WIP: Support private ranges

multicodec/constants.py

@@ -446,3 +446,4 @@
 
 NAME_TABLE = {name: value['prefix'] for name, value in CODECS.items()}
 CODE_TABLE = {value['prefix']: name for name, value in CODECS.items()}
+PRIVATE_RANGE = (0x300000, 0x3FFFFF)

multicodec/multicodec.py

@@ -1,6 +1,6 @@
 import varint
 
-from .constants import NAME_TABLE, CODE_TABLE
+from .constants import NAME_TABLE, CODE_TABLE, PRIVATE_RANGE
 
 
 def extract_prefix(bytes_):
@@ -22,11 +22,14 @@ def get_prefix(multicodec):
     """
     Returns prefix for a given multicodec
 
-    :param str multicodec: multicodec codec name
+    :param str / int multicodec: str for multicodec name, int if you wish to use a private code
     :return: the prefix for the given multicodec
     :rtype: byte
     :raises ValueError: if an invalid multicodec name is provided
     """
+    if is_private_codec(multicodec):
+        return varint.encode(multicodec)
+
     try:
         prefix = varint.encode(NAME_TABLE[multicodec])
     except KeyError:
@@ -38,7 +41,7 @@ def add_prefix(multicodec, bytes_):
     """
     Adds multicodec prefix to the given bytes input
 
-    :param str multicodec: multicodec to use for prefixing
+    :param str / int multicodec: str for multicodec to use for prefixing, int if you wish to use a private code
     :param bytes bytes_: data to prefix
     :return: prefixed byte data
     :rtype: bytes
@@ -65,16 +68,32 @@ def get_codec(bytes_):
     Gets the codec used for prefix the multicodec prefixed data
 
     :param bytes bytes_: multicodec prefixed data bytes
-    :return: name of the multicodec used to prefix
-    :rtype: str
+    :return: name of the multicodec used to prefix, int codec if it is part of private space
+    :rtype: str / int
     """
     prefix = extract_prefix(bytes_)
+    if is_private_codec(prefix):
+        return prefix
+
     try:
         return CODE_TABLE[prefix]
     except KeyError:
         raise ValueError('Prefix {} not present in the lookup table'.format(prefix))
 
 
+def is_private_codec(codec):
+    """
+    Check if the codec is within the private range or not
+
+    :param int codec: codec to check for permitted to use under private space
+    :return: True if the codec lies within the private usage range, False otherwise
+    :rtype: bool
+    """
+    if isinstance(codec, int) and PRIVATE_RANGE[0] <= codec <= PRIVATE_RANGE[1]:
+        return True
+    return False
+
+
 def is_codec(name):
     """
     Check if the codec is a valid codec or not

tests/test_multicodec.py

@@ -29,6 +29,17 @@ def test_verify_prefix_complete(multicodec, prefix):
     assert extract_prefix(prefixed_data) == prefix_int
 
 
+@pytest.mark.parametrize('multicodec', (0x300000, 0x3FFFFF,))
+def test_verify_private_range_complete(multicodec):
+    data = b'testbytesbuffer'
+    prefix_int = multicodec
+    prefixed_data = add_prefix(multicodec, data)
+
+    assert get_codec(prefixed_data) == multicodec
+    assert remove_prefix(prefixed_data) == data
+    assert extract_prefix(prefixed_data) == prefix_int
+
+
 @pytest.mark.parametrize('multicodec,_', INVALID_CODECS)
 def test_get_prefix_invalid_prefix(multicodec, _):
     with pytest.raises(ValueError) as excinfo: