This file is indexed.

/usr/share/perl5/Text/Markdown.pm is in libtext-markdown-perl 1.0.26-1.

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
package Text::Markdown;
require 5.008_000;
use strict;
use warnings;
use re 'eval';

use Digest::MD5 qw(md5_hex);
use Encode      qw();
use Carp        qw(croak);
use base        'Exporter';

our $VERSION   = '1.0.26';
our @EXPORT_OK = qw(markdown);

=head1 NAME

Text::Markdown - Convert Markdown syntax to (X)HTML

=head1 SYNOPSIS

    use Text::Markdown 'markdown';
    my $html = markdown($text);

    use Text::Markdown 'markdown';
    my $html = markdown( $text, {
        empty_element_suffix => '>',
        tab_width => 2,
    } );

    use Text::Markdown;
    my $m = Text::Markdown->new;
    my $html = $m->markdown($text);

    use Text::Markdown;
    my $m = Text::MultiMarkdown->new(
        empty_element_suffix => '>',
        tab_width => 2,
    );
    my $html = $m->markdown( $text );

=head1 DESCRIPTION

Markdown is a text-to-HTML filter; it translates an easy-to-read /
easy-to-write structured text format into HTML. Markdown's text format
is most similar to that of plain text email, and supports features such
as headers, *emphasis*, code blocks, blockquotes, and links.

Markdown's syntax is designed not as a generic markup language, but
specifically to serve as a front-end to (X)HTML. You can use span-level
HTML tags anywhere in a Markdown document, and you can use block level
HTML tags (like <div> and <table> as well).

=head1 SYNTAX

This module implements the 'original' Markdown markdown syntax from:

    http://daringfireball.net/projects/markdown/

Note that L<Text::Markdown> ensures that the output always ends with
B<one> newline. The fact that multiple newlines are collapsed into one
makes sense, because this is the behavior of HTML towards whispace. The
fact that there's always a newline at the end makes sense again, given
that the output will always be nested in a B<block>-level element (as
opposed to an inline element). That block element can be a C<< <p> >>
(most often), or a C<< <table> >>.

Markdown is B<not> interpreted in HTML block-level elements, in order for
chunks of pasted HTML (e.g. JavaScript widgets, web counters) to not be
magically (mis)interpreted. For selective processing of Markdown in some,
but not other, HTML block elements, add a C<markdown> attribute to the block
element and set its value to C<1>, C<on> or C<yes>:

    <div markdown="1" class="navbar">
    * Home
    * About
    * Contact
    <div>

The extra C<markdown> attribute will be stripped when generating the output.

=head1 OPTIONS

Text::Markdown supports a number of options to its processor which control
the behaviour of the output document.

These options can be supplied to the constructor, or in a hash within
individual calls to the L</markdown> method. See the SYNOPSIS for examples
of both styles.

The options for the processor are:

=over

=item empty_element_suffix

This option controls the end of empty element tags:

    '/>' for XHTML (default)
    '>' for HTML

=item tab_width

Controls indent width in the generated markup. Defaults to 4.

=item trust_list_start_value

If true, ordered lists will use the first number as the starting point for
numbering.  This will let you pick up where you left off by writing:

  1. foo
  2. bar

  some paragraph

  3. baz
  6. quux

(Note that in the above, quux will be numbered 4.)

=back

=cut

# Regex to match balanced [brackets]. See Friedl's
# "Mastering Regular Expressions", 2nd Ed., pp. 328-331.
our ($g_nested_brackets, $g_nested_parens);
$g_nested_brackets = qr{
    (?>                                 # Atomic matching
       [^\[\]]+                         # Anything other than brackets
     |
       \[
         (??{ $g_nested_brackets })     # Recursive set of nested brackets
       \]
    )*
}x;
# Doesn't allow for whitespace, because we're using it to match URLs:
$g_nested_parens = qr{
    (?>                                 # Atomic matching
       [^()\s]+                            # Anything other than parens or whitespace
     |
       \(
         (??{ $g_nested_parens })        # Recursive set of nested brackets
       \)
    )*
}x;

# Table of hash values for escaped characters:
our %g_escape_table;
foreach my $char (split //, '\\`*_{}[]()>#+-.!') {
    $g_escape_table{$char} = md5_hex($char);
}

=head1 METHODS

=head2 new

A simple constructor, see the SYNTAX and OPTIONS sections for more information.

=cut

sub new {
    my ($class, %p) = @_;

    $p{base_url} ||= ''; # This is the base URL to be used for WikiLinks

    $p{tab_width} = 4 unless (defined $p{tab_width} and $p{tab_width} =~ m/^\d+$/);

    $p{empty_element_suffix} ||= ' />'; # Change to ">" for HTML output

    $p{trust_list_start_value} = $p{trust_list_start_value} ? 1 : 0;

    my $self = { params => \%p };
    bless $self, ref($class) || $class;
    return $self;
}

=head2 markdown

The main function as far as the outside world is concerned. See the SYNOPSIS
for details on use.

=cut

sub markdown {
    my ( $self, $text, $options ) = @_;

    # Detect functional mode, and create an instance for this run
    unless (ref $self) {
        if ( $self ne __PACKAGE__ ) {
            my $ob = __PACKAGE__->new();
                                # $self is text, $text is options
            return $ob->markdown($self, $text);
        }
        else {
            croak('Calling ' . $self . '->markdown (as a class method) is not supported.');
        }
    }

    $options ||= {};

    %$self = (%{ $self->{params} }, %$options, params => $self->{params});

    $self->_CleanUpRunData($options);

    return $self->_Markdown($text);
}

sub _CleanUpRunData {
    my ($self, $options) = @_;
    # Clear the global hashes. If we don't clear these, you get conflicts
    # from other articles when generating a page which contains more than
    # one article (e.g. an index page that shows the N most recent
    # articles).
    $self->{_urls}        = $options->{urls} ? $options->{urls} : {}; # FIXME - document passing this option (tested in 05options.t).
    $self->{_titles}      = {};
    $self->{_html_blocks} = {};
    # Used to track when we're inside an ordered or unordered list
    # (see _ProcessListItems() for details)
    $self->{_list_level} = 0;

}

sub _Markdown {
#
# Main function. The order in which other subs are called here is
# essential. Link and image substitutions need to happen before
# _EscapeSpecialChars(), so that any *'s or _'s in the <a>
# and <img> tags get encoded.
#
    my ($self, $text, $options) = @_;

    $text = $self->_CleanUpDoc($text);

    # Turn block-level HTML elements into hash entries, and interpret markdown in them if they have a 'markdown="1"' attribute
    $text = $self->_HashHTMLBlocks($text, {interpret_markdown_on_attribute => 1});

    $text = $self->_StripLinkDefinitions($text);

    $text = $self->_RunBlockGamut($text, {wrap_in_p_tags => 1});

    $text = $self->_UnescapeSpecialChars($text);

    $text = $self->_ConvertCopyright($text);

    return $text . "\n";
}

=head2 urls

Returns a reference to a hash with the key being the markdown reference
and the value being the URL.

Useful for building scripts which preprocess a list of links before the
main content. See F<t/05options.t> for an example of this hashref being
passed back into the markdown method to create links.

=cut

sub urls {
    my ( $self ) = @_;

    return $self->{_urls};
}

sub _CleanUpDoc {
    my ($self, $text) = @_;

    # Standardize line endings:
    $text =~ s{\r\n}{\n}g;  # DOS to Unix
    $text =~ s{\r}{\n}g;    # Mac to Unix

    # Make sure $text ends with a couple of newlines:
    $text .= "\n\n";

    # Convert all tabs to spaces.
    $text = $self->_Detab($text);

    # Strip any lines consisting only of spaces and tabs.
    # This makes subsequent regexen easier to write, because we can
    # match consecutive blank lines with /\n+/ instead of something
    # contorted like /[ \t]*\n+/ .
    $text =~ s/^[ \t]+$//mg;

    return $text;
}

sub _StripLinkDefinitions {
#
# Strips link definitions from text, stores the URLs and titles in
# hash references.
#
    my ($self, $text) = @_;
    my $less_than_tab = $self->{tab_width} - 1;

    # Link defs are in the form: ^[id]: url "optional title"
    while ($text =~ s{
            ^[ ]{0,$less_than_tab}\[(.+)\]: # id = \$1
              [ \t]*
              \n?               # maybe *one* newline
              [ \t]*
            <?(\S+?)>?          # url = \$2
              [ \t]*
              \n?               # maybe one newline
              [ \t]*
            (?:
                (?<=\s)         # lookbehind for whitespace
                ["(]
                (.+?)           # title = \$3
                [")]
                [ \t]*
            )?  # title is optional
            (?:\n+|\Z)
        }{}omx) {
        $self->{_urls}{lc $1} = $self->_EncodeAmpsAndAngles( $2 );    # Link IDs are case-insensitive
        if ($3) {
            $self->{_titles}{lc $1} = $3;
            $self->{_titles}{lc $1} =~ s/"/&quot;/g;
        }

    }

    return $text;
}

sub _md5_utf8 {
    # Internal function used to safely MD5sum chunks of the input, which might be Unicode in Perl's internal representation.
    my $input = shift;
    return unless defined $input;
    if (Encode::is_utf8 $input) {
        return md5_hex(Encode::encode('utf8', $input));
    }
    else {
        return md5_hex($input);
    }
}

sub _HashHTMLBlocks {
    my ($self, $text, $options) = @_;
    my $less_than_tab = $self->{tab_width} - 1;

    # Hashify HTML blocks (protect from further interpretation by encoding to an md5):
    # We only want to do this for block-level HTML tags, such as headers,
    # lists, and tables. That's because we still want to wrap <p>s around
    # "paragraphs" that are wrapped in non-block-level tags, such as anchors,
    # phrase emphasis, and spans. The list of tags we're looking for is
    # hard-coded:
    my $block_tags = qr{
          (?:
            p         |  div     |  h[1-6]  |  blockquote  |  pre       |  table  |
            dl        |  ol      |  ul      |  script      |  noscript  |  form   |
            fieldset  |  iframe  |  math    |  ins         |  del
          )
        }x;

    my $tag_attrs = qr{
                        (?:                 # Match one attr name/value pair
                            \s+             # There needs to be at least some whitespace
                                            # before each attribute name.
                            [\w.:_-]+       # Attribute name
                            \s*=\s*
                            (?:
                                ".+?"       # "Attribute value"
                             |
                                '.+?'       # 'Attribute value'
                             |
                                [^\s]+?      # AttributeValue (HTML5)
                            )
                        )*                  # Zero or more
                    }x;

    my $empty_tag = qr{< \w+ $tag_attrs \s* />}oxms;
    my $open_tag =  qr{< $block_tags $tag_attrs \s* >}oxms;
    my $close_tag = undef;       # let Text::Balanced handle this
    my $prefix_pattern = undef;  # Text::Balanced
    my $markdown_attr = qr{ \s* markdown \s* = \s* (['"]) (.*?) \1 }xs;

    use Text::Balanced qw(gen_extract_tagged);
    my $extract_block = gen_extract_tagged($open_tag, $close_tag, $prefix_pattern, { ignore => [$empty_tag] });

    my @chunks;
    # parse each line, looking for block-level HTML tags
    while ($text =~ s{^(([ ]{0,$less_than_tab}<)?.*\n)}{}m) {
        my $cur_line = $1;
        if (defined $2) {
            # current line could be start of code block

            my ($tag, $remainder, $prefix, $opening_tag, $text_in_tag, $closing_tag) = $extract_block->($cur_line . $text);
            if ($tag) {
                if ($options->{interpret_markdown_on_attribute} and $opening_tag =~ s/$markdown_attr//i) {
                    my $markdown = $2;
                    if ($markdown =~ /^(1|on|yes)$/) {
                        # interpret markdown and reconstruct $tag to include the interpreted $text_in_tag
                        my $wrap_in_p_tags = $opening_tag =~ /^<(div|iframe)/;
                        $tag = $prefix . $opening_tag . "\n"
                          . $self->_RunBlockGamut($text_in_tag, {wrap_in_p_tags => $wrap_in_p_tags})
                          . "\n" . $closing_tag
                        ;
                    } else {
                        # just remove the markdown="0" attribute
                        $tag = $prefix . $opening_tag . $text_in_tag . $closing_tag;
                    }
                }
                my $key = _md5_utf8($tag);
                $self->{_html_blocks}{$key} = $tag;
                push @chunks, "\n\n" . $key . "\n\n";
                $text = $remainder;
            }
            else {
                # No tag match, so toss $cur_line into @chunks
                push @chunks, $cur_line;
            }
        }
        else {
            # current line could NOT be start of code block
            push @chunks, $cur_line;
        }

    }
    push @chunks, $text;  # whatever is left

    $text = join '', @chunks;

    return $text;
}

sub _HashHR {
    my ($self, $text) = @_;
    my $less_than_tab = $self->{tab_width} - 1;

    $text =~ s{
                (?:
                    (?<=\n\n)        # Starting after a blank line
                    |                # or
                    \A\n?            # the beginning of the doc
                )
                (                        # save in $1
                    [ ]{0,$less_than_tab}
                    <(hr)                # start tag = $2
                    \b                    # word break
                    ([^<>])*?            #
                    /?>                    # the matching end tag
                    [ \t]*
                    (?=\n{2,}|\Z)        # followed by a blank line or end of document
                )
    }{
        my $key = _md5_utf8($1);
        $self->{_html_blocks}{$key} = $1;
        "\n\n" . $key . "\n\n";
    }egx;

    return $text;
}

sub _HashHTMLComments {
    my ($self, $text) = @_;
    my $less_than_tab = $self->{tab_width} - 1;

    # Special case for standalone HTML comments:
    $text =~ s{
                (?:
                    (?<=\n\n)        # Starting after a blank line
                    |                # or
                    \A\n?            # the beginning of the doc
                )
                (                        # save in $1
                    [ ]{0,$less_than_tab}
                    (?s:
                        <!
                        (--.*?--\s*)+
                        >
                    )
                    [ \t]*
                    (?=\n{2,}|\Z)        # followed by a blank line or end of document
                )
    }{
        my $key = _md5_utf8($1);
        $self->{_html_blocks}{$key} = $1;
        "\n\n" . $key . "\n\n";
    }egx;

    return $text;
}

sub _HashPHPASPBlocks {
    my ($self, $text) = @_;
    my $less_than_tab = $self->{tab_width} - 1;

    # PHP and ASP-style processor instructions (<?…?> and <%…%>)
    $text =~ s{
                (?:
                    (?<=\n\n)        # Starting after a blank line
                    |                # or
                    \A\n?            # the beginning of the doc
                )
                (                        # save in $1
                    [ ]{0,$less_than_tab}
                    (?s:
                        <([?%])            # $2
                        .*?
                        \2>
                    )
                    [ \t]*
                    (?=\n{2,}|\Z)        # followed by a blank line or end of document
                )
            }{
                my $key = _md5_utf8($1);
                $self->{_html_blocks}{$key} = $1;
                "\n\n" . $key . "\n\n";
            }egx;
    return $text;
}

sub _RunBlockGamut {
#
# These are all the transformations that form block-level
# tags like paragraphs, headers, and list items.
#
    my ($self, $text, $options) = @_;

    # Do headers first, as these populate cross-refs
    $text = $self->_DoHeaders($text);

    # Do Horizontal Rules:
    my $less_than_tab = $self->{tab_width} - 1;
    $text =~ s{^[ ]{0,$less_than_tab}(\*[ ]?){3,}[ \t]*$}{\n<hr$self->{empty_element_suffix}\n}gmx;
    $text =~ s{^[ ]{0,$less_than_tab}(-[ ]?){3,}[ \t]*$}{\n<hr$self->{empty_element_suffix}\n}gmx;
    $text =~ s{^[ ]{0,$less_than_tab}(_[ ]?){3,}[ \t]*$}{\n<hr$self->{empty_element_suffix}\n}gmx;

    $text = $self->_DoLists($text);

    $text = $self->_DoCodeBlocks($text);

    $text = $self->_DoBlockQuotes($text);

    # We already ran _HashHTMLBlocks() before, in Markdown(), but that
    # was to escape raw HTML in the original Markdown source. This time,
    # we're escaping the markup we've just created, so that we don't wrap
    # <p> tags around block-level tags.
    $text = $self->_HashHTMLBlocks($text);

    # Special case just for <hr />. It was easier to make a special case than
    # to make the other regex more complicated.
    $text = $self->_HashHR($text);

    $text = $self->_HashHTMLComments($text);

    $text = $self->_HashPHPASPBlocks($text);

    $text = $self->_FormParagraphs($text, {wrap_in_p_tags => $options->{wrap_in_p_tags}});

    return $text;
}

sub _RunSpanGamut {
#
# These are all the transformations that occur *within* block-level
# tags like paragraphs, headers, and list items.
#
    my ($self, $text) = @_;

    $text = $self->_DoCodeSpans($text);
    $text = $self->_EscapeSpecialCharsWithinTagAttributes($text);
    $text = $self->_EscapeSpecialChars($text);

    # Process anchor and image tags. Images must come first,
    # because ![foo][f] looks like an anchor.
    $text = $self->_DoImages($text);
    $text = $self->_DoAnchors($text);

    # Make links out of things like `<http://example.com/>`
    # Must come after _DoAnchors(), because you can use < and >
    # delimiters in inline links like [this](<url>).
    $text = $self->_DoAutoLinks($text);

    $text = $self->_EncodeAmpsAndAngles($text);

    $text = $self->_DoItalicsAndBold($text);

    # FIXME - Is hard coding space here sane, or does this want to be related to tab width?
    # Do hard breaks:
    $text =~ s/ {2,}\n/ <br$self->{empty_element_suffix}\n/g;

    return $text;
}

sub _EscapeSpecialChars {
    my ($self, $text) = @_;
    my $tokens ||= $self->_TokenizeHTML($text);

    $text = '';   # rebuild $text from the tokens
#   my $in_pre = 0;  # Keep track of when we're inside <pre> or <code> tags.
#   my $tags_to_skip = qr!<(/?)(?:pre|code|kbd|script|math)[\s>]!;

    foreach my $cur_token (@$tokens) {
        if ($cur_token->[0] eq "tag") {
            # Within tags, encode * and _ so they don't conflict
            # with their use in Markdown for italics and strong.
            # We're replacing each such character with its
            # corresponding MD5 checksum value; this is likely
            # overkill, but it should prevent us from colliding
            # with the escape values by accident.
            $cur_token->[1] =~  s! \* !$g_escape_table{'*'}!ogx;
            $cur_token->[1] =~  s! _  !$g_escape_table{'_'}!ogx;
            $text .= $cur_token->[1];
        } else {
            my $t = $cur_token->[1];
            $t = $self->_EncodeBackslashEscapes($t);
            $text .= $t;
        }
    }
    return $text;
}

sub _EscapeSpecialCharsWithinTagAttributes {
#
# Within tags -- meaning between < and > -- encode [\ ` * _] so they
# don't conflict with their use in Markdown for code, italics and strong.
# We're replacing each such character with its corresponding MD5 checksum
# value; this is likely overkill, but it should prevent us from colliding
# with the escape values by accident.
#
    my ($self, $text) = @_;
    my $tokens ||= $self->_TokenizeHTML($text);
    $text = '';   # rebuild $text from the tokens

    foreach my $cur_token (@$tokens) {
        if ($cur_token->[0] eq "tag") {
            $cur_token->[1] =~  s! \\ !$g_escape_table{'\\'}!gox;
            $cur_token->[1] =~  s{ (?<=.)</?code>(?=.)  }{$g_escape_table{'`'}}gox;
            $cur_token->[1] =~  s! \* !$g_escape_table{'*'}!gox;
            $cur_token->[1] =~  s! _  !$g_escape_table{'_'}!gox;
        }
        $text .= $cur_token->[1];
    }
    return $text;
}

sub _DoAnchors {
#
# Turn Markdown link shortcuts into XHTML <a> tags.
#
    my ($self, $text) = @_;

    #
    # First, handle reference-style links: [link text] [id]
    #
    $text =~ s{
        (                   # wrap whole match in $1
          \[
            ($g_nested_brackets)    # link text = $2
          \]

          [ ]?              # one optional space
          (?:\n[ ]*)?       # one optional newline followed by spaces

          \[
            (.*?)       # id = $3
          \]
        )
    }{
        my $whole_match = $1;
        my $link_text   = $2;
        my $link_id     = lc $3;

        if ($link_id eq "") {
            $link_id = lc $link_text;   # for shortcut links like [this][].
        }

        $link_id =~ s{[ ]*\n}{ }g; # turn embedded newlines into spaces

        $self->_GenerateAnchor($whole_match, $link_text, $link_id);
    }xsge;

    #
    # Next, inline-style links: [link text](url "optional title")
    #
    $text =~ s{
        (               # wrap whole match in $1
          \[
            ($g_nested_brackets)    # link text = $2
          \]
          \(            # literal paren
            [ \t]*
            ($g_nested_parens)   # href = $3
            [ \t]*
            (           # $4
              (['"])    # quote char = $5
              (.*?)     # Title = $6
              \5        # matching quote
              [ \t]*    # ignore any spaces/tabs between closing quote and )
            )?          # title is optional
          \)
        )
    }{
        my $result;
        my $whole_match = $1;
        my $link_text   = $2;
        my $url         = $3;
        my $title       = $6;

        $self->_GenerateAnchor($whole_match, $link_text, undef, $url, $title);
    }xsge;

    #
    # Last, handle reference-style shortcuts: [link text]
    # These must come last in case you've also got [link test][1]
    # or [link test](/foo)
    #
    $text =~ s{
        (                    # wrap whole match in $1
          \[
            ([^\[\]]+)        # link text = $2; can't contain '[' or ']'
          \]
        )
    }{
        my $result;
        my $whole_match = $1;
        my $link_text   = $2;
        (my $link_id = lc $2) =~ s{[ ]*\n}{ }g; # lower-case and turn embedded newlines into spaces

        $self->_GenerateAnchor($whole_match, $link_text, $link_id);
    }xsge;

    return $text;
}

sub _GenerateAnchor {
    # FIXME - Fugly, change to named params?
    my ($self, $whole_match, $link_text, $link_id, $url, $title, $attributes) = @_;

    my $result;

    $attributes = '' unless defined $attributes;

    if ( !defined $url && defined $self->{_urls}{$link_id}) {
        $url = $self->{_urls}{$link_id};
    }

    if (!defined $url) {
        return $whole_match;
    }

    $url =~ s! \* !$g_escape_table{'*'}!gox;    # We've got to encode these to avoid
    $url =~ s!  _ !$g_escape_table{'_'}!gox;    # conflicting with italics/bold.
    $url =~ s{^<(.*)>$}{$1};                    # Remove <>'s surrounding URL, if present

    $result = qq{<a href="$url"};

    if ( !defined $title && defined $link_id && defined $self->{_titles}{$link_id} ) {
        $title = $self->{_titles}{$link_id};
    }

    if ( defined $title ) {
        $title =~ s/"/&quot;/g;
        $title =~ s! \* !$g_escape_table{'*'}!gox;
        $title =~ s!  _ !$g_escape_table{'_'}!gox;
        $result .=  qq{ title="$title"};
    }

    $result .= "$attributes>$link_text</a>";

    return $result;
}

sub _DoImages {
#
# Turn Markdown image shortcuts into <img> tags.
#
    my ($self, $text) = @_;

    #
    # First, handle reference-style labeled images: ![alt text][id]
    #
    $text =~ s{
        (               # wrap whole match in $1
          !\[
            (.*?)       # alt text = $2
          \]

          [ ]?              # one optional space
          (?:\n[ ]*)?       # one optional newline followed by spaces

          \[
            (.*?)       # id = $3
          \]

        )
    }{
        my $result;
        my $whole_match = $1;
        my $alt_text    = $2;
        my $link_id     = lc $3;

        if ($link_id eq '') {
            $link_id = lc $alt_text;     # for shortcut links like ![this][].
        }

        $self->_GenerateImage($whole_match, $alt_text, $link_id);
    }xsge;

    #
    # Next, handle inline images:  ![alt text](url "optional title")
    # Don't forget: encode * and _

    $text =~ s{
        (               # wrap whole match in $1
          !\[
            (.*?)       # alt text = $2
          \]
          \(            # literal paren
            [ \t]*
            ($g_nested_parens)  # src url - href = $3
            [ \t]*
            (           # $4
              (['"])    # quote char = $5
              (.*?)     # title = $6
              \5        # matching quote
              [ \t]*
            )?          # title is optional
          \)
        )
    }{
        my $result;
        my $whole_match = $1;
        my $alt_text    = $2;
        my $url         = $3;
        my $title       = '';
        if (defined($6)) {
            $title      = $6;
        }

        $self->_GenerateImage($whole_match, $alt_text, undef, $url, $title);
    }xsge;

    return $text;
}

sub _GenerateImage {
    # FIXME - Fugly, change to named params?
    my ($self, $whole_match, $alt_text, $link_id, $url, $title, $attributes) = @_;

    my $result;

    $attributes = '' unless defined $attributes;

    $alt_text ||= '';
    $alt_text =~ s/"/&quot;/g;
    # FIXME - how about >

    if ( !defined $url && defined $self->{_urls}{$link_id}) {
        $url = $self->{_urls}{$link_id};
    }

    # If there's no such link ID, leave intact:
    return $whole_match unless defined $url;

    $url =~ s! \* !$g_escape_table{'*'}!ogx;     # We've got to encode these to avoid
    $url =~ s!  _ !$g_escape_table{'_'}!ogx;     # conflicting with italics/bold.
    $url =~ s{^<(.*)>$}{$1};                    # Remove <>'s surrounding URL, if present

    if (!defined $title && length $link_id && defined $self->{_titles}{$link_id} && length $self->{_titles}{$link_id}) {
        $title = $self->{_titles}{$link_id};
    }

    $result = qq{<img src="$url" alt="$alt_text"};
    if (defined $title && length $title) {
        $title =~ s! \* !$g_escape_table{'*'}!ogx;
        $title =~ s!  _ !$g_escape_table{'_'}!ogx;
        $title    =~ s/"/&quot;/g;
        $result .=  qq{ title="$title"};
    }
    $result .= $attributes . $self->{empty_element_suffix};

    return $result;
}

sub _DoHeaders {
    my ($self, $text) = @_;

    # Setext-style headers:
    #     Header 1
    #     ========
    #
    #     Header 2
    #     --------
    #
    $text =~ s{ ^(.+)[ \t]*\n=+[ \t]*\n+ }{
        $self->_GenerateHeader('1', $1);
    }egmx;

    $text =~ s{ ^(.+)[ \t]*\n-+[ \t]*\n+ }{
        $self->_GenerateHeader('2', $1);
    }egmx;


    # atx-style headers:
    #   # Header 1
    #   ## Header 2
    #   ## Header 2 with closing hashes ##
    #   ...
    #   ###### Header 6
    #
    my $l;
    $text =~ s{
            ^(\#{1,6})  # $1 = string of #'s
            [ \t]*
            (.+?)       # $2 = Header text
            [ \t]*
            \#*         # optional closing #'s (not counted)
            \n+
        }{
            my $h_level = length($1);
            $self->_GenerateHeader($h_level, $2);
        }egmx;

    return $text;
}

sub _GenerateHeader {
    my ($self, $level, $id) = @_;

    return "<h$level>"  .  $self->_RunSpanGamut($id)  .  "</h$level>\n\n";
}

sub _DoLists {
#
# Form HTML ordered (numbered) and unordered (bulleted) lists.
#
    my ($self, $text) = @_;
    my $less_than_tab = $self->{tab_width} - 1;

    # Re-usable patterns to match list item bullets and number markers:
    my $marker_ul  = qr/[*+-]/;
    my $marker_ol  = qr/\d+[.]/;
    my $marker_any = qr/(?:$marker_ul|$marker_ol)/;

    # Re-usable pattern to match any entirel ul or ol list:
    my $whole_list = qr{
        (                               # $1 = whole list
          (                             # $2
            [ ]{0,$less_than_tab}
            (${marker_any})             # $3 = first list item marker
            [ \t]+
          )
          (?s:.+?)
          (                             # $4
              \z
            |
              \n{2,}
              (?=\S)
              (?!                       # Negative lookahead for another list item marker
                [ \t]*
                ${marker_any}[ \t]+
              )
          )
        )
    }mx;

    # We use a different prefix before nested lists than top-level lists.
    # See extended comment in _ProcessListItems().
    #
    # Note: There's a bit of duplication here. My original implementation
    # created a scalar regex pattern as the conditional result of the test on
    # $self->{_list_level}, and then only ran the $text =~ s{...}{...}egmx
    # substitution once, using the scalar as the pattern. This worked,
    # everywhere except when running under MT on my hosting account at Pair
    # Networks. There, this caused all rebuilds to be killed by the reaper (or
    # perhaps they crashed, but that seems incredibly unlikely given that the
    # same script on the same server ran fine *except* under MT. I've spent
    # more time trying to figure out why this is happening than I'd like to
    # admit. My only guess, backed up by the fact that this workaround works,
    # is that Perl optimizes the substition when it can figure out that the
    # pattern will never change, and when this optimization isn't on, we run
    # afoul of the reaper. Thus, the slightly redundant code to that uses two
    # static s/// patterns rather than one conditional pattern.

    if ($self->{_list_level}) {
        $text =~ s{
                ^
                $whole_list
            }{
                my $list = $1;
                my $marker = $3;
                my $list_type = ($marker =~ m/$marker_ul/) ? "ul" : "ol";
                # Turn double returns into triple returns, so that we can make a
                # paragraph for the last item in a list, if necessary:
                $list =~ s/\n{2,}/\n\n\n/g;
                my $result = ( $list_type eq 'ul' ) ?
                    $self->_ProcessListItemsUL($list, $marker_ul)
                  : $self->_ProcessListItemsOL($list, $marker_ol);

                $result = $self->_MakeList($list_type, $result, $marker);
                $result;
            }egmx;
    }
    else {
        $text =~ s{
                (?:(?<=\n\n)|\A\n?)
                $whole_list
            }{
                my $list = $1;
                my $marker = $3;
                my $list_type = ($marker =~ m/$marker_ul/) ? "ul" : "ol";
                # Turn double returns into triple returns, so that we can make a
                # paragraph for the last item in a list, if necessary:
                $list =~ s/\n{2,}/\n\n\n/g;
                my $result = ( $list_type eq 'ul' ) ?
                    $self->_ProcessListItemsUL($list, $marker_ul)
                  : $self->_ProcessListItemsOL($list, $marker_ol);
                $result = $self->_MakeList($list_type, $result, $marker);
                $result;
            }egmx;
    }


    return $text;
}

sub _MakeList {
  my ($self, $list_type, $content, $marker) = @_;

  if ($list_type eq 'ol' and $self->{trust_list_start_value}) {
    my ($num) = $marker =~ /^(\d+)[.]/;
    return "<ol start='$num'>\n" . $content . "</ol>\n";
  }

  return "<$list_type>\n" . $content . "</$list_type>\n";
}

sub _ProcessListItemsOL {
#
#   Process the contents of a single ordered list, splitting it
#   into individual list items.
#

    my ($self, $list_str, $marker_any) = @_;


    # The $self->{_list_level} global keeps track of when we're inside a list.
    # Each time we enter a list, we increment it; when we leave a list,
    # we decrement. If it's zero, we're not in a list anymore.
    #
    # We do this because when we're not inside a list, we want to treat
    # something like this:
    #
    #       I recommend upgrading to version
    #       8. Oops, now this line is treated
    #       as a sub-list.
    #
    # As a single paragraph, despite the fact that the second line starts
    # with a digit-period-space sequence.
    #
    # Whereas when we're inside a list (or sub-list), that line will be
    # treated as the start of a sub-list. What a kludge, huh? This is
    # an aspect of Markdown's syntax that's hard to parse perfectly
    # without resorting to mind-reading. Perhaps the solution is to
    # change the syntax rules such that sub-lists must start with a
    # starting cardinal number; e.g. "1." or "a.".

    $self->{_list_level}++;

    # trim trailing blank lines:
    $list_str =~ s/\n{2,}\z/\n/;


    $list_str =~ s{
        (\n)?                           # leading line = $1
        (^[ \t]*)                       # leading whitespace = $2
        ($marker_any) [ \t]+            # list marker = $3
        ((?s:.+?)                       # list item text   = $4
        (\n{1,2}))
        (?= \n* (\z | \2 ($marker_any) [ \t]+))
    }{
        my $item = $4;
        my $leading_line = $1;
        my $leading_space = $2;

        if ($leading_line or ($item =~ m/\n{2,}/)) {
            $item = $self->_RunBlockGamut($self->_Outdent($item), {wrap_in_p_tags => 1});
        }
        else {
            # Recursion for sub-lists:
            $item = $self->_DoLists($self->_Outdent($item));
            chomp $item;
            $item = $self->_RunSpanGamut($item);
        }

        "<li>" . $item . "</li>\n";
    }egmxo;

    $self->{_list_level}--;
    return $list_str;
}

sub _ProcessListItemsUL {
#
#   Process the contents of a single unordered list, splitting it
#   into individual list items.
#

    my ($self, $list_str, $marker_any) = @_;


    # The $self->{_list_level} global keeps track of when we're inside a list.
    # Each time we enter a list, we increment it; when we leave a list,
    # we decrement. If it's zero, we're not in a list anymore.
    #
    # We do this because when we're not inside a list, we want to treat
    # something like this:
    #
    #       I recommend upgrading to version
    #       8. Oops, now this line is treated
    #       as a sub-list.
    #
    # As a single paragraph, despite the fact that the second line starts
    # with a digit-period-space sequence.
    #
    # Whereas when we're inside a list (or sub-list), that line will be
    # treated as the start of a sub-list. What a kludge, huh? This is
    # an aspect of Markdown's syntax that's hard to parse perfectly
    # without resorting to mind-reading. Perhaps the solution is to
    # change the syntax rules such that sub-lists must start with a
    # starting cardinal number; e.g. "1." or "a.".

    $self->{_list_level}++;

    # trim trailing blank lines:
    $list_str =~ s/\n{2,}\z/\n/;


    $list_str =~ s{
        (\n)?                           # leading line = $1
        (^[ \t]*)                       # leading whitespace = $2
        ($marker_any) [ \t]+            # list marker = $3
        ((?s:.+?)                       # list item text   = $4
        (\n{1,2}))
        (?= \n* (\z | \2 ($marker_any) [ \t]+))
    }{
        my $item = $4;
        my $leading_line = $1;
        my $leading_space = $2;

        if ($leading_line or ($item =~ m/\n{2,}/)) {
            $item = $self->_RunBlockGamut($self->_Outdent($item), {wrap_in_p_tags => 1});
        }
        else {
            # Recursion for sub-lists:
            $item = $self->_DoLists($self->_Outdent($item));
            chomp $item;
            $item = $self->_RunSpanGamut($item);
        }

        "<li>" . $item . "</li>\n";
    }egmxo;

    $self->{_list_level}--;
    return $list_str;
}

sub _DoCodeBlocks {
#
# Process Markdown code blocks (indented with 4 spaces or 1 tab):
# * outdent the spaces/tab
# * encode <, >, & into HTML entities
# * escape Markdown special characters into MD5 hashes
# * trim leading and trailing newlines
#

    my ($self, $text) = @_;

     $text =~ s{
        (?:\n\n|\A)
        (                # $1 = the code block -- one or more lines, starting with a space/tab
          (?:
            (?:[ ]{$self->{tab_width}} | \t)   # Lines must start with a tab or a tab-width of spaces
            .*\n+
          )+
        )
        ((?=^[ ]{0,$self->{tab_width}}\S)|\Z)    # Lookahead for non-space at line-start, or end of doc
    }{
        my $codeblock = $1;
        my $result;  # return value

        $codeblock = $self->_EncodeCode($self->_Outdent($codeblock));
        $codeblock = $self->_Detab($codeblock);
        $codeblock =~ s/\A\n+//;  # trim leading newlines
        $codeblock =~ s/\n+\z//;  # trim trailing newlines

        $result = "\n\n<pre><code>" . $codeblock . "\n</code></pre>\n\n";

        $result;
    }egmx;

    return $text;
}

sub _DoCodeSpans {
#
#   *   Backtick quotes are used for <code></code> spans.
#
#   *   You can use multiple backticks as the delimiters if you want to
#       include literal backticks in the code span. So, this input:
#
#         Just type ``foo `bar` baz`` at the prompt.
#
#       Will translate to:
#
#         <p>Just type <code>foo `bar` baz</code> at the prompt.</p>
#
#       There's no arbitrary limit to the number of backticks you
#       can use as delimters. If you need three consecutive backticks
#       in your code, use four for delimiters, etc.
#
#   *   You can use spaces to get literal backticks at the edges:
#
#         ... type `` `bar` `` ...
#
#       Turns to:
#
#         ... type <code>`bar`</code> ...
#

    my ($self, $text) = @_;

    $text =~ s@
            (?<!\\)        # Character before opening ` can't be a backslash
            (`+)        # $1 = Opening run of `
            (.+?)        # $2 = The code block
            (?<!`)
            \1            # Matching closer
            (?!`)
        @
             my $c = "$2";
             $c =~ s/^[ \t]*//g; # leading whitespace
             $c =~ s/[ \t]*$//g; # trailing whitespace
             $c = $self->_EncodeCode($c);
            "<code>$c</code>";
        @egsx;

    return $text;
}

sub _EncodeCode {
#
# Encode/escape certain characters inside Markdown code runs.
# The point is that in code, these characters are literals,
# and lose their special Markdown meanings.
#
    my $self = shift;
    local $_ = shift;

    # Encode all ampersands; HTML entities are not
    # entities within a Markdown code span.
    s/&/&amp;/g;

    # Encode $'s, but only if we're running under Blosxom.
    # (Blosxom interpolates Perl variables in article bodies.)
    {
        no warnings 'once';
        if (defined($blosxom::version)) {
            s/\$/&#036;/g;
        }
    }


    # Do the angle bracket song and dance:
    s! <  !&lt;!gx;
    s! >  !&gt;!gx;

    # Now, escape characters that are magic in Markdown:
    s! \* !$g_escape_table{'*'}!ogx;
    s! _  !$g_escape_table{'_'}!ogx;
    s! {  !$g_escape_table{'{'}!ogx;
    s! }  !$g_escape_table{'}'}!ogx;
    s! \[ !$g_escape_table{'['}!ogx;
    s! \] !$g_escape_table{']'}!ogx;
    s! \\ !$g_escape_table{'\\'}!ogx;

    return $_;
}

sub _DoItalicsAndBold {
    my ($self, $text) = @_;

    # Handle at beginning of lines:
    $text =~ s{ ^(\*\*|__) (?=\S) (.+?[*_]*) (?<=\S) \1 }
        {<strong>$2</strong>}gsx;

    $text =~ s{ ^(\*|_) (?=\S) (.+?) (?<=\S) \1 }
        {<em>$2</em>}gsx;

    # <strong> must go first:
    $text =~ s{ (?<=\W) (\*\*|__) (?=\S) (.+?[*_]*) (?<=\S) \1 }
        {<strong>$2</strong>}gsx;

    $text =~ s{ (?<=\W) (\*|_) (?=\S) (.+?) (?<=\S) \1 }
        {<em>$2</em>}gsx;

    # And now, a second pass to catch nested strong and emphasis special cases
    $text =~ s{ (?<=\W) (\*\*|__) (?=\S) (.+?[*_]*) (?<=\S) \1 }
        {<strong>$2</strong>}gsx;

    $text =~ s{ (?<=\W) (\*|_) (?=\S) (.+?) (?<=\S) \1 }
        {<em>$2</em>}gsx;

    return $text;
}

sub _DoBlockQuotes {
    my ($self, $text) = @_;

    $text =~ s{
          (                             # Wrap whole match in $1
            (
              ^[ \t]*>[ \t]?            # '>' at the start of a line
                .+\n                    # rest of the first line
              (.+\n)*                   # subsequent consecutive lines
              \n*                       # blanks
            )+
          )
        }{
            my $bq = $1;
            $bq =~ s/^[ \t]*>[ \t]?//gm;    # trim one level of quoting
            $bq =~ s/^[ \t]+$//mg;          # trim whitespace-only lines
            $bq = $self->_RunBlockGamut($bq, {wrap_in_p_tags => 1});      # recurse

            $bq =~ s/^/  /mg;
            # These leading spaces screw with <pre> content, so we need to fix that:
            $bq =~ s{
                    (\s*<pre>.+?</pre>)
                }{
                    my $pre = $1;
                    $pre =~ s/^  //mg;
                    $pre;
                }egsx;

            "<blockquote>\n$bq\n</blockquote>\n\n";
        }egmx;


    return $text;
}

sub _FormParagraphs {
#
#   Params:
#       $text - string to process with html <p> tags
#
    my ($self, $text, $options) = @_;

    # Strip leading and trailing lines:
    $text =~ s/\A\n+//;
    $text =~ s/\n+\z//;

    my @grafs = split(/\n{2,}/, $text);

    #
    # Wrap <p> tags.
    #
    foreach (@grafs) {
        unless (defined( $self->{_html_blocks}{$_} )) {
            $_ = $self->_RunSpanGamut($_);
            if ($options->{wrap_in_p_tags}) {
                s/^([ \t]*)/<p>/;
                $_ .= "</p>";
            }
        }
    }

    #
    # Unhashify HTML blocks
    #
    foreach (@grafs) {
        if (defined( $self->{_html_blocks}{$_} )) {
            $_ = $self->{_html_blocks}{$_};
        }
    }

    return join "\n\n", @grafs;
}

sub _EncodeAmpsAndAngles {
# Smart processing for ampersands and angle brackets that need to be encoded.

    my ($self, $text) = @_;
    return '' if (!defined $text or !length $text);

    # Ampersand-encoding based entirely on Nat Irons's Amputator MT plugin:
    #   http://bumppo.net/projects/amputator/
    $text =~ s/&(?!#?[xX]?(?:[0-9a-fA-F]+|\w+);)/&amp;/g;

    # Encode naked <'s
    $text =~ s{<(?![a-z/?\$!])}{&lt;}gi;

    # And >'s - added by Fletcher Penney
#   $text =~ s{>(?![a-z/?\$!])}{&gt;}gi;
#   Causes problems...

    # Remove encoding inside comments
    $text =~ s{
        (?<=<!--) # Begin comment
        (.*?)     # Anything inside
        (?=-->)   # End comments
    }{
        my $t = $1;
        $t =~ s/&amp;/&/g;
        $t =~ s/&lt;/</g;
        $t;
    }egsx;

    return $text;
}

sub _EncodeBackslashEscapes {
#
#   Parameter:  String.
#   Returns:    The string, with after processing the following backslash
#               escape sequences.
#
    my $self = shift;
    local $_ = shift;

    s! \\\\  !$g_escape_table{'\\'}!ogx;     # Must process escaped backslashes first.
    s! \\`   !$g_escape_table{'`'}!ogx;
    s! \\\*  !$g_escape_table{'*'}!ogx;
    s! \\_   !$g_escape_table{'_'}!ogx;
    s! \\\{  !$g_escape_table{'{'}!ogx;
    s! \\\}  !$g_escape_table{'}'}!ogx;
    s! \\\[  !$g_escape_table{'['}!ogx;
    s! \\\]  !$g_escape_table{']'}!ogx;
    s! \\\(  !$g_escape_table{'('}!ogx;
    s! \\\)  !$g_escape_table{')'}!ogx;
    s! \\>   !$g_escape_table{'>'}!ogx;
    s! \\\#  !$g_escape_table{'#'}!ogx;
    s! \\\+  !$g_escape_table{'+'}!ogx;
    s! \\\-  !$g_escape_table{'-'}!ogx;
    s! \\\.  !$g_escape_table{'.'}!ogx;
    s{ \\!  }{$g_escape_table{'!'}}ogx;

    return $_;
}

sub _DoAutoLinks {
    my ($self, $text) = @_;

    $text =~ s{<((https?|ftp):[^'">\s]+)>}{<a href="$1">$1</a>}gi;

    # Email addresses: <address@domain.foo>
    $text =~ s{
        <
        (?:mailto:)?
        (
            [-.\w\+]+
            \@
            [-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+
        )
        >
    }{
        $self->_EncodeEmailAddress( $self->_UnescapeSpecialChars($1) );
    }egix;

    return $text;
}

sub _EncodeEmailAddress {
#
#   Input: an email address, e.g. "foo@example.com"
#
#   Output: the email address as a mailto link, with each character
#       of the address encoded as either a decimal or hex entity, in
#       the hopes of foiling most address harvesting spam bots. E.g.:
#
#     <a href="&#x6D;&#97;&#105;&#108;&#x74;&#111;:&#102;&#111;&#111;&#64;&#101;
#       x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;">&#102;&#111;&#111;
#       &#64;&#101;x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;</a>
#
#   Based on a filter by Matthew Wickline, posted to the BBEdit-Talk
#   mailing list: <http://tinyurl.com/yu7ue>
#

    my ($self, $addr) = @_;

    my @encode = (
        sub { '&#' .                 ord(shift)   . ';' },
        sub { '&#x' . sprintf( "%X", ord(shift) ) . ';' },
        sub {                            shift          },
    );

    $addr = "mailto:" . $addr;

    $addr =~ s{(.)}{
        my $char = $1;
        if ( $char eq '@' ) {
            # this *must* be encoded. I insist.
            $char = $encode[int rand 1]->($char);
        }
        elsif ( $char ne ':' ) {
            # leave ':' alone (to spot mailto: later)
            my $r = rand;
            # roughly 10% raw, 45% hex, 45% dec
            $char = (
                $r > .9   ?  $encode[2]->($char)  :
                $r < .45  ?  $encode[1]->($char)  :
                             $encode[0]->($char)
            );
        }
        $char;
    }gex;

    $addr = qq{<a href="$addr">$addr</a>};
    $addr =~ s{">.+?:}{">}; # strip the mailto: from the visible part

    return $addr;
}

sub _UnescapeSpecialChars {
#
# Swap back in all the special characters we've hidden.
#
    my ($self, $text) = @_;

    while( my($char, $hash) = each(%g_escape_table) ) {
        $text =~ s/$hash/$char/g;
    }
    return $text;
}

sub _TokenizeHTML {
#
#   Parameter:  String containing HTML markup.
#   Returns:    Reference to an array of the tokens comprising the input
#               string. Each token is either a tag (possibly with nested,
#               tags contained therein, such as <a href="<MTFoo>">, or a
#               run of text between tags. Each element of the array is a
#               two-element array; the first is either 'tag' or 'text';
#               the second is the actual value.
#
#
#   Derived from the _tokenize() subroutine from Brad Choate's MTRegex plugin.
#       <http://www.bradchoate.com/past/mtregex.php>
#

    my ($self, $str) = @_;
    my $pos = 0;
    my $len = length $str;
    my @tokens;

    my $depth = 6;
    my $nested_tags = join('|', ('(?:<[a-z/!$](?:[^<>]') x $depth) . (')*>)' x  $depth);
    my $match = qr/(?s: <! ( -- .*? -- \s* )+ > ) |  # comment
                   (?s: <\? .*? \?> ) |              # processing instruction
                   $nested_tags/iox;                   # nested tags

    while ($str =~ m/($match)/og) {
        my $whole_tag = $1;
        my $sec_start = pos $str;
        my $tag_start = $sec_start - length $whole_tag;
        if ($pos < $tag_start) {
            push @tokens, ['text', substr($str, $pos, $tag_start - $pos)];
        }
        push @tokens, ['tag', $whole_tag];
        $pos = pos $str;
    }
    push @tokens, ['text', substr($str, $pos, $len - $pos)] if $pos < $len;
    \@tokens;
}

sub _Outdent {
#
# Remove one level of line-leading tabs or spaces
#
    my ($self, $text) = @_;

    $text =~ s/^(\t|[ ]{1,$self->{tab_width}})//gm;
    return $text;
}

sub _Detab {
#
# Cribbed from a post by Bart Lateur:
# <http://www.nntp.perl.org/group/perl.macperl.anyperl/154>
#
    my ($self, $text) = @_;

    # FIXME - Better anchor/regex would be quicker.

    # Original:
    #$text =~ s{(.*?)\t}{$1.(' ' x ($self->{tab_width} - length($1) % $self->{tab_width}))}ge;

    # Much swifter, but pretty hateful:
    do {} while ($text =~ s{^(.*?)\t}{$1.(' ' x ($self->{tab_width} - length($1) % $self->{tab_width}))}mge);
    return $text;
}

sub _ConvertCopyright {
    my ($self, $text) = @_;
    # Convert to an XML compatible form of copyright symbol

    $text =~ s/&copy;/&#xA9;/gi;

    return $text;
}

1;

__END__

=head1 OTHER IMPLEMENTATIONS

Markdown has been re-implemented in a number of languages, and with a number of additions.

Those that I have found are listed below:

=over

=item C - <http://www.pell.portland.or.us/~orc/Code/discount>

Discount - Original Markdown, but in C. Fastest implementation available, and passes MDTest.
Adds its own set of custom features.

=item python - <http://www.freewisdom.org/projects/python-markdown/>

Python Markdown which is mostly compatible with the original, with an interesting extension API.

=item ruby (maruku) - <http://maruku.rubyforge.org/>

One of the nicest implementations out there. Builds a parse tree internally so very flexible.

=item php - <http://michelf.com/projects/php-markdown/>

A direct port of Markdown.pl, also has a separately maintained 'extra' version,
which adds a number of features that were borrowed by MultiMarkdown.

=item lua - <http://www.frykholm.se/files/markdown.lua>

Port to lua. Simple and lightweight (as lua is).

=item haskell - <http://johnmacfarlane.net/pandoc/>

Pandoc is a more general library, supporting Markdown, reStructuredText, LaTeX and more.

=item javascript - <http://www.attacklab.net/showdown-gui.html>

Direct(ish) port of Markdown.pl to JavaScript

=back

=head1 BUGS

To file bug reports or feature requests please send email to:

    bug-Text-Markdown@rt.cpan.org

Please include with your report: (1) the example input; (2) the output
you expected; (3) the output Markdown actually produced.

=head1 VERSION HISTORY

See the Changes file for detailed release notes for this version.

=head1 AUTHOR

    John Gruber
    http://daringfireball.net/

    PHP port and other contributions by Michel Fortin
    http://michelf.com/

    MultiMarkdown changes by Fletcher Penney
    http://fletcher.freeshell.org/

    CPAN Module Text::MultiMarkdown (based on Text::Markdown by Sebastian
    Riedel) originally by Darren Kulp (http://kulp.ch/)
    
    Support for markdown="1" by Dan Dascalescu (http://dandascalescu.com)

    This module is maintained by: Tomas Doran http://www.bobtfish.net/

=head1 THIS DISTRIBUTION

Please note that this distribution is a fork of John Gruber's original Markdown project,
and it *is not* in any way blessed by him.

Whilst this code aims to be compatible with the original Markdown.pl (and incorporates
and passes the Markdown test suite) whilst fixing a number of bugs in the original -
there may be differences between the behaviour of this module and Markdown.pl. If you find
any differences where you believe Text::Markdown behaves contrary to the Markdown spec,
please report them as bugs.

Text::Markdown *does not* extend the markdown dialect in any way from that which is documented at
daringfireball. If you want additional features, you should look at L<Text::MultiMarkdown>.

=head1 SOURCE CODE

You can find the source code repository for L<Text::Markdown> and L<Text::MultiMarkdown>
on GitHub at <http://github.com/bobtfish/text-markdown>.

=head1 COPYRIGHT AND LICENSE

Original Code Copyright (c) 2003-2004 John Gruber
<http://daringfireball.net/>
All rights reserved.

MultiMarkdown changes Copyright (c) 2005-2006 Fletcher T. Penney
<http://fletcher.freeshell.org/>
All rights reserved.

Text::MultiMarkdown changes Copyright (c) 2006-2009 Darren Kulp
<http://kulp.ch> and Tomas Doran <http://www.bobtfish.net>

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

* Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.

* Neither the name "Markdown" nor the names of its contributors may
  be used to endorse or promote products derived from this software
  without specific prior written permission.

This software is provided by the copyright holders and contributors "as
is" and any express or implied warranties, including, but not limited
to, the implied warranties of merchantability and fitness for a
particular purpose are disclaimed. In no event shall the copyright owner
or contributors be liable for any direct, indirect, incidental, special,
exemplary, or consequential damages (including, but not limited to,
procurement of substitute goods or services; loss of use, data, or
profits; or business interruption) however caused and on any theory of
liability, whether in contract, strict liability, or tort (including
negligence or otherwise) arising in any way out of the use of this
software, even if advised of the possibility of such damage.

=cut