Merge pull request #753 from dslicenc/cm16876-ospfv6-mtu

[mirror_frr.git] / lib / graph.c

/*
 * Graph data structure.
 *
 * --
 * Copyright (C) 2016 Cumulus Networks, Inc.
 *
 * This file is part of GNU Zebra.
 *
 * GNU Zebra 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, or (at your option) any
 * later version.
 *
 * GNU Zebra 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 this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */
#include <zebra.h>
#include "graph.h"
#include "memory.h"

DEFINE_MTYPE_STATIC(LIB, GRAPH,      "Graph")
DEFINE_MTYPE_STATIC(LIB, GRAPH_NODE, "Graph Node")
struct graph *
graph_new ()
{
  struct graph *graph = XCALLOC (MTYPE_GRAPH, sizeof(struct graph));
  graph->nodes = vector_init (VECTOR_MIN_SIZE);

  return graph;
}

struct graph_node *
graph_new_node (struct graph *graph, void *data, void (*del) (void*))
{
  struct graph_node *node =
     XCALLOC(MTYPE_GRAPH_NODE, sizeof(struct graph_node));

  node->from = vector_init (VECTOR_MIN_SIZE);
  node->to   = vector_init (VECTOR_MIN_SIZE);
  node->data = data;
  node->del  = del;

  vector_set (graph->nodes, node);

  return node;
}

static void
vector_remove (vector v, unsigned int ix)
{
  if (ix >= v->active)
    return;

  /* v->active is guaranteed >= 1 because ix can't be lower than 0
   * and v->active is > ix. */
  v->active--;
  /* if ix == v->active--, we set the item to itself, then to NULL...
   * still correct, no check neccessary. */
  v->index[ix] = v->index[v->active];
  v->index[v->active] = NULL;
}

void
graph_delete_node (struct graph *graph, struct graph_node *node)
{
  if (!node) return;

  // an adjacent node
  struct graph_node *adj;

  // remove all edges from other nodes to us
  for (unsigned int i = vector_active (node->from); i--; /**/)
    {
      adj = vector_slot (node->from, i);
      graph_remove_edge (adj, node);
    }

  // remove all edges from us to other nodes
  for (unsigned int i = vector_active (node->to); i--; /**/)
    {
      adj = vector_slot (node->to, i);
      graph_remove_edge (node, adj);
    }

  // if there is a deletion callback, call it
  if (node->del && node->data)
    (*node->del) (node->data);

  // free adjacency lists
  vector_free (node->to);
  vector_free (node->from);

  // remove node from graph->nodes
  for (unsigned int i = vector_active (graph->nodes); i--; /**/)
    if (vector_slot (graph->nodes, i) == node)
      {
        vector_remove (graph->nodes, i);
        break;
      }

  // free the node itself
  XFREE (MTYPE_GRAPH_NODE, node);
}

struct graph_node *
graph_add_edge (struct graph_node *from, struct graph_node *to)
{
  vector_set (from->to, to);
  vector_set (to->from, from);
  return to;
}

void
graph_remove_edge (struct graph_node *from, struct graph_node *to)
{
  // remove from from to->from
  for (unsigned int i = vector_active (to->from); i--; /**/)
    if (vector_slot (to->from, i) == from)
      {
        vector_remove (to->from, i);
        break;
      }
  // remove to from from->to
  for (unsigned int i = vector_active (from->to); i--; /**/)
    if (vector_slot (from->to, i) == to)
      {
        vector_remove (from->to, i);
        break;
      }
}

void
graph_delete_graph (struct graph *graph)
{
  // delete each node in the graph
  for (unsigned int i = vector_active (graph->nodes); i--; /**/)
    graph_delete_node (graph, vector_slot (graph->nodes, i));

  vector_free (graph->nodes);
  XFREE (MTYPE_GRAPH, graph);
}