/*
 * Structure of a tree node.
 */

typedef	struct node	*nodeptr;

struct node {
   int n_type;			/* node type */
   int n_line;			/* line number in source program */
   int n_col;			/* column number in source program */
   union {
      int n_val;		/* integer-valued fields */
      char *n_str;		/* string-valued fields */
      nodeptr n_ptr;   	     	/* subtree pointers */
      } n_field[4];
   };

/*
 * Macros to access fields of parse tree nodes.
 */

#define TYPE(t)		t->n_type
#define LINE(t)		t->n_line
#define COL(t)		t->n_col
#define TREE0(t)	t->n_field[0].n_ptr
#define TREE1(t)	t->n_field[1].n_ptr
#define TREE2(t)	t->n_field[2].n_ptr
#define TREE3(t)	t->n_field[3].n_ptr
#define VAL0(t)		t->n_field[0].n_val
#define VAL1(t)		t->n_field[1].n_val
#define VAL2(t)		t->n_field[2].n_val
#define VAL3(t)		t->n_field[3].n_val
#define STR0(t)		t->n_field[0].n_str
#define STR1(t)		t->n_field[1].n_str
#define STR2(t)		t->n_field[2].n_str
#define STR3(t)		t->n_field[3].n_str

/*
 * External declarations.
 */

extern nodeptr tree;		/* parse tree space */
extern nodeptr tfree;		/* free pointer for tree space */
extern nodeptr tend;		/* end of tree space */
extern int tsize;		/* parse tree size (integers) */
extern nodeptr tree1();		/* tree node allocator routines */
extern nodeptr tree3();
extern nodeptr tree4();
extern nodeptr tree5();
extern nodeptr tree6();
extern nodeptr yylval;		/* parser's current token value */

/*
 * Node types.
 */

#define N_ACTIVAT	 1		/* activation control structure */
#define N_ALT		 2		/* alternation operator */
#define N_AUGOP		 3		/* augmented operator */
#define N_BAR		 4		/* generator control structure */
#define N_BINOP		 5		/* other binary operator */
#define N_BREAK		 6		/* break statement */
#define N_CASE		 7		/* case statement */
#define N_CCLS		 8		/* case clause */
#define N_CLIST		 9		/* list of case clauses */
#define N_CONJ		10		/* conjunction operator */
#define N_CREATE	11		/* create control structure */
#define N_CSET		12		/* cset literal */
#define N_ELIST		14		/* list of expressions */
#define N_EMPTY		15		/* empty expression or statement */
#define N_FIELD		16		/* record field reference */
#define N_ID		17		/* identifier token */
#define N_IF		18		/* if-then-else statement */
#define N_INT		19		/* integer literal */
#define N_INVOK		20		/* procedure call */
#define N_KEY		21		/* keyword */
#define N_LIMIT		22		/* LIMIT control structure */
#define N_LIST		23		/* [ ... ] style list */
#define N_LOOP		24		/* while, until, every, or repeat */
#define N_NOT		25		/* not prefix control structure */
#define N_NEXT		26		/* next statement */
#define N_OP		27		/* operator token */
#define N_PROC		28		/* procedure */
#define N_REAL		29		/* real literal */
#define N_RES		30		/* reserved word token */
#define N_RET		31		/* fail, return, or succeed */
#define N_SCAN		32		/* scan-using statement */
#define N_SECT		33		/* s[i:j] (section) */
#define N_SLIST		34		/* list of statements */
#define N_STR		35		/* string literal */
#define N_SUSP		36		/* suspend statement */
#define N_TO		37		/* TO operator */
#define N_TOBY		38		/* TO-BY operator */
#define N_UNOP		39		/* unary operator */

/*
 * Node constructor macros.
 */

#define ACTIVNODE(a,b,c)	tree6(N_ACTIVAT,LINE(a),COL(a),a,b,c) 
#define ALTNODE(a,b,c)		tree5(N_ALT,LINE(a),COL(a),b,c) 
#define AUGOPNODE(a,b,c)	tree6(N_AUGOP,LINE(a),COL(a),a,b,c) 
#define BARNODE(a)		tree4(N_BAR,LINE(a),COL(a),a) 
#define BINOPNODE(a,b,c)	tree6(N_BINOP,LINE(a),COL(a),a,b,c) 
#define BREAKNODE(a,b)		tree4(N_BREAK,LINE(a),COL(a),b) 
#define CASENODE(a,b,c)		tree5(N_CASE,LINE(a),COL(a),b,c) 
#define CCLSNODE(a,b,c)		tree5(N_CCLS,LINE(a),COL(a),b,c) 
#define CLISTNODE(a,b,c)	tree5(N_CLIST,LINE(a),COL(a),b,c) 
#define CONJNODE(a,b,c)		tree6(N_CONJ,LINE(a),COL(a),a,b,c) 
#define CREATENODE(a,b)		tree4(N_CREATE,LINE(a),COL(a),b) 
#define CSETNODE(a,b)		tree5(N_CSET,tline,tcol,a,b) 
#define ELISTNODE(a,b,c)	tree5(N_ELIST,LINE(a),COL(a),b,c) 
#define EMPTYNODE		tree1(N_EMPTY) 
#define FIELDNODE(a,b,c)	tree5(N_FIELD,LINE(a),COL(a),b,c) 
#define IDNODE(a)		tree4(N_ID,tline,tcol,a) 
#define IFNODE(a,b,c,d)		tree6(N_IF,LINE(a),COL(a),b,c,d) 
#define INTNODE(a)		tree4(N_INT,tline,tcol,a) 
#define INVOKNODE(a,b,c)	tree5(N_INVOK,LINE(a),COL(a),b,c) 
#define KEYNODE(a,b)		tree4(N_KEY,LINE(a),COL(a),b) 
#define LIMITNODE(a,b)		tree5(N_LIMIT,LINE(a),COL(a),a,b) 
#define LISTNODE(a,b)		tree4(N_LIST,LINE(a),COL(a),b) 
#define LOOPNODE(a,b,c)		tree6(N_LOOP,LINE(a),COL(a),a,b,c) 
#define NOTNODE(a)		tree4(N_NOT,LINE(a),COL(a),a) 
#define NEXTNODE(a)		tree3(N_NEXT,LINE(a),COL(a)) 
#define OPNODE(a)		tree4(N_OP,tline,tcol,a) 
#define PROCNODE(a,b,c,d)	tree7(N_PROC,LINE(a),COL(a),a,b,c,d) 
#define REALNODE(a)		tree4(N_REAL,tline,tcol,a) 
#define RESNODE(a)		tree4(N_RES,tline,tcol,a) 
#define RETNODE(a,b)		tree5(N_RET,LINE(a),COL(a),a,b) 
#define SCANNODE(a,b,c)		tree6(N_SCAN,LINE(a),COL(a),a,b,c) 
#define SECTNODE(a,b,c,d)	tree7(N_SECT,LINE(a),COL(a),a,b,c,d) 
#define SLISTNODE(a,b,c)	tree5(N_SLIST,LINE(a),COL(a),b,c) 
#define STRNODE(a,b)		tree5(N_STR,tline,tcol,a,b) 
#define SUSPNODE(a,b)		tree4(N_SUSP,LINE(a),COL(a),b) 
#define TOBYNODE(a,b,c,d)	tree6(N_TOBY,LINE(a),COL(a),b,c,d) 
#define TONODE(a,b,c)		tree5(N_TO,LINE(a),COL(a),b,c) 
#define UNOPNODE(a,b)		tree5(N_UNOP,LINE(a),COL(a),a,b)