/***  Example of character classification in a lexical analyzer  ***/ 

#define is_end_of_input(ch)       ((ch) == '\0') 
#define is_layout(ch)             (!is_end_of_input(ch)  && (ch) <= ' ') 
#define is_comment_starter(ch)    ((ch) == '{') 
#define is_comment_stopper(ch)    ((ch) == '}' ) 
#define is_uc_letter(ch)          ('A' <= (ch) && (ch) <= 'Z') 
#define is_lc_letter(ch)          ('a' <= (ch) && (ch) <= 'z') 
#define is_letter(ch)             (is_uc_letter(ch) || is_lc_letter(ch)) 
#define is_digit(ch)              ('0' <= (ch) && (ch) <= '9') 
#define is_letter_or_digit(ch)    (is_letter(ch) || is_digit(ch)) 
#define is_operator(ch)           (strchr("+-*/",   (ch)) != 0) 
#define is_separator(ch)          (strchr(";,()",   (ch)) != 0) 
#define is_blank(ch)              ((ch) == ' ')
#define is_delim(ch)              (is_operator(ch) || is_separator(ch) || is_blank(ch))