/*
 * scanner.c
 */
#include "scanner.h"
#include <stdio.h>
#include <ctype.h>

static long needchar = 1;
static char ch;

long gettoken (Token* tok)
{
	long state = 0;
	double sign = 1.0;
	double numval;
	long valint;
	if (needchar) {
		ch = getchar(); 
		needchar = 0;
	}
	while (state >= 0) {
	  switch (state) {
	    case 0:
		if (ch == '(' ) {
			tok -> tokentype = lprtok;
			needchar = 1;
			state = -1;
		}
		else if (ch == ')' ) {
			tok -> tokentype = rprtok;
			needchar = 1;
			state = -1;
		}
		else if ((ch == '+') || (ch == '-') ) {
			tok -> tokenval.numval = 0.0;
			if (ch == '-' ) sign = -1.0;
			ch = getchar();
			state = 3;
		}
		else if (isdigit(ch) ) {
			tok -> tokenval.numval = (double) (ch - '0');
			ch = getchar();
			state = 5;
		}
		else if (isalpha(ch) ) {
			valint = 0;
			tok -> tokenval.alfval[valint] = ch;
			ch = getchar();
			state = 7;
		}
		else if ((ch == ' ') || (ch == '\n') ) {
			ch = getchar();
			state = 0;
		}
		else {
			printf("ILLEGAL CHARACTER:%c\n", ch);
			ch = getchar();
			state = 0;
		}
		break;
	    case 3:
	    	if (isdigit(ch) ) {
			tok -> tokenval.numval = (double) (ch - '0');
			ch = getchar();
			state = 5;
		}
		else {
			printf("ILLEGAL CONSTANT\n");
			tok -> tokenval.numval= 0.0;
			state = 5;
		}
		break;
	    case 5:
	    	if (isdigit(ch) ) {
			tok -> tokenval.numval = 
			   tok -> tokenval.numval*10.0 + (ch -'0');
			ch = getchar();
		}
		else {
			tok -> tokentype = numtok;
			tok -> tokenval.numval =
			   tok -> tokenval.numval*sign;
			state = -1;
		}
		break;
	    case 7:
		if (isalnum(ch) ) {
			valint = valint + 1;
			if (valint < ALF - 1 ) {
				tok -> tokenval.alfval[valint] = ch;
				ch = getchar();
			}
			else {
				printf("ATOM TOO LARGE\n");
				ch = getchar();
			}
		}
		else {
			tok -> tokentype = alftok;
			valint = valint + 1;
			tok -> tokenval.alfval[valint] = '\0';
			state = -1;
		}
		break;
	  } /* end of switch */
	} /* end of while */
}