A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 14. IMPLEMENTING A SIMPLE DSL 120
let create short options (al : argument list) : exp =
let short arg of arg (a : argument) : string =
a.argShort¢(if a.argOption then ":" else "")
in
al | > L.map short arg of arg
|> S.concat ""
|> mkString
The function getMainArgs just extracts the varinfos for argv and argv from the list of formal
parameters.
let getMainArgs (main : fundec) : varinfo × varinfo =
match main.sformals with
| argc :: argv :: → argc, argv
| → E.s (E.error "Must give main argc and argv")
The function string of short arg gives the integer code for the character used as the short form
of an argument. This is needed since we can't write string or character literals in the interpreted
constructor. The function string of arg opt returns the string 1 if the argument has an option,
and the string 0 otherwise.
let string of short arg (a : argument) : string =
a.argShort.[0] | > int of char | > string of int
let string of arg opt (a : argument) : string =
if a.argOption then "1" else "0"
The function create def int string creates a string for a C else statement to be used for setting
an argument of integer type without any options to 1.
let create def int string (a : argument) : string =
if isIntegralType a.argType ∧ ¬(a.argOption)
then "else {%l:"¢a.argVi.vname¢"l = 1;}"
else ""
The function create if str creates a string for the C code that processes a particular argument.
The return of getopt long is given in the variable c. If c is equal to the character code for the
short version of the argument, then we check to see if the argument has an option, which we parse
using sscanf. In case the argument is for a boolean ag, we include the string obtained with
create def int string. Finally, we set the global variable that indicates that the argument was
given.