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(*
* Undirected graph view. This makes a graph look undirected.
*
* -- Allen
*)
signature UNDIRECTED_GRAPH_VIEW =
sig
val undirected_view : ('n,'e,'g) Graph.graph -> ('n,'e,'g) Graph.graph
end
structure UndirectedGraphView : UNDIRECTED_GRAPH_VIEW =
struct
structure G = Graph
structure Sort = ListMergeSort
fun undirected_view (G.GRAPH G) =
let fun adjacent_edges i =
let val in_edges = map (fn (i,j,e) => (j,i,e)) (#in_edges G i)
val out_edges = #out_edges G i
in
Sort.uniqueSort (fn ((i,j,_),(i',j',_)) =>
if i < i' then LESS
else if i = i' then
if j < j' then LESS
else if j = j' then EQUAL
else GREATER
else GREATER)
(in_edges @ out_edges)
end
fun adjacent_nodes i =
let val succ = #succ G i
val pred = #pred G i
in
Sort.uniqueSort Int.compare (succ @ pred)
end
fun has_edge (i,j) = #has_edge G (i,j) orelse #has_edge G (j,i)
in
G.GRAPH
{ name = #name G,
graph_info = #graph_info G,
new_id = #new_id G,
add_node = #add_node G,
add_edge = #add_edge G,
remove_node = #remove_node G,
set_in_edges = #set_in_edges G,
set_out_edges = #set_out_edges G,
set_entries = #set_exits G,
set_exits = #set_entries G,
garbage_collect = #garbage_collect G,
nodes = #nodes G,
edges = #edges G,
order = #order G,
size = #size G,
capacity = #capacity G,
out_edges = adjacent_edges,
in_edges = adjacent_edges,
succ = adjacent_nodes,
pred = adjacent_nodes,
has_edge = has_edge,
has_node = #has_node G,
node_info = #node_info G,
entries = #exits G,
exits = #entries G,
entry_edges = #entry_edges G,
exit_edges = #exit_edges G,
forall_nodes = #forall_nodes G,
forall_edges = #forall_edges G
}
end
end
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