[breaking change] refactor data pipeline (#6901)

* refactor data

* rename file

Former-commit-id: 7a1a4ce6451cb782573d0bd9dd27a5e443e3a18b

tests/data/processor/test_processor_utils.py

@@ -0,0 +1,35 @@
+# Copyright 2025 the LlamaFactory team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from typing import Tuple
+
+import pytest
+
+from llamafactory.data.processor.processor_utils import infer_seqlen
+
+
+@pytest.mark.parametrize(
+    "test_input,test_output",
+    [
+        ((3000, 2000, 1000), (600, 400)),
+        ((2000, 3000, 1000), (400, 600)),
+        ((1000, 100, 1000), (900, 100)),
+        ((100, 1000, 1000), (100, 900)),
+        ((100, 500, 1000), (100, 500)),
+        ((500, 100, 1000), (500, 100)),
+        ((10, 10, 1000), (10, 10)),
+    ],
+)
+def test_infer_seqlen(test_input: Tuple[int, int, int], test_output: Tuple[int, int]):
+    assert test_output == infer_seqlen(*test_input)