.. include:: headings.inc



.. _FileSystemHandler:

==========================================================================================================================================
|phoenix_title|  **FileSystemHandler**
==========================================================================================================================================

Classes derived from :ref:`FileSystemHandler`  are used to access virtual file systems.          

Its public interface consists of two methods: :meth:`FileSystemHandler.CanOpen`   and :meth:`FileSystemHandler.OpenFile` . 

It provides additional protected methods to simplify the process of opening the file: :meth:`~FileSystemHandler.GetProtocol`, :meth:`~FileSystemHandler.GetLeftLocation`, :meth:`~FileSystemHandler.GetRightLocation`, :meth:`~FileSystemHandler.GetAnchor`, :meth:`~FileSystemHandler.GetMimeTypeFromExt`. 

Please have a look at overview (see :ref:`FileSystem`) if you don't know how locations are constructed. 

Also consult the :ref:`list of available handlers <list of available handlers>`. 

Note that the handlers are shared by all instances of :ref:`FileSystem`. 








         



.. note:: 

   ``HTML`` library provides handlers for local files and ``HTTP`` or ``FTP`` protocol.  







.. note:: 

   The location parameter passed to :meth:`OpenFile`   or :meth:`CanOpen`   methods is always an absolute path. You don't need to check the FS's current path.  







.. seealso:: :ref:`FileSystem`, :ref:`FSFile`, :ref:`FileSystem Overview <filesystem overview>`    







|

|class_hierarchy| Inheritance Diagram
=====================================

Inheritance diagram for class **FileSystemHandler**

.. raw:: html

   <p class="graphviz">
   <img src="_static/images/inheritance/FileSystemHandler_inheritance.png" alt="Inheritance diagram of FileSystemHandler" usemap="#dummy" class="inheritance"/>
   <map id="dummy" name="dummy"> <area shape="rect" id="node1" href="Object.html" title="This is the root class of many of the wxWidgets classes." alt="" coords="5,5,77,35"/> <area shape="rect" id="node2" href="FileSystemHandler.html" title="Classes derived from FileSystemHandler  are used to access virtual file systems." alt="" coords="127,5,284,35"/> </map> 
   </p>

|


|sub_classes| Known Subclasses
==============================

:ref:`ArchiveFSHandler`, :ref:`FilterFSHandler`, :ref:`InternetFSHandler`, :ref:`MemoryFSHandler`

|


|method_summary| Methods Summary
================================

================================================================================ ================================================================================
:meth:`~FileSystemHandler.__init__`                                              Constructor.
:meth:`~FileSystemHandler.CanOpen`                                               Returns ``True`` if the handler is able to open this file.
:meth:`~FileSystemHandler.FindFirst`                                             Works like :func:`FindFirstFile`.
:meth:`~FileSystemHandler.FindNext`                                              Returns next filename that matches parameters passed to :meth:`FileSystem.FindFirst` .
:meth:`~FileSystemHandler.GetMimeTypeFromExt`                                    Returns the ``MIME`` type based on **extension**  of `location`.
:meth:`~FileSystemHandler.OpenFile`                                              Opens the file and returns :ref:`FSFile`  pointer or ``None`` if failed.
================================================================================ ================================================================================


|


|api| Class API
===============
   

.. class:: FileSystemHandler(Object)

   Classes derived from FileSystemHandler are used to access virtual file systems.
   
   **Possible constructors**::

       FileSystemHandler()
       



   .. method:: __init__(self)

      Constructor.                   





   .. method:: CanOpen(self, location)

      Returns ``True`` if the handler is able to open this file.                  

      This function doesn't check whether the file exists or not, it only checks if it knows the protocol. Example: 

      ::

                  def CanOpen(self, location):
            
                      return self.GetProtocol(location) == "http"



      Must be overridden in derived handlers.                  


      :param `location`: 
      :type `location`: string




      :rtype: `bool`








   .. method:: FindFirst(self, wildcard, flags=0)

      Works like :func:`FindFirstFile`.                  

      Returns the name of the first filename (within filesystem's current path) that matches `wildcard`. `flags`  may be one of ``FILE`` (only files), ``DIR`` (only directories) or 0 (both). 

      This method is only called if :meth:`CanOpen`   returns ``True``.                  


      :param `wildcard`: 
      :type `wildcard`: string
      :param `flags`: 
      :type `flags`: int




      :rtype: `string`








   .. method:: FindNext(self)

      Returns next filename that matches parameters passed to :meth:`FileSystem.FindFirst` .                  

      This method is only called if :meth:`CanOpen`   returns ``True`` and :meth:`FindFirst`   returned a non-empty string.                  

      :rtype: `string`








   .. staticmethod:: GetMimeTypeFromExt(location)

      Returns the ``MIME`` type based on **extension**  of `location`.                  

      (While :meth:`FSFile.GetMimeType`   returns real ``MIME`` type - either extension-based or queried from ``HTTP``.) 

      Example: ::

                  if GetMimeTypeFromExt("index.htm") == "text/html":
                      wx.MessageBox("Is HTML!")

                 


      :param `location`: 
      :type `location`: string




      :rtype: `string`








   .. method:: OpenFile(self, fs, location)

      Opens the file and returns :ref:`FSFile`  pointer or ``None`` if failed.                  

      Must be overridden in derived handlers. 




      :param `fs`: Parent ``FS`` (the ``FS`` from that OpenFile was called). See the ``ZIP`` handler for details of how to use it.   
      :type `fs`: FileSystem
      :param `location`: The absolute location of file.   
      :type `location`: string








      :rtype: :ref:`FSFile`