mirror of
https://github.com/privatevoid-net/nix-super.git
synced 2024-11-11 00:36:20 +02:00
87 lines
1.9 KiB
C++
87 lines
1.9 KiB
C++
|
#ifndef __EVAL_H
|
||
|
|
#define __EVAL_H
|
||
|
|
|
||
|
|
extern "C" {
|
||
|
|
#include <aterm2.h>
|
||
|
|
}
|
||
|
|
|
||
|
|
#include "hash.hh"
|
||
|
|
|
||
|
|
using namespace std;
|
||
|
|
|
||
|
|
|
||
|
|
/* Abstract syntax of Nix values:
|
||
|
|
|
||
|
|
e := Hash(h) -- reference to expression value
|
||
|
|
| External(h) -- reference to non-expression value
|
||
|
|
| Str(s) -- string constant
|
||
|
|
| Bool(b) -- boolean constant
|
||
|
|
| App(e, e) -- application
|
||
|
|
| Lam(x, e) -- lambda abstraction
|
||
|
|
| Exec(platform, e, [(s, e)])
|
||
|
|
-- primitive; execute e with args e* on platform
|
||
|
|
;
|
||
|
|
|
||
|
|
Semantics
|
||
|
|
|
||
|
|
Each rules given as eval(e) => (e', h'), i.e., expression e has a
|
||
|
|
normal form e' with hash code h'. evalE = fst . eval. evalH = snd
|
||
|
|
. eval.
|
||
|
|
|
||
|
|
eval(Hash(h)) => eval(loadExpr(h))
|
||
|
|
|
||
|
|
eval(External(h)) => (External(h), h)
|
||
|
|
|
||
|
|
eval(Str(s)@e) => (e, 0) # idem for Bool
|
||
|
|
|
||
|
|
eval(App(e1, e2)) => eval(App(e1', e2))
|
||
|
|
where e1' = evalE(e1)
|
||
|
|
|
||
|
|
eval(App(Lam(var, body), arg)@in) =>
|
||
|
|
eval(subst(var, arg, body))@out
|
||
|
|
[AND write out to storage, and dbNFs[hash(in)] = hash(out) ???]
|
||
|
|
|
||
|
|
eval(Exec(platform, prog, args)@e) =>
|
||
|
|
(External(h), h)
|
||
|
|
where
|
||
|
|
hIn = hashExpr(e)
|
||
|
|
|
||
|
|
fn = ... form name involving hIn ...
|
||
|
|
|
||
|
|
h =
|
||
|
|
if exec(evalE(platform) => Str(...)
|
||
|
|
, getFile(evalH(prog))
|
||
|
|
, map(makeArg . eval, args)
|
||
|
|
) then
|
||
|
|
hashExternal(fn)
|
||
|
|
else
|
||
|
|
undef
|
||
|
|
|
||
|
|
makeArg((argn, (External(h), h))) => (argn, getFile(h))
|
||
|
|
makeArg((argn, (Str(s), _))) => (argn, s)
|
||
|
|
makeArg((argn, (Bool(True), _))) => (argn, "1")
|
||
|
|
makeArg((argn, (Bool(False), _))) => (argn, undef)
|
||
|
|
|
||
|
|
getFile :: Hash -> FileName
|
||
|
|
loadExpr :: Hash -> FileName
|
||
|
|
hashExpr :: Expr -> Hash
|
||
|
|
hashExternal :: FileName -> Hash
|
||
|
|
exec :: Platform -> FileName -> [(String, String)] -> Status
|
||
|
|
*/
|
||
|
|
|
||
|
|
typedef ATerm Expr;
|
||
|
|
|
||
|
|
|
||
|
|
struct EvalResult
|
||
|
|
{
|
||
|
|
Expr e;
|
||
|
|
Hash h;
|
||
|
|
};
|
||
|
|
|
||
|
|
|
||
|
|
/* Evaluate an expression. */
|
||
|
|
EvalResult evalValue(Expr e);
|
||
|
|
|
||
|
|
|
||
|
|
#endif /* !__EVAL_H */
|