TagSoup - Just Keep On Truckin'

  Introduction

   This is the home page of TagSoup, a SAX-compliant parser written in
   Java that, instead of parsing well-formed or valid XML, parses HTML as
   it is found in the wild: [1]poor, nasty and brutish, though quite often
   far from short. TagSoup is designed for people who have to process this
   stuff using some semblance of a rational application design. By
   providing a SAX interface, it allows standard XML tools to be applied
   to even the worst HTML. TagSoup also includes a command-line processor
   that reads HTML files and can generate either clean HTML or well-formed
   XML that is a close approximation to XHTML.

   This is also the README file packaged with TagSoup.

   TagSoup is free and Open Source software. As of version 1.2, it is
   licensed under the [2]Apache License, Version 2.0, which allows
   proprietary re-use as well as use with GPL 3.0 or GPL 2.0-or-later
   projects. (If anyone needs a GPL 2.0 license for a GPL 2.0-only
   project, feel free to ask.)

  Warning: TagSoup will not build on stock Java 5.x or 6.x!

   Due to a bug in the versions of Xalan shipped with Java 5.x and 6.x,
   TagSoup will not build out of the box. You need to retrieve [3]Saxon
   6.5.5, which does not have the bug. Unpack the zipfile in an empty
   directory and copy the saxon.jar and saxon-xml-apis.jar files to
   $ANT_HOME/lib. The Ant build process for TagSoup will then notice that
   Saxon is available and use it instead.

  TagSoup 1.2 released

   There are a great many changes, most of them fixes for long-standing
   bugs, in this release. Only the most important are listed here; for the
   rest, see the CHANGES file in the source distribution. Very special
   thanks to Jojo Dijamco, whose intensive efforts at debugging made this
   release a usable upgrade rather than a useless mass of undetected bugs.
     * As noted above, I have changed the license to Apache 2.0.
     * The default content model for bogons (unknown elements) is now ANY
       rather than EMPTY. This is a breaking change, which I have done
       only because there was so much demand for it. It can be undone on
       the command line with the --emptybogons switch, or programmatically
       with parser.setFeature(Parser.emptyBogonsFeature, true).
     * The processing of entity references in attribute values has finally
       been fixed to do what browsers do. That is, a reference is only
       recognized if it is properly terminated by a semicolon; otherwise
       it is treated as plain text. This means that URIs like
       foo?cdown=32&cup=42 are no longer seen as containing an instance of
       the )U character (whose name happens to be cup).
     * Several new switches have been added:
          + --doctype-system and --doctype-public force a DOCTYPE
            declaration to be output and allow setting the system and
            public identifiers.
          + --standalone and --version allow control of the XML
            declaration that is output. (Note that TagSoup's XML output is
            always version 1.0, even if you use --version=1.1.)
          + --norootbogons causes unknown elements not to be allowed as
            the document root element. Instead, they are made children of
            the default root element (the html element for HTML).
     * The TagSoup core now supports character entities with values above
       U+FFFF. As a consequence, the HTML schema now supports all 2,210
       standard character entities from the [4]2007-12-14 draft of XML
       Entity Definitions for Characters, except the 94 which require more
       than one Unicode character to represent.
     * The SAX events startPrefixMapping and endPrefixMapping are now
       being reported for all cases of foreign elements and attributes.
     * All bugs around newline processing on Windows should now be gone.
     * A number of content models have been loosened to allow elements to
       appear in new and non-standard (but commonly found) places. In
       particular, tables are now allowed inside paragraphs, against the
       letter of the W3C specification.
     * Since the span element is intended for fine control of appearance
       using CSS, it should never have been a restartable element. This
       very long-standing bug has now been fixed.
     * The following non-standard elements are now at least partly
       supported: bgsound, blink, canvas, comment, listing, marquee, nobr,
       rbc, rb, rp, rtc, rt, ruby, wbr, xmp.
     * In HTML output mode, boolean attributes like checked are now output
       as such, rather than in XML style as checked="checked".
     * Runs of < characters such as << and <<< are now handled correctly
       in text rather than being transformed into extremely bogus
       start-tags.

   [5]Download the TagSoup 1.2 jar file here. It's about 87K long.
   [6]Download the full TagSoup 1.2 source here. If you don't have zip,
   you can use jar to unpack it.
   [7]Download the current CHANGES file here.

  TagSoup 1.1 released

   TagSoup 1.1 adds Tatu Saloranta's JAXP support for TagSoup. To use
   TagSoup within the JAXP framework (which is not something I necessarily
   recommend, but it is part of the Java XML platform), you can create a
   SAXParser by calling
   org.ccil.cowan.tagsoup.jaxp.SAXParserImpl.newInstance(). You can also
   set the system property javax.xml.parsers.SAXParserFactory to
   org.ccil.cowan.tagsoup.jaxp.SAXFactoryImpl, but be aware that doing
   this will cause all JAXP-based XML parsing to go through TagSoup, which
   is a Bad Thing if your application also reads XML documents.

  What TagSoup does

   TagSoup is designed as a parser, not a whole application; it isn't
   intended to permanently clean up bad HTML, as [8]HTML Tidy does, only
   to parse it on the fly. Therefore, it does not convert presentation
   HTML to CSS or anything similar. It does guarantee well-structured
   results: tags will wind up properly nested, default attributes will
   appear appropriately, and so on.

   The semantics of TagSoup are as far as practical those of actual HTML
   browsers. In particular, never, never will it throw any sort of syntax
   error: the TagSoup motto is [9]"Just Keep On Truckin'". But there's
   much, much more. For example, if the first tag is LI, it will supply
   the application with enclosing HTML, BODY, and UL tags. Why UL? Because
   that's what browsers assume in this situation. For the same reason,
   overlapping tags are correctly restarted whenever possible: text like:
This is <B>bold, <I>bold italic, </b>italic, </i>normal text

   gets correctly rewritten as:
This is <b>bold, <i>bold italic, </i></b><i>italic, </i>normal text.

   By intention, TagSoup is small and fast. It does not depend on the
   existence of any framework other than SAX, and should be able to work
   with any framework that can accept SAX parsers. In particular, [10]XOM
   is known to work.

   You can replace the low-level HTML scanner with one based on Sean
   McGrath's [11]PYX format (very close to James Clark's ESIS format). You
   can also supply an AutoDetector that peeks at the incoming byte stream
   and guesses a character encoding for it. Otherwise, the platform
   default is used. If you need an autodetector of character sets,
   consider trying to adapt the [12]Mozilla one; if you succeed, let me
   know.

  Note: TagSoup in Java 1.1

   If you go through the TagSoup source and replace all references to
   HashMap with Hashtable and recompile, TagSoup will work fine in Java
   1.1 VMs. Thanks to Thorbjørn Vinne for this discovery.

  The TSaxon XSLT-for-HTML processor

   [13]I am also distributing [14]TSaxon, a repackaging of version 6.5.5
   of Michael Kay's Saxon XSLT version 1.0 implementation that includes
   TagSoup. TSaxon is a drop-in replacement for Saxon, and can be used to
   process either HTML or XML documents with XSLT stylesheets.

  TagSoup as a stand-alone program

   It is possible to run TagSoup as a program by saying java -jar
   tagsoup-1.0.1 [option ...] [file ...]. Files mentioned on the command
   line will be parsed individually. If no files are specified, the
   standard input is read.

   The following options are understood:

   --files
          Output into individual files, with html extensions changed to
          xhtml. Otherwise, all output is sent to the standard output.

   --html
          Output is in clean HTML: the XML declaration is suppressed, as
          are end-tags for the known empty elements.

   --omit-xml-declaration
          The XML declaration is suppressed.

   --method=html
          End-tags for the known empty HTML elements are suppressed.

   --doctype-system=systemid
          Forces the output of a DOCTYPE declaration with the specified
          systemid.

   --doctype-public=publicid
          Forces the output of a DOCTYPE declaration with the specified
          publicid.

   --version=version
          Sets the version string in the XML declaration.

   --standalone=[yes|no]
          Sets the standalone declaration to yes or no.

   --pyx
          Output is in PYX format.

   --pyxin
          Input is in PYXoid format (need not be well-formed).

   --nons
          Namespaces are suppressed. Normally, all elements are in the
          XHTML 1.x namespace, and all attributes are in no namespace.

   --nobogons
          Bogons (unknown elements) are suppressed.

   --nodefaults
          suppress default attribute values

   --nocolons
          change explicit colons in element and attribute names to
          underscores

   --norestart
          don't restart any normally restartable elements

   --ignorable
          output whitespace in elements with element-only content

   --emptybogons
          Bogons are given a content model of EMPTY rather than ANY.

   --any
          Bogons are given a content model of ANY rather than EMPTY
          (default).

   --norootbogons
          Don't allow bogons to be root elements; make them subordinate to
          the root.

   --lexical
          Pass through HTML comments and DOCTYPE declarations. Has no
          effect when output is in PYX format.

   --reuse
          Reuse a single instance of TagSoup parser throughout. Normally,
          a new one is instantiated for each input file.

   --nocdata
          Change the content models of the script and style elements to
          treat them as ordinary #PCDATA (text-only) elements, as in
          XHTML, rather than with the special CDATA content model.

   --encoding=encoding
          Specify the input encoding. The default is the Java platform
          default.

   --output-encoding=encoding
          Specify the output encoding. The default is the Java platform
          default.

   --help
          Print help.

   --version
          Print the version number.

  SAX features and properties

   TagSoup supports the following SAX features in addition to the standard
   ones:

   http://www.ccil.org/~cowan/tagsoup/features/ignore-bogons
          A value of "true" indicates that the parser will ignore unknown
          elements.

   http://www.ccil.org/~cowan/tagsoup/features/bogons-empty
          A value of "true" indicates that the parser will give unknown
          elements a content model of EMPTY; a value of "false", a content
          model of ANY.

   http://www.ccil.org/~cowan/tagsoup/features/root-bogons
          A value of "true" indicates that the parser will allow unknown
          elements to be the root of the output document.

   http://www.ccil.org/~cowan/tagsoup/features/default-attributes
          A value of "true" indicates that the parser will return default
          attribute values for missing attributes that have default
          values.

   http://www.ccil.org/~cowan/tagsoup/features/translate-colons
          A value of "true" indicates that the parser will translate
          colons into underscores in names.

   http://www.ccil.org/~cowan/tagsoup/features/restart-elements
          A value of "true" indicates that the parser will attempt to
          restart the restartable elements.

   http://www.ccil.org/~cowan/tagsoup/features/ignorable-whitespace
          A value of "true" indicates that the parser will transmit
          whitespace in element-only content via the SAX
          ignorableWhitespace callback. Normally this is not done, because
          HTML is an SGML application and SGML suppresses such whitespace.

   http://www.ccil.org/~cowan/tagsoup/features/cdata-elements
          A value of "true" indicates that the parser will process the
          script and style elements (or any elements with type='cdata' in
          the TSSL schema) as SGML CDATA elements (that is, no markup is
          recognized except the matching end-tag).

   TagSoup supports the following SAX properties in addition to the
   standard ones:

   http://www.ccil.org/~cowan/tagsoup/properties/scanner
          Specifies the Scanner object this parser uses.

   http://www.ccil.org/~cowan/tagsoup/properties/schema
          Specifies the Schema object this parser uses.

   http://www.ccil.org/~cowan/tagsoup/properties/auto-detector
          Specifies the AutoDetector (for encoding detection) this parser
          uses.

  More information

   I gave a presentation (a nocturne, so it's not on the schedule) at
   [15]Extreme Markup Languages 2004 about TagSoup, updated from the one
   presented in 2002 at the New York City XML SIG and at XML 2002. This is
   the main high-level documentation about how TagSoup works. Formats:
   [16]OpenDocument [17]Powerpoint [18]PDF.

   I also had people add [19]"evil" HTML to a large poster so that I could
   [20]clean it up; View Source is probably more useful than ordinary
   browsing. The original instructions were:

                         SOUPE DE BALISES (BE EVIL)!
   Ecritez une balise ouvrante (sans attributs)
   ou fermante HTML ici, s.v.p.

   There is a [21]tagsoup-friends mailing list hosted at [22]Yahoo Groups.
   You can [23]join via the Web, or by sending a blank email to
   [24]tagsoup-friends-subscribe@yahoogroups.com. The [25]archives are
   open to all.

   Online TagSoup processing for publicly accessible HTML documents is now
   [26]available courtesy of Leigh Dodds.

References

   1. http://oregonstate.edu/instruct/phl302/texts/hobbes/leviathan-c.html
   2. http://opensource.org/licenses/apache2.0.php
   3. http://prdownloads.sourceforge.net/saxon/saxon6-5-5.zip
   4. http://www.w3.org/TR/2007/WD-xml-entity-names-20071214
   5. http://home.ccil.org/~cowan/XML/tagsoup/tagsoup-1.2.jar
   6. http://home.ccil.org/~cowan/XML/tagsoup/tagsoup-1.2-src.zip
   7. http://home.ccil.org/~cowan/XML/tagsoup/CHANGES
   8. http://tidy.sf.net/
   9. http://www.crumbmuseum.com/truckin.html
  10. http://www.cafeconleche.org/XOM
  11. http://gnosis.cx/publish/programming/xml_matters_17.html
  12. http://jchardet.sourceforge.net/
  13. http://www.ccil.org/~cowan
  14. http://home.ccil.org/~cowan/XML/tagsoup/tsaxon
  15. http://www.extrememarkup.com/extreme/2004
  16. http://home.ccil.org/~cowan/XML/tagsoup/tagsoup.odp
  17. http://home.ccil.org/~cowan/XML/tagsoup/tagsoup.ppt
  18. http://home.ccil.org/~cowan/XML/tagsoup/tagsoup.pdf
  19. http://home.ccil.org/~cowan/XML/tagsoup/extreme.html
  20. http://home.ccil.org/~cowan/XML/tagsoup/extreme.xhtml
  21. http://groups.yahoo.com/group/tagsoup-friends
  22. http://groups.yahoo.com/
  23. http://groups.yahoo.com/group/tagsoup-friends/join
  24. mailto:tagsoup-friends-subscribe@yahoogroups.com
  25. http://groups.yahoo.com/group/tagsoup-friends/messages
  26. http://xmlarmyknife.org/docs/xhtml/tagsoup/