datanode Struct Reference

A node composed of a key-value pair, metadata, and child nodes. More...

Collaboration diagram for datanode:

Public Attributes
struct datanode *	first_child
	Beginning of a linked list of child nodes or NULL.
char *	key
	String to match during lookup and pathing.
struct datanode *	last_child
	End of linked list; NULL iff first_child is NULL.
const char *	meta
	Additional information about the node; managed extermally.
int	mod_type
	The intended use of the node; managed externally.
struct datanode *	next
	Pointer to a sibling node in containing linked list.
struct datanode *	parent
	The node's parent; used in pathing and printing.
char *	val
	The node's data; assumed string unless val_type negative.
int	val_type
	The type of data stored at the node; managed externally.

Detailed Description

A node composed of a key-value pair, metadata, and child nodes.

Use datanode_init and datanode_lookup to create and obtain nodes.

Nodes are always stored in linked lists, hence the pointer to the next element. Strings key and val are assumed to be "owned" by the datanode and will be freed when it is destroyed; never set these to string constants. Other pointers specify the heirachy of nodes and are maintained internally.

Fields mod_type and val_type primarily serve as conveniences to external code. The datanode_read and datanode_write functions optionally map mod_type to and from a character, and all functions ignore the value stored at a node if val_type is negative (needed, for instance, if val is not a string). Both fields default to 0.

Field meta allows external code to denote, e.g., constraints for val. It is copied by reference and never freed, and thus may be set to constant or externally managed strings. Its intended use is for lists of nominal values, numeric bounds, and regexp matching.