1 files changed, 36 insertions, 0 deletions
diff --git a/duplicate_finder/types.py b/duplicate_finder/types.py
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+++ b/duplicate_finder/types.py
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+# SPDX-FileCopyrightText: 2026 Dennis Fink <me+coding@dennisfink.me>
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""Types used throughout the duplicate-file finder."""
+
+from collections import defaultdict
+from dataclasses import dataclass
+from pathlib import Path
+
+type FileIdentity = tuple[int, int]
+type FileSize = int
+type FileHash = str
+type FileExtension = str
+
+
+@dataclass(frozen=True, slots=True)
+class FileInfo:
+    """Store filesystem metadata collected while discovering a file.
+
+    :param path: Path through which the file was discovered.
+    :param size: File size in bytes.
+    :param identity: Filesystem identity as ``(device, inode)``.
+    """
+
+    path: Path
+    size: FileSize
+    identity: FileIdentity
+
+
+type FileSet = set[FileInfo]
+type FilesByIdentity = defaultdict[FileIdentity, FileSet]
+
+type CandidateGroupKey = FileSize | tuple[FileSize, FileExtension]
+type FilesByCandidateGroup = dict[CandidateGroupKey, FilesByIdentity]
+type FilesByHash = dict[FileHash, FileSet]