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* Derefencing of hashed expressions.

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This commit is contained in:
Eelco Dolstra 2003-06-17 15:45:43 +00:00
parent a7ab242fb4
commit 6656993f83
4 changed files with 45 additions and 28 deletions
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33
src/eval.cc
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@ -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. */