A CIL Tutorial - Department of Computer Science - ETH Zürich

CHAPTER 14. IMPLEMENTING A SIMPLE DSL 117
module T = Tut8
let req of exp (c : T.ctxt) (loc : location) (e : exp) : exp =
match e with
| CastE(t, z) when z = zero →
t | > getAssertAttr | > T.exp of ap c loc
| → one
The command line arugment specication is the in form of a static initializer on a global variable.
We'll iterate through the list of global variable declarations looking for global variable denitions
(i.e. GVars) whose types have the ciltutarg attribute. The function handle field looks at one
eld of the static initializer on the GVar, and uses it to ll in a eld of the argument type we dened
above.
let handle field (c : T.ctxt) (loc : location) (a : argument)
(off : offset) (ini : init) (t : typ) ()
: unit
=
match off, ini with
| Field(f, NoOffset), SingleInit e → begin
match f.fname with
| "short form" → a.argShort ← string of exp e
| "help text" → a.argHelp ← string of exp e
| "def" → a.argDef ← e;
a.argType ← f.ftype;
a.argVi ← makeGlobalVar a.argName a.argType
| "requires" → a.argReq ← req of exp c loc e
| "format" → a.argFmt ← string of exp e
| "has opt" → a.argOption ← e = one
| → E.s(E.bug "malformed arg struct")
end
| → E.s(E.bug "Unexpected initializer in argument of global")
The function argument of global looks at one global, g, to determine whether it is a command
line argument sepcication, i.e. whether it is a GVar with isArgType returning true. If so, it makes
a new argument, lls in a few of the elds that can be determined immediately, like the name of the
argument, and calls iterCompound. iterCompound iterates over the elds of the static initializer
using the function handle field that we just dened. iterCompound is dened in tututil.ml. It
is based on foldLeftCompound from the CIL library.
let argument of global (c : T.ctxt) (g : global) : argument list =
match g with
| GVar(vi, {init = Some(CompoundInit(t, ini))}, loc)
when isArgType vi.vtype → begin
let a = makeArgument () in