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* listToAttrs: the list now should consist of {name, value} attribute

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sets instead of {attr, value}.  "name" is better than "attr" because
  the *combination* of the two forms the attribute.
This commit is contained in:
Eelco Dolstra 2007-10-09 12:51:25 +00:00
parent 8a9fe6c11c
commit 27a0662828
1 changed files with 29 additions and 28 deletions
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57
src/libexpr/primops.cc
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@ -755,36 +755,37 @@ static Expr prim_hasAttr(EvalState & state, const ATermVector & args)
}
/* takes
* param: list of { attr="attr"; value=value }
* returns an attribute set
* */
/* Builds an attribute set from a list specifying (name, value)
pairs. To be precise, a list [{name = "name1"; value = value1;}
... {name = "nameN"; value = valueN;}] is transformed to {name1 =
value1; ... nameN = valueN;}. */
static Expr prim_listToAttrs(EvalState & state, const ATermVector & args)
{
try {
ATermMap res = ATermMap();
ATermList list;
list = evalList(state, args[0]);
for (ATermIterator i(list); i; ++i){
// *i should now contain a pointer to the list item expression
ATermList attrs;
Expr evaledExpr = evalExpr(state, *i);
if (matchAttrs(evaledExpr, attrs)){
Expr e = evalExpr(state, makeSelect(evaledExpr, toATerm("attr")));
string attr = evalStringNoCtx(state,e);
Expr r = makeSelect(evaledExpr, toATerm("value"));
res.set(toATerm(attr), makeAttrRHS(r, makeNoPos()));
}
else {
throw EvalError(format("passed list item is a %s (value: %s). Set { attr=\"name\"; value=nix expr; } expected.") % showType(evaledExpr) % showValue(evaledExpr));
}
} // for
return makeAttrs(res);
} catch (Error & e) {
e.addPrefix(format("in `listToAttrs':\n"));
throw;
}
try {
ATermMap res = ATermMap();
ATermList list;
list = evalList(state, args[0]);
for (ATermIterator i(list); i; ++i){
// *i should now contain a pointer to the list item expression
ATermList attrs;
Expr evaledExpr = evalExpr(state, *i);
if (matchAttrs(evaledExpr, attrs)){
Expr e = evalExpr(state, makeSelect(evaledExpr, toATerm("name")));
string attr = evalStringNoCtx(state,e);
Expr r = makeSelect(evaledExpr, toATerm("value"));
res.set(toATerm(attr), makeAttrRHS(r, makeNoPos()));
}
else
throw TypeError(format("list element in `listToAttrs' is %s, expected a set { name = \"<name>\"; value = <value>; }")
% showType(evaledExpr));
}
return makeAttrs(res);
} catch (Error & e) {
e.addPrefix(format("in `listToAttrs':\n"));
throw;
}
}
static Expr prim_removeAttrs(EvalState & state, const ATermVector & args)