A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 14. IMPLEMENTING A SIMPLE DSL 123
let makeArgChecks (f : file) (al : argument list) : stmt =
let got arg a = if a.argOpt then one else v2e a.argGot in
let bexp, mexp =
L.fold left (fun b a → BinOp(LAnd, b, a.argReq, intType)) one al,
L.fold left (fun b a → BinOp(LAnd, b, (got arg a), intType)) one al
in
mkStmt (If(BinOp(LOr, UnOp(LNot, mexp, intType), UnOp(LNot, bexp, intType), intType),
mkBlock (printHelp f al), mkBlock[ ],
locUnknown))
If we have found the main function, then the function processFunction inserts the code for processing
command line arguments at the top of the function.
let processFunction (f : file) (al : argument list)
(fd : fundec) (loc : location) : unit =
if fd.svar.vname = "main" then
fd.sbody.bstmts ← (initArgs al) @
(makeArgStmts f fd al) @
[makeArgChecks f al] @
fd.sbody.bstmts
Finally, the function tut14 gathers the argument specications using gatherArguments before calling
processFunction, which generates the argument parsing code.
let tut14 (f : file) : unit =
f | > gatherArguments
|> processFunction f
|> onlyFunctions
|> iterGlobals f;
eraseAttrs f
14.2 test/tut14.c
This C code demonstrates the language extension we wrote for generating code to process command
line arguments. It will accept one argument called boolarg, and another called intarg.
../test/tut14.c
# include
# include
# include // This is where the argument macro is #define'd
The boolarg argument can be passed with --boolarg or -b, and its value can be accessed in the
program through the global variable boolarg of type int. When not given, the default value is 0
or false.