From dd63bfd2bf87b6d97e57620d89a3ec8727a48c00 Mon Sep 17 00:00:00 2001
From: Hao Zhang <hzhangxyz@outlook.com>
Date: Fri, 8 Aug 2025 16:40:38 +0800
Subject: [PATCH 1/2] Add clone function.

---
 grassmann_tensor/tensor.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/grassmann_tensor/tensor.py b/grassmann_tensor/tensor.py
index 30ec73e..9c5d109 100644
--- a/grassmann_tensor/tensor.py
+++ b/grassmann_tensor/tensor.py
@@ -358,3 +358,20 @@ def __itruediv__(self, other: typing.Any) -> GrassmannTensor:
         else:
             self._tensor /= other
         return self
+
+    def clone(self) -> GrassmannTensor:
+        """
+        Create a deep copy of the Grassmann tensor.
+        """
+        return dataclasses.replace(
+            self,
+            _tensor=self._tensor.clone(),
+            _parity=tuple(parity.clone() for parity in self._parity) if self._parity is not None else None,
+            _mask=self._mask.clone() if self._mask is not None else None,
+        )
+
+    def __copy__(self) -> GrassmannTensor:
+        return self.clone()
+
+    def __deepcopy__(self, memo: dict) -> GrassmannTensor:
+        return self.clone()

From 40862f068477cb116971bc5f1c73569deb5dda4d Mon Sep 17 00:00:00 2001
From: Hao Zhang <hzhangxyz@outlook.com>
Date: Fri, 8 Aug 2025 16:56:02 +0800
Subject: [PATCH 2/2] Add tests for clone.

---
 tests/clone_test.py | 50 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 tests/clone_test.py

diff --git a/tests/clone_test.py b/tests/clone_test.py
new file mode 100644
index 0000000..6a67bcc
--- /dev/null
+++ b/tests/clone_test.py
@@ -0,0 +1,50 @@
+import typing
+import copy
+import pytest
+import torch
+from grassmann_tensor import GrassmannTensor
+
+
+@pytest.mark.parametrize("parity,mask", [(True, True), (True, False), (False, False)])
+@pytest.mark.parametrize("which", ["clone", "copy", "deepcopy"])
+def test_clone(
+    parity: bool,
+    mask: bool,
+    which: typing.Literal["clone", "copy", "deepcopy"],
+) -> None:
+    original_tensor = GrassmannTensor(
+        _arrow=(False, True),
+        _edges=((2, 2), (1, 3)),
+        _tensor=torch.randn([4, 4]),
+    )
+
+    if parity:
+        _ = original_tensor.parity
+    if mask:
+        _ = original_tensor.mask
+
+    match which:
+        case "clone":
+            cloned_tensor = original_tensor.clone()
+        case "copy":
+            cloned_tensor = copy.copy(original_tensor)
+        case "deepcopy":
+            cloned_tensor = copy.deepcopy(original_tensor)
+
+    assert cloned_tensor._arrow == original_tensor._arrow
+    assert cloned_tensor._edges == original_tensor._edges
+    assert torch.equal(cloned_tensor._tensor, original_tensor._tensor)
+    if parity:
+        assert cloned_tensor._parity is not None
+        assert original_tensor._parity is not None
+        assert all(torch.equal(c, o) for c, o in zip(cloned_tensor._parity, original_tensor._parity))
+    else:
+        assert cloned_tensor._parity is original_tensor._parity
+    if mask:
+        assert cloned_tensor._mask is not None
+        assert original_tensor._mask is not None
+        assert torch.equal(cloned_tensor._mask, original_tensor._mask)
+    else:
+        assert cloned_tensor._mask is original_tensor._mask
+
+    assert id(original_tensor.tensor) != id(cloned_tensor.tensor)