add more stuff to kompress; less kython deps

my/kython/kompress.py

@@ -0,0 +1,47 @@
+"""
+Various helpers for compression
+"""
+from pathlib import Path, PosixPath
+from typing import Union
+
+PathIsh = Union[Path, str]
+
+
+def _zstd_open(path: Path):
+    import zstandard as zstd # type: ignore
+    fh = path.open('rb')
+    dctx = zstd.ZstdDecompressor()
+    reader = dctx.stream_reader(fh)
+    return reader
+
+
+def kopen(path: PathIsh, *args, **kwargs): # TODO is it bytes stream??
+    pp = Path(path)
+    suf = pp.suffix
+    if suf in {'.xz'}:
+        import lzma
+        return lzma.open(pp, *args, **kwargs)
+    elif suf in {'.zip'}:
+        from zipfile import ZipFile
+        return ZipFile(pp).open(*args, **kwargs)
+    elif suf in {'.lz4'}:
+        import lz4.frame # type: ignore
+        return lz4.frame.open(str(pp))
+    elif suf in {'.zstd'}:
+        return _zstd_open(pp)
+    else:
+        return pp.open(*args, **kwargs)
+
+
+class CPath(PosixPath):
+    """
+    Ugh. So, can't override Path because of some _flavour thing.
+    Path only has _accessor and _closed slots, so can't directly set .open method
+    _accessor.open has to return file descriptor, doesn't work for compressed stuff.
+    """
+    def open(self, *args, **kwargs):
+        # TODO assert read only?
+        return kopen(str(self))
+
+
+open = kopen # TODO FIXME remove?