fix: select

nix-js/runtime-ts/src/helpers.ts

@@ -46,44 +46,50 @@ export const resolvePath = (path: NixValue): string => {
   return Deno.core.ops.op_resolve_path(path_str);
 };
 
-/**
- * Select an attribute from an attribute set
- * Used by codegen for attribute access (e.g., obj.key)
- *
- * @param obj - Attribute set to select from
- * @param key - Key to select
- * @returns The value at obj[key]
- * @throws Error if obj is null/undefined or key not found
- */
-export const select = (obj: NixValue, key: NixValue): NixValue => {
-  const forced_obj = forceAttrs(obj);
-  const forced_key = forceString(key);
+export const select = (obj: NixValue, attrpath: NixValue[]): NixValue => {
+  let attrs = forceAttrs(obj);
 
-  if (!(forced_key in forced_obj)) {
-    throw new Error(`Attribute '${forced_key}' not found`);
+  for (const attr of attrpath.slice(0, -1)) {
+    const key = forceString(attr)
+    if (!(key in attrs)) {
+      throw new Error(`Attribute '${key}' not found`);
+    }
+    const cur = force(attrs[forceString(attr)]);
+    if (!isAttrs(cur)) {
+      // throw new Error(`Attribute '${forced_key}' not found`);
+      // FIXME: error
+      throw new Error(`Attribute not found`);
+    }
+    attrs = cur;
   }
 
-  return forced_obj[forced_key];
+  const last = forceString(attrpath[attrpath.length - 1])
+  if (!(last in attrs)) {
+    throw new Error(`Attribute '${last}' not found`);
+  }
+  return attrs[last];
 };
 
-/**
- * Select an attribute with a default value
- * Used for Nix's `obj.key or default` syntax
- *
- * @param obj - Attribute set to select from
- * @param key - Key to select
- * @param default_val - Value to return if key not found (will be forced if it's a thunk)
- * @returns obj[key] if exists, otherwise force(default_val)
- */
-export const selectWithDefault = (obj: NixValue, key: NixValue, default_val: NixValue): NixValue => {
-  const attrs = forceAttrs(obj);
-  const forced_key = forceString(key);
+export const selectWithDefault = (obj: NixValue, attrpath: NixValue[], default_val: NixValue): NixValue => {
+  let attrs = forceAttrs(obj);
 
-  if (!(forced_key in attrs)) {
-    return force(default_val);
+  for (const attr of attrpath.slice(0, -1)) {
+    const key = forceString(attr)
+    if (!(key in attrs)) {
+      return default_val
+    }
+    const cur = force(attrs[key]);
+    if (!isAttrs(cur)) {
+      return default_val;
+    }
+    attrs = cur;
   }
 
-  return attrs[forced_key];
+  const last = forceString(attrpath[attrpath.length - 1]);
+  if (last in attrs) {
+    return attrs[last]
+  }
+  return default_val;
 };
 
 export const hasAttr = (obj: NixValue, attrpath: NixValue[]): NixBool => {
@@ -93,14 +99,14 @@ export const hasAttr = (obj: NixValue, attrpath: NixValue[]): NixBool => {
   let attrs = obj;
 
   for (const attr of attrpath.slice(0, -1)) {
-    const cur = attrs[forceString(attr)];
+    const cur = force(attrs[forceString(attr)]);
     if (!isAttrs(cur)) {
       return false;
     }
     attrs = cur;
   }
 
-  return true;
+  return forceString(attrpath[attrpath.length - 1]) in attrs;
 };
 
 /**

nix-js/src/codegen.rs

@@ -225,47 +225,21 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Let {
 
 impl<Ctx: CodegenContext> Compile<Ctx> for Select {
     fn compile(&self, ctx: &Ctx) -> String {
-        let expr = ctx.get_ir(self.expr).compile(ctx);
-
-        let mut result = expr;
-        let attr_count = self.attrpath.len();
-
-        for (i, attr) in self.attrpath.iter().enumerate() {
-            let is_last = i == attr_count - 1;
-            result = match attr {
-                Attr::Str(sym) => {
-                    let key = ctx.get_sym(*sym).escape_quote();
-                    if let Some(default) = self.default
-                        && is_last
-                    {
-                        let default_val = ctx.get_ir(default).compile(ctx);
-                        format!(
-                            "Nix.selectWithDefault({}, {}, {})",
-                            result, key, default_val
-                        )
+        let lhs = ctx.get_ir(self.expr).compile(ctx);
+        let attrpath = self
+            .attrpath
+            .iter()
+            .map(|attr| match attr {
+                Attr::Str(sym) => ctx.get_sym(*sym).escape_quote(),
+                Attr::Dynamic(expr_id) => ctx.get_ir(*expr_id).compile(ctx),
+            })
+            .join(",");
+        if let Some(default) = self.default {
+            format!("Nix.selectWithDefault({lhs}, [{attrpath}], {})", ctx.get_ir(default).compile(ctx))
         } else {
-                        format!("Nix.select({}, {})", result, key)
+            format!("Nix.select({lhs}, [{attrpath}])")
         }
     }
-                Attr::Dynamic(expr_id) => {
-                    let key = ctx.get_ir(*expr_id).compile(ctx);
-                    if let Some(default) = self.default
-                        && is_last
-                    {
-                        let default_val = ctx.get_ir(default).compile(ctx);
-                        format!(
-                            "Nix.selectWithDefault({}, {}, {})",
-                            result, key, default_val
-                        )
-                    } else {
-                        format!("Nix.select({}, {})", result, key)
-                    }
-                }
-            };
-        }
-
-        result
-    }
 }
 
 impl<Ctx: CodegenContext> Compile<Ctx> for AttrSet {