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lib: Add edge removal to graph data structure

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Ability to remove directed edge between two nodes.
Also ensures that adjacency vectors have no null entries.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>
This commit is contained in:
Quentin Young 2016-09-18 20:31:20 +00:00
parent 535ef5569a
commit ba06a3a0de
2 changed files with 46 additions and 16 deletions
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51
lib/graph.c
View file

@ -50,6 +50,16 @@ graph_new_node (struct graph *graph, void *data, void (*del) (void*))
return node;
}
static void
vector_remove (vector v, unsigned int ix)
{
vector_unset (v, ix);
if (ix == vector_active (v)) return;
for (; ix < vector_active (v) - 1; ix++)
v->index[ix] = v->index[ix+1];
v->active--;
}
void
graph_delete_node (struct graph *graph, struct graph_node *node)
{
@ -58,25 +68,23 @@ graph_delete_node (struct graph *graph, struct graph_node *node)
// an adjacent node
struct graph_node *adj;
// for all nodes that have an edge to us, remove us from their ->to
for (unsigned int i = 0; i < vector_active (node->from); i++)
// remove all edges from other nodes to us
vector edges = vector_copy (node->from);
for (unsigned int i = 0; i < vector_active (edges); i++)
{
adj = vector_slot (node->from, i);
if (!adj) continue;
for (unsigned int j = 0; j < vector_active (adj->to); j++)
if (vector_slot (adj->to, j) == node)
vector_unset (adj->to, j);
adj = vector_slot (edges, i);
graph_remove_edge (adj, node);
}
vector_free (edges);
// for all nodes that we have an edge to, remove us from their ->from
for (unsigned int i = 0; i < vector_active (node->to); i++)
// remove all edges from us to other nodes
edges = vector_copy (node->to);
for (unsigned int i = 0; i < vector_active (edges); i++)
{
adj = vector_slot (node->to, i);
if (!adj) continue;
for (unsigned int j = 0; j < vector_active (adj->from); j++)
if (vector_slot (adj->from, j) == node)
vector_unset (adj->from, j);
adj = vector_slot (edges, i);
graph_remove_edge (node, adj);
}
vector_free (edges);
// if there is a deletion callback, call it
if (node->del && node->data)
@ -89,7 +97,7 @@ graph_delete_node (struct graph *graph, struct graph_node *node)
// remove node from graph->nodes
for (unsigned int i = 0; i < vector_active (graph->nodes); i++)
if (vector_slot (graph->nodes, i) == node)
vector_unset (graph->nodes, i);
vector_remove (graph->nodes, i);
// free the node itself
XFREE (MTYPE_GRAPH_NODE, node);
@ -103,6 +111,19 @@ graph_add_edge (struct graph_node *from, struct graph_node *to)
return to;
}
void
graph_remove_edge (struct graph_node *from, struct graph_node *to)
{
// remove from from to->from
for (unsigned int i = 0; i < vector_active (to->from); i++)
if (vector_slot (to->from, i) == from)
vector_remove (to->from, i);
// remove to from from->to
for (unsigned int i = 0; i < vector_active (from->to); i++)
if (vector_slot (from->to, i) == to)
vector_remove (from->to, i);
}
void
graph_delete_graph (struct graph *graph)
{

11
lib/graph.h
View file

@ -64,6 +64,7 @@ graph_new_node (struct graph *graph, void *data, void (*del) (void*));
* If *data and *del are non-null, the following call is made:
* (*node->del) (node->data);
*
* @param[in] graph the graph this node belongs to
* @param[out] node pointer to node to delete
*/
void
@ -80,8 +81,16 @@ struct graph_node *
graph_add_edge (struct graph_node *from, struct graph_node *to);
/**
* Deletes a graph.
* Removes a directed edge between two nodes.
*
* @param[in] from
* @param[in] to
*/
void
graph_remove_edge (struct graph_node *from, struct graph_node *to);
/**
* Deletes a graph.
* Calls graph_delete_node on each node before freeing the graph struct itself.
*
* @param graph the graph to delete