path: root/src/jarabe/journal/lazymodel.py

# Copyright (C) 2009, Aleksey Lim
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

import gtk
import logging
from gobject import GObject, SIGNAL_RUN_FIRST, TYPE_PYOBJECT


class Source(GObject):

    __gsignals__ = {
            'objects-updated': (SIGNAL_RUN_FIRST, None, []),
            'row-delayed-fetch': (SIGNAL_RUN_FIRST, None, 2 * [TYPE_PYOBJECT]),
            }

    def get_count(self):
        """ Returns number of objects """
        pass

    def get_row(self, offset):
        """ Get object

        Returns:
            objects     in dict {field_name: value, ...}
            False       can't fint object
            None        wait for reply signal

        """
        pass

    def get_order(self):
        """ Get current order, returns (field_name, gtk.SortType) """
        pass

    def set_order(self, field_name, sort_type):
        """ Set current order """
        pass


class LazyModel(gtk.GenericTreeModel):

    def __init__(self, columns, calc_columns=None):
        """ columns/calc_columns = {field_name: (column_num, column_type)} """
        gtk.GenericTreeModel.__init__(self)

        self.columns_by_name = {}
        self.columns_by_num = {}
        self.columns_types = {}

        for name, i in columns.items():
            self.columns_by_name[name] = i[0]
            self.columns_by_num[i[0]] = name
            self.columns_types[i[0]] = i[1]

        if calc_columns is not None:
            for name, i in calc_columns.items():
                self.columns_types[i[0]] = i[1]

        self._n_columns = max(self.columns_types.keys()) + 1

        self._source = None
        self._closing = False
        self._view = None
        self._last_count = 0
        self._cache = {}
        self._frame = (0, -1)
        self._in_process = {}
        self._postponed = []

        self.set_source(None, force=True)
        self.set_view(None, force=True)

    def on_calc_value(self, row, column):
        # stub
        pass

    def get_source(self):
        return self._source

    def set_source(self, source, force=False):
        if self._source == source and not force:
            return

        if self._source is not None:
            self._source.disconnect_by_func(self.refresh)
            self._source.disconnect_by_func(self.__delayed_fetch_cb)

        self._source = source
        if self._source is not None:
            self._source.connect('objects-updated', self.refresh)
            self._source.connect('row-delayed-fetch', self.__delayed_fetch_cb)

        self.refresh()

    source = property(get_source, set_source)

    def get_view(self):
        return self._view

    def set_view(self, view, force=False):
        if self._view == view and not force:
            return

        cursor = None

        if self._view is not None:
            cursor = self._view.get_cursor()
            try:
                self._closing = True
                self._view.set_model(None)
            finally:
                self._closing = False

        self._view = view
        self._cache = {}
        self._frame = (0, -1)
        self._in_process = {}
        self._postponed = []

        if self._source is None:
            self._last_count = 0
        else:
            self._last_count = self._source.get_count()

        if self._source is not None and view is not None:
            self._update_columns()
            view.set_model(self)
            if cursor is not None:
                view.set_cursor(*cursor)

    view = property(get_view, set_view)

    def get_order(self):
        if self._source is None:
            return None
        order = self._source.get_order()
        if order is None:
            return None
        return (self.columns_by_name[order[0]], order[1])

    def set_order(self, column, order):
        if self._source is None:
            return
        self._source.set_order(self.columns_by_num[column], order)
        self._update_columns()

    def refresh(self, sender=None):
        if self._source is None or self._view is None:
            return

        if self._last_count == 0:
            self.set_view(self._view, force=True)

        self._update_columns()

        # TODO how to handle large update,
        #      commented for now since in TableView
        #      it works fine w/o these updates
        #
        #for i in range(self._last_count, count):
        #    self.emit('row-inserted', (i, ), self.get_iter((i, )))
        #for i in reversed(range(count, self._last_count)):
        #    self.emit('row-deleted', (i, ))

        count = self._source.get_count()
        if self._frame[0] >= count:
            self._frame = (0, -1)
        elif self._frame[1] >= count:
            self._frame = (self._frame[0], count-1)

        self._cache = {}

        for i in range(self._frame[0], self._frame[1]+1):
            self.emit('row-changed', (i, ), self.get_iter((i, )))

        self._last_count = count

    def recalc(self, fields):
        for i, row in self._cache.items():
            for field in fields:
                if field in row:
                    del row[field]
            self.emit('row-changed', (i, ), self.get_iter((i, )))

    def get_row(self, pos, frame=None):
        if self._source is None:
            return False
        if not isinstance(pos, tuple):
            pos = self.get_path(pos)
        return self._get_row(pos[0], frame or (pos, pos))

    def __delayed_fetch_cb(self, source, offset, metadata):
        if not offset in self._in_process:
            logging.debug('__delayed_fetch_cb: no offset=%s' % offset)
            return

        logging.debug('__delayed_fetch_cb: get %s' % offset)

        path = (offset, )
        iterator = self.get_iter(path)
        row = Row(self, path, iterator, metadata)

        if self.in_frame(offset):
            self._cache[offset] = row

        del self._in_process[offset]
        self.emit('row-changed', path, iterator)
        if self._in_process:
            return

        while self._postponed:
            offset, force = self._postponed.pop()
            if not force and not self.in_frame(offset):
                continue
            row = self.get_row((offset, ))
            if row is not None and row != False:
                self.emit('row-changed', row.path, row.iterator)
            else:
                break

    def _get_row(self, offset, frame):

        def fetch():
            row = self._source.get_row(offset)

            if row is None or row == False:
                if row is not None:
                    logging.debug('_get_row: can not find row for %s' % offset)
                    return False
                logging.debug('_get_row: wait for reply for %s' % offset)
                self._in_process[offset] = True
                return None

            row = Row(self, (offset, ), self.get_iter(offset), row)
            self._cache[offset] = row
            return row

        out = self._cache.get(offset)
        if out is not None:
            return out

        if frame[0] >= frame[1]:
            # just return requested single row and do not change cache
            # if requested frame has <= 1 rows
            if self._in_process:
                self._postponed.append((offset, True))
                return None
            else:
                return fetch()

        if frame != self._frame:
            # switch to new frame
            intersect_min = max(frame[0], self._frame[0])
            intersect_max = min(frame[1], self._frame[1])
            if intersect_min > intersect_max:
                self._cache = {}
            else:
                for i in range(self._frame[0], intersect_min):
                    if i in self._cache:
                        del self._cache[i]
                for i in range(intersect_max+1, self._frame[1]+1):
                    if i in self._cache:
                        del self._cache[i]
            self._frame = frame

        if self._in_process:
            self._postponed.append((offset, False))
            return None

        return fetch()

    def _update_columns(self):
        order = self.get_order()
        if order is None or not hasattr(self._view, 'get_columns'):
            return

        for column in self._view.get_columns():
            if column.get_sort_column_id() == order[0]:
                column.props.sort_indicator = True
                column.props.sort_order = order[1]
            else:
                column.props.sort_indicator = False

    def in_frame(self, offset):
        return offset >= self._frame[0] and offset <= self._frame[1]

    def on_get_n_columns(self):
        return self._n_columns

    def on_get_column_type(self, index):
        return self.columns_types.get(index, bool)

    def on_iter_n_children(self, iterator):
        if iterator is None and not self._closing:
            return self._source.get_count()
        else:
            return 0

    def on_get_value(self, offset, column):
        if self._view is None or offset >= self._source.get_count():
            return None

        # return value only if iterator came from visible range
        # (on setting model, gtk.TreeView scans all items)
        vrange = self._view.get_visible_range()
        if vrange and offset >= vrange[0][0] and offset <= vrange[1][0]:
            row = self._get_row(offset, (vrange[0][0], vrange[1][0]))
            return row is not None and row != False and row[column]

        return None

    def on_iter_nth_child(self, iterator, n):
        return n

    def on_get_path(self, iterator):
        return iterator

    def on_get_iter(self, path):
        if self._source.get_count() and not self._closing:
            return path[0]
        else:
            return False

    def on_iter_next(self, iterator):
        if iterator is not None:
            if iterator >= self._source.get_count() - 1 or self._closing:
                return None
            return iterator + 1
        return None

    def on_get_flags(self):
        return gtk.TREE_MODEL_ITERS_PERSIST | gtk.TREE_MODEL_LIST_ONLY

    def on_iter_children(self, iterator):
        return None

    def on_iter_has_child(self, iterator):
        return False

    def on_iter_parent(self, iterator):
        return None


class Row:

    def __init__(self, model, path, iterator, metadata):
        self.model = model
        self.iterator = iterator
        self.path = path
        self.metadata = metadata
        self.row = [None] * len(model.columns_by_name)
        self._calced_row = {}

        for name, value in metadata.items():
            column = model.columns_by_name.get(str(name), -1)
            if column != -1:
                self.row[column] = value

    def __getitem__(self, key):
        if isinstance(key, int):
            if key < len(self.row):
                return self.row[key]
            else:
                if key in self._calced_row:
                    return self._calced_row[key]
                else:
                    value = self.model.on_calc_value(self, key)
                    if value is not None:
                        self._calced_row[key] = value
                    return value
        else:
            return self.metadata[key]

    def __setitem__(self, key, value):
        if isinstance(key, int):
            if key < len(self.row):
                self.row[key] = value
            else:
                self._calced_row[key] = value
        else:
            self.metadata[key] = value

    def __delitem__(self, key):
        if isinstance(key, int):
            if key < len(self.row):
                del self.row[key]
            else:
                del self._calced_row[key]
        else:
            del self.metadata[key]

    def __contains__(self, key):
        if isinstance(key, int):
            return key < len(self.row) or key in self._calced_row
        else:
            return self.metadata.__contains__(key)

    def has_key(self, key):
        return self.__contains__(key)

    def get(self, key, default=None):
        if key in self:
            return self.__getitem__(key)
        else:
            return default