1 files changed, 161 insertions, 0 deletions
diff --git a/lib/graph.h b/lib/graph.h
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+++ b/lib/graph.h
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Graph data structure.
+ *
+ * --
+ * Copyright (C) 2016 Cumulus Networks, Inc.
+ */
+
+#ifndef _ZEBRA_COMMAND_GRAPH_H
+#define _ZEBRA_COMMAND_GRAPH_H
+
+#include <stdbool.h>
+#include "vector.h"
+#include "buffer.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct graph {
+	vector nodes;
+};
+
+struct graph_node {
+	vector from; // nodes which have edges to this node
+	vector to;   // nodes which this node has edges to
+
+	void *data;		 // node data
+	void (*del)(void *data); // deletion callback
+};
+
+struct graph *graph_new(void);
+
+/**
+ * Creates a new node.
+ *
+ * @struct graph the graph this node exists in
+ * @param[in] data this node's data
+ * @param[in] del data deletion callback
+ * @return the new node
+ */
+struct graph_node *graph_new_node(struct graph *graph, void *data,
+				  void (*del)(void *));
+
+/**
+ * Deletes a node.
+ *
+ * Before deletion, this function removes all edges to and from this node from
+ * any neighbor nodes.
+ *
+ * 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 graph_delete_node(struct graph *graph, struct graph_node *node);
+
+/**
+ * Makes a directed edge between two nodes.
+ *
+ * @param[in] from
+ * @param[in] to
+ * @return to
+ */
+struct graph_node *graph_add_edge(struct graph_node *from,
+				  struct graph_node *to);
+
+/**
+ * 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
+ */
+void graph_delete_graph(struct graph *graph);
+
+/*
+ * Finds a node in the graph.
+ *
+ * @param[in] graph the graph to search in
+ * @param[in] data the data to key off
+ * @return the first graph node whose data pointer matches `data`
+ */
+struct graph_node *graph_find_node(struct graph *graph, void *data);
+
+
+/*
+ * Determines whether two nodes have a directed edge between them.
+ *
+ * @param from
+ * @param to
+ * @return whether there is a directed edge from `from` to `to`.
+ */
+bool graph_has_edge(struct graph_node *from, struct graph_node *to);
+
+/*
+ * Depth-first search.
+ *
+ * Performs a depth-first traversal of the given graph, visiting each node
+ * exactly once and calling the user-provided callback for each visit.
+ *
+ * @param graph the graph to operate on
+ * @param start the node to take as the root
+ * @param dfs_cb callback called for each node visited in the traversal
+ * @param arg argument to provide to dfs_cb
+ */
+void graph_dfs(struct graph *graph, struct graph_node *start,
+	       void (*dfs_cb)(struct graph_node *, void *), void *arg);
+
+#ifndef BUILDING_CLIPPY
+/*
+ * Clippy relies on a small subset of sources in lib/, but it cannot link
+ * libfrr since clippy itself is required to build libfrr. Instead it directly
+ * includes the sources it needs. One of these is the command graph
+ * implementation, which wraps this graph implementation. Since we need to use
+ * the buffer.[ch] sources here, which indirectly rely on most of libfrr, we
+ * have to ignore them when compiling clippy to avoid build dependency issues.
+ *
+ * TODO: Fix clippy build.
+ */
+
+/*
+ * Default node printer for use with graph_dump_dot.
+ *
+ * @param gn the node to print
+ * @param buf the buffer to print into
+ */
+void graph_dump_dot_default_print_cb(struct graph_node *gn, struct buffer *buf);
+
+/*
+ * Prints a graph in the DOT language.
+ *
+ * The generated output is produced from a depth-first traversal of the graph.
+ *
+ * @param graph the graph to print
+ * @param start the node to take as the root
+ * @param pcb callback called for each node in the traversal that should
+ *        print the node in the DOT language. Passing NULL for this argument
+ *        will use the default printer. See graph_dump_dot_default_print_cb for
+ *        an example.
+ * @return representation of graph in DOT language, allocated with MTYPE_TMP.
+ *         Caller is responsible for freeing this string.
+ */
+char *graph_dump_dot(struct graph *graph, struct graph_node *start,
+		     void (*pcb)(struct graph_node *, struct buffer *buf));
+
+#endif /* BUILDING_CLIPPY */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _ZEBRA_COMMAND_GRAPH_H */