.. py:currentmodule:: tulip

Graph/Properties observation
=============================

Tulip offers a mechanism to observe and get informed on modifications
performed on the graph structure, the subgraphs hierarchy and the properties
values attached to the graph. This is achieved by implementing an object deriving
from the :class:`tlp.Observable`. To get informed on modifications performed on
the graph or properties values, you have to implement the :meth:`tlp.Observable.treatEvent` method.

Observing a graph
-----------------

A special type of event is available to keep track of graph modifications : :class:`tlp.GraphEvent`.
Instances of that type of event are sent by instances of :class:`tlp.Graph`. Call :meth:`tlp.Observable.addListener`
to register an observer to a graph. The sample code below illustrates that observation mechanism::

    from tulip import tlp

    class GraphObserver(tlp.Observable):
      def __init__(self):
        tlp.Observable.__init__(self)

      def treatEvent(self, event):
        if isinstance(event, tlp.GraphEvent):
          graph = event.getGraph()
          if event.getType() == tlp.GraphEvent.TLP_ADD_NODE:
            print("The node", event.getNode(), "has been added to the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_DEL_NODE:
            print("The node", event.getNode(), "has been deleted from the graph", graph)

          if event.getType() == tlp.GraphEvent.TLP_ADD_EDGE:
            print("The edge", event.getEdge(), "has been added to the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_DEL_EDGE:
            print("The edge", event.getEdge(), "has been deleted from the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_REVERSE_EDGE:
            print("The edge", event.getEdge(), "has been reversed in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_SET_ENDS:
            print("The edge", event.getEdge(), "will have its ends modified. Current source is", graph.source(event.getEdge()),\
                  "Current target is", graph.target(event.getEdge()))

          elif event.getType() == tlp.GraphEvent.TLP_AFTER_SET_ENDS:
            print("The edge", event.getEdge(), "had its ends modified. Current source is", graph.source(event.getEdge()),\
                  "Current target is", graph.target(event.getEdge()))

          elif event.getType() == tlp.GraphEvent.TLP_ADD_NODES:
            print("The nodes", event.getNodes(), "have been added to the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_ADD_EDGES:
            print("The edges", event.getEdges(), "have been added to the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_ADD_DESCENDANTGRAPH:
            print("A descendant graph", event.getSubGraph(), "is about to be added in the subgraphs hierarchy of graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_AFTER_ADD_DESCENDANTGRAPH:
            print("A descendant graph", event.getSubGraph(), "has been added in the subgraphs hierarchy of graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_DEL_DESCENDANTGRAPH:
            print("A descendant graph", event.getSubGraph(), "is about to be deleted in the subgraphs hierarchy of graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_AFTER_DEL_DESCENDANTGRAPH:
            print("A descendant graph", event.getSubGraph(), "has been deleted in the subgraphs hierarchy of graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_ADD_SUBGRAPH:
            print("A subgraph", event.getSubGraph(), "is about to be added in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_AFTER_ADD_SUBGRAPH:
            print("A subgraph", event.getSubGraph(), "has been added in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_DEL_SUBGRAPH:
            print("A subgraph", event.getSubGraph(), "is about to be deleted in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_AFTER_DEL_SUBGRAPH:
            print("A subgraph", event.getSubGraph(), "has been deleted in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_ADD_LOCAL_PROPERTY:
            print("A local property", event.getPropertyName(), "is about to be added in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_ADD_LOCAL_PROPERTY:
            print("A local property", event.getPropertyName(), "has been added in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_DEL_LOCAL_PROPERTY:
            print("A local property", event.getPropertyName(), "is about to be deleted in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_AFTER_DEL_LOCAL_PROPERTY:
            print("A local property", event.getPropertyName(), "has been deleted in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_ADD_INHERITED_PROPERTY:
            print("An inherited property", event.getPropertyName(), "is about to be added in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_ADD_INHERITED_PROPERTY:
            print("An inherited property", event.getPropertyName(), "has been added in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_DEL_INHERITED_PROPERTY:
            print("An inherited property", event.getPropertyName(), "is about to be deleted in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_AFTER_DEL_INHERITED_PROPERTY:
            print("An inherited property", event.getPropertyName(), "has been deleted in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_BEFORE_SET_ATTRIBUTE:
            print("An attribute", event.getAttributeName(), "is about to be set/modified in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_AFTER_SET_ATTRIBUTE:
            print("An attribute", event.getAttributeName(), "has been set/modified in the graph", graph)

          elif event.getType() == tlp.GraphEvent.TLP_REMOVE_ATTRIBUTE:
            print("An attribute", event.getAttributeName(), "has been removed in the graph", graph)

    root = tlp.newGraph()
    root.setName("root")
    graph = root.addSubGraph("graph")

    obs = GraphObserver()
    graph.addListener(obs)

    n = graph.addNode()
    n2 = graph.addNode()
    e = graph.addEdge(n, n2)
    graph.reverse(e)
    graph.setEnds(e, n, n2)

    nodes = graph.addNodes(4)
    edges = graph.addEdges([(nodes[0], nodes[1]), (nodes[2], nodes[3])])

    sg = graph.addSubGraph("sg1")
    sg2 = sg.addSubGraph("sg2")

    sg.delSubGraph(sg2)
    graph.delSubGraph(sg)

    prop = graph.getDoubleProperty("metric")
    propRoot = root.getDoubleProperty("metric_root")

    graph.delLocalProperty("metric")
    root.delLocalProperty("metric_root")

    graph.setAttribute("author", "me")
    graph.removeAttribute("author")

    graph.delEdge(e)
    graph.delNode(n)
    graph.delNode(n2)

The output of that script is the following::

    The node <node 0> has been added to the graph <graph "graph" (id 1) >
    The node <node 1> has been added to the graph <graph "graph" (id 1) >
    The edge <edge 0> has been added to the graph <graph "graph" (id 1) >
    The edge <edge 0> has been reversed in the graph <graph "graph" (id 1) >
    The edge <edge 0> will have its ends modified. Current source is <node 0> Current target is <node 1>
    The edge <edge 0> had its ends modified. Current source is <node 0> Current target is <node 1>
    The nodes [<node 2>, <node 3>, <node 4>, <node 5>] have been added to the graph <graph "graph" (id 1) >
    The edges [<edge 1>, <edge 2>] have been added to the graph <graph "graph" (id 1) >
    A subgraph <graph "sg1" (id 2) > is about to be added in the graph <graph "graph" (id 1) >
    A descendant graph <graph "sg1" (id 2) > is about to be added in the subgraphs hierarchy of graph <graph "graph" (id 1) >
    A subgraph <graph "sg1" (id 2) > has been added in the graph <graph "graph" (id 1) >
    A descendant graph <graph "sg1" (id 2) > has been added in the subgraphs hierarchy of graph <graph "graph" (id 1) >
    A descendant graph <graph "sg2" (id 3) > is about to be added in the subgraphs hierarchy of graph <graph "graph" (id 1) >
    A descendant graph <graph "sg2" (id 3) > has been added in the subgraphs hierarchy of graph <graph "graph" (id 1) >
    A descendant graph <graph "sg2" (id 3) > is about to be deleted in the subgraphs hierarchy of graph <graph "graph" (id 1) >
    A descendant graph <graph "sg2" (id 3) > has been deleted in the subgraphs hierarchy of graph <graph "graph" (id 1) >
    A subgraph <graph "sg1" (id 2) > is about to be deleted in the graph <graph "graph" (id 1) >
    A descendant graph <graph "sg1" (id 2) > is about to be deleted in the subgraphs hierarchy of graph <graph "graph" (id 1) >
    A subgraph <graph "sg1" (id 2) > has been deleted in the graph <graph "graph" (id 1) >
    A descendant graph <graph "sg1" (id 2) > has been deleted in the subgraphs hierarchy of graph <graph "graph" (id 1) >
    A local property metric is about to be added in the graph <graph "graph" (id 1) >
    A local property metric has been added in the graph <graph "graph" (id 1) >
    An inherited property metric_root is about to be added in the graph <graph "graph" (id 1) >
    An inherited property metric_root has been added in the graph <graph "graph" (id 1) >
    A local property metric is about to be deleted in the graph <graph "graph" (id 1) >
    A local property metric has been deleted in the graph <graph "graph" (id 1) >
    An inherited property metric_root is about to be deleted in the graph <graph "graph" (id 1) >
    An inherited property metric_root has been deleted in the graph <graph "graph" (id 1) >
    An attribute author is about to be set/modified in the graph <graph "graph" (id 1) >
    An attribute author has been set/modified in the graph <graph "graph" (id 1) >
    An attribute author has been removed in the graph <graph "graph" (id 1) >
    The edge <edge 0> has been deleted from the graph <graph "graph" (id 1) >
    The node <node 0> has been deleted from the graph <graph "graph" (id 1) >
    The node <node 1> has been deleted from the graph <graph "graph" (id 1) >

Observing a graph property
---------------------------

Another special type of event is available to keep track of a property modifications : :class:`tlp.PropertyEvent`.
Instances of that type of event are sent by derived instances of :class:`tlp.PropertyInterface`. Call :meth:`tlp.Observable.addListener`
to register an observer to a property. The sample code below illustrates that observation mechanism::

    from tulip import tlp

    class PropertyObserver(tlp.Observable):

      def __init__(self):
        tlp.Observable.__init__(self)

      def treatEvent(self, event):
        if isinstance(event, tlp.PropertyEvent):
          prop = event.getProperty()
          if event.getType() == tlp.PropertyEvent.TLP_BEFORE_SET_NODE_VALUE:
            print("Value for node", event.getNode(), "in property", prop, "is about to be modified. Current value is", prop[event.getNode()])
          elif event.getType() == tlp.PropertyEvent.TLP_AFTER_SET_NODE_VALUE:
            print("Value for node", event.getNode(), "in property", prop, "has been modified. New value is", prop[event.getNode()])
          elif event.getType() == tlp.PropertyEvent.TLP_BEFORE_SET_EDGE_VALUE:
            print("Value for edge", event.getEdge(), "in property", prop, "is about to be modified. Current value is", prop[event.getEdge()])
          elif event.getType() == tlp.PropertyEvent.TLP_AFTER_SET_EDGE_VALUE:
            print("Value for edge", event.getEdge(), "in property", prop, "has been modified. New value is", prop[event.getEdge()])
          elif event.getType() == tlp.PropertyEvent.TLP_BEFORE_SET_ALL_NODE_VALUE:
            print("Value for all nodes", "in property", prop, "is about to be modified.")
          elif event.getType() == tlp.PropertyEvent.TLP_AFTER_SET_ALL_NODE_VALUE:
            print("Value for all nodes", "in property", prop, "has been modified.")
          elif event.getType() == tlp.PropertyEvent.TLP_BEFORE_SET_ALL_EDGE_VALUE:
            print("Value for all edges", "in property", prop, "is about to be modified.")
          elif event.getType() == tlp.PropertyEvent.TLP_AFTER_SET_ALL_EDGE_VALUE:
            print("Value for all edges", "in property", prop, "has been modified.")

    graph = tlp.newGraph()
    nodes = graph.addNodes(5)
    edges = graph.addEdges([(nodes[0], nodes[1]), (nodes[2], nodes[3])])

    obs = PropertyObserver()

    metric = graph.getDoubleProperty("metric")
    metric.addListener(obs)


    metric.setAllNodeValue(-1)
    metric.setAllEdgeValue(-1)

    metric[nodes[1]] = 3.2
    metric[edges[0]] = 5.7

The output of that script is the following::

    Value for all nodes in property <Double property metric> is about to be modified.
    Value for all nodes in property <Double property metric> has been modified.
    Value for all edges in property <Double property metric> is about to be modified.
    Value for all edges in property <Double property metric> has been modified.
    Value for node <node 1> in property <Double property metric> is about to be modified. Current value is -1.0
    Value for node <node 1> in property <Double property metric> has been modified. New value is 3.2
    Value for edge <edge 0> in property <Double property metric> is about to be modified. Current value is -1.0
    Value for edge <edge 0> in property <Double property metric> has been modified. New value is 5.7
