Add method to get the URI scheme to support cloud storage

.gitignore

@@ -15,3 +15,5 @@ python/build
 python/dist
 
 notebooks/.ipynb_checkpoints
+
+**/.hypothesis

python/lancedb/util.py

@@ -0,0 +1,38 @@
+#  Copyright 2023 LanceDB Developers
+#
+#  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 urllib.parse import ParseResult, urlparse
+
+from pyarrow import fs
+
+
+def get_uri_scheme(uri: str) -> str:
+    """
+    Get the scheme of a URI. If the URI does not have a scheme, assume it is a file URI.
+
+    Parameters
+    ----------
+    uri : str
+        The URI to parse.
+
+    Returns
+    -------
+    str: The scheme of the URI.
+    """
+    parsed = urlparse(uri)
+    scheme = parsed.scheme
+    if not scheme:
+        scheme = "file"
+    elif scheme in ["s3a", "s3n"]:
+        scheme = "s3"
+    return scheme

python/tests/test_util.py

@@ -0,0 +1,29 @@
+#  Copyright 2023 LanceDB Developers
+#
+#  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 lancedb.util import get_uri_scheme
+
+
+def test_normalize_uri():
+    uris = [
+        "relative/path",
+        "/absolute/path",
+        "file:///absolute/path",
+        "s3://bucket/path",
+        "gs://bucket/path",
+    ]
+    schemes = ["file", "file", "file", "s3", "gs"]
+
+    for uri, expected_scheme in zip(uris, schemes):
+        parsed_scheme = get_uri_scheme(uri)
+        assert parsed_scheme == expected_scheme