BUG: Partially revert #1758

This caused a few failures with downstream code, so I've reverted the
changes to ibis/pandas/core.py.  I've left other fixes from #1758
unchanged.  I'll revisit the reimplementation in the near future.
Author: Phillip Cloud <cpcloud@gmail.com>

Closes #1837 from cpcloud/revert-topo and squashes the following commits:

c9662ac [Phillip Cloud] Just pass kwargs through
5d8ec82 [Phillip Cloud] Make zero argument UDFs work again
9fa4481 [Phillip Cloud] Revert toposort change
d9c00ef [Phillip Cloud] Remove unnecessary code
deed6aa [Phillip Cloud] Revert select parts

ibis/file/client.py

@@ -2,8 +2,7 @@
 
 import ibis
 import ibis.expr.types as ir
-from ibis.pandas.core import execute
-from ibis.pandas.dispatch import execute_last
+from ibis.pandas.core import execute_and_reset
 
 
 class FileClient(ibis.client.Client):
@@ -35,15 +34,8 @@ def database(self, name=None, path=None):
         return FileDatabase(name, self, path=path)
 
     def execute(self, expr, params=None, **kwargs):  # noqa
-        assert isinstance(expr, ir.Expr), "Expected ir.Expr, got {}".format(
-            type(expr)
-        )
-        return execute_last(
-            expr.op(),
-            execute(expr, params=params, **kwargs),
-            params=params,
-            **kwargs,
-        )
+        assert isinstance(expr, ir.Expr)
+        return execute_and_reset(expr, params=params, **kwargs)
 
     def list_tables(self, path=None):
         raise NotImplementedError

ibis/file/tests/test_csv.py

@@ -74,6 +74,9 @@ def test_read(csv, data):
     expected['time'] = expected['time'].astype(str)
     tm.assert_frame_equal(result, expected)
 
+    result = closes.execute()
+    tm.assert_frame_equal(result, expected)
+
 
 def test_read_with_projection(csv2, data):
 

ibis/file/tests/test_hdf5.py

@@ -90,6 +90,9 @@ def test_read(hdf, data):
     expected = data['close']
     tm.assert_frame_equal(result, expected)
 
+    result = closes.execute()
+    tm.assert_frame_equal(result, expected)
+
 
 def test_insert(transformed, tmpdir):
 

ibis/file/tests/test_parquet.py

@@ -4,7 +4,6 @@
 from pandas.util import testing as tm
 
 import ibis
-
 from ibis.file.client import FileDatabase
 
 pa = pytest.importorskip('pyarrow')  # isort:skip
@@ -87,6 +86,9 @@ def test_read(parquet, data):
     expected = data['close']
     tm.assert_frame_equal(result, expected)
 
+    result = closes.execute()
+    tm.assert_frame_equal(result, expected)
+
 
 def test_write(transformed, tmpdir):
     t = transformed

ibis/pandas/client.py

@@ -20,8 +20,7 @@
 import ibis.expr.schema as sch
 import ibis.expr.types as ir
 from ibis.compat import CategoricalDtype, DatetimeTZDtype
-from ibis.pandas.core import execute
-from ibis.pandas.dispatch import execute_last
+from ibis.pandas.core import execute_and_reset
 
 try:
     infer_pandas_dtype = pd.api.types.infer_dtype
@@ -370,9 +369,7 @@ def execute(self, query, params=None, limit='default', **kwargs):
                     type(query).__name__
                 )
             )
-        result = execute(query, params=params, **kwargs)
-        query_op = query.op()
-        return execute_last(query_op, result, params=params, **kwargs)
+        return execute_and_reset(query, params=params, **kwargs)
 
     def compile(self, expr, *args, **kwargs):
         """Compile `expr`.