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Diffstat (limited to '')
| -rw-r--r-- | lib/graph.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/lib/graph.c b/lib/graph.c new file mode 100644 index 0000000..e6c2386 --- /dev/null +++ b/lib/graph.c @@ -0,0 +1,215 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Graph data structure. + * + * -- + * Copyright (C) 2016 Cumulus Networks, Inc. + */ +#include <zebra.h> +#include "graph.h" +#include "memory.h" +#include "buffer.h" + +DEFINE_MTYPE_STATIC(LIB, GRAPH, "Graph"); +DEFINE_MTYPE_STATIC(LIB, GRAPH_NODE, "Graph Node"); +struct graph *graph_new(void) +{ + struct graph *graph = XCALLOC(MTYPE_GRAPH, sizeof(struct graph)); + graph->nodes = vector_init(VECTOR_MIN_SIZE); + + return graph; +} + +void graph_delete_graph(struct graph *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); +} + +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 graph_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 necessary. */ + 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) { + graph_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) { + graph_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) { + graph_vector_remove(from->to, i); + break; + } +} + +struct graph_node *graph_find_node(struct graph *graph, void *data) +{ + struct graph_node *g; + + for (unsigned int i = vector_active(graph->nodes); i--; /**/) { + g = vector_slot(graph->nodes, i); + if (g->data == data) + return g; + } + + return NULL; +} + +bool graph_has_edge(struct graph_node *from, struct graph_node *to) +{ + for (unsigned int i = vector_active(from->to); i--; /**/) + if (vector_slot(from->to, i) == to) + return true; + + return false; +} + +static void _graph_dfs(struct graph *graph, struct graph_node *start, + vector visited, + void (*dfs_cb)(struct graph_node *, void *), void *arg) +{ + /* check that we have not visited this node */ + for (unsigned int i = 0; i < vector_active(visited); i++) { + if (start == vector_slot(visited, i)) + return; + } + + /* put this node in visited stack */ + vector_ensure(visited, vector_active(visited)); + vector_set_index(visited, vector_active(visited), start); + + /* callback */ + dfs_cb(start, arg); + + /* recurse into children */ + for (unsigned int i = vector_active(start->to); i--; /**/) { + struct graph_node *c = vector_slot(start->to, i); + + _graph_dfs(graph, c, visited, dfs_cb, arg); + } +} + +void graph_dfs(struct graph *graph, struct graph_node *start, + void (*dfs_cb)(struct graph_node *, void *), void *arg) +{ + vector visited = vector_init(VECTOR_MIN_SIZE); + + _graph_dfs(graph, start, visited, dfs_cb, arg); + vector_free(visited); +} + +#ifndef BUILDING_CLIPPY + +void graph_dump_dot_default_print_cb(struct graph_node *gn, struct buffer *buf) +{ + char nbuf[64]; + + for (unsigned int i = 0; i < vector_active(gn->to); i++) { + struct graph_node *adj = vector_slot(gn->to, i); + + snprintf(nbuf, sizeof(nbuf), " n%p -> n%p;\n", gn, adj); + buffer_putstr(buf, nbuf); + } +} + +char *graph_dump_dot(struct graph *graph, struct graph_node *start, + void (*pcb)(struct graph_node *, struct buffer *)) +{ + struct buffer *buf = buffer_new(0); + char *ret; + + pcb = (pcb) ? pcb : graph_dump_dot_default_print_cb; + buffer_putstr(buf, "digraph {\n"); + + graph_dfs(graph, start, (void (*)(struct graph_node *, void *))pcb, + buf); + + buffer_putstr(buf, "}\n"); + + ret = buffer_getstr(buf); + buffer_free(buf); + + return ret; +} + +#endif /* BUILDING_CLIPPY */ |