aga: Depth first search

This implements depth first search for the abstract graph algorithms
module.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/ccan/aga/_info b/ccan/aga/_info
index 9e44b2cfa37463b78ff1314d42df3e578e7af954..a56f1c324ffce2ddcc4392de68da71d339a828f1 100644 (file)
--- a/ccan/aga/_info
+++ b/ccan/aga/_info
@@ -31,12 +31,14 @@ int main(int argc, char *argv[])
        if (strcmp(argv[1], "depends") == 0) {
                printf("ccan/build_assert\n");
                printf("ccan/check_type\n");
+               printf("ccan/lstack\n");
                return 0;
        }
 
        if (strcmp(argv[1], "testdepends") == 0) {
                printf("ccan/container_of\n");
                printf("ccan/ptrint\n");
+               printf("ccan/array_size\n");
                return 0;
        }
 

diff --git a/ccan/aga/aga.h b/ccan/aga/aga.h
index d5cc434b50ccb33ee0d5c3f7204d67ffeeb76cfa..7d6016ff70606765145fa9f90be5014ba918c757 100644 (file)
--- a/ccan/aga/aga.h
+++ b/ccan/aga/aga.h
@@ -113,6 +113,7 @@
 
 #include <ccan/build_assert/build_assert.h>
 #include <ccan/check_type/check_type.h>
+#include <ccan/lstack/lstack.h>
 
 struct aga_graph;
 struct aga_node;
@@ -140,7 +141,10 @@ typedef int (*aga_edge_info_fn)(const struct aga_graph *g,
 struct aga_node {
        int sequence;
        union {
-               /* Per-algorithm state here */
+               struct {
+                       struct lstack_link parent;
+                       const void *edge;
+               } dfs;
        } u;
 };
 
@@ -202,4 +206,14 @@ int aga_edge_info(const struct aga_graph *g, const struct aga_node *n,
             (_e) = aga_next_edge((_g), (_n), (_e)))                    \
                if ((_ei).to)
 
+/*
+ * Depth first search
+ */
+
+int aga_dfs_start(struct aga_graph *g);
+struct aga_node *aga_dfs_explore(struct aga_graph *g, struct aga_node *n);
+
+#define aga_dfs(_n, _g, _start)                                        \
+       for ((_n) = (_start); ((_n) = aga_dfs_explore((_g), (_n))) != NULL; )
+
 #endif /* CCAN_AGA_H */

diff --git a/ccan/aga/dfs.c b/ccan/aga/dfs.c
new file mode 100644 (file)
index 0000000..638481c
--- /dev/null
+++ b/ccan/aga/dfs.c
@@ -0,0 +1,94 @@
+/* Licensed under LGPLv2+ - see LICENSE file for details */
+#include "config.h"
+
+#include <stdbool.h>
+#include <stdlib.h>
+#include <assert.h>
+
+#include <ccan/aga/aga.h>
+#include "private.h"
+
+/*
+ * Depth first search
+ */
+
+static bool dfs_push(struct aga_graph *g, struct lstack *stack,
+                    struct aga_node *n)
+{
+       if (!aga_update_node(g, n))
+               return false;
+
+       lstack_push(stack, n, u.dfs.parent);
+       n->u.dfs.edge = aga_first_edge(g, n);
+       return true;
+}
+
+static void dfs_pop(struct lstack *stack)
+{
+       lstack_pop(stack, struct aga_node, u.dfs.parent);
+}
+
+static struct aga_node *dfs_top(struct lstack *stack)
+{
+       return lstack_top(stack, struct aga_node, u.dfs.parent);
+}
+
+int aga_dfs_start(struct aga_graph *g)
+{
+       int rc;
+
+       rc = aga_start(g);
+       if (rc < 0)
+               return rc;
+
+       return 0;
+}
+
+struct aga_node *aga_dfs_explore(struct aga_graph *g, struct aga_node *n)
+{
+       LSTACK(stack);
+
+       if (!aga_check_state(g))
+               return NULL;
+
+       if (!n)
+               return NULL;
+
+       if (dfs_push(g, &stack, n))
+               return n;
+
+       lstack_init_from_top(&stack, n, u.dfs.parent);
+
+       while ((n = dfs_top(&stack))) {
+               const void *e = n->u.dfs.edge;
+               int err;
+               struct aga_edge_info ei;
+
+               if (!e) {
+                       /* out of edges, back up */
+                       dfs_pop(&stack);
+                       continue;
+               }
+
+               n->u.dfs.edge = aga_next_edge(g, n, e);
+
+               err = aga_edge_info(g, n, e, &ei);
+               if (err < 0) {
+                       aga_fail(g, err);
+                       return NULL;
+               }
+               if (!ei.to) {
+                       /* missing edge */
+                       continue;
+               }
+
+               if (!dfs_push(g, &stack, ei.to)) {
+                       /* already visited node */
+                       continue;
+               }
+
+               return ei.to;
+       }
+       
+       return NULL;
+}

diff --git a/ccan/aga/test/api-dfs.c b/ccan/aga/test/api-dfs.c
new file mode 100644 (file)
index 0000000..8ab1591
--- /dev/null
+++ b/ccan/aga/test/api-dfs.c
@@ -0,0 +1,104 @@
+#include "config.h"
+
+#include <stddef.h>
+#include <assert.h>
+
+#include <ccan/tap/tap.h>
+#include <ccan/array_size/array_size.h>
+
+#include <ccan/aga/aga.h>
+
+#include "simple-graph.h"
+
+#define test_dfs_partial(sg, first, ...)                               \
+       do {                                                            \
+               int cmp[] = { __VA_ARGS__ };                            \
+               bool stillok = true;                                    \
+               struct aga_node *node;                                  \
+               int i = 0;                                              \
+               aga_dfs(node, &(sg)->g, &(sg)->nodes[first]) {          \
+                       int index = node - (sg)->nodes;                 \
+                       diag("Visited %d\n", index);                    \
+                       if (i >= ARRAY_SIZE(cmp) || (index != cmp[i]))  \
+                               stillok = false;                        \
+                       i++;                                            \
+               }                                                       \
+               ok1(stillok);                                           \
+       } while (0)
+
+#define test_dfs(sg, first, ...)                                       \
+       do {                                                            \
+               ok1(aga_dfs_start(&(sg)->g) == 0);                      \
+               test_dfs_partial(sg, first, __VA_ARGS__);               \
+               aga_finish(&(sg)->g);                                   \
+       } while (0)
+
+int main(void)
+{
+       struct trivial_graph tg;
+       struct parallel_graph pg;
+       struct full_graph fg;
+       struct chain_graph cg;
+       struct grid_graph gg1, gg2;
+       struct error_graph eg;
+       struct traversal1_graph t1g;
+       struct aga_node *node;
+       
+       plan_tests(2 * 13 + 10 + 10);
+
+       trivial_graph_init(&tg);
+       test_dfs(&tg.sg, 1, 1);
+
+       parallel_graph_init(&pg, 3);
+       test_dfs(&pg.sg, 1, 1, 2);
+
+       full_graph_init(&fg, 5);
+       test_dfs(&fg.sg, 1, 1, 2, 3, 4, 5);
+       test_dfs(&fg.sg, 3, 3, 1, 2, 4, 5);
+
+       chain_graph_init(&cg, 8);
+       test_dfs(&cg.fg.sg, 1, 1, 2, 3, 4, 5, 6, 7, 8);
+       test_dfs(&cg.fg.sg, 8, 8, 7, 6, 5, 4, 3, 2, 1);
+       test_dfs(&cg.fg.sg, 5, 5, 4, 3, 2, 1, 6, 7, 8);
+
+       grid_graph_init(&gg1, 3, 3, true, true, false, false);
+       test_dfs(&gg1.sg, 1, 1, 2, 3, 6, 9, 5, 8, 4, 7);
+       test_dfs(&gg1.sg, 5, 5, 6, 9, 8);
+       test_dfs(&gg1.sg, 9, 9);
+
+       grid_graph_init(&gg2, 3, 3, true, true, true, true);
+       test_dfs(&gg2.sg, 1, 1, 2, 3, 6, 9, 8, 7, 4, 5);
+       test_dfs(&gg2.sg, 5, 5, 6, 9, 8, 7, 4, 1, 2, 3);
+       test_dfs(&gg2.sg, 9, 9, 8, 7, 4, 5, 6, 3, 2, 1);
+
+       error_graph_init(&eg);
+       test_dfs(&eg.sg, 1, 1, 2);
+       ok(aga_dfs_start(&eg.sg.g) == 0, "started error traversal");
+       node = aga_dfs_explore(&eg.sg.g, &eg.sg.nodes[3]);
+       ok(node == &eg.sg.nodes[3], "Expected node #3 (%p), actually #%ld (%p)",
+          &eg.sg.nodes[3], node - eg.sg.nodes, node);
+       node = aga_dfs_explore(&eg.sg.g, node);
+       ok(node == &eg.sg.nodes[4], "Expected node #4 (%p), actually #%ld (%p)",
+          &eg.sg.nodes[4], node - eg.sg.nodes, node);
+       ok1(aga_dfs_explore(&eg.sg.g, node) == NULL);
+       ok1(aga_error(&eg.sg.g) == -1);
+       ok1(aga_dfs_explore(&eg.sg.g, node) == NULL);
+       aga_finish(&eg.sg.g);
+       test_dfs(&eg.sg, 1, 1, 2);
+
+       traversal1_graph_init(&t1g);
+       test_dfs(&t1g.sg, 1, 1, 2, 4, 5, 3, 6);
+       test_dfs(&t1g.sg, 9, 9, 8, 6, 5, 7, 4);
+
+       ok1(aga_dfs_start(&t1g.sg.g) == 0);
+       test_dfs_partial(&t1g.sg, 1, 1, 2, 4, 5, 3, 6);
+       test_dfs_partial(&t1g.sg, 9, 9, 8, 7);
+       aga_finish(&t1g.sg.g);
+
+       ok1(aga_dfs_start(&t1g.sg.g) == 0);
+       test_dfs_partial(&t1g.sg, 9, 9, 8, 6, 5, 7, 4);
+       test_dfs_partial(&t1g.sg, 1, 1, 2, 3);
+       aga_finish(&t1g.sg.g);
+
+       return exit_status();
+}