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[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 GNU Zebra; see the file COPYING.  If not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, 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);
}