13 typedef struct Node	Node;  typedef
14 struct Node{			/* parse tree node */  struct
15 	int (*op)(Node *); 	/* operator function */  argument
16 	Node *args[2];		/* argument nodes */  argument
21 Node	nodes[25];		/* node pool */  argument
22 Node	*nfree;			/* next available node */
36 Node	*alloc(int (*op)(Node *));
37 int	builtin(Node *np);
38 Node	*command(void);
41 Node	*list(void);
43 Node	*pipeline(void);
44 void	redirect(Node *np);
45 int	setio(Node *np);
46 Node	*simple(void);
47 int	xpipeline(Node *np);
48 int	xsimple(Node *np);
49 int	xsubshell(Node *np);
50 int	xnowait(Node *np);
51 int	xwait(Node *np);
56 	Node *np;  in main()
90 Node*
91 alloc(int (*op)(Node *))  in alloc()  argument
107 builtin(Node *np)  in builtin()
193 Node*
196 	Node *np;  in command()
264 Node*
267 	Node *np, *np1;  in list()
300 Node*
303 	Node *np, *np1;  in pipeline()
320 redirect(Node *np)  in redirect()
353 setio(Node *np)  in setio()
373 Node*
376 	Node *np;  in simple()
394 xpipeline(Node *np)  in xpipeline()
432 xsimple(Node *np)  in xsimple()
459 xsubshell(Node *np)  in xsubshell()
476 xnowait(Node *np)  in xnowait()
488 int xwait(Node *np)  in xwait()