feat(tvix/eval): Support builtins.attrNames

Define `.len()` method on `NixAttrs` to preallocate the capacity of the result
vector.

Also anchor an errant comment to its context (I think).

Change-Id: I268f15025d453d7b3ae1146558c80e51433dd2a8
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6546
Reviewed-by: wpcarro <wpcarro@gmail.com>
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI
This commit is contained in:
William Carroll 2022-09-05 11:43:17 -07:00 committed by clbot
parent 04503cf063
commit e834a2cbc4
4 changed files with 36 additions and 2 deletions

View file

@ -51,6 +51,18 @@ fn pure_builtins() -> Vec<Builtin> {
args.pop().unwrap().to_str()?.as_str().to_owned(),
));
}),
Builtin::new("attrNames", 1, |args, vm| {
force!(vm, &args[0], value, {
let xs = value.to_attrs()?;
let mut output = Vec::with_capacity(xs.len());
for (key, _val) in xs.iter() {
output.push(Value::String(key.clone()));
}
Ok(Value::List(NixList::construct(output.len(), output)))
})
}),
Builtin::new("catAttrs", 2, |mut args, _| {
let list = args.pop().unwrap().to_list()?;
let key = args.pop().unwrap().to_str()?;

View file

@ -0,0 +1 @@
[ [ ] [ "bar" "baz" "foo" ] [ "Baz" "Foo" "bar" ] [ "Eric Idle" "Graham Chapman" "John Cleese" "Michael Palin" "Terry Gilliam" "Terry Jones" ] ]

View file

@ -0,0 +1,13 @@
[
(builtins.attrNames {})
(builtins.attrNames { foo = 1; bar = 2; baz = 3; })
(builtins.attrNames { Foo = 1; bar = 2; Baz = 3; })
(builtins.attrNames {
"Graham Chapman" = true;
"John Cleese" = true;
"Terry Gilliam" = true;
"Eric Idle" = true;
"Terry Jones" = true;
"Michael Palin" = true;
})
]

View file

@ -207,6 +207,15 @@ impl NixAttrs {
}
}
/// Return the number of key-value entries in an attrset.
pub fn len(&self) -> usize {
match &self.0 {
AttrsRep::Map(map) => map.len(),
AttrsRep::Empty => 0,
AttrsRep::KV { .. } => 2,
}
}
/// Select a value from an attribute set by key.
pub fn select(&self, key: &str) -> Option<&Value> {
self.0.select(key)
@ -216,6 +225,7 @@ impl NixAttrs {
self.0.contains(key)
}
/// Provide an iterator over all values of the attribute set.
#[allow(clippy::needless_lifetimes)]
pub fn iter<'a>(&'a self) -> Iter<KeyValue<'a>> {
Iter(match &self.0 {
@ -233,8 +243,6 @@ impl NixAttrs {
})
}
/// Provide an iterator over all values of the attribute set.
/// Implement construction logic of an attribute set, to encapsulate
/// logic about attribute set optimisations inside of this module.
pub fn construct(count: usize, mut stack_slice: Vec<Value>) -> Result<Self, ErrorKind> {