move field access to front, do getitem, then use rest

src/dask_awkward/lib/core.py

@@ -1397,15 +1397,16 @@ def _getitem_slice_on_zero(self, where):
         )
 
     def _getitem_tuple(self, where):
-        where = field_access_to_front(where)
+        where, n_field_accesses = field_access_to_front(where)
+
         if isinstance(where[0], int):
             return self._getitem_outer_int(where)
 
         elif isinstance(where[0], (str, list)):
-            first, rest = where[0], where[1:]
+            first, rest = where[:n_field_accesses], where[n_field_accesses:]
             if rest:
-                return self[first][rest]
-            return self[first]
+                return self._getitem_trivial_map_partitions(first)[rest]
+            return self._getitem_trivial_map_partitions(first)
 
         elif isinstance(where[0], slice) and is_empty_slice(where[0]):
             return self._getitem_trivial_map_partitions(where)

src/dask_awkward/utils.py

@@ -1,8 +1,7 @@
 from __future__ import annotations
 
-from collections.abc import Callable, Iterable, Mapping
+from collections.abc import Callable, Iterable, Mapping, Sequence
 from typing import TYPE_CHECKING, Any, TypeVar
-from collections.abc import Sequence
 
 from typing_extensions import ParamSpec
 
@@ -160,7 +159,7 @@ def field_access_like(entry: Any) -> bool:
     return False
 
 
-def field_access_to_front(seq: Sequence[Any]) -> tuple[Any, ...]:
+def field_access_to_front(seq: Sequence[Any]) -> tuple[tuple[Any, ...], int]:
     new_seq = []
     n_front = 0
     for entry in seq:
@@ -169,4 +168,4 @@ def field_access_to_front(seq: Sequence[Any]) -> tuple[Any, ...]:
             n_front += 1
         else:
             new_seq.append(entry)
-    return tuple(new_seq)
+    return tuple(new_seq), n_front

tests/test_utils.py

@@ -45,28 +45,36 @@ def test_hyphenize() -> None:
         (
             (1, 3, 2, "z", "a"),
             ("z", "a", 1, 3, 2),
+            2,
         ),
         (
             ("a", 1, 2, ["1", "2"]),
             ("a", ["1", "2"], 1, 2),
+            2,
         ),
         (
             (0, ["a", "b", "c"]),
             (["a", "b", "c"], 0),
+            1,
         ),
         (
             ("hello", "abc"),
             ("hello", "abc"),
+            2,
         ),
         (
             (1, 2, slice(None, None, 2), 3),
             (1, 2, slice(None, None, 2), 3),
+            0,
         ),
         (
             (0, ["a", 0], ["a", "b"]),
             (["a", "b"], 0, ["a", 0]),
+            1,
         ),
     ],
 )
 def test_field_access_to_front(pairs):
-    assert field_access_to_front(pairs[0]) == pairs[1]
+    res = field_access_to_front(pairs[0])
+    assert res[0] == pairs[1]
+    assert res[1] == pairs[2]