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

AST *readNum(void);

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

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

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