dgraph: new module for directed graphs.

ccan/dgraph/LICENSE

@@ -0,0 +1 @@
+../../licenses/LGPL-2.1

ccan/dgraph/_info

@@ -0,0 +1,24 @@
+#include "config.h"
+#include <string.h>
+
+/**
+ * dgraph - simple directed graph module
+ *
+ * This code implements a simple directed graph, with nodes and edges.
+ *
+ * License: LGPL (v2.1 or any later version)
+ */
+int main(int argc, char *argv[])
+{
+	/* Expect exactly one argument */
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		printf("ccan/tlist\n");
+		printf("ccan/typesafe_cb\n");
+		return 0;
+	}
+
+	return 1;
+}

ccan/dgraph/dgraph.c

@@ -0,0 +1,80 @@
+/* Licensed under LGPLv2.1+ - see LICENSE file for details */
+#include <ccan/dgraph/dgraph.h>
+#include <stdlib.h>
+
+void dgraph_init_node(struct dgraph_node *n)
+{
+	tlist_init(&n->edge[DGRAPH_FROM]);
+	tlist_init(&n->edge[DGRAPH_TO]);
+}
+
+static void free_edge(struct dgraph_edge *e)
+{
+	tlist_del_from(&e->n[DGRAPH_FROM]->edge[DGRAPH_FROM],
+		       e, list[DGRAPH_FROM]);
+	tlist_del_from(&e->n[DGRAPH_TO]->edge[DGRAPH_TO],
+		       e, list[DGRAPH_TO]);
+	free(e);
+}
+
+void dgraph_clear_node(struct dgraph_node *n)
+{
+	struct dgraph_edge *e;
+	unsigned int i;
+
+	for (i = DGRAPH_FROM; i <= DGRAPH_TO; i++) {
+		while ((e = tlist_top(&n->edge[i], list[i])) != NULL) {
+			assert(e->n[i] == n);
+			free_edge(e);
+		}
+	}
+}
+
+void dgraph_add_edge(struct dgraph_node *from, struct dgraph_node *to)
+{
+	struct dgraph_edge *e = malloc(sizeof(*e));
+	e->n[DGRAPH_FROM] = from;
+	e->n[DGRAPH_TO] = to;
+	tlist_add(&from->edge[DGRAPH_FROM], e, list[DGRAPH_FROM]);
+	tlist_add(&to->edge[DGRAPH_TO], e, list[DGRAPH_TO]);
+}
+
+bool dgraph_del_edge(struct dgraph_node *from, struct dgraph_node *to)
+{
+	struct dgraph_edge *e, *next;
+
+	dgraph_for_each_edge_safe(from, e, next, DGRAPH_FROM) {
+		if (e->n[DGRAPH_TO] == to) {
+			free_edge(e);
+			return true;
+		}
+	}
+	return false;
+}
+
+static bool traverse_depth_first(struct dgraph_node *n,
+				 enum dgraph_dir dir,
+				 bool (*fn)(struct dgraph_node *, void *),
+				 const void *data)
+{
+	struct dgraph_edge *e, *next;
+
+	dgraph_for_each_edge_safe(n, e, next, dir) {
+		if (!traverse_depth_first(e->n[!dir], dir, fn, data))
+			return false;
+	}
+	return fn(n, (void *)data);
+}
+
+void dgraph_traverse(struct dgraph_node *n,
+		     enum dgraph_dir dir,
+		     bool (*fn)(struct dgraph_node *, void *),
+		     const void *data)
+{
+	struct dgraph_edge *e, *next;
+
+	dgraph_for_each_edge_safe(n, e, next, dir) {
+		if (!traverse_depth_first(e->n[!dir], dir, fn, data))
+			break;
+	}
+}

ccan/dgraph/dgraph.h

@@ -0,0 +1,67 @@
+/* Licensed under LGPLv2.1+ - see LICENSE file for details */
+#ifndef CCAN_DGRAPH_H
+#define CCAN_DGRAPH_H
+#include "config.h"
+#include <ccan/tlist/tlist.h>
+#include <ccan/typesafe_cb/typesafe_cb.h>
+#include <stdbool.h>
+
+enum dgraph_dir {
+	DGRAPH_FROM,
+	DGRAPH_TO
+};
+
+/* strust tlist_dgraph_edge: a list of edges */
+TLIST_TYPE(dgraph_edge, struct dgraph_edge);
+
+/**
+ * struct dgraph_node - a node in a directed graph.
+ * @edge: edges indexed by enum dgraph_dir.
+ *
+ * edge[DGRAPH_FROM] edges have n[DGRAPH_FROM] == this.
+ * edge[DGRAPH_TO] edges have n[DGRAPH_TO] == this.
+ */
+struct dgraph_node {
+	struct tlist_dgraph_edge edge[2];
+};
+
+/**
+ * struct dgraph_edge - an edge in a directed graph.
+ * @list: our nodes's list of edges, indexed by enum dgraph_dir.
+ * @n: the nodes, indexed by enum dgraph_dir.
+ */
+struct dgraph_edge {
+	struct list_node list[2];
+	struct dgraph_node *n[2];
+};
+
+void dgraph_init_node(struct dgraph_node *n);
+void dgraph_clear_node(struct dgraph_node *n);
+void dgraph_add_edge(struct dgraph_node *from, struct dgraph_node *to);
+bool dgraph_del_edge(struct dgraph_node *from, struct dgraph_node *to);
+
+/* You can dgraph_clear_node() the node you're on safely. */
+#define dgraph_traverse_from(n, fn, arg)				\
+	dgraph_traverse((n), DGRAPH_FROM,				\
+			typesafe_cb_preargs(bool, void *, (fn), (arg),	\
+					    struct dgraph_node *),	\
+			(arg))
+
+#define dgraph_traverse_to(n, fn, arg)					\
+	dgraph_traverse((n), DGRAPH_TO,					\
+			typesafe_cb_preargs(bool, void *, (fn), (arg),	\
+					    struct dgraph_node *),	\
+			(arg))
+
+void dgraph_traverse(struct dgraph_node *n,
+		     enum dgraph_dir dir,
+		     bool (*fn)(struct dgraph_node *from, void *data),
+		     const void *data);
+
+#define dgraph_for_each_edge(n, i, dir)		\
+	tlist_for_each(&(n)->edge[dir], i, list[dir])
+
+#define dgraph_for_each_edge_safe(n, i, next, dir)		\
+	tlist_for_each_safe(&(n)->edge[dir], i, next, list[dir])
+
+#endif /* CCAN_DGRAPH_H */

ccan/dgraph/test/run.c

@@ -0,0 +1,116 @@
+#include <ccan/dgraph/dgraph.h>
+/* Include the C files directly. */
+#include <ccan/dgraph/dgraph.c>
+#include <ccan/tap/tap.h>
+
+static bool count_nodes(struct dgraph_node *n, unsigned int *count)
+{
+	(*count)++;
+	return true;
+}
+
+static bool stop_traverse(struct dgraph_node *n, unsigned int *count)
+{
+	if (--(*count) == 0)
+		return false;
+	return true;
+}
+
+int main(void)
+{
+	struct dgraph_node n1, n2, n3;
+	unsigned int count = 0;
+
+	/* This is how many tests you plan to run */
+	plan_tests(25);
+
+	dgraph_init_node(&n1);
+	count = 0;
+	dgraph_traverse_from(&n1, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_to(&n1, count_nodes, &count);
+	ok1(count == 0);
+
+	dgraph_init_node(&n2);
+	dgraph_add_edge(&n1, &n2);
+	count = 0;
+	dgraph_traverse_from(&n1, count_nodes, &count);
+	ok1(count == 1);
+	count = 0;
+	dgraph_traverse_to(&n1, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_from(&n2, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_to(&n2, count_nodes, &count);
+	ok1(count == 1);
+
+	dgraph_init_node(&n3);
+	dgraph_add_edge(&n2, &n3);
+	count = 0;
+	dgraph_traverse_from(&n1, count_nodes, &count);
+	ok1(count == 2);
+	count = 0;
+	dgraph_traverse_to(&n1, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_from(&n2, count_nodes, &count);
+	ok1(count == 1);
+	count = 0;
+	dgraph_traverse_to(&n2, count_nodes, &count);
+	ok1(count == 1);
+	count = 0;
+	dgraph_traverse_from(&n3, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_to(&n3, count_nodes, &count);
+	ok1(count == 2);
+
+	/* Check stopping traverse. */
+	count = 1;
+	dgraph_traverse_from(&n1, stop_traverse, &count);
+	ok1(count == 0);
+	count = 2;
+	dgraph_traverse_from(&n1, stop_traverse, &count);
+	ok1(count == 0);
+	count = 3;
+	dgraph_traverse_from(&n1, stop_traverse, &count);
+	ok1(count == 1);
+
+	dgraph_clear_node(&n1);
+
+	count = 0;
+	dgraph_traverse_from(&n2, count_nodes, &count);
+	ok1(count == 1);
+	count = 0;
+	dgraph_traverse_to(&n2, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_from(&n3, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_to(&n3, count_nodes, &count);
+	ok1(count == 1);
+
+	ok1(dgraph_del_edge(&n2, &n3));
+	count = 0;
+	dgraph_traverse_from(&n2, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_to(&n2, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_from(&n3, count_nodes, &count);
+	ok1(count == 0);
+	count = 0;
+	dgraph_traverse_to(&n3, count_nodes, &count);
+	ok1(count == 0);
+
+	ok1(!dgraph_del_edge(&n2, &n3));
+	dgraph_clear_node(&n2);
+
+	/* This exits depending on whether all tests passed */
+	return exit_status();
+}