:mod:`htmllib` --- A parser for HTML documents

==============================================

.. module:: htmllib

   :synopsis: A parser for HTML documents.

   :deprecated:

.. deprecated:: 2.6

    The :mod:`htmllib` module has been removed in Python 3.0.

.. index::

   single: HTML

   single: hypertext

.. index::

   module: sgmllib

   module: formatter

   single: SGMLParser (in module sgmllib)

This module defines a class which can serve as a base for parsing text files

formatted in the HyperText Mark-up Language (HTML).  The class is not directly

concerned with I/O --- it must be provided with input in string form via a

method, and makes calls to methods of a "formatter" object in order to produce

output.  The :class:`HTMLParser` class is designed to be used as a base class

for other classes in order to add functionality, and allows most of its methods

to be extended or overridden.  In turn, this class is derived from and extends

the :class:`SGMLParser` class defined in module :mod:`sgmllib`.  The

:class:`HTMLParser` implementation supports the HTML 2.0 language as described

in :rfc:`1866`.  Two implementations of formatter objects are provided in the

:mod:`formatter` module; refer to the documentation for that module for

information on the formatter interface.

The following is a summary of the interface defined by

:class:`sgmllib.SGMLParser`:

* The interface to feed data to an instance is through the :meth:`feed` method,

  which takes a string argument.  This can be called with as little or as much

  text at a time as desired; ``p.feed(a); p.feed(b)`` has the same effect as

  ``p.feed(a+b)``.  When the data contains complete HTML markup constructs, these

  are processed immediately; incomplete constructs are saved in a buffer.  To

  force processing of all unprocessed data, call the :meth:`close` method.

  For example, to parse the entire contents of a file, use::

     parser.feed(open('myfile.html').read())

     parser.close()

* The interface to define semantics for HTML tags is very simple: derive a class

  and define methods called :meth:`start_tag`, :meth:`end_tag`, or :meth:`do_tag`.

  The parser will call these at appropriate moments: :meth:`start_tag` or

  :meth:`do_tag` is called when an opening tag of the form ``<tag ...>`` is

  encountered; :meth:`end_tag` is called when a closing tag of the form ``<tag>``

  is encountered.  If an opening tag requires a corresponding closing tag, like

  ``<H1>`` ... ``</H1>``, the class should define the :meth:`start_tag` method; if

  a tag requires no closing tag, like ``<P>``, the class should define the

  :meth:`do_tag` method.

The module defines a parser class and an exception:

.. class:: HTMLParser(formatter)

   This is the basic HTML parser class.  It supports all entity names required by

   the XHTML 1.0 Recommendation (http://www.w3.org/TR/xhtml1).   It also defines

   handlers for all HTML 2.0 and many HTML 3.0 and 3.2 elements.

.. exception:: HTMLParseError

   Exception raised by the :class:`HTMLParser` class when it encounters an error

   while parsing.

   .. versionadded:: 2.4

.. seealso::

   Module :mod:`formatter`

      Interface definition for transforming an abstract flow of formatting events into

      specific output events on writer objects.

   Module :mod:`HTMLParser`

      Alternate HTML parser that offers a slightly lower-level view of the input, but

      is designed to work with XHTML, and does not implement some of the SGML syntax

      not used in "HTML as deployed" and which isn't legal for XHTML.

   Module :mod:`htmlentitydefs`

      Definition of replacement text for XHTML 1.0  entities.

   Module :mod:`sgmllib`

      Base class for :class:`HTMLParser`.

.. _html-parser-objects:

HTMLParser Objects

------------------

In addition to tag methods, the :class:`HTMLParser` class provides some

additional methods and instance variables for use within tag methods.

.. attribute:: HTMLParser.formatter

   This is the formatter instance associated with the parser.

.. attribute:: HTMLParser.nofill

   Boolean flag which should be true when whitespace should not be collapsed, or

   false when it should be.  In general, this should only be true when character

   data is to be treated as "preformatted" text, as within a ``<PRE>`` element.

   The default value is false.  This affects the operation of :meth:`handle_data`

   and :meth:`save_end`.

.. method:: HTMLParser.anchor_bgn(href, name, type)

   This method is called at the start of an anchor region.  The arguments

   correspond to the attributes of the ``<A>`` tag with the same names.  The

   default implementation maintains a list of hyperlinks (defined by the ``HREF``

   attribute for ``<A>`` tags) within the document.  The list of hyperlinks is

   available as the data attribute :attr:`anchorlist`.

.. method:: HTMLParser.anchor_end()

   This method is called at the end of an anchor region.  The default

   implementation adds a textual footnote marker using an index into the list of

   hyperlinks created by :meth:`anchor_bgn`.

.. method:: HTMLParser.handle_image(source, alt[, ismap[, align[, width[, height]]]])

   This method is called to handle images.  The default implementation simply

   passes the *alt* value to the :meth:`handle_data` method.

.. method:: HTMLParser.save_bgn()

   Begins saving character data in a buffer instead of sending it to the formatter

   object.  Retrieve the stored data via :meth:`save_end`. Use of the

   :meth:`save_bgn` / :meth:`save_end` pair may not be nested.

.. method:: HTMLParser.save_end()

   Ends buffering character data and returns all data saved since the preceding

   call to :meth:`save_bgn`.  If the :attr:`nofill` flag is false, whitespace is

   collapsed to single spaces.  A call to this method without a preceding call to

   :meth:`save_bgn` will raise a :exc:`TypeError` exception.

:mod:`htmlentitydefs` --- Definitions of HTML general entities

==============================================================

.. module:: htmlentitydefs

   :synopsis: Definitions of HTML general entities.

.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org>

.. note::

   The :mod:`htmlentitydefs` module has been renamed to :mod:`html.entities` in

   Python 3.0.  The :term:`2to3` tool will automatically adapt imports when

   converting your sources to 3.0.

This module defines three dictionaries, ``name2codepoint``, ``codepoint2name``,

and ``entitydefs``. ``entitydefs`` is used by the :mod:`htmllib` module to

provide the :attr:`entitydefs` member of the :class:`HTMLParser` class.  The

definition provided here contains all the entities defined by XHTML 1.0  that

can be handled using simple textual substitution in the Latin-1 character set

(ISO-8859-1).

.. data:: entitydefs

   A dictionary mapping XHTML 1.0 entity definitions to their replacement text in

   ISO Latin-1.

.. data:: name2codepoint

   A dictionary that maps HTML entity names to the Unicode codepoints.

   .. versionadded:: 2.3

.. data:: codepoint2name

   A dictionary that maps Unicode codepoints to HTML entity names.

   .. versionadded:: 2.3