Add primop ‘catAttrs’

This commit is contained in:
Eelco Dolstra 2014-10-04 18:15:03 +02:00
parent d4fcbe1687
commit c3f0a489f9
3 changed files with 32 additions and 0 deletions

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@ -1123,6 +1123,35 @@ static void prim_intersectAttrs(EvalState & state, const Pos & pos, Value * * ar
}
/* Collect each attribute named `attr' from a list of attribute sets.
Sets that don't contain the named attribute are ignored.
Example:
catAttrs "a" [{a = 1;} {b = 0;} {a = 2;}]
=> [1 2]
*/
static void prim_catAttrs(EvalState & state, const Pos & pos, Value * * args, Value & v)
{
Symbol attrName = state.symbols.create(state.forceStringNoCtx(*args[0], pos));
state.forceList(*args[1], pos);
Value * res[args[1]->list.length];
unsigned int found = 0;
for (unsigned int n = 0; n < args[1]->list.length; ++n) {
Value & v2(*args[1]->list.elems[n]);
state.forceAttrs(v2, pos);
Bindings::iterator i = v2.attrs->find(attrName);
if (i != v2.attrs->end())
res[found++] = i->value;
}
state.mkList(v, found);
for (unsigned int n = 0; n < found; ++n)
v.list.elems[n] = res[n];
}
/* Return a set containing the names of the formal arguments expected
by the function `f'. The value of each attribute is a Boolean
denoting whether has a default value. For instance,
@ -1530,6 +1559,7 @@ void EvalState::createBaseEnv()
addPrimOp("removeAttrs", 2, prim_removeAttrs);
addPrimOp("__listToAttrs", 1, prim_listToAttrs);
addPrimOp("__intersectAttrs", 2, prim_intersectAttrs);
addPrimOp("__catAttrs", 2, prim_catAttrs);
addPrimOp("__functionArgs", 1, prim_functionArgs);
// Lists

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@ -0,0 +1 @@
[ 1 2 ]

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@ -0,0 +1 @@
builtins.catAttrs "a" [ { a = 1; } { b = 0; } { a = 2; } ]