#include <stdio.h>
#include "exprParser.h"

Expr *readNum(void);

Expr *readExpr()
{
    int t;
    Expr *e,*ee;

    e = readNum();
    while(currentToken == PLUS_OP || currentToken == MINUS_OP){
	ee = (Expr *)malloc(sizeof(Expr));
	ee->kind = currentToken;
	getToken();
	ee->left = e;
	ee->right = readNum();
	e = ee;
    }
    return e;
}

Expr *readNum()
{
    Expr *e;
    if(currentToken == NUM){
	e = (Expr *)malloc(sizeof(Expr));
	e->kind = NUM;
	e->val = tokenVal;
	getToken();
	return e;
    } else {
	fprintf(stderr,"bad expression: NUM expected\n");
	exit(1);
    }
}