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* New built-in function `builtins.attrNames' that returns the

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names of the attributes in an attribute set.
This commit is contained in:
Eelco Dolstra 2006-12-12 16:14:31 +00:00
parent 5e6699188f
commit 1a7e88bbd9
4 changed files with 51 additions and 0 deletions
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21
src/libexpr/primops.cc
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@ -620,6 +620,26 @@ static Expr primGetEnv(EvalState & state, const ATermVector & args)
}
/* Return the names of the attributes in an attribute set as a sorted
list of strings. */
static Expr primAttrNames(EvalState & state, const ATermVector & args)
{
ATermMap attrs(128); /* !!! */
queryAllAttrs(evalExpr(state, args[0]), attrs);
StringSet names;
for (ATermMap::const_iterator i = attrs.begin(); i != attrs.end(); ++i)
names.insert(aterm2String(i->key));
ATermList list = ATempty;
for (StringSet::const_reverse_iterator i = names.rbegin();
i != names.rend(); ++i)
list = ATinsert(list, makeStr(*i, PathSet()));
return makeList(list);
}
/* Apply a function to every element of a list. */
static Expr primMap(EvalState & state, const ATermVector & args)
{
@ -732,6 +752,7 @@ void EvalState::addPrimOps()
addPrimOp("__head", 1, primHead);
addPrimOp("__tail", 1, primTail);
addPrimOp("__getEnv", 1, primGetEnv);
addPrimOp("__attrNames", 1, primAttrNames);
addPrimOp("map", 2, primMap);
addPrimOp("__getAttr", 2, primGetAttr);