path: root/doc/extdev/appapi.rst

.. highlight:: rest

Application API
===============

.. module:: sphinx.application
   :synopsis: Application class and extensibility interface.


Each Sphinx extension is a Python module with at least a :func:`setup` function.
This function is called at initialization time with one argument, the
application object representing the Sphinx process.

.. class:: Sphinx

   This application object has the public API described in the following.

Extension setup
---------------

These methods are usually called in an extension's ``setup()`` function.

Examples of using the Sphinx extension API can be seen in the :mod:`sphinx.ext`
package.

.. method:: Sphinx.setup_extension(name)

   Load the extension given by the module *name*.  Use this if your extension
   needs the features provided by another extension.

.. method:: Sphinx.add_builder(builder)

   Register a new builder.  *builder* must be a class that inherits from
   :class:`~sphinx.builders.Builder`.

.. method:: Sphinx.add_config_value(name, default, rebuild)

   Register a configuration value.  This is necessary for Sphinx to recognize
   new values and set default values accordingly.  The *name* should be prefixed
   with the extension name, to avoid clashes.  The *default* value can be any
   Python object.  The string value *rebuild* must be one of those values:

   * ``'env'`` if a change in the setting only takes effect when a document is
     parsed -- this means that the whole environment must be rebuilt.
   * ``'html'`` if a change in the setting needs a full rebuild of HTML
     documents.
   * ``''`` if a change in the setting will not need any special rebuild.

   .. versionchanged:: 0.4
      If the *default* value is a callable, it will be called with the config
      object as its argument in order to get the default value.  This can be
      used to implement config values whose default depends on other values.

   .. versionchanged:: 0.6
      Changed *rebuild* from a simple boolean (equivalent to ``''`` or
      ``'env'``) to a string.  However, booleans are still accepted and
      converted internally.

.. method:: Sphinx.add_domain(domain)

   Make the given *domain* (which must be a class; more precisely, a subclass of
   :class:`~sphinx.domains.Domain`) known to Sphinx.

   .. versionadded:: 1.0

.. method:: Sphinx.override_domain(domain)

   Make the given *domain* class known to Sphinx, assuming that there is already
   a domain with its ``.name``.  The new domain must be a subclass of the
   existing one.

   .. versionadded:: 1.0

.. method:: Sphinx.add_index_to_domain(domain, index)

   Add a custom *index* class to the domain named *domain*.  *index* must be a
   subclass of :class:`~sphinx.domains.Index`.

   .. versionadded:: 1.0

.. method:: Sphinx.add_event(name)

   Register an event called *name*.  This is needed to be able to emit it.

.. method:: Sphinx.set_translator(name, translator_class)

   Register or override a Docutils translator class. This is used to register
   a custom output translator or to replace a builtin translator.
   This allows extensions to use custom translator and define custom
   nodes for the translator (see :meth:`add_node`).

   This is a API version of :confval:`html_translator_class` for all other
   builders. Note that if :confval:`html_translator_class` is specified and
   this API is called for html related builders, API overriding takes
   precedence.

   .. versionadded:: 1.3

.. method:: Sphinx.add_node(node, **kwds)

   Register a Docutils node class.  This is necessary for Docutils internals.
   It may also be used in the future to validate nodes in the parsed documents.

   Node visitor functions for the Sphinx HTML, LaTeX, text and manpage writers
   can be given as keyword arguments: the keyword should be one or more of
   ``'html'``, ``'latex'``, ``'text'``, ``'man'``, ``'texinfo'`` or any other
   supported translators, the value a 2-tuple of ``(visit, depart)`` methods.
   ``depart`` can be ``None`` if the ``visit`` function raises
   :exc:`docutils.nodes.SkipNode`.  Example:

   .. code-block:: python

      class math(docutils.nodes.Element): pass

      def visit_math_html(self, node):
          self.body.append(self.starttag(node, 'math'))
      def depart_math_html(self, node):
          self.body.append('</math>')

      app.add_node(math, html=(visit_math_html, depart_math_html))

   Obviously, translators for which you don't specify visitor methods will choke
   on the node when encountered in a document to translate.

   .. versionchanged:: 0.5
      Added the support for keyword arguments giving visit functions.

.. method:: Sphinx.add_directive(name, func, content, arguments, **options)
            Sphinx.add_directive(name, directiveclass)

   Register a Docutils directive.  *name* must be the prospective directive
   name.  There are two possible ways to write a directive:

   * In the docutils 0.4 style, *obj* is the directive function.  *content*,
     *arguments* and *options* are set as attributes on the function and
     determine whether the directive has content, arguments and options,
     respectively.  **This style is deprecated.**

   * In the docutils 0.5 style, *directiveclass* is the directive class.  It
     must already have attributes named *has_content*, *required_arguments*,
     *optional_arguments*, *final_argument_whitespace* and *option_spec* that
     correspond to the options for the function way.  See `the Docutils docs
     <http://docutils.sourceforge.net/docs/howto/rst-directives.html>`_ for
     details.

     The directive class must inherit from the class
     ``docutils.parsers.rst.Directive``.

   For example, the (already existing) :rst:dir:`literalinclude` directive would
   be added like this:

   .. code-block:: python

      from docutils.parsers.rst import directives
      add_directive('literalinclude', literalinclude_directive,
                    content = 0, arguments = (1, 0, 0),
                    linenos = directives.flag,
                    language = direcitves.unchanged,
                    encoding = directives.encoding)

   .. versionchanged:: 0.6
      Docutils 0.5-style directive classes are now supported.

.. method:: Sphinx.add_directive_to_domain(domain, name, func, content, arguments, **options)
            Sphinx.add_directive_to_domain(domain, name, directiveclass)

   Like :meth:`add_directive`, but the directive is added to the domain named
   *domain*.

   .. versionadded:: 1.0

.. method:: Sphinx.add_role(name, role)

   Register a Docutils role.  *name* must be the role name that occurs in the
   source, *role* the role function (see the `Docutils documentation
   <http://docutils.sourceforge.net/docs/howto/rst-roles.html>`_ on details).

.. method:: Sphinx.add_role_to_domain(domain, name, role)

   Like :meth:`add_role`, but the role is added to the domain named *domain*.

   .. versionadded:: 1.0

.. method:: Sphinx.add_generic_role(name, nodeclass)

   Register a Docutils role that does nothing but wrap its contents in the
   node given by *nodeclass*.

   .. versionadded:: 0.6

.. method:: Sphinx.add_object_type(directivename, rolename, indextemplate='', parse_node=None, \
                                   ref_nodeclass=None, objname='', doc_field_types=[])

   This method is a very convenient way to add a new :term:`object` type that
   can be cross-referenced.  It will do this:

   * Create a new directive (called *directivename*) for documenting an object.
     It will automatically add index entries if *indextemplate* is nonempty; if
     given, it must contain exactly one instance of ``%s``.  See the example
     below for how the template will be interpreted.
   * Create a new role (called *rolename*) to cross-reference to these
     object descriptions.
   * If you provide *parse_node*, it must be a function that takes a string and
     a docutils node, and it must populate the node with children parsed from
     the string.  It must then return the name of the item to be used in
     cross-referencing and index entries.  See the :file:`conf.py` file in the
     source for this documentation for an example.
   * The *objname* (if not given, will default to *directivename*) names the
     type of object.  It is used when listing objects, e.g. in search results.

   For example, if you have this call in a custom Sphinx extension::

      app.add_object_type('directive', 'dir', 'pair: %s; directive')

   you can use this markup in your documents::

      .. rst:directive:: function

         Document a function.

      <...>

      See also the :rst:dir:`function` directive.

   For the directive, an index entry will be generated as if you had prepended ::

      .. index:: pair: function; directive

   The reference node will be of class ``literal`` (so it will be rendered in a
   proportional font, as appropriate for code) unless you give the
   *ref_nodeclass* argument, which must be a docutils node class.  Most useful
   are ``docutils.nodes.emphasis`` or ``docutils.nodes.strong`` -- you can also
   use ``docutils.nodes.generated`` if you want no further text decoration.  If
   the text should be treated as literal (e.g. no smart quote replacement), but
   not have typewriter styling, use ``sphinx.addnodes.literal_emphasis`` or
   ``sphinx.addnodes.literal_strong``.

   For the role content, you have the same syntactical possibilities as for
   standard Sphinx roles (see :ref:`xref-syntax`).

   This method is also available under the deprecated alias
   ``add_description_unit``.

.. method:: Sphinx.add_crossref_type(directivename, rolename, indextemplate='', ref_nodeclass=None, objname='')

   This method is very similar to :meth:`add_object_type` except that the
   directive it generates must be empty, and will produce no output.

   That means that you can add semantic targets to your sources, and refer to
   them using custom roles instead of generic ones (like :rst:role:`ref`).
   Example call::

      app.add_crossref_type('topic', 'topic', 'single: %s', docutils.nodes.emphasis)

   Example usage::

      .. topic:: application API

      The application API
      -------------------

      <...>

      See also :topic:`this section <application API>`.

   (Of course, the element following the ``topic`` directive needn't be a
   section.)

.. method:: Sphinx.add_transform(transform)

   Add the standard docutils :class:`Transform` subclass *transform* to the list
   of transforms that are applied after Sphinx parses a reST document.

.. method:: Sphinx.add_javascript(filename)

   Add *filename* to the list of JavaScript files that the default HTML template
   will include.  The filename must be relative to the HTML static path, see
   :confval:`the docs for the config value <html_static_path>`.  A full URI with
   scheme, like ``http://example.org/foo.js``, is also supported.

   .. versionadded:: 0.5

.. method:: Sphinx.add_stylesheet(filename)

   Add *filename* to the list of CSS files that the default HTML template will
   include.  Like for :meth:`add_javascript`, the filename must be relative to
   the HTML static path, or a full URI with scheme.

   .. versionadded:: 1.0

.. method:: Sphinx.add_latex_package(packagename, options=None)

   Add *packagename* to the list of packages that LaTeX source code will include.
   If you provide *options*, it will be taken to `\usepackage` declaration.

   .. code-block:: python

      app.add_latex_package('mypackage')             # => \usepackage{mypackage}
      app.add_latex_package('mypackage', 'foo,bar')  # => \usepackage[foo,bar]{mypackage}

   .. versionadded:: 1.3

.. method:: Sphinx.add_lexer(alias, lexer)

   Use *lexer*, which must be an instance of a Pygments lexer class, to
   highlight code blocks with the given language *alias*.

   .. versionadded:: 0.6

.. method:: Sphinx.add_autodocumenter(cls)

   Add *cls* as a new documenter class for the :mod:`sphinx.ext.autodoc`
   extension.  It must be a subclass of :class:`sphinx.ext.autodoc.Documenter`.
   This allows to auto-document new types of objects.  See the source of the
   autodoc module for examples on how to subclass :class:`Documenter`.

   .. XXX add real docs for Documenter and subclassing

   .. versionadded:: 0.6

.. method:: Sphinx.add_autodoc_attrgetter(type, getter)

   Add *getter*, which must be a function with an interface compatible to the
   :func:`getattr` builtin, as the autodoc attribute getter for objects that are
   instances of *type*.  All cases where autodoc needs to get an attribute of a
   type are then handled by this function instead of :func:`getattr`.

   .. versionadded:: 0.6

.. method:: Sphinx.add_search_language(cls)

   Add *cls*, which must be a subclass of :class:`sphinx.search.SearchLanguage`,
   as a support language for building the HTML full-text search index.  The
   class must have a *lang* attribute that indicates the language it should be
   used for.  See :confval:`html_search_language`.

   .. versionadded:: 1.1

.. method:: Sphinx.require_sphinx(version)

   Compare *version* (which must be a ``major.minor`` version string,
   e.g. ``'1.1'``) with the version of the running Sphinx, and abort the build
   when it is too old.

   .. versionadded:: 1.0

.. method:: Sphinx.connect(event, callback)

   Register *callback* to be called when *event* is emitted.  For details on
   available core events and the arguments of callback functions, please see
   :ref:`events`.

   The method returns a "listener ID" that can be used as an argument to
   :meth:`disconnect`.

.. method:: Sphinx.disconnect(listener_id)

   Unregister callback *listener_id*.


.. exception:: ExtensionError

   All these methods raise this exception if something went wrong with the
   extension API.


Emitting events
---------------

.. method:: Sphinx.emit(event, *arguments)

   Emit *event* and pass *arguments* to the callback functions.  Return the
   return values of all callbacks as a list.  Do not emit core Sphinx events
   in extensions!

.. method:: Sphinx.emit_firstresult(event, *arguments)

   Emit *event* and pass *arguments* to the callback functions.  Return the
   result of the first callback that doesn't return ``None``.

   .. versionadded:: 0.5


Producing messages / logging
----------------------------

The application object also provides support for emitting leveled messages.

.. note::

   There is no "error" call: in Sphinx, errors are defined as things that stop
   the build; just raise an exception (:exc:`sphinx.errors.SphinxError` or a
   custom subclass) to do that.

.. automethod:: Sphinx.warn

.. automethod:: Sphinx.info

.. automethod:: Sphinx.verbose

.. automethod:: Sphinx.debug

.. automethod:: Sphinx.debug2


.. _events:

Sphinx core events
------------------

These events are known to the core.  The arguments shown are given to the
registered event handlers.  Use :meth:`.connect` in an extension's ``setup``
function (note that ``conf.py`` can also have a ``setup`` function) to connect
handlers to the events.  Example:

.. code-block:: python

   def source_read_handler(app, docname, source):
       print('do something here...')

   def setup(app):
       app.connect('source-read', source_read_handler)


.. event:: builder-inited (app)

   Emitted when the builder object has been created.  It is available as
   ``app.builder``.

.. event:: env-get-outdated (app, env, added, changed, removed)

   Emitted when the environment determines which source files have changed and
   should be re-read.  *added*, *changed* and *removed* are sets of docnames
   that the environment has determined.  You can return a list of docnames to
   re-read in addition to these.

   .. versionadded:: 1.1

.. event:: env-purge-doc (app, env, docname)

   Emitted when all traces of a source file should be cleaned from the
   environment, that is, if the source file is removed or before it is freshly
   read.  This is for extensions that keep their own caches in attributes of the
   environment.

   For example, there is a cache of all modules on the environment.  When a
   source file has been changed, the cache's entries for the file are cleared,
   since the module declarations could have been removed from the file.

   .. versionadded:: 0.5

.. event:: env-before-read-docs (app, env, docnames)

   Emitted after the environment has determined the list of all added and
   changed files and just before it reads them.  It allows extension authors to
   reorder the list of docnames (*inplace*) before processing, or add more
   docnames that Sphinx did not consider changed (but never add any docnames
   that are not in ``env.found_docs``).

   You can also remove document names; do this with caution since it will make
   Sphinx treat changed files as unchanged.

   .. versionadded:: 1.3

.. event:: source-read (app, docname, source)

   Emitted when a source file has been read.  The *source* argument is a list
   whose single element is the contents of the source file.  You can process the
   contents and replace this item to implement source-level transformations.

   For example, if you want to use ``$`` signs to delimit inline math, like in
   LaTeX, you can use a regular expression to replace ``$...$`` by
   ``:math:`...```.

   .. versionadded:: 0.5

.. event:: doctree-read (app, doctree)

   Emitted when a doctree has been parsed and read by the environment, and is
   about to be pickled.  The *doctree* can be modified in-place.

.. event:: missing-reference (app, env, node, contnode)

   Emitted when a cross-reference to a Python module or object cannot be
   resolved.  If the event handler can resolve the reference, it should return a
   new docutils node to be inserted in the document tree in place of the node
   *node*.  Usually this node is a :class:`reference` node containing *contnode*
   as a child.

   :param env: The build environment (``app.builder.env``).
   :param node: The :class:`pending_xref` node to be resolved.  Its attributes
      ``reftype``, ``reftarget``, ``modname`` and ``classname`` attributes
      determine the type and target of the reference.
   :param contnode: The node that carries the text and formatting inside the
      future reference and should be a child of the returned reference node.

   .. versionadded:: 0.5

.. event:: doctree-resolved (app, doctree, docname)

   Emitted when a doctree has been "resolved" by the environment, that is, all
   references have been resolved and TOCs have been inserted.  The *doctree* can
   be modified in place.

   Here is the place to replace custom nodes that don't have visitor methods in
   the writers, so that they don't cause errors when the writers encounter them.

.. event:: env-merge-info (env, docnames, other)

   This event is only emitted when parallel reading of documents is enabled.  It
   is emitted once for every subprocess that has read some documents.

   You must handle this event in an extension that stores data in the
   environment in a custom location.  Otherwise the environment in the main
   process will not be aware of the information stored in the subprocess.

   *other* is the environment object from the subprocess, *env* is the
   environment from the main process.  *docnames* is a set of document names
   that have been read in the subprocess.

   For a sample of how to deal with this event, look at the standard
   ``sphinx.ext.todo`` extension.  The implementation is often similar to that
   of :event:`env-purge-doc`, only that information is not removed, but added to
   the main environment from the other environment.

   .. versionadded:: 1.3

.. event:: env-updated (app, env)

   Emitted when the :meth:`update` method of the build environment has
   completed, that is, the environment and all doctrees are now up-to-date.

   .. versionadded:: 0.5

.. event:: html-collect-pages (app)

   Emitted when the HTML builder is starting to write non-document pages.  You
   can add pages to write by returning an iterable from this event consisting of
   ``(pagename, context, templatename)``.

   .. versionadded:: 1.0

.. event:: html-page-context (app, pagename, templatename, context, doctree)

   Emitted when the HTML builder has created a context dictionary to render a
   template with -- this can be used to add custom elements to the context.

   The *pagename* argument is the canonical name of the page being rendered,
   that is, without ``.html`` suffix and using slashes as path separators.  The
   *templatename* is the name of the template to render, this will be
   ``'page.html'`` for all pages from reST documents.

   The *context* argument is a dictionary of values that are given to the
   template engine to render the page and can be modified to include custom
   values.  Keys must be strings.

   The *doctree* argument will be a doctree when the page is created from a reST
   documents; it will be ``None`` when the page is created from an HTML template
   alone.

   You can return a string from the handler, it will then replace
   ``'page.html'`` as the HTML template for this page.

   .. versionadded:: 0.4

   .. versionchanged:: 1.3
      The return value can now specify a template name.

.. event:: build-finished (app, exception)

   Emitted when a build has finished, before Sphinx exits, usually used for
   cleanup.  This event is emitted even when the build process raised an
   exception, given as the *exception* argument.  The exception is reraised in
   the application after the event handlers have run.  If the build process
   raised no exception, *exception* will be ``None``.  This allows to customize
   cleanup actions depending on the exception status.

   .. versionadded:: 0.5


Checking the Sphinx version
---------------------------

.. currentmodule:: sphinx

Use this to adapt your extension to API changes in Sphinx.

.. data:: version_info

   A tuple of five elements; for Sphinx version 1.2.1 beta 3 this would be
   ``(1, 2, 1, 'beta', 3)``.

   .. versionadded:: 1.2
      Before version 1.2, check the string ``sphinx.__version__``.


The Config object
-----------------

.. module:: sphinx.config

.. class:: Config

   The config object makes the values of all config values available as
   attributes.

   It is available as the ``config`` attribute on the application and
   environment objects.  For example, to get the value of :confval:`language`,
   use either ``app.config.language`` or ``env.config.language``.


.. _template-bridge:

The template bridge
-------------------

.. currentmodule:: sphinx.application

.. autoclass:: TemplateBridge
   :members:


.. _exceptions:

Exceptions
----------

.. module:: sphinx.errors

.. exception:: SphinxError

   This is the base class for "nice" exceptions.  When such an exception is
   raised, Sphinx will abort the build and present the exception category and
   message to the user.

   Extensions are encouraged to derive from this exception for their custom
   errors.

   Exceptions *not* derived from :exc:`SphinxError` are treated as unexpected
   and shown to the user with a part of the traceback (and the full traceback
   saved in a temporary file).

   .. attribute:: category

      Description of the exception "category", used in converting the exception
      to a string ("category: message").  Should be set accordingly in
      subclasses.

.. exception:: ConfigError

   Used for erroneous values or nonsensical combinations of configuration
   values.

.. exception:: ExtensionError

   Used for errors in setting up extensions.

.. exception:: ThemeError

   Used for errors to do with themes.

.. exception:: VersionRequirementError

   Raised when the docs require a higher Sphinx version than the current one.