Add A-star module

[ccan] / ccan / a_star / a_star.h

diff --git a/ccan/a_star/a_star.h b/ccan/a_star/a_star.h
new file mode 100644 (file)
index 0000000..c37a36b
--- /dev/null
+++ b/ccan/a_star/a_star.h
@@ -0,0 +1,69 @@
+#ifndef A_STAR_H__
+#define A_STAR_H__
+/*
+       Copyright (C) 2016 Stephen M. Cameron
+       Author: Stephen M. Cameron
+
+       This file is part of Spacenerds In Space.
+
+       Spacenerds in Space is free software; you can redistribute it and/or modify
+       it under the terms of the GNU General Public License as published by
+       the Free Software Foundation; either version 2 of the License, or
+       (at your option) any later version.
+
+       Spacenerds in Space is distributed in the hope that it will be useful,
+       but WITHOUT ANY WARRANTY; without even the implied warranty of
+       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+       GNU General Public License for more details.
+
+       You should have received a copy of the GNU General Public License
+       along with Spacenerds in Space; if not, write to the Free Software
+       Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+*/
+
+struct a_star_path {
+       int node_count;
+       __extension__ void *path[0];
+};
+
+typedef float (*a_star_node_cost_fn)(void *context, void *first, void *second);
+typedef void *(*a_star_neighbor_iterator_fn)(void *context, void *node, int neighbor);
+
+/**
+ *
+ * a_star - runs the 'A*' algorithm to find a path from the start to the goal.
+ *
+ * @context: an opaque pointer which the algorithm does not use, but passes
+ *           along intact to the callback functions described below.
+ * @start: an opaque pointer to the start node
+ * @goal:  an opaque pointer to the goal node
+ *
+ * @maxnodes: the maximum number of nodes the algorithm will encounter (ie.
+ *           the number of possible locations in a maze you are traversing.)
+ *
+ * @distance: a function which you provide which returns the distance (however you
+ *            choose to define that) between two arbitrary nodes
+ *
+ * @cost_estimate: a function you provide which provides a heuristic cost estimate
+ *                for traversing between two nodes
+ *
+ * @nth_neighbor: a function you provide which returns the nth neighbor of a given
+ *                node, or NULL if n is greater than the number of neighbors - 1.
+ *
+ * Returns:
+ *   The return value is an allocated struct a_star_path.  the node_count is the
+ *   number of nodes in the path, and the path array is a pointer to an array of
+ *   node_count nodes in order from start to goal.
+ *
+ * See test/run.c example of how to use this.
+ *
+ */
+
+struct a_star_path *a_star(void *context,
+               void *start,
+               void *goal,
+               int maxnodes,
+               a_star_node_cost_fn distance,
+               a_star_node_cost_fn cost_estimate,
+               a_star_neighbor_iterator_fn nth_neighbor);
+#endif