35 lines
810 B
Plaintext
35 lines
810 B
Plaintext
|
|
||
|
|
:- module(topsort, [topsort/2]).
|
||
|
|
|
||
|
|
:- use_module(library(dgraphs),
|
||
|
|
[dgraph_new/1,
|
||
|
|
dgraph_add_edges/3,
|
||
|
|
dgraph_add_vertices/3,
|
||
|
|
dgraph_top_sort/2]).
|
||
|
|
|
||
|
|
/* simple implementation of a topological sorting algorithm */
|
||
|
|
/* graph is as Node-[Parents] */
|
||
|
|
|
||
|
|
topsort(Graph0, Sorted) :-
|
||
|
|
mkedge_list(Graph0, EdgeList, []),
|
||
|
|
mkvertices_list(Graph0, VList, []),
|
||
|
|
dgraph_new(DGraph0),
|
||
|
|
dgraph_add_vertices(DGraph0, VList, DGraph1),
|
||
|
|
dgraph_add_edges(DGraph1, EdgeList, DGraph2),
|
||
|
|
dgraph_top_sort(DGraph2, Sorted).
|
||
|
|
|
||
|
|
mkvertices_list([]) --> [].
|
||
|
|
mkvertices_list([V-_|More]) --> [V],
|
||
|
|
mkvertices_list(More).
|
||
|
|
|
||
|
|
mkedge_list([]) --> [].
|
||
|
|
mkedge_list([V-Parents|More]) -->
|
||
|
|
add_edges(Parents, V),
|
||
|
|
mkedge_list(More).
|
||
|
|
|
||
|
|
add_edges([], _V) --> [].
|
||
|
|
add_edges([P|Parents], V) --> [P-V],
|
||
|
|
add_edges(Parents, V).
|
||
|
|
|
||
|
|
|