Renamed module tracer → trace

This is consistent with the other module names.

blender_asset_tracer/trace/file_sequence.py

@@ -0,0 +1,49 @@
+import logging
+import pathlib
+import typing
+
+log = logging.getLogger(__name__)
+
+
+class DoesNotExist(OSError):
+    """Indicates a path does not exist on the filesystem."""
+
+    def __init__(self, path: pathlib.Path):
+        super().__init__(path)
+        self.path = path
+
+
+def expand_sequence(path: pathlib.Path) -> typing.Iterator[pathlib.Path]:
+    """Expand a file sequence path into the actual file paths.
+
+    :param path: can be either a glob pattern (must contain a * character)
+        or the path of the first file in the sequence.
+    """
+
+    if '*' in str(path):  # assume it is a glob
+        import glob
+        log.debug('expanding glob %s', path)
+        for fname in sorted(glob.glob(str(path), recursive=True)):
+            yield pathlib.Path(fname)
+        return
+
+    if not path.exists():
+        raise DoesNotExist(path)
+
+    if path.is_dir():
+        raise TypeError('path is a directory: %s' % path)
+
+    log.debug('expanding file sequence %s', path)
+
+    import string
+    stem_no_digits = path.stem.rstrip(string.digits)
+    if stem_no_digits == path.stem:
+        # Just a single file, no digits here.
+        yield path
+        return
+
+    # Return everything start starts with 'stem_no_digits' and ends with the
+    # same suffix as the first file. This may result in more files than used
+    # by Blender, but at least it shouldn't miss any.
+    pattern = '%s*%s' % (stem_no_digits, path.suffix)
+    yield from sorted(path.parent.glob(pattern))