agar: Re-entrant Abstract Graph Algorithms

[ccan] / ccan / agar / agar.c

diff --git a/ccan/agar/agar.c b/ccan/agar/agar.c
new file mode 100644 (file)
index 0000000..b2809ab
--- /dev/null
+++ b/ccan/agar/agar.c
@@ -0,0 +1,232 @@
+/* Licensed under LGPLv2+ - see LICENSE file for details */
+#include "config.h"
+
+#include <stdbool.h>
+
+#include <ccan/aga/aga.h>
+#include <ccan/hash/hash.h>
+#include <ccan/htable/htable.h>
+#include <ccan/container_of/container_of.h>
+#include <ccan/tal/tal.h>
+
+#include <ccan/agar/agar.h>
+
+#define HASH_BASE 0
+
+struct agar_node {
+       const void *nr;
+       struct aga_node n;
+};
+
+struct agar_state {
+       struct agar_graph *gr;
+       struct aga_graph g;
+       struct htable nodes;
+};
+
+static size_t agar_node_hash(const struct agar_node *nn)
+{
+       return hash_pointer(nn->nr, HASH_BASE);
+}
+
+static size_t agar_rehash(const void *elem, void *p)
+{
+       return agar_node_hash(elem);
+}
+
+static bool agar_node_cmp(const void *candidate, void *ptr)
+{
+       struct agar_node *nn = (struct agar_node *)candidate;
+
+       return (nn->nr == ptr);
+}
+
+static struct aga_node *nr_to_n(struct agar_state *sr, const void *nr)
+{
+       struct agar_node *nn;
+       size_t hash = hash_pointer(nr, HASH_BASE);
+       bool rc;
+
+       nn = htable_get(&sr->nodes, hash, agar_node_cmp, nr);
+       if (!nn) {
+               nn = tal(sr, struct agar_node);
+               assert(nn);
+
+               nn->nr = nr;
+               aga_node_init(&nn->n);
+
+               rc = htable_add(&sr->nodes, hash, nn);
+               assert(rc);
+       }
+
+       return nn ? &nn->n : NULL;
+}
+
+static const void *n_to_nr(struct agar_state *sr, const struct aga_node *n)
+{
+       struct agar_node *nn = container_of(n, struct agar_node, n);
+
+       return nn->nr;
+}
+
+static int convert_edge_info(const struct aga_graph *g,
+                            const struct aga_node *n,
+                            const void *e, struct aga_edge_info *ei)
+{
+       struct agar_state *sr = container_of(g, struct agar_state, g);
+       const void *nr = n_to_nr(sr, n);
+       struct agar_edge_info eir;
+       int rc;
+
+       eir.to = NULL;
+
+       rc = sr->gr->edge_info(sr->gr, nr, e, &eir);
+
+       if (eir.to)
+               ei->to = nr_to_n(sr, eir.to);
+       else
+               ei->to = NULL;
+
+       return rc;
+}
+
+static const void *convert_first_edge(const struct aga_graph *g,
+                                     const struct aga_node *n)
+{
+       struct agar_state *sr = container_of(g, struct agar_state, g);
+       const void *nr = n_to_nr(sr, n);
+
+       return sr->gr->first_edge(sr->gr, nr);
+}
+
+static const void *convert_next_edge(const struct aga_graph *g,
+                                    const struct aga_node *n,
+                                    const void *e)
+{
+       struct agar_state *sr = container_of(g, struct agar_state, g);
+       const void *nr = n_to_nr(sr, n);
+
+       return sr->gr->next_edge(sr->gr, nr, e);
+}
+
+void agar_init_graph(struct agar_graph *gr,
+                    agar_first_edge_fn first_edge,
+                    agar_next_edge_fn next_edge,
+                    agar_edge_info_fn edge_info)
+{
+       gr->edge_info = edge_info;
+       gr->first_edge = first_edge;
+       gr->next_edge = next_edge;
+}
+
+int agar_error(struct agar_state *sr)
+{
+       return aga_error(&sr->g);
+}
+
+static void agar_destruct_htable(struct agar_state *sr)
+{
+       htable_clear(&sr->nodes);
+}
+
+static struct agar_state *agar_new(void *ctx, struct agar_graph *gr)
+{
+       struct agar_state *sr = tal(ctx, struct agar_state);
+
+       assert(sr);
+
+       sr->gr = gr;
+       htable_init(&sr->nodes, agar_rehash, NULL);
+       tal_add_destructor(sr, agar_destruct_htable);
+       aga_init_graph(&sr->g, convert_first_edge, convert_next_edge,
+                      convert_edge_info);
+
+       return sr;
+}
+
+const void *agar_first_edge(const struct agar_graph *gr, const void *nr)
+{
+       return gr->first_edge(gr, nr);
+}
+
+const void *agar_next_edge(const struct agar_graph *gr,
+                          const void *nr, const void *e)
+{
+       if (!e)
+               return NULL;
+       else
+               return gr->next_edge(gr, nr, e);
+}
+
+int agar_edge_info(const struct agar_graph *gr, const void *nr, const void *e,
+                  struct agar_edge_info *eir)
+{
+       int rc;
+
+       eir->to = NULL;
+       rc = gr->edge_info(gr, nr, e, eir);
+       assert(rc <= 0);
+       return rc;
+}
+
+/*
+ * Depth first search
+ */
+
+struct agar_dfs_state {
+       struct agar_state sr;
+};
+
+struct agar_state *agar_dfs_new(void *ctx, struct agar_graph *gr)
+{
+       struct agar_state *sr = agar_new(ctx, gr);
+
+       if (aga_dfs_start(&sr->g) < 0) {
+               tal_free(sr);
+               return NULL;
+       }
+
+       return sr;
+}
+
+bool agar_dfs_explore(struct agar_state *sr, const void *nr,
+                     const void **nextr)
+{
+       struct aga_node *next;
+
+       next = aga_dfs_explore(&sr->g, nr_to_n(sr, nr));
+       if (!next)
+               return false;
+
+       *nextr = n_to_nr(sr, next);
+       return true;
+}
+
+/*
+ * Breadth first search
+ */
+
+struct agar_state *agar_bfs_new(void *ctx, struct agar_graph *gr)
+{
+       struct agar_state *sr = agar_new(ctx, gr);
+
+       if (aga_bfs_start(&sr->g) < 0) {
+               tal_free(sr);
+               return NULL;
+       }
+
+       return sr;
+}
+
+bool agar_bfs_explore(struct agar_state *sr, const void *nr,
+                     const void **nextr)
+{
+       struct aga_node *next;
+
+       next = aga_bfs_explore(&sr->g, nr_to_n(sr, nr));
+       if (!next)
+               return false;
+
+       *nextr = n_to_nr(sr, next);
+       return true;
+}