/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/session.py

Diff of /branches/WIP-pyshapelib-bramz/Thuban/Model/session.py

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-revision 582 by jonathan,
Tue Apr  1 10:22:01 2003 UTC
+revision 1124 by bh,
Mon Jun  2 14:14:25 2003 UTC
 Line 1
- # Copyright (c) 2001, 2002 by Intevation GmbH
+ # Copyright (c) 2001, 2002, 2003 by Intevation GmbH
  # Authors:
  # Bernhard Herzog <[email protected]>
  # Jan-Oliver Wagner <[email protected]>
 Line 8
  __version__ = "$Revision$"
- from Thuban.Lib.connector import Publisher
+ import os
+ from tempfile import mktemp
+ import weakref
  from messages import MAPS_CHANGED, EXTENSIONS_CHANGED, FILENAME_CHANGED, \
       MAP_LAYERS_CHANGED, MAP_PROJECTION_CHANGED, \
       LAYER_CHANGED, LAYER_PROJECTION_CHANGED, LAYER_VISIBILITY_CHANGED,\
-      EXTENSION_CHANGED, EXTENSION_OBJECTS_CHANGED, CHANGED
+      EXTENSION_CHANGED, EXTENSION_OBJECTS_CHANGED, CHANGED, \
+      TABLE_REMOVED
  from Thuban import _
  from base import TitledObject, Modifiable
  from map import Map
+ from data import ShapefileStore
+ from table import DBFTable
+ from transientdb import TransientDatabase, AutoTransientTable
+ class AutoRemoveFile:
+     """Remove a file once all references go away."""
+     def __init__(self, filename, tempdir = None):
+         """Initialize the AutoRemoveFile
+         Parameters:
+            filename -- The name of the file to remove in __del__
+            tempdir -- Another object simple stored as an instance variable.
+         As the name suggests the tempdir parameter is intended for a
+         temporary directory the file might be located in. The intended
+         use is that it's an instance of AutoRemoveDir.
+         """
+         self.filename = filename
+         self.tempdir = tempdir
+     def __del__(self, remove = os.remove):
+         remove(self.filename)
+ class AutoRemoveDir:
+     """Remove a directory once all references go away
+     The intended use of this class together with AutoRemoveFile is for
+     temporary directories and files containd therein. An AutoRemoveDir
+     should be instantiated for the directory and passed as the tempdir
+     parameter to every AutoRemoveFile instance created for files in the
+     directory. An AutoRemoveFile shold be instantiated for every file
+     created in the directory so that the directory is automatically
+     removed once the last file is removed.
+     """
+     def __init__(self, filename):
+         """Initialize the AutoRemoveDir
+         The parameter is the name of the directory.
+         """
+         self.filename = filename
+     def __del__(self, rmdir = os.rmdir):
+         rmdir(self.filename)
+ # WeakKey dictionary mapping objects like the transient_db to
+ # AutoRemoveDir or AutoRemoveFile instances to make sure that the
+ # temporary files and the directory are deleted but not before the
+ # objects that use them go away.
+ auto_remover = weakref.WeakKeyDictionary()
  class Session(TitledObject, Modifiable):
-Line 75 
 class Session(TitledObject, Modifiable):
+Line 131 
 class Session(TitledObject, Modifiable):
          self.filename = None
          self.maps = []
          self.tables = []
+         self.shapestores = []
          self.extensions = []
+         self.temp_dir = None
+         self.transient_db = None
      def changed(self, channel = None, *args):
          """Like the inherited version but issue a CHANGED message as well.
-Line 122 
 class Session(TitledObject, Modifiable):
+Line 181 
 class Session(TitledObject, Modifiable):
              extension.Subscribe(channel, self.forward, channel)
          self.changed(EXTENSIONS_CHANGED)
+     def ShapeStores(self):
+         """Return a list of all ShapeStore objects open in the session"""
+         return [store() for store in self.shapestores]
+     def _add_shapestore(self, store):
+         """Internal: Add the shapestore to the list of shapestores"""
+         self.shapestores.append(weakref.ref(store,
+                                             self._clean_weak_store_refs))
+     def _clean_weak_store_refs(self, weakref):
+         """Internal: Remove the weakref from the shapestores list"""
+         self.shapestores = [store for store in self.shapestores
+                                   if store is not weakref]
+     def Tables(self):
+         """Return a list of all table objects open in the session
+         The list includes all tables that are indirectly opened through
+         shape stores and the tables that have been opened explicitly.
+         """
+         return self.tables + [store.Table() for store in self.ShapeStores()]
+     def UnreferencedTables(self):
+         """Return the tables that are not referenced by other data sources"""
+         known = {}
+         for table in self.tables:
+             known[id(table)] = 0
+         for table in self.tables + self.ShapeStores():
+             for dep in table.Dependencies():
+                 known[id(dep)] = 1
+         return [table for table in self.tables if known[id(table)] == 0]
+     def AddTable(self, table):
+         """Add the table to the session
+         All tables associated with the session that are not implicitly
+         created by the OpenShapefile method (and maybe other Open*
+         methods in the future) have to be passed to this method to make
+         sure the session knows about it. The session keeps a reference
+         to the table. Only tables managed by the session in this way
+         should be used for layers contained in one of the session's
+         maps.
+         The table parameter may be any object implementing the table
+         interface. If it's not already one of the transient tables
+         instantiate an AutoTransientTable with it and use that instead
+         of the original table (note that the AutoTransientTable keeps a
+         reference to the original table).
+         Return the table object actually used by the session.
+         """
+         if not hasattr(table, "transient_table"):
+             transient_table = AutoTransientTable(self.TransientDB(), table)
+         else:
+             transient_table = table
+         self.tables.append(transient_table)
+         self.changed()
+         return transient_table
+     def RemoveTable(self, table):
+         """Remove the table from the session.
+         The table object must be a table object previously returned by
+         the AddTable method. If the table is not part of the session
+         raise a ValueError.
+         Issue a TABLE_REMOVED message after the table has been removed.
+         The message has the removed table as the single parameter.
+         """
+         tables = [t for t in self.tables if t is not table]
+         if len(tables) == len(self.tables):
+             raise ValueError
+         self.tables = tables
+         self.changed(TABLE_REMOVED, table)
+     def OpenTableFile(self, filename):
+         """Open the table file filename and return the table object.
+         The filename argument must be the name of a DBF file.
+         """
+         return self.AddTable(DBFTable(filename))
+     def temp_directory(self):
+         """
+         Return the name of the directory for session specific temporary files
+         Create the directory if it doesn't exist yet.
+         """
+         if self.temp_dir is None:
+             temp_dir = mktemp()
+             os.mkdir(temp_dir, 0700)
+             self.temp_dir = temp_dir
+             self.temp_dir_remover = AutoRemoveDir(self.temp_dir)
+         return self.temp_dir
+     def OpenShapefile(self, filename):
+         """Return a shapefile store object for the data in the given file"""
+         store = ShapefileStore(self, filename)
+         self._add_shapestore(store)
+         return store
+     def AddShapeStore(self, shapestore):
+         """Add the shapestore to the session.
+         The session only holds a weak reference to the shapestore, so it
+         will automatically be removed from the session when the last
+         reference goes away.
+         """
+         self._add_shapestore(shapestore)
+         return shapestore
+     def TransientDB(self):
+         if self.transient_db is None:
+             filename = os.path.join(self.temp_directory(), "transientdb")
+             self.transient_db = TransientDatabase(filename)
+             #print self.temp_dir_remover
+             auto_remover[self.transient_db] = AutoRemoveFile(filename,
+                                                         self.temp_dir_remover)
+         return self.transient_db
      def Destroy(self):
          for map in self.maps:
              map.Destroy()
-Line 129 
 class Session(TitledObject, Modifiable):
+Line 308 
 class Session(TitledObject, Modifiable):
          self.tables = []
          Modifiable.Destroy(self)
+         # Close the transient DB explicitly so that it removes any
+         # journal files from the temporary directory
+         if self.transient_db is not None:
+             self.transient_db.close()
      def forward(self, *args):
          """Reissue events.

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