char yytext[100];

/* for debug */
int getChar(){
    int c;
    c = getc(stdin);
    return c;
}

void ungetChar(int c)
{
    ungetc(c,stdin);
}

int yylex()
{
    int c,n;
    char *p;
again:
    c = getChar();
    if(isspace(c)) goto again;
    switch(c){
    case '+':
    case '-':
    case '*':
    case '>':
    case '<':
    case '(':
    case ')':
    case '{':
    case '}':
    case ']':
    case '[':
    case ';':
    case ',':
    case '=':
    case EOF:
	return c;
    case '"':
	p = yytext;
	while((c = getChar()) != '"'){
	    *p++ = c;
	}
	*p = '\0';
	yylval.val = makeNum((int)strdup(yytext));
	return STRING;
    }
    if(isdigit(c)){
	n = 0;
	do {
	    n = n*10 + c - '0';
	    c = getChar();
	} while(isdigit(c));
	ungetChar(c);
	yylval.val = makeNum(n);
	return NUMBER;
    }
    if(isalpha(c)){
	p = yytext;
	do {
	    *p++ = c;
	    c = getChar();
	} while(isalpha(c));
	*p = '\0';
	ungetChar(c);
	if(strcmp(yytext,"var") == 0) 
	    return VAR;
	else if(strcmp(yytext,"if") == 0) 
	    return IF;
	else if(strcmp(yytext,"else") == 0) 
	    return ELSE;
	else if(strcmp(yytext,"return") == 0) 
	    return RETURN;
	else if(strcmp(yytext,"while") == 0) 
	    return WHILE;
	else if(strcmp(yytext,"for") == 0) 
	    return FOR;
	else if(strcmp(yytext,"println") == 0) 
	    return PRINTLN;
	else {
	    yylval.val = makeSymbol(yytext);
	    return SYMBOL;
	}
    }
    fprintf(stderr,"bad char '%c'\n",c);
    exit(1);
}

void yyerror()
{
    printf("syntax error!\n");
    exit(1);
}