Simplify engine/internals/nodes.py (#10487)

[ci skip-rust]
[ci skip-build-wheels]

src/python/pants/engine/internals/nodes.py

@@ -1,57 +1,21 @@
-# Copyright 2015 Pants project contributors (see CONTRIBUTORS.md).
+# Copyright 2020 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
-import logging
-from abc import ABC
 from dataclasses import dataclass
 from typing import Any, Optional, Tuple
 
-logger = logging.getLogger(__name__)
-
-
-def _satisfied_by(t, o):
-    """Pickleable type check function."""
-    return t.satisfied_by(o)
-
-
-class State(ABC):
-    @classmethod
-    def raise_unrecognized(cls, state):
-        raise ValueError("Unrecognized Node State: {}".format(state))
-
-    @staticmethod
-    def from_components(components):
-        """Given the components of a State, construct the State."""
-        cls, remainder = components[0], components[1:]
-        return cls._from_components(remainder)
-
-    def to_components(self):
-        """Return a flat tuple containing individual pickleable components of the State.
-
-        TODO: Consider https://docs.python.org/2.7/library/pickle.html#pickling-and-unpickling-external-objects
-        for this usecase?
-        """
-        return (type(self),) + self._to_components()
-
 
 @dataclass(frozen=True)
-class Return(State):
+class Return:
     """Indicates that a Node successfully returned a value."""
 
     value: Any
 
-    @classmethod
-    def _from_components(cls, components):
-        return cls(components[0])
-
-    def _to_components(self):
-        return (self.value,)
-
 
 @dataclass(frozen=True)
-class Throw(State):
+class Throw:
     """Indicates that a Node should have been able to return a value, but failed."""
 
     exc: Exception
     python_traceback: Optional[str] = None
-    engine_traceback: Tuple[str, ...] = tuple()
+    engine_traceback: Tuple[str, ...] = ()