Thuban/Model/session.py

# Copyright (c) 2001, 2002, 2003 by Intevation GmbH
# Authors:
# Bernhard Herzog <[email protected]>
# Jan-Oliver Wagner <[email protected]>
#
# This program is free software under the GPL (>=v2)
# Read the file COPYING coming with Thuban for details.

__version__ = "$Revision$"

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, \
     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):

    """A complete session.

    A Session consists of arbitrary numbers of maps, tables and extensions

    Session objects send the following events:

        TITLE_CHANGED -- The title has changed. Parameters: the session.

        FILENAME_CHANGED -- The filename has changed. No parameters.

        MAPS_CHANGED -- Maps were added, removed.

        EXTENSIONS_CHANGED -- Extensions were added, removed.

        MAP_LAYERS_CHANGED -- Same as the map's event of the same name.
                          It's simply resent from the session to make
                          subscriptions easier.

        CHANGED -- Generic changed event. Parameters: the session. The
                   event is always issued when any other changed event
                   is issused. This is useful for code that needs to be
                   notified whenever something in the session has
                   changed but it's too cumbersome or error-prone to
                   subscribe to all the individual events.
    """

    # message channels that have to be forwarded from maps contained in
    # the session.
    forwarded_channels = (
        # generic channels
        CHANGED,

        # map specific channels
        MAP_PROJECTION_CHANGED,
        MAP_LAYERS_CHANGED,

        # layer channels forwarded by the map
        LAYER_PROJECTION_CHANGED,
        LAYER_CHANGED,
        LAYER_VISIBILITY_CHANGED,

        # channels forwarded by an extension
        EXTENSION_CHANGED,
        EXTENSION_OBJECTS_CHANGED)

    def __init__(self, title):
        TitledObject.__init__(self, title)
        Modifiable.__init__(self)
        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.

        The CHANGED message is only issued if channel given is a
        different channel than CHANGED.
        """
        Modifiable.changed(self, channel, *args)
        if channel != CHANGED:
            self.issue(CHANGED, self)

    def SetFilename(self, filename):
        self.filename = filename
        self.changed(FILENAME_CHANGED)

    def Maps(self):
        return self.maps

    def HasMaps(self):
        return len(self.maps) > 0

    def AddMap(self, map):
        self.maps.append(map)
        for channel in self.forwarded_channels:
            map.Subscribe(channel, self.forward, channel)
        self.changed(MAPS_CHANGED)

    def RemoveMap(self, map):
        for channel in self.forwarded_channels:
            map.Unsubscribe(channel, self.forward, channel)
        self.maps.remove(map)
        self.changed(MAPS_CHANGED)
        map.Destroy()

    def Extensions(self):
        return self.extensions

    def HasExtensions(self):
        return len(self.extensions) > 0

    def AddExtension(self, extension):
        self.extensions.append(extension)
        for channel in self.forwarded_channels:
            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)
        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()
        self.maps = []
        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.

        If the channel the event is forwarded to is a changed-channel
        that is not the CHANGED channel issue CHANGED as well. An
        channel is considered to be a changed-channel if it's name ends
        with 'CHANGED'.
        """
        if len(args) > 1:
            args = (args[-1],) + args[:-1]
        apply(self.issue, args)
        channel = args[0]
        # It's a bit of a kludge to rely on the channel name for this.
        if channel.endswith("CHANGED") and channel != CHANGED:
            self.issue(CHANGED, self)

    def WasModified(self):
        """Return true if the session or one of the maps was modified"""
        if self.modified:
            return 1
        else:
            for map in self.maps:
                if map.WasModified():
                    return 1
        return 0

    def UnsetModified(self):
        """Unset the modified flag of the session and the maps"""
        Modifiable.UnsetModified(self)
        for map in self.maps:
            map.UnsetModified()

    def TreeInfo(self):
        items = []
        if self.filename is None:
            items.append(_("Filename:"))
        else:
            items.append(_("Filename: %s") % self.filename)

        if self.WasModified():
            items.append(_("Modified"))
        else:
            items.append(_("Unmodified"))

        items.extend(self.maps)
        items.extend(self.extensions)

        return (_("Session: %s") % self.title, items)


def create_empty_session():
    """Return an empty session useful as a starting point"""
    import os
    session = Session(_('unnamed session'))
    session.SetFilename(None)
    session.AddMap(Map(_('unnamed map')))
    session.UnsetModified()
    return session
1	bh	723	# Copyright (c) 2001, 2002, 2003 by Intevation GmbH
2	bh	6	# Authors:
3			# Bernhard Herzog <[email protected]>
4	jan	197	# Jan-Oliver Wagner <[email protected]>
5	bh	6	#
6			# This program is free software under the GPL (>=v2)
7			# Read the file COPYING coming with Thuban for details.
8
9			__version__ = "$Revision$"
10
11	bh	765	import os
12			from tempfile import mktemp
13			import weakref
14
15	jan	197	from messages import MAPS_CHANGED, EXTENSIONS_CHANGED, FILENAME_CHANGED, \
16	jonathan	548	MAP_LAYERS_CHANGED, MAP_PROJECTION_CHANGED, \
17	jonathan	582	LAYER_CHANGED, LAYER_PROJECTION_CHANGED, LAYER_VISIBILITY_CHANGED,\
18	bh	1068	EXTENSION_CHANGED, EXTENSION_OBJECTS_CHANGED, CHANGED, \
19			TABLE_REMOVED
20	bh	6
21	jan	374	from Thuban import _
22
23	bh	6	from base import TitledObject, Modifiable
24			from map import Map
25	bh	723	from data import ShapefileStore
26	bh	1036	from table import DBFTable
27	bh	6
28	bh	982	from transientdb import TransientDatabase, AutoTransientTable
29	bh	6
30	bh	765	class AutoRemoveFile:
31
32			"""Remove a file once all references go away."""
33
34			def __init__(self, filename, tempdir = None):
35			"""Initialize the AutoRemoveFile
36
37			Parameters:
38			filename -- The name of the file to remove in __del__
39			tempdir -- Another object simple stored as an instance variable.
40
41			As the name suggests the tempdir parameter is intended for a
42			temporary directory the file might be located in. The intended
43			use is that it's an instance of AutoRemoveDir.
44			"""
45			self.filename = filename
46			self.tempdir = tempdir
47
48			def __del__(self, remove = os.remove):
49			remove(self.filename)
50
51			class AutoRemoveDir:
52
53			"""Remove a directory once all references go away
54
55			The intended use of this class together with AutoRemoveFile is for
56			temporary directories and files containd therein. An AutoRemoveDir
57			should be instantiated for the directory and passed as the tempdir
58			parameter to every AutoRemoveFile instance created for files in the
59			directory. An AutoRemoveFile shold be instantiated for every file
60			created in the directory so that the directory is automatically
61			removed once the last file is removed.
62			"""
63
64			def __init__(self, filename):
65			"""Initialize the AutoRemoveDir
66
67			The parameter is the name of the directory.
68			"""
69			self.filename = filename
70
71			def __del__(self, rmdir = os.rmdir):
72			rmdir(self.filename)
73
74
75			# WeakKey dictionary mapping objects like the transient_db to
76			# AutoRemoveDir or AutoRemoveFile instances to make sure that the
77			# temporary files and the directory are deleted but not before the
78			# objects that use them go away.
79			auto_remover = weakref.WeakKeyDictionary()
80
81	bh	6	class Session(TitledObject, Modifiable):
82
83			"""A complete session.
84
85	jan	197	A Session consists of arbitrary numbers of maps, tables and extensions
86	bh	6
87			Session objects send the following events:
88
89			TITLE_CHANGED -- The title has changed. Parameters: the session.
90
91			FILENAME_CHANGED -- The filename has changed. No parameters.
92
93			MAPS_CHANGED -- Maps were added, removed.
94
95	jan	197	EXTENSIONS_CHANGED -- Extensions were added, removed.
96
97	jonathan	548	MAP_LAYERS_CHANGED -- Same as the map's event of the same name.
98	bh	6	It's simply resent from the session to make
99			subscriptions easier.
100	bh	232
101			CHANGED -- Generic changed event. Parameters: the session. The
102			event is always issued when any other changed event
103			is issused. This is useful for code that needs to be
104			notified whenever something in the session has
105			changed but it's too cumbersome or error-prone to
106			subscribe to all the individual events.
107	bh	6	"""
108
109	bh	128	# message channels that have to be forwarded from maps contained in
110			# the session.
111			forwarded_channels = (
112	bh	318	# generic channels
113			CHANGED,
114
115	bh	128	# map specific channels
116			MAP_PROJECTION_CHANGED,
117	jonathan	548	MAP_LAYERS_CHANGED,
118	bh	128
119			# layer channels forwarded by the map
120			LAYER_PROJECTION_CHANGED,
121	jonathan	582	LAYER_CHANGED,
122	jan	197	LAYER_VISIBILITY_CHANGED,
123	bh	128
124	jan	197	# channels forwarded by an extension
125			EXTENSION_CHANGED,
126			EXTENSION_OBJECTS_CHANGED)
127
128	bh	6	def __init__(self, title):
129			TitledObject.__init__(self, title)
130			Modifiable.__init__(self)
131			self.filename = None
132			self.maps = []
133			self.tables = []
134	bh	851	self.shapestores = []
135	jan	197	self.extensions = []
136	bh	765	self.temp_dir = None
137			self.transient_db = None
138	bh	6
139	bh	232	def changed(self, channel = None, *args):
140			"""Like the inherited version but issue a CHANGED message as well.
141
142			The CHANGED message is only issued if channel given is a
143			different channel than CHANGED.
144			"""
145			Modifiable.changed(self, channel, *args)
146			if channel != CHANGED:
147			self.issue(CHANGED, self)
148
149	bh	6	def SetFilename(self, filename):
150			self.filename = filename
151			self.changed(FILENAME_CHANGED)
152
153			def Maps(self):
154			return self.maps
155
156			def HasMaps(self):
157			return len(self.maps) > 0
158
159			def AddMap(self, map):
160			self.maps.append(map)
161	bh	128	for channel in self.forwarded_channels:
162	bh	6	map.Subscribe(channel, self.forward, channel)
163			self.changed(MAPS_CHANGED)
164
165	bh	241	def RemoveMap(self, map):
166			for channel in self.forwarded_channels:
167			map.Unsubscribe(channel, self.forward, channel)
168			self.maps.remove(map)
169			self.changed(MAPS_CHANGED)
170			map.Destroy()
171
172	jan	197	def Extensions(self):
173			return self.extensions
174
175			def HasExtensions(self):
176			return len(self.extensions) > 0
177
178			def AddExtension(self, extension):
179			self.extensions.append(extension)
180			for channel in self.forwarded_channels:
181			extension.Subscribe(channel, self.forward, channel)
182			self.changed(EXTENSIONS_CHANGED)
183
184	bh	851	def ShapeStores(self):
185			"""Return a list of all ShapeStore objects open in the session"""
186			return [store() for store in self.shapestores]
187
188			def _add_shapestore(self, store):
189			"""Internal: Add the shapestore to the list of shapestores"""
190			self.shapestores.append(weakref.ref(store,
191			self._clean_weak_store_refs))
192
193			def _clean_weak_store_refs(self, weakref):
194			"""Internal: Remove the weakref from the shapestores list"""
195			self.shapestores = [store for store in self.shapestores
196			if store is not weakref]
197
198			def Tables(self):
199	bh	982	"""Return a list of all table objects open in the session
200	bh	851
201	bh	982	The list includes all tables that are indirectly opened through
202			shape stores and the tables that have been opened explicitly.
203			"""
204			return self.tables + [store.Table() for store in self.ShapeStores()]
205
206	bh	1068	def UnreferencedTables(self):
207			"""Return the tables that are not referenced by other data sources"""
208			known = {}
209			for table in self.tables:
210			known[id(table)] = 0
211			for table in self.tables + self.ShapeStores():
212			for dep in table.Dependencies():
213			known[id(dep)] = 1
214			return [table for table in self.tables if known[id(table)] == 0]
215
216	bh	982	def AddTable(self, table):
217			"""Add the table to the session
218
219			All tables associated with the session that are not implicitly
220			created by the OpenShapefile method (and maybe other Open*
221			methods in the future) have to be passed to this method to make
222			sure the session knows about it. The session keeps a reference
223			to the table. Only tables managed by the session in this way
224			should be used for layers contained in one of the session's
225			maps.
226
227			The table parameter may be any object implementing the table
228			interface. If it's not already one of the transient tables
229			instantiate an AutoTransientTable with it and use that instead
230			of the original table (note that the AutoTransientTable keeps a
231			reference to the original table).
232
233			Return the table object actually used by the session.
234			"""
235			if not hasattr(table, "transient_table"):
236			transient_table = AutoTransientTable(self.TransientDB(), table)
237			else:
238			transient_table = table
239			self.tables.append(transient_table)
240			return transient_table
241
242	bh	987	def RemoveTable(self, table):
243			"""Remove the table from the session.
244
245			The table object must be a table object previously returned by
246			the AddTable method. If the table is not part of the session
247			raise a ValueError.
248	bh	1068
249			Issue a TABLE_REMOVED message after the table has been removed.
250			The message has the removed table as the single parameter.
251	bh	987	"""
252			tables = [t for t in self.tables if t is not table]
253			if len(tables) == len(self.tables):
254			raise ValueError
255			self.tables = tables
256	bh	1068	self.changed(TABLE_REMOVED, table)
257	bh	987
258	bh	1036	def OpenTableFile(self, filename):
259			"""Open the table file filename and return the table object.
260
261			The filename argument must be the name of a DBF file.
262			"""
263			return self.AddTable(DBFTable(filename))
264
265	bh	765	def temp_directory(self):
266			"""
267			Return the name of the directory for session specific temporary files
268
269			Create the directory if it doesn't exist yet.
270			"""
271			if self.temp_dir is None:
272			temp_dir = mktemp()
273			os.mkdir(temp_dir, 0700)
274			self.temp_dir = temp_dir
275			self.temp_dir_remover = AutoRemoveDir(self.temp_dir)
276			return self.temp_dir
277
278	bh	723	def OpenShapefile(self, filename):
279			"""Return a shapefile store object for the data in the given file"""
280	bh	851	store = ShapefileStore(self, filename)
281			self._add_shapestore(store)
282			return store
283	bh	723
284	bh	1016	def AddShapeStore(self, shapestore):
285			"""Add the shapestore to the session.
286
287			The session only holds a weak reference to the shapestore, so it
288			will automatically be removed from the session when the last
289			reference goes away.
290			"""
291			self._add_shapestore(shapestore)
292			return shapestore
293
294	bh	765	def TransientDB(self):
295			if self.transient_db is None:
296			filename = os.path.join(self.temp_directory(), "transientdb")
297			self.transient_db = TransientDatabase(filename)
298			#print self.temp_dir_remover
299			auto_remover[self.transient_db] = AutoRemoveFile(filename,
300			self.temp_dir_remover)
301			return self.transient_db
302
303	bh	6	def Destroy(self):
304			for map in self.maps:
305			map.Destroy()
306			self.maps = []
307			self.tables = []
308	bh	250	Modifiable.Destroy(self)
309	bh	6
310	bh	778	# Close the transient DB explicitly so that it removes any
311			# journal files from the temporary directory
312			if self.transient_db is not None:
313			self.transient_db.close()
314
315	bh	6	def forward(self, *args):
316	bh	232	"""Reissue events.
317
318			If the channel the event is forwarded to is a changed-channel
319			that is not the CHANGED channel issue CHANGED as well. An
320			channel is considered to be a changed-channel if it's name ends
321			with 'CHANGED'.
322			"""
323	bh	6	if len(args) > 1:
324			args = (args[-1],) + args[:-1]
325			apply(self.issue, args)
326	bh	232	channel = args[0]
327			# It's a bit of a kludge to rely on the channel name for this.
328			if channel.endswith("CHANGED") and channel != CHANGED:
329			self.issue(CHANGED, self)
330	bh	6
331			def WasModified(self):
332			"""Return true if the session or one of the maps was modified"""
333			if self.modified:
334			return 1
335			else:
336			for map in self.maps:
337			if map.WasModified():
338			return 1
339			return 0
340
341			def UnsetModified(self):
342			"""Unset the modified flag of the session and the maps"""
343			Modifiable.UnsetModified(self)
344			for map in self.maps:
345			map.UnsetModified()
346
347	bh	217	def TreeInfo(self):
348			items = []
349			if self.filename is None:
350	jan	374	items.append(_("Filename:"))
351	bh	217	else:
352	jan	374	items.append(_("Filename: %s") % self.filename)
353	bh	6
354	bh	217	if self.WasModified():
355	jan	374	items.append(_("Modified"))
356	bh	217	else:
357	jan	374	items.append(_("Unmodified"))
358	bh	6
359	bh	217	items.extend(self.maps)
360			items.extend(self.extensions)
361
362	jan	374	return (_("Session: %s") % self.title, items)
363	bh	217
364
365	bh	6	def create_empty_session():
366			"""Return an empty session useful as a starting point"""
367	jan	103	import os
368	jan	374	session = Session(_('unnamed session'))
369	jan	103	session.SetFilename(None)
370	jan	374	session.AddMap(Map(_('unnamed map')))
371	bh	56	session.UnsetModified()
372	bh	6	return session
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