GraphRewriting.Graph.Write

Functions for modifying the graph. Although the graph structure is entirely expressed by the graph's node collection, for convenience and efficiency the graph representation also comprises a complementary collection of edges, that has to be synchronised with the node collection. Therefore each of the functions below involves a test for whether the graph structure has been changed, and if so, measures are taken to ensure the graph remains consistent.

Invariants for graph consistency:

• Every edge attached to some node points back to that node: ∀n∊N ∀e∊E: n→e ⇔ e→n
• There are no orphaned edges: ∀e∊E ∃n∊N: e→n

Documentation

writeNode :: View [Port] n => Node -> n -> Rewrite n ()

assign new value to given node

modifyNode :: View [Port] n => Node -> (n -> n) -> Rewrite n ()

modify the node value

updateNode :: (View [Port] n, View v n) => Node -> v -> Rewrite n ()

Wraps update to update aspect v of a node.

adjustNode :: (View [Port] n, View v n) => Node -> (v -> v) -> Rewrite n ()

Wraps adjust to adjust aspect v of a node.

adjustNodeM :: (View [Port] n, View v n) => Node -> (v -> Rewrite n v) -> Rewrite n ()

newNode :: View [Port] n => n -> Rewrite n Node

add a new node with value n to the graph

copyNode :: (View [Port] n, View v n) => Node -> v -> Rewrite n Node

Create a new node by cloning another, at the same time updating aspect v. When defining rewrites in a context where it is not known what type n the nodes of the graph have, this is the only way to add new nodes to the graph.

newEdge :: Rewrite n Edge

Create a new (unconnected) edge. It is expected that the created edge is connected to a port sooner or later. Otherwise the graph will invove unconnected edges.

deleteNode :: View [Port] n => Node -> Rewrite n ()

remove node from the graph

deleteEdge :: View [Port] n => Edge -> Rewrite n [Edge]

Disconnect ports connected to the given edge by assigning a new (dangling) edge to each of the ports. Then the edge is deleted.

mergeEdges :: View [Port] n => Edge -> Edge -> Rewrite n ()

Reconnects the ports connected to the second edge to the first one. Then the second edge is deleted.

module GraphRewriting.Graph.Types

module Data.View