (for a
  // given D) anyway, because out of bound or not, we need this value
  // at this step to be able to compute the value of the point on the
  // "next" diagonal for the next D.
  v[k_plus_delta] = x;

  if (x == -1 && y == -1)
    ;
  else if (x < -1 || y < -1)
    return false;

  s.set(begin, intermediate, diag_start, end);
  s.set_forward(false);
  snak = s;

  return true;
}

/// Tests if a given point is a match point in an edit graph.
///
/// @param a_begin the begin iterator of the first input sequence of
/// the edit graph.
///
/// @param a_end the end iterator of the first input sequence of the
/// edit graph.  This points to one element passed the end of the
/// sequence.
///
/// @param b_begin the begin iterator of the second input sequence of
/// the edit graph.
///
/// @param b_end the end iterator of the second input sequence of the
/// edit graph.  This points the one element passed the end of the
/// sequence.
///
/// @param point the point to test for being a match point.
///
/// @return true iff \a point is a match point.
template<typename RandomAccessOutputIterator>
bool
is_match_point(RandomAccessOutputIterator a_begin,
	       RandomAccessOutputIterator a_end,
	       RandomAccessOutputIterator b_begin,
	       RandomAccessOutputIterator b_end,
	       const point& point)
{
  int a_size = a_end - a_begin, b_size = b_end - b_begin;

  if (point.x() < 0
      || point.x () >= a_size
      || point.y() < 0
      || point.y() >= b_size)
    return false;

  return (a_begin[point.x()] == b_begin[point.y()]);
}

/// Returns the middle snake of two sequences A and B, as well as the
/// length of their shortest editing script.
///
///  This uses the "linear space refinement" algorithm presented in
/// section 4b in the paper.  As the paper says, "The idea for doing
/// so is to simultaneously run the basic algorithm in both the
/// forward and reverse directions until furthest reaching forward and
/// reverse paths starting at opposing corners ‘‘overlap’’."
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param a_begin an iterator pointing to the begining of sequence A.
///
/// @param a_end an iterator pointing to the end of sequence A.  Note
/// that this points right /after/ the end of vector A.
///
/// @param b_begin an iterator pointing to the begining of sequence B.
///
/// @param b_end an iterator pointing to the end of sequence B.  Note
/// that this points right /after/ the end of vector B
///
/// @param snak out parameter.  This is the snake current when the two
/// paths overlapped.  This is set iff the function returns true;
/// otherwise, this is not touched.
///
/// @return true is the snake was found, false otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
bool
compute_middle_snake(RandomAccessOutputIterator a_begin,
		     RandomAccessOutputIterator a_end,
		     RandomAccessOutputIterator b_begin,
		     RandomAccessOutputIterator b_end,
		     snake& snak, int& ses_len)
{
  int a_size = a_end - a_begin;
  int N = a_size;
  int b_size = b_end - b_begin;
  int M = b_size;
  int delta = N - M;
  d_path_vec forward_d_paths(a_size, b_size);
  d_path_vec reverse_d_paths(a_size, b_size);
  // These points below are the top leftmost point and bottom
  // right-most points of the edit graph.
  point first_point(-1, -1), last_point(a_size -1, b_size -1), point_zero(0, 0);

  // We want the initial step (D = 0, k = 0 in the paper) to find a
  // furthest reaching point on diagonal k == 0; For that, we need the
  // value of x for k == 1; So let's set that value to -1; that is for
  // k == 1 (diagonal 1), the point in the edit graph is (-1,-2).
  // That way, to get the furthest reaching point on diagonal 0 (k ==
  // 0), we go down from (-1,-2) on diagonal 1 and we hit diagonal 0
  // on (-1,-1); that is the starting value that the algorithm expects
  // for k == 0.
  forward_d_paths[1] = -1;

  // Similarly for the reverse paths, for diagonal delta + 1 (note
  // that diagonals are centered on delta, unlike for forward paths
  // where they are centered on zero), we set the initial point to
  // (a_size, b_size - 1).  That way, at step D == 0 and k == delta,
  // to reach diagonal delta from the point (a_size, b_size - 1) on
  // diagonal delta + 1, we just have to move left, and we hit
  // diagonal delta on (a_size - 1, b_size -1); that is the starting
  // point value the algorithm expects for k == 0 in the reverse case.
  reverse_d_paths[delta + 1] = a_size;

  int d_max = (M + N) / 2 + 1;
  for (int d = 0; d <= d_max; ++d)
    {
      // First build forward paths.
      for (int k = -d; k <= d; k += 2)
	{
	  snake s;
	  bool found =
	    end_of_fr_d_path_in_k<RandomAccessOutputIterator,
				  EqualityFunctor>(k, d,
						   a_begin, a_end,
						   b_begin, b_end,
						   forward_d_paths, s);
	  if (!found)
	    continue;

	  // As the paper says in 4b while explaining the middle snake
	  // algorithm:
	  //
	  // "Thus when delta is odd, check for overlap only while
	  //  extending forward paths ..."
	  if ((delta % 2)
	      && (k >= (delta - (d - 1))) && (k <= (delta + (d - 1))))
	    {
	      point reverse_end;
	      reverse_end.x(reverse_d_paths[k]);
	      reverse_end.y(reverse_end.x() - k);
	      if (ends_of_furthest_d_paths_overlap(s.end(), reverse_end))
		{
		  ses_len = 2 * d - 1;
		  snak = s;
		  return true;
		}
	    }
	}

      // Now build reverse paths.
      for (int k = -d; k <= d; k += 2)
	{
	  snake s;
	  bool found =
	    end_of_frr_d_path_in_k_plus_delta<RandomAccessOutputIterator,
					      EqualityFunctor>(k, d,
							       a_begin, a_end,
							       b_begin, b_end,
							       reverse_d_paths,
							       s);

	  if (!found)
	    continue;

	  // And the paper continues by saying:
	  //
	  // "... and when delta is even, check for overlap only while
	  // extending reverse paths."
	  int k_plus_delta = k + delta;
	  if (!(delta % 2)
	      && (k_plus_delta >= -d) && (k_plus_delta <= d))
	    {
	      point forward_end;
	      forward_end.x(forward_d_paths[k_plus_delta]);
	      forward_end.y(forward_end.x() - k_plus_delta);
	      if (ends_of_furthest_d_paths_overlap(forward_end, s.end()))
		{
		    ses_len = 2 * d;
		    snak = s;
		    return true;
		}
	    }
	}
    }
  return false;
}

bool
compute_middle_snake(const char* str1, const char* str2,
		     snake& s, int& ses_len);

/// This prints the middle snake of two strings.
///
/// @param a_begin the beginning of the first string.
///
/// @param b_begin the beginning of the second string.
///
/// @param s the snake to print.
///
/// @param out the output stream to print the snake to.
template<typename RandomAccessOutputIterator>
void
print_snake(RandomAccessOutputIterator a_begin,
	    RandomAccessOutputIterator b_begin,
	    const snake s, ostream& out)
{
  if (s.is_empty())
    return;

   out << "snake start: ";
   out << "(" << s.begin().x() << ", " << s.end().y() << ")\n";

   out << "snake intermediate: ";
   out << "(" << s.intermediate().x() << ", " << s.intermediate().y() << ")\n";

   out << "diagonal point(s): ";
   if (s.has_diagonal_edge())
     for (int x = s.intermediate().x(), y = s.intermediate().y();
	  x <= s.end().x() && y <= s.end().y();
	  ++x, ++y)
       {
	 assert(a_begin[x] == b_begin[y]);
	 out << "(" << x << "," << y << ") ";
       }
   out << "\n";

   out << "snake end: ";
   out << "(" << s.end().x() << ", " << s.end().y() << ")\n";
}

/// Compute the length of the shortest edit script for two sequences a
/// and b.  This is done using the "Greedy LCS/SES" of figure 2 in the
/// paper.  It can walk the edit graph either foward (when reverse is
/// false) or backward starting from the end (when reverse is true).
///
/// Here, note that the real content of a and b should start at index
/// 1, for this implementatikon algorithm to match the paper's
/// algorithm in a straightforward manner.  So pleast make sure that
/// at index 0, we just get some non-used value.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param a the first sequence we care about.
///
/// @param b the second sequence we care about.
///
/// @param v the vector that contains the end points of the furthest
/// reaching d-path and (d-1)-path.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
int
ses_len(RandomAccessOutputIterator a_begin,
	RandomAccessOutputIterator a_end,
	RandomAccessOutputIterator b_begin,
	RandomAccessOutputIterator b_end,
	d_path_vec& v, bool reverse)
{
  unsigned a_size = a_end - a_begin;
  unsigned b_size = b_end - b_begin;
  snake snak;

  assert(v.max_d() == a_size + b_size);

  int delta = a_size - b_size;

  if (reverse)
    // Set a fictitious (M, N-1) into v[1], to find the furthest
    // reaching reverse 0-path (i.e, when we are at d == 0 and k == 0).
    v[delta + 1] = a_size - 1;
  else
    // Set a fictitious (-1,-2) point into v[1], to find the furthest
    // reaching forward 0-path (i.e, when we are at d == 0 and k == 0).
    v[1] = -1;

  for (unsigned d = 0; d <= v.max_d(); ++d)
    {
      for (int k = -d; k <= (int) d; k += 2)
	{
	  point end;
	  if (reverse)
	    {
	      bool found =
		end_of_frr_d_path_in_k_plus_delta<RandomAccessOutputIterator,
						  EqualityFunctor>(k, d,
								   a_begin, a_end,
								   b_begin, b_end,
								   v, snak);
	      // If we reached the upper left corner of the edit graph then
	      // we are done.
	      if (found && snak.end().x() == -1 && snak.end().y() == -1)
		return d;
	    }
	  else
	    {
	      end_of_fr_d_path_in_k<RandomAccessOutputIterator,
				    EqualityFunctor>(k, d,
						     a_begin, a_end,
						     b_begin, b_end,
						     v, snak);
	      // If we reached the lower right corner of the edit
	      // graph then we are done.
	      if ((snak.end().x() == (int) a_size - 1)
		  && (snak.end().y() == (int) b_size - 1))
		return d;
	    }
	}
    }
  return 0;
}

/// Compute the length of the shortest edit script for two sequences a
/// and b.  This is done using the "Greedy LCS/SES" of figure 2 in the
/// paper.  It can walk the edit graph either foward (when reverse is
/// false) or backward starting from the end (when reverse is true).
///
/// Here, note that the real content of a and b should start at index
/// 1, for this implementatikon algorithm to match the paper's
/// algorithm in a straightforward manner.  So pleast make sure that
/// at index 0, we just get some non-used value.
///
/// Note that the equality operator used to compare the elements
/// passed in argument to this function is the default "==" operator.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @param a the first sequence we care about.
///
/// @param b the second sequence we care about.
///
/// @param v the vector that contains the end points of the furthest
/// reaching d-path and (d-1)-path.
template<typename RandomAccessOutputIterator>
int
ses_len(RandomAccessOutputIterator a_begin,
	RandomAccessOutputIterator a_end,
	RandomAccessOutputIterator b_begin,
	RandomAccessOutputIterator b_end,
	d_path_vec& v, bool reverse)
{
  return ses_len<RandomAccessOutputIterator, default_eq_functor>(a_begin, a_end,
								 b_begin, b_end,
								 v, reverse);
}

int
ses_len(const char* str1,
	const char* str2,
	bool reverse = false);

bool
snake_end_points(const snake& s, point&, point&);

/// Compute the longest common subsequence of two (sub-regions of)
/// sequences as well as the shortest edit script from transforming
/// the first (sub-region of) sequence into the second (sub-region of)
/// sequence.
///
/// A sequence is determined by a base, a beginning offset and an end
/// offset.  The base always points to the container that contains the
/// sequence to consider.  The beginning offset is an iterator that
/// points the beginning of the sub-region of the sequence that we
/// actually want to consider.  The end offset is an iterator that
/// points to the end of the sub-region of the sequence that we
/// actually want to consider.
///
/// This uses the LCS algorithm of the paper at section 4b.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param a_base the iterator to the base of the first sequence.
///
/// @param a_start an iterator to the beginning of the sub-region
/// of the first sequence to actually consider.
///
/// @param a_end an iterator to the end of the sub-region of the first
/// sequence to consider.
///
///@param b_base an iterator to the base of the second sequence to
///consider.
///
/// @param b_start an iterator to the beginning of the sub-region
/// of the second sequence to actually consider.
///
/// @param b_end an iterator to the end of the sub-region of the
/// second sequence to actually consider.
///
/// @param lcs the resulting lcs.  This is set iff the function
/// returns true.
///
/// @param ses the resulting shortest editing script.
///
/// @param ses_len the length of the ses above.  Normally this can be
/// retrieved from ses.length(), but this parameter is here for sanity
/// check purposes.  The function computes the length of the ses in
/// two redundant ways and ensures that both methods lead to the same
/// result.
///
/// @return true upon successful completion, false otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
void
compute_diff(RandomAccessOutputIterator a_base,
	     RandomAccessOutputIterator a_begin,
	     RandomAccessOutputIterator a_end,
	     RandomAccessOutputIterator b_base,
	     RandomAccessOutputIterator b_begin,
	     RandomAccessOutputIterator b_end,
	     vector<point>& lcs,
	     edit_script& ses,
	     int& ses_len)
{
  int a_size = a_end - a_begin;
  int b_size = b_end - b_begin;
  unsigned a_offset = a_begin - a_base, b_offset = b_begin - b_base;

  if (a_size == 0 || b_size == 0)
    {
      if (a_size > 0 && b_size == 0)
	// All elements of the first sequences have been deleted.  So add
	// the relevant deletions to the edit script.
	for (RandomAccessOutputIterator i = a_begin; i < a_end; ++i)
	  ses.deletions().push_back(deletion(i - a_base));

      if (b_size > 0 && a_size == 0)
	{
	  // All elements present in the second sequence are part of
	  // an insertion into the first sequence at a_end.  So add
	  // that insertion to the edit script.
	  int a_full_size = a_end - a_base;
	  int insertion_index = a_full_size ? a_full_size - 1 : -1;
	  insertion ins(insertion_index);
	  for (RandomAccessOutputIterator i = b_begin; i < b_end; ++i)
	    ins.inserted_indexes().push_back(i - b_base);

	  ses.insertions().push_back(ins);
	}

      ses_len =  a_size + b_size;
      return;
    }

  int d = 0;
  snake snak;
  vector<point> trace; // the trace of the edit graph.  Read the paper
		       // to understand what a trace is.
  bool has_snake =
    compute_middle_snake<RandomAccessOutputIterator,
			 EqualityFunctor>(a_begin, a_end,
					  b_begin, b_end,
					  snak, d);
  if (has_snake)
    {
      // So middle_{begin,end} are expressed wrt a_begin and b_begin.
      // Let's express them wrt a_base and b_base.
      snak.add(a_offset, b_offset);
      ses_len = d;
    }

  if (has_snake)
    {
      if ( snak.has_diagonal_edge())
	for (int x = snak.diagonal_start().x(), y = snak.diagonal_start().y();
	     x <= snak.end().x() && y <= snak.end().y();
	     ++x, ++y)
	  {
	    point p(x, y);
	    trace.push_back(p);
	  }
    }
  else
    {
      // So there is no middle snake.  That means there is no lcs, so
      // the two sequences are different.

      // In other words, all the elements of the first sequence have
      // been deleted ...
      for (RandomAccessOutputIterator i = a_begin; i < a_end; ++i)
	ses.deletions().push_back(deletion(i - a_base));

      // ... and all the elements of the second sequence are insertions
      // that happen at the beginning of the first sequence.
      insertion ins(a_begin - a_base);
      for (RandomAccessOutputIterator i = b_begin; i < b_end; ++i)
	ins.inserted_indexes().push_back(i - b_base);
      ses.insertions().push_back(ins);

      ses_len = a_size + b_size;
      assert(ses_len == ses.length());
      return;
    }

  if (d > 1)
    {
      int tmp_ses_len0 = 0;
      edit_script tmp_ses0;
      point px, pu;
      snake_end_points(snak, px, pu);
      compute_diff<RandomAccessOutputIterator,
		   EqualityFunctor>(a_base, a_begin, a_base + px.x() + 1,
				    b_base, b_begin, b_base + px.y() + 1,
				    lcs, tmp_ses0, tmp_ses_len0);

      lcs.insert(lcs.end(), trace.begin(), trace.end());

      int tmp_ses_len1 = 0;
      edit_script tmp_ses1;
      compute_diff<RandomAccessOutputIterator,
		   EqualityFunctor>(a_base, a_base + pu.x() + 1, a_end,
				    b_base, b_base + pu.y() + 1, b_end,
				    lcs, tmp_ses1, tmp_ses_len1);
      assert(tmp_ses0.length() + tmp_ses1.length() == d);
      assert(tmp_ses_len0 + tmp_ses_len1 == d);
      ses.append(tmp_ses0);
      ses.append(tmp_ses1);
    }
  else if (d == 1)
    {
      if (snak.has_diagonal_edge())
	{
	  for (int x = snak.diagonal_start().x(), y = snak.diagonal_start().y();
	       x <= snak.end().x() && y <= snak.end().y();
	       ++x, ++y)
	    {
	      point p(x, y);
	      trace.push_back(p);
	    }
	}

      if (snak.has_vertical_edge())
	{
	  point p = snak.intermediate();
	  insertion ins(p.x());
	  ins.inserted_indexes().push_back(p.y());
	  ses.insertions().push_back(ins);
	}
      else if (snak.has_horizontal_edge())
	{
	  if (snak.is_forward())
	    {
	      deletion del(snak.intermediate().x());
	      ses.deletions().push_back(del);
	    }
	  else
	    {
	      deletion del(snak.begin().x());
	      ses.deletions().push_back(del);
	    }
	}
    }
  else if (d == 0)
    {
      // Obviously on the middle snake is part of the solution, as
      // there is no edit script; iow, the two sequences are
      // identical.
      lcs.insert(lcs.end(), trace.begin(), trace.end());
      ses_len = 0;
    }

  assert(ses_len == ses.length());
}

/// Compute the longest common subsequence of two (sub-regions of)
/// sequences as well as the shortest edit script from transforming
/// the first (sub-region of) sequence into the second (sub-region of)
/// sequence.
///
/// This uses the LCS algorithm of the paper at section 4b.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param a_start an iterator to the beginning of the first sequence
/// to consider.
///
/// @param a_end an iterator to the end of the first sequence to
/// consider.
///
/// @param b_start an iterator to the beginning of the second sequence
/// to consider.
///
/// @param b_end an iterator to the end of the second sequence to
/// consider.
///
/// @param lcs the resulting lcs.  This is set iff the function
/// returns true.
///
/// @param ses the resulting shortest editing script.
///
/// @param ses_len the length of the ses above.  Normally this can be
/// retrieved from ses.length(), but this parameter is here for sanity
/// check purposes.  The function computes the length of the ses in
/// two redundant ways and ensures that both methods lead to the same
/// result.
///
/// @return true upon successful completion, false otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
void
compute_diff(RandomAccessOutputIterator a_begin,
	     RandomAccessOutputIterator a_end,
	     RandomAccessOutputIterator b_begin,
	     RandomAccessOutputIterator b_end,
	     vector<point>& lcs,
	     edit_script& ses,
	     int& ses_len)
{
  compute_diff<RandomAccessOutputIterator,
	       EqualityFunctor>(a_begin, a_begin, a_end,
				b_begin, b_begin, b_end,
				lcs, ses, ses_len);
}

/// Compute the longest common subsequence of two (sub-regions of)
/// sequences as well as the shortest edit script from transforming
/// the first (sub-region of) sequence into the second (sub-region of)
/// sequence.
///
/// A sequence is determined by a base, a beginning offset and an end
/// offset.  The base always points to the container that contains the
/// sequence to consider.  The beginning offset is an iterator that
/// points the beginning of the sub-region of the sequence that we
/// actually want to consider.  The end offset is an iterator that
/// points to the end of the sub-region of the sequence that we
/// actually want to consider.
///
/// This uses the LCS algorithm of the paper at section 4b.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param a_base the iterator to the base of the first sequence.
///
/// @param a_start an iterator to the beginning of the sub-region
/// of the first sequence to actually consider.
///
/// @param a_end an iterator to the end of the sub-region of the first
/// sequence to consider.
///
///@param b_base an iterator to the base of the second sequence to
///consider.
///
/// @param b_start an iterator to the beginning of the sub-region
/// of the second sequence to actually consider.
///
/// @param b_end an iterator to the end of the sub-region of the
/// second sequence to actually consider.
///
/// @param lcs the resulting lcs.  This is set iff the function
/// returns true.
///
/// @param ses the resulting shortest editing script.
///
/// @return true upon successful completion, false otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
void
compute_diff(RandomAccessOutputIterator a_base,
	     RandomAccessOutputIterator a_begin,
	     RandomAccessOutputIterator a_end,
	     RandomAccessOutputIterator b_base,
	     RandomAccessOutputIterator b_begin,
	     RandomAccessOutputIterator b_end,
	     vector<point>& lcs,
	     edit_script& ses)
{
  int ses_len = 0;

  compute_diff<RandomAccessOutputIterator,
	       EqualityFunctor>(a_base, a_begin, a_end,
				b_base, b_begin, b_end,
				lcs, ses, ses_len);
}

/// Compute the longest common subsequence of two (sub-regions of)
/// sequences as well as the shortest edit script from transforming
/// the first (sub-region of) sequence into the second (sub-region of)
/// sequence.
///
/// This uses the LCS algorithm of the paper at section 4b.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param a_start an iterator to the beginning of the first sequence
/// to consider.
///
/// @param a_end an iterator to the end of the first sequence to
/// consider.
///
/// @param b_start an iterator to the beginning of the sequence to
/// actually consider.
///
/// @param b_end an iterator to the end of second sequence to
/// consider.
///
/// @param lcs the resulting lcs.  This is set iff the function
/// returns true.
///
/// @param ses the resulting shortest editing script.
///
/// @return true upon successful completion, false otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
void
compute_diff(RandomAccessOutputIterator a_begin,
	     RandomAccessOutputIterator a_end,
	     RandomAccessOutputIterator b_begin,
	     RandomAccessOutputIterator b_end,
	     vector<point>& lcs,
	     edit_script& ses)
{
  compute_diff<RandomAccessOutputIterator,
	       EqualityFunctor>(a_begin, a_begin, a_end,
				b_begin, b_begin, b_end,
				lcs, ses);
}

/// Compute the longest common subsequence of two (sub-regions of)
/// sequences as well as the shortest edit script from transforming
/// the first (sub-region of) sequence into the second (sub-region of)
/// sequence.
///
/// This uses the LCS algorithm of the paper at section 4b.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @param a_start an iterator to the beginning of the first sequence
/// to consider.
///
/// @param a_end an iterator to the end of the first sequence to
/// consider.
///
/// @param b_start an iterator to the beginning of the sequence to
/// actually consider.
///
/// @param b_end an iterator to the end of second sequence to
/// consider.
///
/// @param lcs the resulting lcs.  This is set iff the function
/// returns true.
///
/// @param ses the resulting shortest editing script.
///
/// @return true upon successful completion, false otherwise.
template<typename RandomAccessOutputIterator>
void
compute_diff(RandomAccessOutputIterator a_begin,
	     RandomAccessOutputIterator a_end,
	     RandomAccessOutputIterator b_begin,
	     RandomAccessOutputIterator b_end,
	     vector<point>& lcs,
	     edit_script& ses)
{
  compute_diff<RandomAccessOutputIterator,
	       default_eq_functor>(a_begin, a_end, b_begin, b_end, lcs, ses);
}

/// Compute the longest common subsequence of two (sub-regions of)
/// sequences as well as the shortest edit script from transforming
/// the first (sub-region of) sequence into the second (sub-region of)
/// sequence.
///
/// A sequence is determined by a base, a beginning offset and an end
/// offset.  The base always points to the container that contains the
/// sequence to consider.  The beginning offset is an iterator that
/// points the beginning of the sub-region of the sequence that we
/// actually want to consider.  The end offset is an iterator that
/// points to the end of the sub-region of the sequence that we
/// actually want to consider.
///
/// This uses the LCS algorithm of the paper at section 4b.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param a_base the iterator to the base of the first sequence.
///
/// @param a_start an iterator to the beginning of the sub-region
/// of the first sequence to actually consider.
///
/// @param a_end an iterator to the end of the sub-region of the first
/// sequence to consider.
///
/// @param b_base an iterator to the base of the second sequence to
/// consider.
///
/// @param b_start an iterator to the beginning of the sub-region
/// of the second sequence to actually consider.
///
/// @param b_end an iterator to the end of the sub-region of the
/// second sequence to actually consider.
///
/// @param ses the resulting shortest editing script.
///
/// @return true upon successful completion, false otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
void
compute_diff(RandomAccessOutputIterator a_base,
	     RandomAccessOutputIterator a_begin,
	     RandomAccessOutputIterator a_end,
	     RandomAccessOutputIterator b_base,
	     RandomAccessOutputIterator b_begin,
	     RandomAccessOutputIterator b_end,
	     edit_script& ses)
{
  vector<point> lcs;

  compute_diff<RandomAccessOutputIterator,
	       EqualityFunctor>(a_base, a_begin, a_end,
				b_base, b_begin, b_end,
				lcs, ses);
}

/// Compute the longest common subsequence of two (sub-regions of)
/// sequences as well as the shortest edit script from transforming
/// the first (sub-region of) sequence into the second (sub-region of)
/// sequence.
///
/// This uses the LCS algorithm of the paper at section 4b.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @tparm EqualityFunctor this must be a class that declares a public
/// call operator member returning a boolean and taking two arguments
/// that must be of the same type as the one pointed to by the @ref
/// RandomAccessOutputIterator template parameter. This functor is
/// used to compare the elements referred to by the iterators pased in
/// argument to this function.
///
/// @param a_start an iterator to the beginning of the first sequence
/// to consider.
///
/// @param a_end an iterator to the end of the first sequence to
/// consider.
///
/// @param b_start an iterator to the beginning of the second sequence
/// to consider.
///
/// @param b_end an iterator to the end of the second sequence to
/// consider.
///
/// @param ses the resulting shortest editing script.
///
/// @return true upon successful completion, false otherwise.
template<typename RandomAccessOutputIterator,
	 typename EqualityFunctor>
void
compute_diff(RandomAccessOutputIterator a_begin,
	     RandomAccessOutputIterator a_end,
	     RandomAccessOutputIterator b_begin,
	     RandomAccessOutputIterator b_end,
	     edit_script& ses)
{
  compute_diff<RandomAccessOutputIterator,
	       EqualityFunctor>(a_begin, a_begin, a_end,
				b_begin, b_begin, b_end,
				ses);
}

/// Compute the longest common subsequence of two (sub-regions of)
/// sequences as well as the shortest edit script from transforming
/// the first (sub-region of) sequence into the second (sub-region of)
/// sequence.
///
/// This uses the LCS algorithm of the paper at section 4b.
///
/// @tparm RandomAccessOutputIterator the type of iterators passed to
/// this function.  It must be a random access output iterator kind.
///
/// @param a_start an iterator to the beginning of the first sequence
/// to consider.
///
/// @param a_end an iterator to the end of the first sequence to
/// consider.
///
/// @param b_start an iterator to the beginning of the second sequence
/// to consider.
///
/// @param b_end an iterator to the end of the second sequence to
/// consider.
///
/// @param ses the resulting shortest editing script.
///
/// @return true upon successful completion, false otherwise.
template<typename RandomAccessOutputIterator>
void
compute_diff(RandomAccessOutputIterator a_begin,
	     RandomAccessOutputIterator a_end,
	     RandomAccessOutputIterator b_begin,
	     RandomAccessOutputIterator b_end,
	     edit_script& ses)
{
  compute_diff<RandomAccessOutputIterator, default_eq_functor>(a_begin, a_end,
							       b_begin, b_end,
							       ses);
}

void
compute_lcs(const char* str1, const char* str2, int &ses_len, string& lcs);

void
compute_ses(const char* str1, const char* str2, edit_script& ses);

/// Display an edit script on standard output.
///
/// @param es the edit script to display
///
/// @param str1_base the first string the edit script is about.
///
/// @pram str2_base the second string the edit script is about.
template<typename RandomAccessOutputIterator>
void
display_edit_script(const edit_script& es,
		    const RandomAccessOutputIterator str1_base,
		    const RandomAccessOutputIterator str2_base,
		    ostream& out)
{
  if (es.num_deletions() == 0)
    out << "no deletion:\n";
  else if (es.num_deletions() == 1)
    {
      out << "1 deletion:\n"
	  << "\t happened at index: ";;
    }
  else
    {
      out << es.num_deletions() << " deletions:\n"
	   << "\t happened at indexes: ";
    }

  for (vector<deletion>::const_iterator i = es.deletions().begin();
       i != es.deletions().end();
       ++i)
    {
      if (i != es.deletions().begin())
	out << ", ";
      out << i->index() << " (" << str1_base[i->index()] << ")";
    }
  out << "\n\n";

  if (es.num_insertions() == 0)
    out << "no insertion\n";
  else if (es.num_insertions() == 1)
    out << "1 insertion\n";
  else
      out << es.num_insertions() << " insertions:\n";
  for (vector<insertion>::const_iterator i = es.insertions().begin();
       i != es.insertions().end();
       ++i)
    {
      int idx = i->insertion_point_index();
      if (idx < 0)
	out << "\t before index of first sequence: " << idx + 1
	    << " (" << str1_base[idx + 1] << ")\n";
      else
	out << "\t after index of first sequence: " << idx
	    << " (" << str1_base[idx] << ")\n";

      if (!i->inserted_indexes().empty())
	out << "\t\t inserted indexes from second sequence: ";

      for (vector<unsigned>::const_iterator j = i->inserted_indexes().begin();
	   j != i->inserted_indexes().end();
	   ++j)
	{
	  if (j != i->inserted_indexes().begin())
	    out << ", ";
	  out << *j << " (" << str2_base[*j] << ")";
	}
      out << "\n";
    }
  out << "\n\n";
}

}//end namespace diff_utils

}//end namespace abigail
#endif // __ABG_DIFF_UTILS_H__