Connection.py

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"""
Copyright 2008 Free Software Foundation, Inc.
This file is part of GNU Radio

GNU Radio Companion 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.

GNU Radio Companion 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 Street, Fifth Floor, Boston, MA  02110-1301, USA
"""
##@package grc.elements.Connection
#Flow graph connection.
#A connection exists between 2 ports.
#One port must be input, one output.
#The port decided whether it can have the connection.
#@author Josh Blum

from grc.elements.Element import Element
from grc.Utils import odict

class Connection(Element):

        def __init__(self, flow_graph, porta, portb):
                """!
                Make a new connection given the parent and 2 ports.
                @param flow_graph the parent of this element
                @param porta a port (any direction)
                @param portb a port (any direction)
                @throws Error cannot make connection
                @return a new connection
                """
                Element.__init__(self, flow_graph)
                source = sink = None
                #separate the source and sink
                for port in (porta, portb):
                        if port.is_source(): source = port
                        if port.is_sink(): sink = port
                #verify the source and sink
                assert(source and sink)
                assert(not source.is_full())
                assert(not sink.is_full())
                self._source = source
                self._sink = sink

        def __str__(self): return 'Connection (%s -> %s)'%(self.get_source(), self.get_sink())

        def is_connection(self): return True

        def validate(self):
                """
                Validate the connections.
                The ports must match in type.
                """
                source_type = self.get_source().get_type()
                sink_type = self.get_sink().get_type()
                try: assert source_type == sink_type
                except AssertionError: self._add_error_message('Source type "%s" does not match sink type "%s".'%(source_type, sink_type))

        def get_enabled(self):
                """!
                Get the enabled state of this connection.
                @return true if source and sink blocks are enabled
                """
                return self.get_source().get_parent().get_enabled() and \
                        self.get_sink().get_parent().get_enabled()

        #############################
        # Access Ports
        #############################
        def get_sink(self): return self._sink
        def get_source(self): return self._source

        ##############################################
        ## Import/Export Methods
        ##############################################
        def export_data(self):
                """
                Export this connection's info.
                @return a nested data odict
                """
                n = odict()
                n['source_block_id'] = self.get_source().get_parent().get_id()
                n['sink_block_id'] = self.get_sink().get_parent().get_id()
                n['source_key'] = self.get_source().get_key()
                n['sink_key'] = self.get_sink().get_key()
                return n

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