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(*
* A singleton graph view (i.e. graph with one node.)
*
* -- Allen
*)
signature SINGLETON_GRAPH_VIEW =
sig
val singleton_view : ('n,'e,'g) Graph.graph ->
Graph.node_id -> ('n,'e,'g) Graph.graph
end
structure SingletonGraphView : SINGLETON_GRAPH_VIEW =
struct
structure G = Graph
fun singleton_view (G.GRAPH G) n =
let fun unimplemented _ = raise G.Readonly
fun none _ = []
fun entries () = case #in_edges G n of [] => [] | _ => [n]
fun exits () = case #out_edges G n of [] => [] | _ => [n]
in
G.GRAPH
{ name = #name G,
graph_info = #graph_info G,
new_id = #new_id G,
add_node = unimplemented,
add_edge = unimplemented,
remove_node = unimplemented,
set_in_edges = unimplemented,
set_out_edges = unimplemented,
set_entries = unimplemented,
set_exits = unimplemented,
garbage_collect = unimplemented,
nodes = fn _ => [(n,#node_info G n)],
edges = none,
order = fn _ => 1,
size = fn _ => 0,
capacity = #capacity G,
out_edges = none,
in_edges = none,
succ = none,
pred = none,
has_edge = fn _ => false,
has_node = fn i => i = n,
node_info = #node_info G,
entries = entries,
exits = exits,
entry_edges = fn i => if i = n then #in_edges G i else [],
exit_edges = fn i => if i = n then #out_edges G i else [],
forall_nodes = fn f => f(n,#node_info G n),
forall_edges = fn f => ()
}
end
end
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