From 7b3bda9e089fe9de2d28a28f64ef8532abb3ac9c Mon Sep 17 00:00:00 2001
From: Griffin Smith <root@gws.fyi>
Date: Sun, 23 Oct 2022 12:28:23 -0400
Subject: [PATCH] feat(tvix/eval): Implement builtins.mapAttrs

I played around a little bit with doing this in-place, but ended up
going with this perhaps slightly clone-heavy approach for now because
ideally most clones on Value are cheap - but later we should benchmark
alternate approaches that get to reuse allocations better if necessary
or possible.

Change-Id: If998eb2056cedefdf2fb480b0568ac8329ccfc44
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7068
Autosubmit: grfn <grfn@gws.fyi>
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI
---
 tvix/eval/src/builtins/mod.rs                       | 13 +++++++++++++
 .../{notyetpassing => }/eval-okay-mapattrs.exp      |  0
 .../{notyetpassing => }/eval-okay-mapattrs.nix      |  0
 tvix/eval/src/value/attrs.rs                        | 10 ++++++++++
 4 files changed, 23 insertions(+)
 rename tvix/eval/src/tests/nix_tests/{notyetpassing => }/eval-okay-mapattrs.exp (100%)
 rename tvix/eval/src/tests/nix_tests/{notyetpassing => }/eval-okay-mapattrs.nix (100%)

diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs
index d6b52e20a..e7eb4e8bf 100644
--- a/tvix/eval/src/builtins/mod.rs
+++ b/tvix/eval/src/builtins/mod.rs
@@ -435,6 +435,19 @@ fn pure_builtins() -> Vec<Builtin> {
                 .map(|list| Value::List(NixList::from(list)))
                 .map_err(Into::into)
         }),
+        Builtin::new(
+            "mapAttrs",
+            &[true, true],
+            |args: Vec<Value>, vm: &mut VM| {
+                let attrs = args[1].to_attrs()?;
+                let mut res = BTreeMap::new();
+                for (key, value) in attrs.as_ref() {
+                    let value = vm.call_with(&args[0], [key.clone().into(), value.clone()])?;
+                    res.insert(key.clone(), value);
+                }
+                Ok(Value::attrs(NixAttrs::from_map(res)))
+            },
+        ),
         Builtin::new(
             "match",
             &[true, true],
diff --git a/tvix/eval/src/tests/nix_tests/notyetpassing/eval-okay-mapattrs.exp b/tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.exp
similarity index 100%
rename from tvix/eval/src/tests/nix_tests/notyetpassing/eval-okay-mapattrs.exp
rename to tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.exp
diff --git a/tvix/eval/src/tests/nix_tests/notyetpassing/eval-okay-mapattrs.nix b/tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.nix
similarity index 100%
rename from tvix/eval/src/tests/nix_tests/notyetpassing/eval-okay-mapattrs.nix
rename to tvix/eval/src/tests/nix_tests/eval-okay-mapattrs.nix
diff --git a/tvix/eval/src/value/attrs.rs b/tvix/eval/src/value/attrs.rs
index 17c7b422c..c0f82b921 100644
--- a/tvix/eval/src/value/attrs.rs
+++ b/tvix/eval/src/value/attrs.rs
@@ -517,3 +517,13 @@ impl<'a> Iterator for Keys<'a> {
         }
     }
 }
+
+impl<'a> IntoIterator for &'a NixAttrs {
+    type Item = (&'a NixString, &'a Value);
+
+    type IntoIter = Iter<KeyValue<'a>>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}