aga,agar: Dijkstra's algorithm

[ccan] / ccan / agar / agar.c

diff --git a/ccan/agar/agar.c b/ccan/agar/agar.c
index 2be9dafedfade6a8fbec23d640c76dd77d6fed46..e930d7aa6c7eeabde50110474502b087b78f05ae 100644 (file)
--- a/ccan/agar/agar.c
+++ b/ccan/agar/agar.c
@@ -234,3 +234,60 @@ bool agar_bfs_explore(struct agar_state *sr, const void *nr,
        *nextr = n_to_nr(sr, next);
        return true;
 }
+
+/*
+ * Dijkstra's algorithm
+ */
+
+struct agar_state *agar_dijkstra_new(void *ctx, struct agar_graph *gr,
+                                    const void *nr)
+{
+       struct agar_state *sr = agar_new(ctx, gr);
+
+       if (aga_dijkstra_start(&sr->g, nr_to_n(sr, nr)) < 0) {
+               tal_free(sr);
+               return NULL;
+       }
+
+       return sr;
+}
+
+bool agar_dijkstra_step(struct agar_state *sr, const void **nextr)
+{
+       struct aga_node *next = aga_dijkstra_step(&sr->g);
+
+       if (!next)
+               return false;
+
+       *nextr = n_to_nr(sr, next);
+       return true;
+}
+
+bool agar_dijkstra_path(struct agar_state *sr, const void *destr,
+                       aga_icost_t *total_cost,
+                       const void **prevr, const void **prevedge)
+{
+       struct aga_node *dest = nr_to_n(sr, destr);
+       struct aga_node *prev;
+
+       if (!aga_dijkstra_path(&sr->g, dest, total_cost, &prev, prevedge))
+               return false;
+
+       /*
+        * When destr is the same as the source node, there obviously
+        * isn't a previous node or edge.  In that case aga, sets them
+        * to NULL.  But for agar, NULL could be a valid node
+        * references (particularly if using ptrint).  So we don't
+        * have much choice here but to leave *prevr as undefined when
+        * destr is the source node. */
+       if (prevr && prev)
+               *prevr = n_to_nr(sr, prev);
+
+       return true;
+}
+
+void agar_dijkstra_all_paths(struct agar_state *sr)
+{
+       aga_dijkstra_all_paths(&sr->g);
+}
+