ENH: Implement DataFrame snapshot store for versioning support

Author: AkiTheMemeGod

pandas/core/frame_versioning.py

@@ -0,0 +1,69 @@
+# pandas/core/frame_versioning.py
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import datetime
+import uuid
+from typing import Dict, Optional
+
+import pandas as pd
+
+
+def _generate_snapshot_id(name: Optional[str] = None) -> str:
+    if name:
+        return name
+    ts = datetime.utcnow().strftime("%Y%m%dT%H%M%S%fZ")
+    uid = uuid.uuid4().hex[:8]
+    return f"{ts}-{uid}"
+
+
+@dataclass
+class SnapshotMeta:
+    name: str
+    created_at: datetime
+
+
+class DataFrameSnapshotStore:
+    """
+    Per-DataFrame snapshot store.
+    Stores deep copies of DataFrames (safe, simple).
+    """
+
+    def __init__(self) -> None:
+        # snapshot_id -> DataFrame
+        self._snapshots: Dict[str, pd.DataFrame] = {}
+        self._meta: Dict[str, SnapshotMeta] = {}
+
+    def snapshot(self, df: pd.DataFrame, name: Optional[str] = None) -> str:
+        sid = _generate_snapshot_id(name)
+        # deep copy for safety
+        self._snapshots[sid] = df.copy(deep=True)
+        self._meta[sid] = SnapshotMeta(name=sid, created_at=datetime.utcnow())
+        return sid
+
+    def restore(self, name: str) -> pd.DataFrame:
+        if name not in self._snapshots:
+            raise KeyError(f"Snapshot not found: {name}")
+        # return a deep copy so modifications don't change stored snapshot
+        return self._snapshots[name].copy(deep=True)
+
+    def list(self) -> list[str]:
+        return list(self._snapshots.keys())
+
+    def drop(self, name: str) -> None:
+        if name not in self._snapshots:
+            raise KeyError(f"Snapshot not found: {name}")
+        del self._snapshots[name]
+        del self._meta[name]
+
+    def clear(self) -> None:
+        self._snapshots.clear()
+        self._meta.clear()
+
+    def info(self, name: Optional[str] = None) -> dict:
+        if name:
+            if name not in self._meta:
+                raise KeyError(f"Snapshot not found: {name}")
+            meta = self._meta[name]
+            return {"name": meta.name, "created_at": meta.created_at.isoformat()}
+        return {"count": len(self._snapshots), "snapshots": [m.name for m in self._meta.values()]}