#69 Komprimering og dekomprimering

soitool/compressor.py

+"""Functions for compression and decompression."""
+
+import lzma
+import json
+import codecs
+
+
+def compress(obj):
+    """
+    Compress a json compatible object using the lzma algorithm.
+
+    JSON compatible object are python types that are possible to convert to
+    JSON types. Se overview in this link:
+    https://docs.python.org/3/library/json.html#py-to-json-table
+
+    Parameters
+    ----------
+    obj : json compatible object
+        Object to compress
+
+    Returns
+    -------
+    string
+        The compressed data casted from bytest to string
+    """
+    obj = json.dumps(obj)
+    obj = obj.encode(encoding="ascii")
+    return str(lzma.compress(obj))
+
+
+def decompress(lzma_compressed_json_string):
+    """
+    Decompress a lzma-compressed json string.
+
+    Decompresses a json compatible python object which is casted from bytes to
+    string.
+
+    Parameters
+    ----------
+    lzma_compressed_json_string : string
+        The string of the lzma-compressed json string
+
+    Returns
+    -------
+    python object
+        One of these python objects:
+        https://docs.python.org/3/library/json.html#py-to-json-table
+    """
+    # Remove extra b' notation
+    lzma_compressed_json_string = lzma_compressed_json_string[2:-1].encode(
+        encoding="ascii"
+    )
+    # Remove double \\
+    lzma_compressed_json_string = codecs.escape_decode(
+        lzma_compressed_json_string, "hex"
+    )
+    # Decompress
+    lzma_compressed_json_string = lzma.decompress(
+        lzma_compressed_json_string[0]
+    )
+    # Cast to ascii string
+    lzma_compressed_json_string = lzma_compressed_json_string.decode(
+        encoding="ascii"
+    )
+    # Return as python datastructure
+    return json.loads(lzma_compressed_json_string)