/*------------------------------------------------------------------*/
/* expr.h                                                           */
/*------------------------------------------------------------------*/

#ifndef EXPR_INCLUDED
#define EXPR_INCLUDED

enum ExprType {EXPR_NUMBER, EXPR_FLIPFLOPREF, 
   EXPR_INPUTREF, EXPR_NOT, EXPR_AND, EXPR_OR};

typedef struct Expr *Expr_T;

/* These functions are called by the Parser module: */

Expr_T Expr_newNumber(int iNumber);
/* Return a new "number" Expr_T whose number is iNumber.  It is a 
   checked runtime error for iNumber to be anything but 0 or 1. */

Expr_T Expr_newInputRef(int iIndex);
/* Return a new "input reference" Expr_T that references the Circuit
   input whose index is iIndex.  It is a checked runtime error for
   iIndex to be negative. */

Expr_T Expr_newFlipFlopRef(int iIndex);
/* Return a new "flip flop reference" Expr_T that references the 
   Circuit flip flop whose index is iIndex.  It is a checked runtime 
   error for iIndex to be negative. */

Expr_T Expr_newNot(Expr_T oChild);
/* Return a new "not" Expr_T whose subexpression is oChild.  It
   is a checked runtime error for oChild to be NULL. */

Expr_T Expr_newAnd(Expr_T oLeftChild, Expr_T oRightChild);
/* Return a new "and" Expr_T whose left subexpression is oLeftChild
   and whose right subexpression is oRightChild.  It is a checked
   runtime error for oLeftChild or oRightChild to be NULL. */

Expr_T Expr_newOr(Expr_T oLeftChild, Expr_T oRightChild);
/* Return a new "or" Expr_T whose left subexpression is oLeftChild
   and whose right subexpression is oRightChild.  It is a checked
   runtime error for oLeftChild or oRightChild to be NULL. */

/* These functions are called by Circuit: */

   /* You should determine. */

/* These functions are called by Simulator: */

   /* You should determine. */

#endif