1 files changed, 85 insertions, 0 deletions
diff --git a/lib/command_graph.h b/lib/command_graph.h
new file mode 100644
index 0000000000..8d23577d37
--- /dev/null
+++ b/lib/command_graph.h
@@ -0,0 +1,85 @@
+#ifndef COMMAND_GRAPH_H
+#define COMMAND_GRAPH_H
+
+#include "vty.h"
+#include "vector.h"
+
+enum graph_node_type
+{
+  WORD_GN,
+  IPV4_GN,
+  IPV4_PREFIX_GN,
+  IPV6_GN,
+  IPV6_PREFIX_GN,
+  VARIABLE_GN,
+  RANGE_GN,
+  NUMBER_GN,
+  SELECTOR_GN,
+  OPTION_GN,
+  NUL_GN
+};
+
+struct graph_node
+{
+  enum graph_node_type type;
+  vector children;
+  int is_root;              // true if first token in command
+  int is_leaf;              // true if last token in command
+  struct graph_node * end;  // pointer to end for selector & option
+
+  int (*func)(struct vty *, int, const char *[]);
+
+  /* various data fields for nodes */
+  char* text;       // for words and variables
+  int value;        // for numbers
+  int min, max;     // for ranges
+};
+
+/*
+ * Adds a child to a node.
+ * If the node already has the exact same child, nothing is done. This is
+ * decided with cmp_node.
+ *
+ * @param[in] parent node
+ * @param[in] child node
+ * @return the new child, or the existing child if the parent already has the
+ *         new child
+ */
+extern struct graph_node *
+add_node(struct graph_node *, struct graph_node *);
+
+/*
+ * Compares two nodes for parsing equivalence.
+ * Equivalence in this case means that a single user input token
+ * should be able to unambiguously match one of the two nodes.
+ * For example, two nodes which have all fields equal except their
+ * function pointers would be considered equal.
+ *
+ * @param[in] first node to compare
+ * @param[in] second node to compare
+ * @return 1 if equal, zero otherwise.
+ */
+extern int
+cmp_node(struct graph_node *, struct graph_node *);
+
+/*
+ * Create a new node.
+ * Initializes all fields to default values and sets the node type.
+ *
+ * @param[in] node type
+ * @return pointer to the newly allocated node
+ */
+extern struct graph_node *
+new_node(enum graph_node_type);
+
+/**
+ * Walks a command DFA, printing structure to stdout.
+ * For debugging.
+ *
+ * @param[in] start node of graph to walk
+ * @param[in] graph depth for recursion, caller passes 0
+ */
+extern void
+walk_graph(struct graph_node *, int);
+
+#endif