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authorVincent Ambo <mail@tazj.in>2022-08-10T12·49+0300
committertazjin <tazjin@tvl.su>2022-08-14T00·24+0000
commit52736a1dbcedcab12e13ccf8a0d02a4b0db57cb1 (patch)
treefb2fcafeabfd2c2757f67abb3dc41c8bf0ab3b48
parent295d6e1d597c491f4bab3cf13c398814588eef49 (diff)
refactor(tvix/rm): introduce helper for AttrSet Entry API r/4443
There are multiple points where an insertion needs to be done into an
attribute set, but copying the key or checking for presence before
insertion should be avoided

As that is a little bit noisy, it's been factored out into a helper
function in this commit.

Change-Id: Ibcb054ebeb25a1236c06c812f47c8e74180d4fc9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6107
Tested-by: BuildkiteCI
Reviewed-by: grfn <grfn@gws.fyi>
-rw-r--r--tvix/eval/src/vm.rs47
1 files changed, 27 insertions, 20 deletions
diff --git a/tvix/eval/src/vm.rs b/tvix/eval/src/vm.rs
index b81281cf51..90f5f45f61 100644
--- a/tvix/eval/src/vm.rs
+++ b/tvix/eval/src/vm.rs
@@ -234,12 +234,7 @@ impl VM {
             //
             let key = self.pop();
             match key {
-                Value::String(ks) => {
-                    // TODO(tazjin): try_insert (rust#82766) or entry API
-                    if attrs.insert(ks.clone(), value).is_some() {
-                        return Err(Error::DuplicateAttrsKey { key: ks.0 });
-                    }
-                }
+                Value::String(ks) => set_attr(&mut attrs, ks, value)?,
 
                 Value::AttrPath(mut path) => {
                     set_nested_attr(
@@ -299,6 +294,29 @@ pub enum NumberPair {
     Integer(i64, i64),
 }
 
+// Set an attribute on an in-construction attribute set, while
+// checking against duplicate key.s
+fn set_attr(
+    attrs: &mut BTreeMap<NixString, Value>,
+    key: NixString,
+    value: Value,
+) -> EvalResult<()> {
+    let entry = attrs.entry(key);
+
+    match entry {
+        std::collections::btree_map::Entry::Occupied(entry) => {
+            return Err(Error::DuplicateAttrsKey {
+                key: entry.key().0.clone(),
+            })
+        }
+
+        std::collections::btree_map::Entry::Vacant(entry) => {
+            entry.insert(value);
+            return Ok(());
+        }
+    };
+}
+
 // Set a nested attribute inside of an attribute set, throwing a
 // duplicate key error if a non-hashmap entry already exists on the
 // path.
@@ -311,25 +329,14 @@ fn set_nested_attr(
     mut path: Vec<NixString>,
     value: Value,
 ) -> EvalResult<()> {
-    let entry = attrs.entry(key);
-
     // If there is no next key we are at the point where we
     // should insert the value itself.
     if path.is_empty() {
-        match entry {
-            std::collections::btree_map::Entry::Occupied(entry) => {
-                return Err(Error::DuplicateAttrsKey {
-                    key: entry.key().0.clone(),
-                })
-            }
-
-            std::collections::btree_map::Entry::Vacant(entry) => {
-                entry.insert(value);
-                return Ok(());
-            }
-        };
+        return set_attr(attrs, key, value);
     }
 
+    let entry = attrs.entry(key);
+
     // If there is not we go one step further down, in which case we
     // need to ensure that there either is no entry, or the existing
     // entry is a hashmap into which to insert the next value.