A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 14. IMPLEMENTING A SIMPLE DSL 121
let create if str (a : argument) : string =
"if (c == "¢(string of short arg a)¢") {"¢
"if ("¢(string of arg opt a)¢") { if(%e:optarg) {"¢
"%l:scan(%e:optarg,%e:"¢a.argVi.vname¢"fmt,%e:"¢a.argVi.vname¢"addr);"¢
"}}"¢
(create def int string a)¢
"%l:"¢a.argGot.vname¢" = 1;"¢
"}"
The if statements created with create if str from the arguments form the body of the loop in
which we repeatedly call getopt long. The function create opt loop str generates the string of
C code for the loop. It calls getopt long before proceeding into the if statements generated by
create\ if str. If the return of getopt long is −1, we break out of the loop.
let create opt loop str (al : argument list) : string =
"while(1) {"¢
"int c;"¢
"c = %l:gol(%e:argc, %e:argv, %e:sstr, %e:lopts, (void * )0);"¢
"if (c == -1) break;"¢
(al | > L.map create if str | > S.concat " else ")¢
"}"
Finally, in the function makeArgStmts we can call Formatcil.cStmts to generate the CIL statements
for argument processing. The calls to findOrCreateFunc and findGlobalVar retrieve varinfos
from the CIL le that we'll need to pass as parameters to the interpreted constructor. Here, we'll
also call the functions that generate the code for allocating and initializing the option array.
let makeArgStmts (f : file) (main : fundec) (al : argument list) : stmt list =
let gol = findOrCreateFunc f "getopt long" intType in
let scan = findOrCreateFunc f "sscanf" intType in
let optarg = findGlobalVar f.globals "optarg" in
let so = create short options al in
let o, m, i = create long options f main al in
let argc, argv = getMainArgs main in
(L.map i2s (m :: i)) @
Formatcil.cStmts (create opt loop str al)
(fun n t → makeTempVar main £name : n t) locUnknown
([("argc", Fe(v2e argc));
("argv", Fe(v2e argv));
("sstr", Fe so);
("lopts", Fe (v2e o));
("gol", Fl(var gol));
("scan", Fl(var scan));
("optarg",Fe(v2e optarg))]@
(L.map (fun a → (a.argVi.vname¢"fmt"), Fe (mkString a.argFmt)) al)@