/*  Header : boolexpr.h
    Author : Richard A. O'Keefe
    Updated: %G%
    Declare: enum BE_Op, BE_Ptr types,
	     {read,write}{,ln}_expr() and free_expr() functions.
*/
#ifndef BOOLEXPR_H_
#define BOOLEXPR_H_ 1			/* version number */
enum BE_Op {LIT,VAR,NOT,AND,IOR,IMP,EQV};

typedef struct BE_Rec *BE_Ptr;
struct BE_Rec {
    BE_Ptr next;				/* hash link */
    BE_Ptr right;				/* right operand */ 
    union {unsigned nombre; BE_Ptr gauche;} x;	/* left operand or number */
    union {unsigned long hash; void *spare;} y;
    enum BE_Op op;				/* what kind of node? */
};
#define left x.gauche
#define number x.nombre

extern void	write_expr(  FILE *, BE_Ptr);
extern void	writeln_expr(FILE *, BE_Ptr);
extern BE_Ptr	read_expr(   FILE *);
extern BE_Ptr   readln_expr( FILE *);
extern void	free_expr(void);

#endif/*BOOLEXPR_H_*/