refactor[types]: remove unused _NodeMetadataJournal

vyper/ast/metadata.py

@@ -1,83 +1,8 @@
-import contextlib
-from typing import Any
-
-from vyper.exceptions import VyperException
-
-
-# a commit/rollback scheme for metadata caching. in the case that an
-# exception is thrown and caught during type checking (currently, only
-# during for loop iterator variable type inference), we can roll back
-# any state updates due to type checking.
-# this is implemented as a stack of changesets, because we need to
-# handle nested rollbacks in the case of nested for loops
-class _NodeMetadataJournal:
-    _NOT_FOUND = object()
-
-    def __init__(self):
-        self._node_updates: list[dict[tuple[int, str, Any], NodeMetadata]] = []
-
-    def register_update(self, metadata, k):
-        KEY = (id(metadata), k)
-        if KEY in self._node_updates[-1]:
-            return
-        prev = metadata.get(k, self._NOT_FOUND)
-        self._node_updates[-1][KEY] = (metadata, prev)
-
-    @contextlib.contextmanager
-    def enter(self):
-        self._node_updates.append({})
-        try:
-            yield
-        except VyperException as e:
-            # note: would be better to only catch typechecker exceptions here.
-            self._rollback_inner()
-            raise e from e
-        else:
-            self._commit_inner()
-
-    def _rollback_inner(self):
-        for (_, k), (metadata, prev) in self._node_updates[-1].items():
-            if prev is self._NOT_FOUND:
-                metadata.pop(k, None)
-            else:
-                metadata[k] = prev
-        self._pop_inner()
-
-    def _commit_inner(self):
-        inner = self._pop_inner()
-
-        if len(self._node_updates) == 0:
-            return
-
-        outer = self._node_updates[-1]
-
-        # register with previous frame in case inner gets committed
-        # but outer needs to be rolled back
-        for (_, k), (metadata, prev) in inner.items():
-            if (id(metadata), k) not in outer:
-                outer[(id(metadata), k)] = (metadata, prev)
-
-    def _pop_inner(self):
-        return self._node_updates.pop()
-
-
 class NodeMetadata(dict):
     """
-    A data structure which allows for journaling.
+    The data structure which represents a Node's metadata
     """
 
-    _JOURNAL: _NodeMetadataJournal = _NodeMetadataJournal()
-
     def __setitem__(self, k, v):
-        # if we are in a context where we need to journal, add
-        # this to the changeset.
-        if len(self._JOURNAL._node_updates) != 0:
-            self._JOURNAL.register_update(self, k)
 
         super().__setitem__(k, v)
-
-    @classmethod
-    @contextlib.contextmanager
-    def enter_typechecker_speculation(cls):
-        with cls._JOURNAL.enter():
-            yield