CNode is a standard tree data structure. The children of a
node are stored as a linked list, with the end of the list
indicated by next==NULL. The start and end fields of a node
indicate the span of the constituent, with the first word
indexed by 0. Leaves are defined by the condition child==NULL.
There are three basic functions to work with the constituent structure:
String linkage_print_constituent_tree(int mode);
The function linkage_constituent_tree returns a pointer to a tree;
In the function linkage_print_constituent_tree, the parameter mode=1
specifies that the tree is displayed using the nested Lisp format,
and mode=2 specifies that a flat tree is displayed using brackets.
When mode=0, no constituent structure is generated and a null string
The string returned by a call to linkage_print_constituent_tree is
automatically freed by garbage collection.