/*
* This function recursively visits the subtree, which root node is node.
*/
void dfs(struct node *node)
/*@ requires unvisited_node_p(node, ?node_children_count,
?node_children, ?node_subtree,
_, _);
@*/
/*@ ensures visited_node_p(node, node_children_count,
node_children, node_subtree,
0, 0);
@*/
{
/*@ open unvisited_node_p(node, node_children_count,
node_children, node_subtree,
_, _);
@*/
node->parent = 0;
node->distance = 0;
/*@ close visiting_node_p(node, node_children_count,
node_children, node_subtree,
0, 0);
@*/
dfs_worker(node, 0);
}
void Graph::dfs_worker(int v, void(*process_vertex_early)(int v),
void(*process_vertex_late)(int v), void(*process_edge)(int v,EdgeNode *p))
{
EdgeNode *p;
int y;
if(finished) return;
discovered[v] = TRUE;
entry_time[v] = ++time;
process_vertex_early(v);
p = this->edges[v];
while(p){
y = p->y;
if(!discovered[y]){
parent[y] = v;
process_edge(v,p);
dfs_worker(y,process_vertex_early, process_vertex_late, process_edge);
}
else if( (!processed[y] && parent[v] != y) || (this->directed)){
process_edge(v,p);
}
if(finished) return;
p = p->next;
}
process_vertex_late(v);
exit_time[v] = ++time;
processed[v] = TRUE;
}
void Graph::dfs(int start){
prepare_search();
dfs_worker(start, &(do_nothing), &(print_vertex), &(do_nothing));
}
/*
* This function recursively visits the subtree, which root node is node.
*
* It sets the node->parent pointer to point to the parent of the node and
* sets node->distance = node->parent->distance + 1.
*/
void dfs_worker(struct node *node, int depth)
/*@ requires depth >= 0 &*&
visiting_node_p(node, ?node_children_count,
?node_children, ?node_subtree,
?parent, depth);
@*/
/*@ ensures visited_node_p(node, node_children_count,
node_children, node_subtree,
parent, depth);
@*/
{
/*@ open visiting_node_p(node, node_children_count,
node_children, node_subtree,
parent, depth);
@*/
int children_count = node->children_count;
struct node *children = node->children;
// Opening just to get the value of the subtree_children.
/*@ open unvisited_children_p(children, node_children_count,
?subtree_children);
@*/
/*@ close unvisited_children_p(children, node_children_count,
subtree_children);
@*/
int i = 0;
/*@ close visited_children_p(
children, 0, subtree_children_nil, node, depth + 1);
@*/
for (; i != children_count; i++)
/*@ invariant unvisited_children_p(
children + i, children_count - i, ?children_nodes1) &*&
visited_children_p(
children, i, ?children_nodes2, node, depth + 1) &*&
(children_merge(children_nodes2, children_nodes1) ==
subtree_children) &*&
i >= 0;
@*/
{
/*@ open unvisited_children_p(children + i, children_count - i,
children_nodes1);
@*/
/*@ open unvisited_children_p(children + i + 1, children_count - i - 1,
?children_nodes1_left);
@*/
/*@ close unvisited_children_p(children + i + 1, children_count - i - 1,
children_nodes1_left);
@*/
struct node *child = children + i;
//@ open unvisited_child_p(child, ?child_subtree);
//@ open unvisited_node_p(child, _, _, child_subtree, _, _);
child->parent = node;
child->distance = depth + 1;
//@ close visiting_node_p(child, _, _, _, node, depth + 1);
dfs_worker(child, depth + 1);
//@ close visited_child_p(child, node, depth + 1, child_subtree);
//@ visited_children_append(children, i);
/*@ children_merge_associative(
children_nodes2,
subtree_children_cons(child_subtree, subtree_children_nil),
children_nodes1_left);
@*/
}
/*@ open visited_children_p(
children, i, ?children_nodes2, node, depth + 1);
@*/
/*@ close visited_children_p(
children, i, children_nodes2, node, depth + 1);
@*/
/*@ open unvisited_children_p(children + i,
children_count - i,
?children_nodes1);
@*/
//@ children_merge_nil(children_nodes2);
//@ assert(children_nodes2 == subtree_children);
assert(children_count - i == 0);
//@ close visited_node_p(node, _, _, node_subtree, _, depth);
}