diff options
| -rw-r--r-- | src/eval.cc | 33 | ||||
| -rw-r--r-- | src/eval.hh | 21 | ||||
| -rw-r--r-- | src/globals.hh | 10 | ||||
| -rw-r--r-- | src/test.cc | 9 |
4 files changed, 45 insertions, 28 deletions
diff --git a/src/eval.cc b/src/eval.cc index ad6f5ae2a2a7..3f8aa7b2326b 100644 --- a/src/eval.cc +++ b/src/eval.cc @@ -217,14 +217,13 @@ static string evalString(Expr e) } -/* Evaluate an expression; the result must be a external - non-expression reference. */ -static Hash evalExternal(Expr e) +/* Evaluate an expression; the result must be a value reference. */ +static Hash evalHash(Expr e) { e = evalValue(e); char * s; - if (ATmatch(e, "External(<str>)", &s)) return parseHash(s); - else throw badTerm("external non-expression value expected", e); + if (ATmatch(e, "Hash(<str>)", &s)) return parseHash(s); + else throw badTerm("value reference expected", e); } @@ -244,7 +243,7 @@ void evalArgs(ATermList args, ATermList & argsNF, Environment & env) char * s; if (ATmatch(eVal, "Str(<str>)", &s)) { env[name] = s; - } else if (ATmatch(eVal, "External(<str>)", &s)) { + } else if (ATmatch(eVal, "Hash(<str>)", &s)) { env[name] = queryValuePath(parseHash(s)); } else throw badTerm("invalid argument value", eVal); @@ -260,7 +259,7 @@ void evalArgs(ATermList args, ATermList & argsNF, Environment & env) Expr evalValue(Expr e) { char * s; - Expr eBuildPlatform, eProg; + Expr eBuildPlatform, eProg, e2; ATermList args; /* Normal forms. */ @@ -269,14 +268,20 @@ Expr evalValue(Expr e) ATmatch(e, "Bool(False)")) return e; - /* External expressions. */ - - /* External non-expressions. */ - if (ATmatch(e, "External(<str>)", &s)) { + /* Value references. */ + if (ATmatch(e, "Hash(<str>)", &s)) { parseHash(s); /* i.e., throw exception if not valid */ return e; } + /* External expression. */ + if (ATmatch(e, "Deref(<term>)", &e2)) { + string fn = queryValuePath(evalHash(e2)); + ATerm e3 = ATreadFromNamedFile(fn.c_str()); + if (!e3) throw Error("reading aterm from " + fn); + return e3; + } + /* Execution primitive. */ if (ATmatch(e, "Exec(<term>, <term>, [<list>])", @@ -286,14 +291,14 @@ Expr evalValue(Expr e) checkPlatform(buildPlatform); - Hash prog = evalExternal(eProg); + Hash prog = evalHash(eProg); Environment env; ATermList argsNF; evalArgs(args, argsNF, env); Hash sourceHash = hashExpr( - ATmake("Exec(Str(<str>), External(<str>), [])", + ATmake("Exec(Str(<str>), Hash(<str>), [])", buildPlatform.c_str(), ((string) prog).c_str())); /* Do we know a normal form for sourceHash? */ @@ -310,7 +315,7 @@ Expr evalValue(Expr e) (string) sourceHash + "-nf", buildPlatform, prog, env); } - return ATmake("External(<str>)", ((string) targetHash).c_str()); + return ATmake("Hash(<str>)", ((string) targetHash).c_str()); } /* Barf. */ diff --git a/src/eval.hh b/src/eval.hh index 1a8edcfdea9e..719edb143354 100644 --- a/src/eval.hh +++ b/src/eval.hh @@ -12,24 +12,28 @@ using namespace std; /* Abstract syntax of Nix values: - e := Hash(h) -- reference to expression value - | External(h) -- reference to non-expression value + e := Deref(e) -- external expression + | Hash(h) -- value reference | Str(s) -- string constant | Bool(b) -- boolean constant + | Var(x) -- variable | App(e, e) -- application | Lam(x, e) -- lambda abstraction | Exec(platform, e, [Arg(e, e)]) -- primitive; execute e with args e* on platform ; + TODO: Deref(e) allows computed external expressions, which might be + too expressive; perhaps this should be Deref(h). + Semantics Each rule given as eval(e) => e', i.e., expression e has a normal form e'. - eval(Hash(h)) => eval(loadExpr(h)) + eval(Deref(Hash(h))) => eval(loadExpr(h)) - eval(External(h)) => External(h) # idem for Str, Bool + eval(Hash(h)) => Hash(h) # idem for Str, Bool eval(App(e1, e2)) => eval(App(e1', e2)) where e1' = eval(e1) @@ -37,8 +41,7 @@ using namespace std; eval(App(Lam(var, body), arg)) => eval(subst(var, arg, body)) - eval(Exec(platform, prog, args)) => - (External(h), h) + eval(Exec(platform, prog, args)) => Hash(h) where fn = ... name of the output (random or by hashing expr) ... h = @@ -47,12 +50,12 @@ using namespace std; , getFile(eval(prog)) , map(makeArg . eval, args) ) then - hashExternal(fn) + hashPath(fn) else undef ... register ... - makeArg(Arg(Str(nm), (External(h), h))) => (nm, getFile(h)) + makeArg(Arg(Str(nm), (Hash(h), h))) => (nm, getFile(h)) makeArg(Arg(Str(nm), (Str(s), _))) => (nm, s) makeArg(Arg(Str(nm), (Bool(True), _))) => (nm, "1") makeArg(Arg(Str(nm), (Bool(False), _))) => (nm, undef) @@ -60,7 +63,7 @@ using namespace std; getFile :: Hash -> FileName loadExpr :: Hash -> FileName hashExpr :: Expr -> Hash - hashExternal :: FileName -> Hash + hashPath :: FileName -> Hash exec :: FileName -> Platform -> FileName -> [(String, String)] -> Status */ diff --git a/src/globals.hh b/src/globals.hh index d4fe4b370f2a..b81a787147c3 100644 --- a/src/globals.hh +++ b/src/globals.hh @@ -21,9 +21,13 @@ extern string dbRefs; /* dbNFs :: Hash -> Hash - Each pair (h1, h2) in this mapping records the fact that the value - referenced by h2 is a normal form obtained by evaluating the value - referenced by value h1. + Each pair (h1, h2) in this mapping records the fact that the normal + form of an expression with hash h1 is Hash(h2). + + TODO: maybe this should be that the normal form of an expression + with hash h1 is an expression with hash h2; this would be more + general, but would require us to store lots of small expressions in + the file system just to support the caching mechanism. */ extern string dbNFs; diff --git a/src/test.cc b/src/test.cc index 56414956202c..39d4b333fa2f 100644 --- a/src/test.cc +++ b/src/test.cc @@ -72,7 +72,7 @@ void runTests() Hash builder1 = addValue("./test-builder-1.sh"); - Expr e1 = ATmake("Exec(Str(<str>), External(<str>), [])", + Expr e1 = ATmake("Exec(Str(<str>), Hash(<str>), [])", thisSystem.c_str(), ((string) builder1).c_str()); evalTest(e1); @@ -80,10 +80,15 @@ void runTests() Hash builder2 = addValue("./test-builder-2.sh"); Expr e2 = ATmake( - "Exec(Str(<str>), External(<str>), [Tup(Str(\"src\"), <term>)])", + "Exec(Str(<str>), Hash(<str>), [Tup(Str(\"src\"), <term>)])", thisSystem.c_str(), ((string) builder2).c_str(), e1); evalTest(e2); + + Hash h3 = addValue("./test-expr.nix"); + Expr e3 = ATmake("Deref(Hash(<str>))", ((string) h3).c_str()); + + evalTest(e3); } |