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
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# :Author: David Goodger, Günter Milde
#          Based on the html4css1 writer by David Goodger.
# :Maintainer: docutils-develop@lists.sourceforge.net
# :Revision: $Revision: 8644 $
# :Date: $Date: 2005-06-28$
# :Copyright: © 2016 David Goodger, Günter Milde
# :License: Released under the terms of the `2-Clause BSD license`_, in short:
#
#    Copying and distribution of this file, with or without modification,
#    are permitted in any medium without royalty provided the copyright
#    notice and this notice are preserved.
#    This file is offered as-is, without any warranty.
#
# .. _2-Clause BSD license: https://opensource.org/licenses/BSD-2-Clause

"""common definitions for Docutils HTML writers"""

import base64
import mimetypes
import os, os.path
import re
import sys

try: # check for the Python Imaging Library
    import PIL.Image
except ImportError:
    try:  # sometimes PIL modules are put in PYTHONPATH's root
        import Image
        class PIL(object): pass  # dummy wrapper
        PIL.Image = Image
    except ImportError:
        PIL = None

import docutils
from docutils import nodes, utils, writers, languages, io
from docutils.utils.error_reporting import SafeString
from docutils.transforms import writer_aux
from docutils.utils.math import (unichar2tex, pick_math_environment,
                                 math2html, latex2mathml, tex2mathml_extern)

if sys.version_info >= (3, 0):
    from urllib.request import url2pathname
else:
    from urllib import url2pathname

if sys.version_info >= (3, 0):
    unicode = str  # noqa


class Writer(writers.Writer):

    supported = ('html', 'xhtml') # update in subclass
    """Formats this writer supports."""

    # default_stylesheets = [] # set in subclass!
    # default_stylesheet_dirs = ['.'] # set in subclass!
    default_template = 'template.txt'
    # default_template_path = ... # set in subclass!
    # settings_spec = ... # set in subclass!

    settings_defaults = {'output_encoding_error_handler': 'xmlcharrefreplace'}

    # config_section = ... # set in subclass!
    config_section_dependencies = ('writers', 'html writers')

    visitor_attributes = (
        'head_prefix', 'head', 'stylesheet', 'body_prefix',
        'body_pre_docinfo', 'docinfo', 'body', 'body_suffix',
        'title', 'subtitle', 'header', 'footer', 'meta', 'fragment',
        'html_prolog', 'html_head', 'html_title', 'html_subtitle',
        'html_body')

    def get_transforms(self):
        return writers.Writer.get_transforms(self) + [writer_aux.Admonitions]

    def translate(self):
        self.visitor = visitor = self.translator_class(self.document)
        self.document.walkabout(visitor)
        for attr in self.visitor_attributes:
            setattr(self, attr, getattr(visitor, attr))
        self.output = self.apply_template()

    def apply_template(self):
        template_file = open(self.document.settings.template, 'rb')
        template = unicode(template_file.read(), 'utf-8')
        template_file.close()
        subs = self.interpolation_dict()
        return template % subs

    def interpolation_dict(self):
        subs = {}
        settings = self.document.settings
        for attr in self.visitor_attributes:
            subs[attr] = ''.join(getattr(self, attr)).rstrip('\n')
        subs['encoding'] = settings.output_encoding
        subs['version'] = docutils.__version__
        return subs

    def assemble_parts(self):
        writers.Writer.assemble_parts(self)
        for part in self.visitor_attributes:
            self.parts[part] = ''.join(getattr(self, part))


class HTMLTranslator(nodes.NodeVisitor):

    """
    Generic Docutils to HTML translator.

    See the `html4css1` and `html5_polyglot` writers for full featured
    HTML writers.

    .. IMPORTANT::
      The `visit_*` and `depart_*` methods use a
      heterogeneous stack, `self.context`.
      When subclassing, make sure to be consistent in its use!

      Examples for robust coding:

      a) Override both `visit_*` and `depart_*` methods, don't call the
         parent functions.

      b) Extend both and unconditionally call the parent functions::

           def visit_example(self, node):
               if foo:
                   self.body.append('<div class="foo">')
               html4css1.HTMLTranslator.visit_example(self, node)

           def depart_example(self, node):
               html4css1.HTMLTranslator.depart_example(self, node)
               if foo:
                   self.body.append('</div>')

      c) Extend both, calling the parent functions under the same
         conditions::

           def visit_example(self, node):
               if foo:
                   self.body.append('<div class="foo">\n')
               else: # call the parent method
                   _html_base.HTMLTranslator.visit_example(self, node)

           def depart_example(self, node):
               if foo:
                   self.body.append('</div>\n')
               else: # call the parent method
                   _html_base.HTMLTranslator.depart_example(self, node)

      d) Extend one method (call the parent), but don't otherwise use the
         `self.context` stack::

           def depart_example(self, node):
               _html_base.HTMLTranslator.depart_example(self, node)
               if foo:
                   # implementation-specific code
                   # that does not use `self.context`
                   self.body.append('</div>\n')

      This way, changes in stack use will not bite you.
    """

    xml_declaration = '<?xml version="1.0" encoding="%s" ?>\n'
    doctype = '<!DOCTYPE html>\n'
    doctype_mathml = doctype

    head_prefix_template = ('<html xmlns="http://www.w3.org/1999/xhtml"'
                            ' xml:lang="%(lang)s" lang="%(lang)s">\n<head>\n')
    content_type = '<meta charset="%s"/>\n'
    generator = ('<meta name="generator" content="Docutils %s: '
                 'http://docutils.sourceforge.net/" />\n')

    # Template for the MathJax script in the header:
    mathjax_script = '<script type="text/javascript" src="%s"></script>\n'

    mathjax_url = 'file:/usr/share/javascript/mathjax/MathJax.js'
    """
    URL of the MathJax javascript library.

    The MathJax library ought to be installed on the same
    server as the rest of the deployed site files and specified
    in the `math-output` setting appended to "mathjax".
    See `Docutils Configuration`__.

    __ http://docutils.sourceforge.net/docs/user/config.html#math-output

    The fallback tries a local MathJax installation at
    ``/usr/share/javascript/mathjax/MathJax.js``.
    """

    stylesheet_link = '<link rel="stylesheet" href="%s" type="text/css" />\n'
    embedded_stylesheet = '<style type="text/css">\n\n%s\n</style>\n'
    words_and_spaces = re.compile(r'[^ \n]+| +|\n')
    # wrap point inside word:
    in_word_wrap_point = re.compile(r'.+\W\W.+|[-?].+', re.U)
    lang_attribute = 'lang' # name changes to 'xml:lang' in XHTML 1.1

    special_characters = {ord('&'): u'&amp;',
                          ord('<'): u'&lt;',
                          ord('"'): u'&quot;',
                          ord('>'): u'&gt;',
                          ord('@'): u'&#64;', # may thwart address harvesters
                         }
    """Character references for characters with a special meaning in HTML."""


    def __init__(self, document):
        nodes.NodeVisitor.__init__(self, document)
        self.settings = settings = document.settings
        lcode = settings.language_code
        self.language = languages.get_language(lcode, document.reporter)
        self.meta = [self.generator % docutils.__version__]
        self.head_prefix = []
        self.html_prolog = []
        if settings.xml_declaration:
            self.head_prefix.append(self.xml_declaration
                                    % settings.output_encoding)
            # self.content_type = ""
            # encoding not interpolated:
            self.html_prolog.append(self.xml_declaration)
        self.head = self.meta[:]
        self.stylesheet = [self.stylesheet_call(path)
                           for path in utils.get_stylesheet_list(settings)]
        self.body_prefix = ['</head>\n<body>\n']
        # document title, subtitle display
        self.body_pre_docinfo = []
        # author, date, etc.
        self.docinfo = []
        self.body = []
        self.fragment = []
        self.body_suffix = ['</body>\n</html>\n']
        self.section_level = 0
        self.initial_header_level = int(settings.initial_header_level)

        self.math_output = settings.math_output.split()
        self.math_output_options = self.math_output[1:]
        self.math_output = self.math_output[0].lower()

        self.context = []
        """Heterogeneous stack.

        Used by visit_* and depart_* functions in conjunction with the tree
        traversal. Make sure that the pops correspond to the pushes."""

        self.topic_classes = []
        self.colspecs = []
        self.compact_p = True
        self.compact_simple = False
        self.compact_field_list = False
        self.in_docinfo = False
        self.in_sidebar = False
        self.in_footnote_list = False
        self.title = []
        self.subtitle = []
        self.header = []
        self.footer = []
        self.html_head = [self.content_type] # charset not interpolated
        self.html_title = []
        self.html_subtitle = []
        self.html_body = []
        self.in_document_title = 0   # len(self.body) or 0
        self.in_mailto = False
        self.author_in_authors = False # for html4css1
        self.math_header = []

    def astext(self):
        return ''.join(self.head_prefix + self.head
                       + self.stylesheet + self.body_prefix
                       + self.body_pre_docinfo + self.docinfo
                       + self.body + self.body_suffix)

    def encode(self, text):
        """Encode special characters in `text` & return."""
        # Use only named entities known in both XML and HTML
        # other characters are automatically encoded "by number" if required.
        # @@@ A codec to do these and all other HTML entities would be nice.
        text = unicode(text)
        return text.translate(self.special_characters)

    def cloak_mailto(self, uri):
        """Try to hide a mailto: URL from harvesters."""
        # Encode "@" using a URL octet reference (see RFC 1738).
        # Further cloaking with HTML entities will be done in the
        # `attval` function.
        return uri.replace('@', '%40')

    def cloak_email(self, addr):
        """Try to hide the link text of a email link from harversters."""
        # Surround at-signs and periods with <span> tags.  ("@" has
        # already been encoded to "&#64;" by the `encode` method.)
        addr = addr.replace('&#64;', '<span>&#64;</span>')
        addr = addr.replace('.', '<span>&#46;</span>')
        return addr

    def attval(self, text,
               whitespace=re.compile('[\n\r\t\v\f]')):
        """Cleanse, HTML encode, and return attribute value text."""
        encoded = self.encode(whitespace.sub(' ', text))
        if self.in_mailto and self.settings.cloak_email_addresses:
            # Cloak at-signs ("%40") and periods with HTML entities.
            encoded = encoded.replace('%40', '&#37;&#52;&#48;')
            encoded = encoded.replace('.', '&#46;')
        return encoded

    def stylesheet_call(self, path):
        """Return code to reference or embed stylesheet file `path`"""
        if self.settings.embed_stylesheet:
            try:
                content = io.FileInput(source_path=path,
                                       encoding='utf-8').read()
                self.settings.record_dependencies.add(path)
            except IOError as err:
                msg = u"Cannot embed stylesheet '%r': %s." % (
                                path, SafeString(err.strerror))
                self.document.reporter.error(msg)
                return '<--- %s --->\n' % msg
            return self.embedded_stylesheet % content
        # else link to style file:
        if self.settings.stylesheet_path:
            # adapt path relative to output (cf. config.html#stylesheet-path)
            path = utils.relative_path(self.settings._destination, path)
        return self.stylesheet_link % self.encode(path)

    def starttag(self, node, tagname, suffix='\n', empty=False, **attributes):
        """
        Construct and return a start tag given a node (id & class attributes
        are extracted), tag name, and optional attributes.
        """
        tagname = tagname.lower()
        prefix = []
        atts = {}
        ids = []
        for (name, value) in attributes.items():
            atts[name.lower()] = value
        classes = []
        languages = []
        # unify class arguments and move language specification
        for cls in node.get('classes', []) + atts.pop('class', '').split():
            if cls.startswith('language-'):
                languages.append(cls[9:])
            elif cls.strip() and cls not in classes:
                classes.append(cls)
        if languages:
            # attribute name is 'lang' in XHTML 1.0 but 'xml:lang' in 1.1
            atts[self.lang_attribute] = languages[0]
        if classes:
            atts['class'] = ' '.join(classes)
        assert 'id' not in atts
        ids.extend(node.get('ids', []))
        if 'ids' in atts:
            ids.extend(atts['ids'])
            del atts['ids']
        if ids:
            atts['id'] = ids[0]
            for id in ids[1:]:
                # Add empty "span" elements for additional IDs.  Note
                # that we cannot use empty "a" elements because there
                # may be targets inside of references, but nested "a"
                # elements aren't allowed in XHTML (even if they do
                # not all have a "href" attribute).
                if empty or isinstance(node,
                            (nodes.bullet_list, nodes.docinfo,
                             nodes.definition_list, nodes.enumerated_list,
                             nodes.field_list, nodes.option_list,
                             nodes.table)):
                    # Insert target right in front of element.
                    prefix.append('<span id="%s"></span>' % id)
                else:
                    # Non-empty tag.  Place the auxiliary <span> tag
                    # *inside* the element, as the first child.
                    suffix += '<span id="%s"></span>' % id
        attlist = sorted(atts.items())
        parts = [tagname]
        for name, value in attlist:
            # value=None was used for boolean attributes without
            # value, but this isn't supported by XHTML.
            assert value is not None
            if isinstance(value, list):
                values = [unicode(v) for v in value]
                parts.append('%s="%s"' % (name.lower(),
                                          self.attval(' '.join(values))))
            else:
                parts.append('%s="%s"' % (name.lower(),
                                          self.attval(unicode(value))))
        if empty:
            infix = ' /'
        else:
            infix = ''
        return ''.join(prefix) + '<%s%s>' % (' '.join(parts), infix) + suffix

    def emptytag(self, node, tagname, suffix='\n', **attributes):
        """Construct and return an XML-compatible empty tag."""
        return self.starttag(node, tagname, suffix, empty=True, **attributes)

    def set_class_on_child(self, node, class_, index=0):
        """
        Set class `class_` on the visible child no. index of `node`.
        Do nothing if node has fewer children than `index`.
        """
        children = [n for n in node if not isinstance(n, nodes.Invisible)]
        try:
            child = children[index]
        except IndexError:
            return
        child['classes'].append(class_)

    def visit_Text(self, node):
        text = node.astext()
        encoded = self.encode(text)
        if self.in_mailto and self.settings.cloak_email_addresses:
            encoded = self.cloak_email(encoded)
        self.body.append(encoded)

    def depart_Text(self, node):
        pass

    def visit_abbreviation(self, node):
        # @@@ implementation incomplete ("title" attribute)
        self.body.append(self.starttag(node, 'abbr', ''))

    def depart_abbreviation(self, node):
        self.body.append('</abbr>')

    def visit_acronym(self, node):
        # @@@ implementation incomplete ("title" attribute)
        self.body.append(self.starttag(node, 'acronym', ''))

    def depart_acronym(self, node):
        self.body.append('</acronym>')

    def visit_address(self, node):
        self.visit_docinfo_item(node, 'address', meta=False)
        self.body.append(self.starttag(node, 'pre',
                                       suffix= '', CLASS='address'))

    def depart_address(self, node):
        self.body.append('\n</pre>\n')
        self.depart_docinfo_item()

    def visit_admonition(self, node):
        node['classes'].insert(0, 'admonition')
        self.body.append(self.starttag(node, 'div'))

    def depart_admonition(self, node=None):
        self.body.append('</div>\n')

    attribution_formats = {'dash': (u'\u2014', ''),
                           'parentheses': ('(', ')'),
                           'parens': ('(', ')'),
                           'none': ('', '')}

    def visit_attribution(self, node):
        prefix, suffix = self.attribution_formats[self.settings.attribution]
        self.context.append(suffix)
        self.body.append(
            self.starttag(node, 'p', prefix, CLASS='attribution'))

    def depart_attribution(self, node):
        self.body.append(self.context.pop() + '</p>\n')

    def visit_author(self, node):
        if not(isinstance(node.parent, nodes.authors)):
            self.visit_docinfo_item(node, 'author')
        self.body.append('<p>')

    def depart_author(self, node):
        self.body.append('</p>')
        if isinstance(node.parent, nodes.authors):
            self.body.append('\n')
        else:
            self.depart_docinfo_item()

    def visit_authors(self, node):
        self.visit_docinfo_item(node, 'authors')

    def depart_authors(self, node):
        self.depart_docinfo_item()

    def visit_block_quote(self, node):
        self.body.append(self.starttag(node, 'blockquote'))

    def depart_block_quote(self, node):
        self.body.append('</blockquote>\n')

    def check_simple_list(self, node):
        """Check for a simple list that can be rendered compactly."""
        visitor = SimpleListChecker(self.document)
        try:
            node.walk(visitor)
        except nodes.NodeFound:
            return False
        else:
            return True

    # Compact lists
    # ------------
    # Include definition lists and field lists (in addition to ordered
    # and unordered lists) in the test if a list is "simple"  (cf. the
    # html4css1.HTMLTranslator docstring and the SimpleListChecker class at
    # the end of this file).

    def is_compactable(self, node):
        # explicite class arguments have precedence
        if 'compact' in node['classes']:
            return True
        if 'open' in node['classes']:
            return False
        # check config setting:
        if (isinstance(node, (nodes.field_list, nodes.definition_list))
            and not self.settings.compact_field_lists):
            return False
        if (isinstance(node, (nodes.enumerated_list, nodes.bullet_list))
            and not self.settings.compact_lists):
            return False
        # Table of Contents:
        if (self.topic_classes == ['contents']):
            # TODO: look in parent nodes, remove self.topic_classes?
            return True
        # check the list items:
        return self.check_simple_list(node)

    def visit_bullet_list(self, node):
        atts = {}
        old_compact_simple = self.compact_simple
        self.context.append((self.compact_simple, self.compact_p))
        self.compact_p = None
        self.compact_simple = self.is_compactable(node)
        if self.compact_simple and not old_compact_simple:
            atts['class'] = 'simple'
        self.body.append(self.starttag(node, 'ul', **atts))

    def depart_bullet_list(self, node):
        self.compact_simple, self.compact_p = self.context.pop()
        self.body.append('</ul>\n')

    def visit_caption(self, node):
        self.body.append(self.starttag(node, 'p', '', CLASS='caption'))

    def depart_caption(self, node):
        self.body.append('</p>\n')

    def visit_citation(self, node):
        # Use definition list for bibliographic references.
        # Join adjacent citation entries.
        # TODO: use <aside>.
        if not self.in_footnote_list:
            listnode = node.copy()
            listnode['ids'] = []
            self.body.append(self.starttag(listnode, 'dl', CLASS='citation'))
            # self.body.append('<dl class="citation">\n')
            self.in_footnote_list = True

    def depart_citation(self, node):
        self.body.append('</dd>\n')
        if not isinstance(node.next_node(descend=False, siblings=True),
                          nodes.citation):
            self.body.append('</dl>\n')
            self.in_footnote_list = False

    def visit_citation_reference(self, node):
        href = '#'
        if 'refid' in node:
            href += node['refid']
        elif 'refname' in node:
            href += self.document.nameids[node['refname']]
        # else: # TODO system message (or already in the transform)?
        # 'Citation reference missing.'
        self.body.append(self.starttag(
            node, 'a', '[', CLASS='citation-reference', href=href))

    def depart_citation_reference(self, node):
        self.body.append(']</a>')

     # classifier
    # ----------
    # don't insert classifier-delimiter here (done by CSS)

    def visit_classifier(self, node):
        self.body.append(self.starttag(node, 'span', '', CLASS='classifier'))

    def depart_classifier(self, node):
        self.body.append('</span>')

    def visit_colspec(self, node):
        self.colspecs.append(node)
        # "stubs" list is an attribute of the tgroup element:
        node.parent.stubs.append(node.attributes.get('stub'))

    def depart_colspec(self, node):
        # write out <colgroup> when all colspecs are processed
        if isinstance(node.next_node(descend=False, siblings=True),
                      nodes.colspec):
            return
        if 'colwidths-auto' in node.parent.parent['classes'] or (
            'colwidths-auto' in self.settings.table_style and
            ('colwidths-given' not in node.parent.parent['classes'])):
            return
        total_width = sum(node['colwidth'] for node in self.colspecs)
        self.body.append(self.starttag(node, 'colgroup'))
        for node in self.colspecs:
            colwidth = int(node['colwidth'] * 100.0 / total_width + 0.5)
            self.body.append(self.emptytag(node, 'col',
                                           style='width: %i%%' % colwidth))
        self.body.append('</colgroup>\n')

    def visit_comment(self, node,
                      sub=re.compile('-(?=-)').sub):
        """Escape double-dashes in comment text."""
        self.body.append('<!-- %s -->\n' % sub('- ', node.astext()))
        # Content already processed:
        raise nodes.SkipNode

    def visit_compound(self, node):
        self.body.append(self.starttag(node, 'div', CLASS='compound'))
        if len(node) > 1:
            node[0]['classes'].append('compound-first')
            node[-1]['classes'].append('compound-last')
            for child in node[1:-1]:
                child['classes'].append('compound-middle')

    def depart_compound(self, node):
        self.body.append('</div>\n')

    def visit_container(self, node):
        self.body.append(self.starttag(node, 'div', CLASS='docutils container'))

    def depart_container(self, node):
        self.body.append('</div>\n')

    def visit_contact(self, node):
        self.visit_docinfo_item(node, 'contact', meta=False)

    def depart_contact(self, node):
        self.depart_docinfo_item()

    def visit_copyright(self, node):
        self.visit_docinfo_item(node, 'copyright')

    def depart_copyright(self, node):
        self.depart_docinfo_item()

    def visit_date(self, node):
        self.visit_docinfo_item(node, 'date')

    def depart_date(self, node):
        self.depart_docinfo_item()

    def visit_decoration(self, node):
        pass

    def depart_decoration(self, node):
        pass

    def visit_definition(self, node):
        self.body.append('</dt>\n')
        self.body.append(self.starttag(node, 'dd', ''))

    def depart_definition(self, node):
        self.body.append('</dd>\n')

    def visit_definition_list(self, node):
        classes = node.setdefault('classes', [])
        if self.is_compactable(node):
            classes.append('simple')
        self.body.append(self.starttag(node, 'dl'))

    def depart_definition_list(self, node):
        self.body.append('</dl>\n')

    def visit_definition_list_item(self, node):
        # pass class arguments, ids and names to definition term:
        node.children[0]['classes'] = (
            node.get('classes', []) + node.children[0].get('classes', []))
        node.children[0]['ids'] = (
            node.get('ids', []) + node.children[0].get('ids', []))
        node.children[0]['names'] = (
            node.get('names', []) + node.children[0].get('names', []))

    def depart_definition_list_item(self, node):
        pass

    def visit_description(self, node):
        self.body.append(self.starttag(node, 'dd', ''))

    def depart_description(self, node):
        self.body.append('</dd>\n')

    def visit_docinfo(self, node):
        self.context.append(len(self.body))
        classes = 'docinfo'
        if (self.is_compactable(node)):
            classes += ' simple'
        self.body.append(self.starttag(node, 'dl', CLASS=classes))

    def depart_docinfo(self, node):
        self.body.append('</dl>\n')
        start = self.context.pop()
        self.docinfo = self.body[start:]
        self.body = []

    def visit_docinfo_item(self, node, name, meta=True):
        if meta:
            meta_tag = '<meta name="%s" content="%s" />\n' \
                       % (name, self.attval(node.astext()))
            self.add_meta(meta_tag)
        self.body.append('<dt class="%s">%s</dt>\n'
                         % (name, self.language.labels[name]))
        self.body.append(self.starttag(node, 'dd', '', CLASS=name))

    def depart_docinfo_item(self):
        self.body.append('</dd>\n')

    def visit_doctest_block(self, node):
        self.body.append(self.starttag(node, 'pre', suffix='',
                                       CLASS='code python doctest'))

    def depart_doctest_block(self, node):
        self.body.append('\n</pre>\n')

    def visit_document(self, node):
        title = (node.get('title', '') or os.path.basename(node['source'])
                 or 'docutils document without title')
        self.head.append('<title>%s</title>\n' % self.encode(title))

    def depart_document(self, node):
        self.head_prefix.extend([self.doctype,
                                 self.head_prefix_template %
                                 {'lang': self.settings.language_code}])
        self.html_prolog.append(self.doctype)
        self.meta.insert(0, self.content_type % self.settings.output_encoding)
        self.head.insert(0, self.content_type % self.settings.output_encoding)
        if 'name="dcterms.' in ''.join(self.meta):
            self.head.append(
             '<link rel="schema.dcterms" href="http://purl.org/dc/terms/"/>')
        if self.math_header:
            if self.math_output == 'mathjax':
                self.head.extend(self.math_header)
            else:
                self.stylesheet.extend(self.math_header)
        # skip content-type meta tag with interpolated charset value:
        self.html_head.extend(self.head[1:])
        self.body_prefix.append(self.starttag(node, 'div', CLASS='document'))
        self.body_suffix.insert(0, '</div>\n')
        self.fragment.extend(self.body) # self.fragment is the "naked" body
        self.html_body.extend(self.body_prefix[1:] + self.body_pre_docinfo
                              + self.docinfo + self.body
                              + self.body_suffix[:-1])
        assert not self.context, 'len(context) = %s' % len(self.context)

    def visit_emphasis(self, node):
        self.body.append(self.starttag(node, 'em', ''))

    def depart_emphasis(self, node):
        self.body.append('</em>')

    def visit_entry(self, node):
        atts = {'class': []}
        if isinstance(node.parent.parent, nodes.thead):
            atts['class'].append('head')
        if node.parent.parent.parent.stubs[node.parent.column]:
            # "stubs" list is an attribute of the tgroup element
            atts['class'].append('stub')
        if atts['class']:
            tagname = 'th'
            atts['class'] = ' '.join(atts['class'])
        else:
            tagname = 'td'
            del atts['class']
        node.parent.column += 1
        if 'morerows' in node:
            atts['rowspan'] = node['morerows'] + 1
        if 'morecols' in node:
            atts['colspan'] = node['morecols'] + 1
            node.parent.column += node['morecols']
        self.body.append(self.starttag(node, tagname, '', **atts))
        self.context.append('</%s>\n' % tagname.lower())
        # TODO: why does the html4css1 writer insert an NBSP into empty cells?
        # if len(node) == 0:              # empty cell
        #     self.body.append('&#0160;') # no-break space

    def depart_entry(self, node):
        self.body.append(self.context.pop())

    def visit_enumerated_list(self, node):
        atts = {}
        if 'start' in node:
            atts['start'] = node['start']
        if 'enumtype' in node:
            atts['class'] = node['enumtype']
        if self.is_compactable(node):
            atts['class'] = (atts.get('class', '') + ' simple').strip()
        self.body.append(self.starttag(node, 'ol', **atts))

    def depart_enumerated_list(self, node):
        self.body.append('</ol>\n')

    def visit_field_list(self, node):
        # Keep simple paragraphs in the field_body to enable CSS
        # rule to start body on new line if the label is too long
        classes = 'field-list'
        if (self.is_compactable(node)):
            classes += ' simple'
        self.body.append(self.starttag(node, 'dl', CLASS=classes))

    def depart_field_list(self, node):
        self.body.append('</dl>\n')

    def visit_field(self, node):
        pass

    def depart_field(self, node):
        pass

    # as field is ignored, pass class arguments to field-name and field-body:

    def visit_field_name(self, node):
        self.body.append(self.starttag(node, 'dt', '',
                                       CLASS=''.join(node.parent['classes'])))

    def depart_field_name(self, node):
        self.body.append('</dt>\n')

    def visit_field_body(self, node):
        self.body.append(self.starttag(node, 'dd', '',
                                       CLASS=''.join(node.parent['classes'])))
        # prevent misalignment of following content if the field is empty:
        if not node.children:
            self.body.append('<p></p>')

    def depart_field_body(self, node):
        self.body.append('</dd>\n')

    def visit_figure(self, node):
        atts = {'class': 'figure'}
        if node.get('width'):
            atts['style'] = 'width: %s' % node['width']
        if node.get('align'):
            atts['class'] += " align-" + node['align']
        self.body.append(self.starttag(node, 'div', **atts))

    def depart_figure(self, node):
        self.body.append('</div>\n')

    # use HTML 5 <footer> element?
    def visit_footer(self, node):
        self.context.append(len(self.body))

    def depart_footer(self, node):
        start = self.context.pop()
        footer = [self.starttag(node, 'div', CLASS='footer'),
                  '<hr class="footer" />\n']
        footer.extend(self.body[start:])
        footer.append('\n</div>\n')
        self.footer.extend(footer)
        self.body_suffix[:0] = footer
        del self.body[start:]

    # TODO: use the new HTML5 element <aside> for footnote text
    # (allows better styling with CSS, the current <dl> list styling
    # with "float" interferes with sidebars).
    def visit_footnote(self, node):
        if not self.in_footnote_list:
            listnode = node.copy()
            listnode['ids'] = []
            classes = 'footnote ' + self.settings.footnote_references
            self.body.append(self.starttag(listnode, 'dl', CLASS=classes))
            # self.body.append('<dl class="%s">\n'%classes)
            self.in_footnote_list = True

    def depart_footnote(self, node):
        self.body.append('</dd>\n')
        if not isinstance(node.next_node(descend=False, siblings=True),
                          nodes.footnote):
            self.body.append('</dl>\n')
            self.in_footnote_list = False

    def visit_footnote_reference(self, node):
        href = '#' + node['refid']
        classes = 'footnote-reference ' + self.settings.footnote_references
        self.body.append(self.starttag(node, 'a', '', #suffix,
                                       CLASS=classes, href=href))

    def depart_footnote_reference(self, node):
        self.body.append('</a>')

    # Docutils-generated text: put section numbers in a span for CSS styling:
    def visit_generated(self, node):
        if 'sectnum' in node['classes']:
            # get section number (strip trailing no-break-spaces)
            sectnum = node.astext().rstrip(u' ')
            self.body.append('<span class="sectnum">%s</span> '
                                    % self.encode(sectnum))
            # Content already processed:
            raise nodes.SkipNode

    def depart_generated(self, node):
        pass

    def visit_header(self, node):
        self.context.append(len(self.body))

    def depart_header(self, node):
        start = self.context.pop()
        header = [self.starttag(node, 'div', CLASS='header')]
        header.extend(self.body[start:])
        header.append('\n<hr class="header"/>\n</div>\n')
        self.body_prefix.extend(header)
        self.header.extend(header)
        del self.body[start:]

    def visit_image(self, node):
        atts = {}
        uri = node['uri']
        mimetype = mimetypes.guess_type(uri)[0]
        # image size
        if 'width' in node:
            atts['width'] = node['width']
        if 'height' in node:
            atts['height'] = node['height']
        if 'scale' in node:
            if (PIL and not ('width' in node and 'height' in node)
                and self.settings.file_insertion_enabled):
                imagepath = url2pathname(uri)
                try:
                    img = PIL.Image.open(
                            imagepath.encode(sys.getfilesystemencoding()))
                except (IOError, UnicodeEncodeError):
                    pass # TODO: warn?
                else:
                    self.settings.record_dependencies.add(
                        imagepath.replace('\\', '/'))
                    if 'width' not in atts:
                        atts['width'] = '%dpx' % img.size[0]
                    if 'height' not in atts:
                        atts['height'] = '%dpx' % img.size[1]
                    del img
            for att_name in 'width', 'height':
                if att_name in atts:
                    match = re.match(r'([0-9.]+)(\S*)$', atts[att_name])
                    assert match
                    atts[att_name] = '%s%s' % (
                        float(match.group(1)) * (float(node['scale']) / 100),
                        match.group(2))
        style = []
        for att_name in 'width', 'height':
            if att_name in atts:
                if re.match(r'^[0-9.]+$', atts[att_name]):
                    # Interpret unitless values as pixels.
                    atts[att_name] += 'px'
                style.append('%s: %s;' % (att_name, atts[att_name]))
                del atts[att_name]
        if style:
            atts['style'] = ' '.join(style)
        if (isinstance(node.parent, nodes.TextElement) or
            (isinstance(node.parent, nodes.reference) and
             not isinstance(node.parent.parent, nodes.TextElement))):
            # Inline context or surrounded by <a>...</a>.
            suffix = ''
        else:
            suffix = '\n'
        if 'align' in node:
            atts['class'] = 'align-%s' % node['align']
        # Embed image file (embedded SVG or data URI):
        if self.settings.embed_images or ('embed' in node):
            err_msg = ''
            if not mimetype:
                err_msg = 'unknown MIME type'
            if not self.settings.file_insertion_enabled:
                err_msg = 'file insertion disabled.'
            try:
                with open(url2pathname(uri), 'rb') as imagefile:
                    imagedata = imagefile.read()
            except IOError as err:
                err_msg = err.strerror
            if err_msg:
                self.document.reporter.error('Cannot embed image %r: %s'
                                             %(uri, err_msg))
            else:
                self.settings.record_dependencies.add(
                                            uri.replace('\\', '/'))
                # TODO: insert SVG as-is?
                # if mimetype == 'image/svg+xml':
                  # read/parse, apply arguments,
                  # insert as <svg ....> ... </svg> # (about 1/3 less data)
                data64 = base64.b64encode(imagedata).decode()
                uri = u'data:%s;base64,%s' % (mimetype, data64)
        if mimetype == 'application/x-shockwave-flash':
            atts['type'] = mimetype
            # do NOT use an empty tag: incorrect rendering in browsers
            tag = (self.starttag(node, 'object', '', data=uri, **atts)
                   + node.get('alt', uri) + '</object>' + suffix)
        else:
            atts['alt'] = node.get('alt', node['uri'])
            tag = self.emptytag(node, 'img', suffix, src=uri, **atts)
        self.body.append(tag)

    def depart_image(self, node):
        pass

    def visit_inline(self, node):
        self.body.append(self.starttag(node, 'span', ''))

    def depart_inline(self, node):
        self.body.append('</span>')

    # footnote and citation labels:
    def visit_label(self, node):
        if (isinstance(node.parent, nodes.footnote)):
            classes = self.settings.footnote_references
        else:
            classes = 'brackets'
        # pass parent node to get id into starttag:
        self.body.append(self.starttag(node.parent, 'dt', '', CLASS='label'))
        self.body.append(self.starttag(node, 'span', '', CLASS=classes))
        # footnote/citation backrefs:
        if self.settings.footnote_backlinks:
            backrefs = node.parent['backrefs']
            if len(backrefs) == 1:
                self.body.append('<a class="fn-backref" href="#%s">'
                                 % backrefs[0])

    def depart_label(self, node):
        if self.settings.footnote_backlinks:
            backrefs = node.parent['backrefs']
            if len(backrefs) == 1:
                self.body.append('</a>')
        self.body.append('</span>')
        if self.settings.footnote_backlinks and len(backrefs) > 1:
            backlinks = ['<a href="#%s">%s</a>' % (ref, i)
                            for (i, ref) in enumerate(backrefs, 1)]
            self.body.append('<span class="fn-backref">(%s)</span>'
                                % ','.join(backlinks))
        self.body.append('</dt>\n<dd>')

    def visit_legend(self, node):
        self.body.append(self.starttag(node, 'div', CLASS='legend'))

    def depart_legend(self, node):
        self.body.append('</div>\n')

    def visit_line(self, node):
        self.body.append(self.starttag(node, 'div', suffix='', CLASS='line'))
        if not len(node):
            self.body.append('<br />')

    def depart_line(self, node):
        self.body.append('</div>\n')

    def visit_line_block(self, node):
        self.body.append(self.starttag(node, 'div', CLASS='line-block'))

    def depart_line_block(self, node):
        self.body.append('</div>\n')

    def visit_list_item(self, node):
        self.body.append(self.starttag(node, 'li', ''))

    def depart_list_item(self, node):
        self.body.append('</li>\n')

    # inline literal
    def visit_literal(self, node):
        # special case: "code" role
        classes = node.get('classes', [])
        if 'code' in classes:
            # filter 'code' from class arguments
            node['classes'] = [cls for cls in classes if cls != 'code']
            self.body.append(self.starttag(node, 'code', ''))
            return
        self.body.append(
            self.starttag(node, 'span', '', CLASS='docutils literal'))
        text = node.astext()
        # remove hard line breaks (except if in a parsed-literal block)
        if not isinstance(node.parent, nodes.literal_block):
            text = text.replace('\n', ' ')
        # Protect text like ``--an-option`` and the regular expression
        # ``[+]?(\d+(\.\d*)?|\.\d+)`` from bad line wrapping
        for token in self.words_and_spaces.findall(text):
            if token.strip() and self.in_word_wrap_point.search(token):
                self.body.append('<span class="pre">%s</span>'
                                    % self.encode(token))
            else:
                self.body.append(self.encode(token))
        self.body.append('</span>')
        # Content already processed:
        raise nodes.SkipNode

    def depart_literal(self, node):
        # skipped unless literal element is from "code" role:
        self.body.append('</code>')

    def visit_literal_block(self, node):
        self.body.append(self.starttag(node, 'pre', '', CLASS='literal-block'))
        if 'code' in node.get('classes', []):
            self.body.append('<code>')

    def depart_literal_block(self, node):
        if 'code' in node.get('classes', []):
            self.body.append('</code>')
        self.body.append('</pre>\n')

    # Mathematics:
    # As there is no native HTML math support, we provide alternatives
    # for the math-output: LaTeX and MathJax simply wrap the content,
    # HTML and MathML also convert the math_code.
    # HTML container
    math_tags = {# math_output: (block, inline, class-arguments)
                 'mathml':      ('div', '', ''),
                 'html':        ('div', 'span', 'formula'),
                 'mathjax':     ('div', 'span', 'math'),
                 'latex':       ('pre', 'tt',   'math'),
                }

    def visit_math(self, node, math_env=''):
        # If the method is called from visit_math_block(), math_env != ''.

        if self.math_output not in self.math_tags:
            self.document.reporter.error(
                'math-output format "%s" not supported '
                'falling back to "latex"'% self.math_output)
            self.math_output = 'latex'
        tag = self.math_tags[self.math_output][math_env == '']
        clsarg = self.math_tags[self.math_output][2]
        # LaTeX container
        wrappers = {# math_mode: (inline, block)
                    'mathml':  ('$%s$',   u'\\begin{%s}\n%s\n\\end{%s}'),
                    'html':    ('$%s$',   u'\\begin{%s}\n%s\n\\end{%s}'),
                    'mathjax': (r'\(%s\)', u'\\begin{%s}\n%s\n\\end{%s}'),
                    'latex':   (None,     None),
                   }
        wrapper = wrappers[self.math_output][math_env != '']
        if self.math_output == 'mathml' and (not self.math_output_options or
                                self.math_output_options[0] == 'blahtexml'):
            wrapper = None
        # get and wrap content
        math_code = node.astext().translate(unichar2tex.uni2tex_table)
        if wrapper:
            try: # wrapper with three "%s"
                math_code = wrapper % (math_env, math_code, math_env)
            except TypeError: # wrapper with one "%s"
                math_code = wrapper % math_code
        # settings and conversion
        if self.math_output in ('latex', 'mathjax'):
            math_code = self.encode(math_code)
        if self.math_output == 'mathjax' and not self.math_header:
            try:
                self.mathjax_url = self.math_output_options[0]
            except IndexError:
                self.document.reporter.warning('No MathJax URL specified, '
                    'using local fallback (see config.html)')
            # append configuration, if not already present in the URL:
            # input LaTeX with AMS, output common HTML
            if '?' not in self.mathjax_url:
                self.mathjax_url += '?config=TeX-AMS_CHTML'
            self.math_header = [self.mathjax_script % self.mathjax_url]
        elif self.math_output == 'html':
            if self.math_output_options and not self.math_header:
                self.math_header = [self.stylesheet_call(
                    utils.find_file_in_dirs(s, self.settings.stylesheet_dirs))
                    for s in self.math_output_options[0].split(',')]
            # TODO: fix display mode in matrices and fractions
            math2html.DocumentParameters.displaymode = (math_env != '')
            math_code = math2html.math2html(math_code)
        elif self.math_output == 'mathml':
            if  'XHTML 1' in self.doctype:
                self.doctype = self.doctype_mathml
                self.content_type = self.content_type_mathml
            converter = ' '.join(self.math_output_options).lower()
            try:
                if converter == 'latexml':
                    math_code = tex2mathml_extern.latexml(math_code,
                                                    self.document.reporter)
                elif converter == 'ttm':
                    math_code = tex2mathml_extern.ttm(math_code,
                                                    self.document.reporter)
                elif converter == 'blahtexml':
                    math_code = tex2mathml_extern.blahtexml(math_code,
                        inline=not(math_env),
                        reporter=self.document.reporter)
                elif not converter:
                    math_code = latex2mathml.tex2mathml(math_code,
                                                        inline=not(math_env))
                else:
                    self.document.reporter.error('option "%s" not supported '
                    'with math-output "MathML"')
            except OSError:
                    raise OSError('is "latexmlmath" in your PATH?')
            except SyntaxError as err:
                err_node = self.document.reporter.error(err, base_node=node)
                self.visit_system_message(err_node)
                self.body.append(self.starttag(node, 'p'))
                self.body.append(u','.join(err.args))
                self.body.append('</p>\n')
                self.body.append(self.starttag(node, 'pre',
                                               CLASS='literal-block'))
                self.body.append(self.encode(math_code))
                self.body.append('\n</pre>\n')
                self.depart_system_message(err_node)
                raise nodes.SkipNode
        # append to document body
        if tag:
            self.body.append(self.starttag(node, tag,
                                           suffix='\n'*bool(math_env),
                                           CLASS=clsarg))
        self.body.append(math_code)
        if math_env: # block mode (equation, display)
            self.body.append('\n')
        if tag:
            self.body.append('</%s>' % tag)
        if math_env:
            self.body.append('\n')
        # Content already processed:
        raise nodes.SkipNode

    def depart_math(self, node):
        pass # never reached

    def visit_math_block(self, node):
        math_env = pick_math_environment(node.astext())
        self.visit_math(node, math_env=math_env)

    def depart_math_block(self, node):
        pass # never reached

    # Meta tags: 'lang' attribute replaced by 'xml:lang' in XHTML 1.1
    # HTML5/polyglot recommends using both
    def visit_meta(self, node):
        meta = self.emptytag(node, 'meta', **node.non_default_attributes())
        self.add_meta(meta)

    def depart_meta(self, node):
        pass

    def add_meta(self, tag):
        self.meta.append(tag)
        self.head.append(tag)

    def visit_option(self, node):
        self.body.append(self.starttag(node, 'span', '', CLASS='option'))

    def depart_option(self, node):
        self.body.append('</span>')
        if isinstance(node.next_node(descend=False, siblings=True),
                      nodes.option):
            self.body.append(', ')

    def visit_option_argument(self, node):
        self.body.append(node.get('delimiter', ' '))
        self.body.append(self.starttag(node, 'var', ''))

    def depart_option_argument(self, node):
        self.body.append('</var>')

    def visit_option_group(self, node):
        self.body.append(self.starttag(node, 'dt', ''))
        self.body.append('<kbd>')

    def depart_option_group(self, node):
        self.body.append('</kbd></dt>\n')

    def visit_option_list(self, node):
        self.body.append(
            self.starttag(node, 'dl', CLASS='option-list'))

    def depart_option_list(self, node):
        self.body.append('</dl>\n')

    def visit_option_list_item(self, node):
        pass

    def depart_option_list_item(self, node):
        pass

    def visit_option_string(self, node):
        pass

    def depart_option_string(self, node):
        pass

    def visit_organization(self, node):
        self.visit_docinfo_item(node, 'organization')

    def depart_organization(self, node):
        self.depart_docinfo_item()

    # Do not omit <p> tags
    # --------------------
    #
    # The HTML4CSS1 writer does this to "produce
    # visually compact lists (less vertical whitespace)". This writer
    # relies on CSS rules for"visual compactness".
    #
    # * In XHTML 1.1, e.g. a <blockquote> element may not contain
    #   character data, so you cannot drop the <p> tags.
    # * Keeping simple paragraphs in the field_body enables a CSS
    #   rule to start the field-body on a new line if the label is too long
    # * it makes the code simpler.
    #
    # TODO: omit paragraph tags in simple table cells?

    def visit_paragraph(self, node):
        self.body.append(self.starttag(node, 'p', ''))

    def depart_paragraph(self, node):
        self.body.append('</p>')
        if not (isinstance(node.parent, (nodes.list_item, nodes.entry)) and
                (len(node.parent) == 1)):
            self.body.append('\n')

    def visit_problematic(self, node):
        if node.hasattr('refid'):
            self.body.append('<a href="#%s">' % node['refid'])
            self.context.append('</a>')
        else:
            self.context.append('')
        self.body.append(self.starttag(node, 'span', '', CLASS='problematic'))

    def depart_problematic(self, node):
        self.body.append('</span>')
        self.body.append(self.context.pop())

    def visit_raw(self, node):
        if 'html' in node.get('format', '').split():
            t = isinstance(node.parent, nodes.TextElement) and 'span' or 'div'
            if node['classes']:
                self.body.append(self.starttag(node, t, suffix=''))
            self.body.append(node.astext())
            if node['classes']:
                self.body.append('</%s>' % t)
        # Keep non-HTML raw text out of output:
        raise nodes.SkipNode

    def visit_reference(self, node):
        atts = {'class': 'reference'}
        if 'refuri' in node:
            atts['href'] = node['refuri']
            if ( self.settings.cloak_email_addresses
                 and atts['href'].startswith('mailto:')):
                atts['href'] = self.cloak_mailto(atts['href'])
                self.in_mailto = True
            atts['class'] += ' external'
        else:
            assert 'refid' in node, \
                   'References must have "refuri" or "refid" attribute.'
            atts['href'] = '#' + node['refid']
            atts['class'] += ' internal'
        if len(node) == 1 and isinstance(node[0], nodes.image):
            atts['class'] += ' image-reference'
        if not isinstance(node.parent, nodes.TextElement):
            assert len(node) == 1 and isinstance(node[0], nodes.image)
            atts['class'] += ' image-reference'
        self.body.append(self.starttag(node, 'a', '', **atts))

    def depart_reference(self, node):
        self.body.append('</a>')
        if not isinstance(node.parent, nodes.TextElement):
            self.body.append('\n')
        self.in_mailto = False

    def visit_revision(self, node):
        self.visit_docinfo_item(node, 'revision', meta=False)

    def depart_revision(self, node):
        self.depart_docinfo_item()

    def visit_row(self, node):
        self.body.append(self.starttag(node, 'tr', ''))
        node.column = 0

    def depart_row(self, node):
        self.body.append('</tr>\n')

    def visit_rubric(self, node):
        self.body.append(self.starttag(node, 'p', '', CLASS='rubric'))

    def depart_rubric(self, node):
        self.body.append('</p>\n')

    def visit_section(self, node):
        self.section_level += 1
        self.body.append(
            self.starttag(node, 'div', CLASS='section'))

    def depart_section(self, node):
        self.section_level -= 1
        self.body.append('</div>\n')

    # TODO: use the new HTML5 element <aside>
    def visit_sidebar(self, node):
        self.body.append(
            self.starttag(node, 'div', CLASS='sidebar'))
        self.in_sidebar = True

    def depart_sidebar(self, node):
        self.body.append('</div>\n')
        self.in_sidebar = False

    def visit_status(self, node):
        self.visit_docinfo_item(node, 'status', meta=False)

    def depart_status(self, node):
        self.depart_docinfo_item()

    def visit_strong(self, node):
        self.body.append(self.starttag(node, 'strong', ''))

    def depart_strong(self, node):
        self.body.append('</strong>')

    def visit_subscript(self, node):
        self.body.append(self.starttag(node, 'sub', ''))

    def depart_subscript(self, node):
        self.body.append('</sub>')

    def visit_substitution_definition(self, node):
        """Internal only."""
        raise nodes.SkipNode

    def visit_substitution_reference(self, node):
        self.unimplemented_visit(node)

    # h1–h6 elements must not be used to markup subheadings, subtitles,
    # alternative titles and taglines unless intended to be the heading for a
    # new section or subsection.
    # -- http://www.w3.org/TR/html/sections.html#headings-and-sections
    def visit_subtitle(self, node):
        if isinstance(node.parent, nodes.sidebar):
            classes = 'sidebar-subtitle'
        elif isinstance(node.parent, nodes.document):
            classes = 'subtitle'
            self.in_document_title = len(self.body)+1
        elif isinstance(node.parent, nodes.section):
            classes = 'section-subtitle'
        self.body.append(self.starttag(node, 'p', '', CLASS=classes))

    def depart_subtitle(self, node):
        self.body.append('</p>\n')
        if isinstance(node.parent, nodes.document):
            self.subtitle = self.body[self.in_document_title:-1]
            self.in_document_title = 0
            self.body_pre_docinfo.extend(self.body)
            self.html_subtitle.extend(self.body)
            del self.body[:]

    def visit_superscript(self, node):
        self.body.append(self.starttag(node, 'sup', ''))

    def depart_superscript(self, node):
        self.body.append('</sup>')

    def visit_system_message(self, node):
        self.body.append(self.starttag(node, 'div', CLASS='system-message'))
        self.body.append('<p class="system-message-title">')
        backref_text = ''
        if len(node['backrefs']):
            backrefs = node['backrefs']
            if len(backrefs) == 1:
                backref_text = ('; <em><a href="#%s">backlink</a></em>'
                                % backrefs[0])
            else:
                i = 1
                backlinks = []
                for backref in backrefs:
                    backlinks.append('<a href="#%s">%s</a>' % (backref, i))
                    i += 1
                backref_text = ('; <em>backlinks: %s</em>'
                                % ', '.join(backlinks))
        if node.hasattr('line'):
            line = ', line %s' % node['line']
        else:
            line = ''
        self.body.append('System Message: %s/%s '
                         '(<span class="docutils literal">%s</span>%s)%s</p>\n'
                         % (node['type'], node['level'],
                            self.encode(node['source']), line, backref_text))

    def depart_system_message(self, node):
        self.body.append('</div>\n')

    def visit_table(self, node):
        atts = {}
        classes = [cls.strip(u' \t\n')
                   for cls in self.settings.table_style.split(',')]
        if 'align' in node:
            classes.append('align-%s' % node['align'])
        if 'width' in node:
            atts['style'] = 'width: %s' % node['width']
        tag = self.starttag(node, 'table', CLASS=' '.join(classes), **atts)
        self.body.append(tag)

    def depart_table(self, node):
        self.body.append('</table>\n')

    def visit_target(self, node):
        if not ('refuri' in node or 'refid' in node
                or 'refname' in node):
            self.body.append(self.starttag(node, 'span', '', CLASS='target'))
            self.context.append('</span>')
        else:
            self.context.append('')

    def depart_target(self, node):
        self.body.append(self.context.pop())

    # no hard-coded vertical alignment in table body
    def visit_tbody(self, node):
        self.body.append(self.starttag(node, 'tbody'))

    def depart_tbody(self, node):
        self.body.append('</tbody>\n')

    def visit_term(self, node):
        self.body.append(self.starttag(node, 'dt', ''))

    def depart_term(self, node):
        """
        Leave the end tag to `self.visit_definition()`, in case there's a
        classifier.
        """
        pass

    def visit_tgroup(self, node):
        self.colspecs = []
        node.stubs = []

    def depart_tgroup(self, node):
        pass

    def visit_thead(self, node):
        self.body.append(self.starttag(node, 'thead'))

    def depart_thead(self, node):
        self.body.append('</thead>\n')

    def visit_title(self, node):
        """Only 6 section levels are supported by HTML."""
        close_tag = '</p>\n'
        if isinstance(node.parent, nodes.topic):
            self.body.append(
                  self.starttag(node, 'p', '', CLASS='topic-title'))
        elif isinstance(node.parent, nodes.sidebar):
            self.body.append(
                  self.starttag(node, 'p', '', CLASS='sidebar-title'))
        elif isinstance(node.parent, nodes.Admonition):
            self.body.append(
                  self.starttag(node, 'p', '', CLASS='admonition-title'))
        elif isinstance(node.parent, nodes.table):
            self.body.append(
                  self.starttag(node, 'caption', ''))
            close_tag = '</caption>\n'
        elif isinstance(node.parent, nodes.document):
            self.body.append(self.starttag(node, 'h1', '', CLASS='title'))
            close_tag = '</h1>\n'
            self.in_document_title = len(self.body)
        else:
            assert isinstance(node.parent, nodes.section)
            h_level = self.section_level + self.initial_header_level - 1
            atts = {}
            if (len(node.parent) >= 2 and
                isinstance(node.parent[1], nodes.subtitle)):
                atts['CLASS'] = 'with-subtitle'
            self.body.append(
                  self.starttag(node, 'h%s' % h_level, '', **atts))
            atts = {}
            if node.hasattr('refid'):
                atts['class'] = 'toc-backref'
                atts['href'] = '#' + node['refid']
            if atts:
                self.body.append(self.starttag({}, 'a', '', **atts))
                close_tag = '</a></h%s>\n' % (h_level)
            else:
                close_tag = '</h%s>\n' % (h_level)
        self.context.append(close_tag)

    def depart_title(self, node):
        self.body.append(self.context.pop())
        if self.in_document_title:
            self.title = self.body[self.in_document_title:-1]
            self.in_document_title = 0
            self.body_pre_docinfo.extend(self.body)
            self.html_title.extend(self.body)
            del self.body[:]

    def visit_title_reference(self, node):
        self.body.append(self.starttag(node, 'cite', ''))

    def depart_title_reference(self, node):
        self.body.append('</cite>')

    def visit_topic(self, node):
        self.body.append(self.starttag(node, 'div', CLASS='topic'))
        self.topic_classes = node['classes']

    def depart_topic(self, node):
        self.body.append('</div>\n')
        self.topic_classes = []

    def visit_transition(self, node):
        self.body.append(self.emptytag(node, 'hr', CLASS='docutils'))

    def depart_transition(self, node):
        pass

    def visit_version(self, node):
        self.visit_docinfo_item(node, 'version', meta=False)

    def depart_version(self, node):
        self.depart_docinfo_item()

    def unimplemented_visit(self, node):
        raise NotImplementedError('visiting unimplemented node type: %s'
                                  % node.__class__.__name__)


class SimpleListChecker(nodes.GenericNodeVisitor):

    """
    Raise `nodes.NodeFound` if non-simple list item is encountered.

    Here "simple" means a list item containing nothing other than a single
    paragraph, a simple list, or a paragraph followed by a simple list.

    This version also checks for simple field lists and docinfo.
    """

    def default_visit(self, node):
        raise nodes.NodeFound

    def visit_list_item(self, node):
        children = [child for child in node.children
                    if not isinstance(child, nodes.Invisible)]
        if (children and isinstance(children[0], nodes.paragraph)
            and (isinstance(children[-1], nodes.bullet_list) or
                 isinstance(children[-1], nodes.enumerated_list) or
                 isinstance(children[-1], nodes.field_list))):
            children.pop()
        if len(children) <= 1:
            return
        else:
            raise nodes.NodeFound

    def pass_node(self, node):
        pass

    def ignore_node(self, node):
        # ignore nodes that are never complex (can contain only inline nodes)
        raise nodes.SkipNode

    # Paragraphs and text
    visit_Text = ignore_node
    visit_paragraph = ignore_node

    # Lists
    visit_bullet_list = pass_node
    visit_enumerated_list = pass_node
    visit_docinfo = pass_node

    # Docinfo nodes:
    visit_author = ignore_node
    visit_authors = visit_list_item
    visit_address = visit_list_item
    visit_contact = pass_node
    visit_copyright = ignore_node
    visit_date = ignore_node
    visit_organization = ignore_node
    visit_status = ignore_node
    visit_version = visit_list_item

    # Definition list:
    visit_definition_list = pass_node
    visit_definition_list_item = pass_node
    visit_term = ignore_node
    visit_classifier = pass_node
    visit_definition = visit_list_item

    # Field list:
    visit_field_list = pass_node
    visit_field = pass_node
    # the field body corresponds to a list item
    visit_field_body = visit_list_item
    visit_field_name = ignore_node

    # Invisible nodes should be ignored.
    visit_comment = ignore_node
    visit_substitution_definition = ignore_node
    visit_target = ignore_node
    visit_pending = ignore_node