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#-------------------------------------------------------------------------------
#
# Defines the TemplateDataName class used for binding a data source to a data
# context.
#
# Written by: David C. Morrill
#
# Date: 07/27/2007
#
# (c) Copyright 2007 by Enthought, Inc.
#
#-------------------------------------------------------------------------------
""" Defines the TemplateDataName class used for binding a data source to a data
context.
"""
#-------------------------------------------------------------------------------
# Imports:
#-------------------------------------------------------------------------------
from traits.api \
import HasPrivateTraits, Instance, Bool, Property, Undefined, \
on_trait_change, cached_property
from itemplate_data_name_item \
import ITemplateDataNameItem
from itemplate_data_context \
import ITemplateDataContext
from template_impl \
import Template
from template_traits \
import TList, TStr, TBool
#-------------------------------------------------------------------------------
# 'TemplateDataName' interface:
#-------------------------------------------------------------------------------
class TemplateDataName ( Template ):
""" Defines the TemplateDataName class used for binding a data source to a
data context.
"""
#-- Public Template Traits -------------------------------------------------
# The list of ITemplateDataNameItem's used to match the data context:
items = TList( ITemplateDataNameItem )
# A description of the template data name (for use in a user interface):
description = TStr
# Is this binding optional?
optional = TBool( False )
#-- Public Non-Template Traits ---------------------------------------------
# The data context the template name is matching against currently:
context = Instance( ITemplateDataContext )
# Is the binding resolved?
resolved = Property( Bool, depends_on = 'items.output_data_context' )
# The actual name of the context data that the data source is bound to:
context_data_name = Property
# The context data the data source is bound to:
context_data = Property
#-- Property Implementations -----------------------------------------------
@cached_property
def _get_resolved ( self ):
if len( self.items ) == 0:
return False
context = self.items[-1].output_data_context
return ((context is not None) and
(len( context.data_context_values ) == 1) and
(len( context.data_contexts ) == 0))
def _get_context_data_name ( self ):
if self.resolved:
context = self.items[-1].output_data_context
path = context.data_context_path
if path != '':
path += '.'
name = context.data_context_name
if name != '':
name += '.'
return '%s%s%s' % ( path, name, context.data_context_values[0] )
return ''
def _get_context_data ( self ):
if self.resolved:
context = self.items[-1].output_data_context
return context.get_data_context_value(
context.data_context_values[0] )
return Undefined
#-- Trait Event Handlers ---------------------------------------------------
def _context_changed ( self, context ):
""" Resets the name whenever the context is changed.
"""
self._reset()
@on_trait_change( ' items' )
def _on_items_changed ( self ):
""" Resets the name whenever any of the name items are changed.
"""
self._reset()
@on_trait_change( 'items:output_data_context' )
def _on_output_data_context_changed ( self, item, name, old, new ):
i = self.items.index( item )
if i < (len( self.items ) - 1):
self.items[ i + 1 ].input_data_context = new
#-- Private Methods --------------------------------------------------------
def _reset ( self ):
""" Resets the name whenever any significant change occurs.
"""
items = self.items
n = len( items )
if n > 0:
items[0].input_data_context = self.context
for i in range( 0, n - 1 ):
items[ i + 1 ].input_data_context = \
items[ i ].output_data_context
|
