add type hint for core/computation/eval

pandas/core/computation/eval.py

@@ -5,17 +5,21 @@
 """
 
 import tokenize
+from typing import Any, Dict, Iterable, List, Optional, Tuple, Union
 import warnings
 
+import numpy as np
+
 from pandas.util._validators import validate_bool_kwarg
 
+import pandas as pd
 from pandas.core.computation.engines import _engines
 from pandas.core.computation.scope import _ensure_scope
 
 from pandas.io.formats.printing import pprint_thing
 
 
-def _check_engine(engine):
+def _check_engine(engine: Optional[str]) -> str:
     """
     Make sure a valid engine is passed.
 
@@ -60,7 +64,7 @@ def _check_engine(engine):
     return engine
 
 
-def _check_parser(parser):
+def _check_parser(parser: str) -> None:
     """
     Make sure a valid parser is passed.
 
@@ -80,7 +84,7 @@ def _check_parser(parser):
                        ' {valid}'.format(parser=parser, valid=_parsers.keys()))
 
 
-def _check_resolvers(resolvers):
+def _check_resolvers(resolvers: Iterable) -> None:
     if resolvers is not None:
         for resolver in resolvers:
             if not hasattr(resolver, '__getitem__'):
@@ -89,7 +93,7 @@ def _check_resolvers(resolvers):
                                 'the __getitem__ method'.format(name=name))
 
 
-def _check_expression(expr):
+def _check_expression(expr: str) -> None:
     """
     Make sure an expression is not an empty string
 
@@ -107,7 +111,7 @@ def _check_expression(expr):
         raise ValueError("expr cannot be an empty string")
 
 
-def _convert_expression(expr):
+def _convert_expression(expr: str) -> str:
     """
     Convert an object to an expression.
 
@@ -136,7 +140,7 @@ def _convert_expression(expr):
     return s
 
 
-def _check_for_locals(expr, stack_level, parser):
+def _check_for_locals(expr: str, stack_level: int, parser: str) -> None:
     from pandas.core.computation.expr import tokenize_string
 
     at_top_of_stack = stack_level == 0
@@ -154,11 +158,20 @@ def _check_for_locals(expr, stack_level, parser):
         for toknum, tokval in tokenize_string(expr):
             if toknum == tokenize.OP and tokval == '@':
                 raise SyntaxError(msg)
-
-
-def eval(expr, parser='pandas', engine=None, truediv=True,
-         local_dict=None, global_dict=None, resolvers=(), level=0,
-         target=None, inplace=False):
+    return None
+
+
+def eval(expr: str,
+         parser: str = 'pandas',
+         engine: str = None,
+         truediv: bool = True,
+         local_dict: List[Dict[str, Any]] = None,
+         global_dict: List[Dict[str, Any]] = None,
+         resolvers: Tuple = (),
+         level: int = 0,
+         target: Union[float, np.ndarray, pd.DataFrame, pd.Series] = None,
+         inplace: bool = False,
+         ) -> Union[float, np.ndarray, pd.DataFrame, pd.Series]:
     """
     Evaluate a Python expression as a string using various backends.
 
@@ -353,3 +366,5 @@ def eval(expr, parser='pandas', engine=None, truediv=True,
     # We want to exclude `inplace=None` as being False.
     if inplace is False:
         return target if target_modified else ret
+    else:
+        return None