Initial commit

pjvm/unpacker.py

@@ -0,0 +1,34 @@
+from io import BytesIO
+from struct import unpack, calcsize
+from typing import Dict, BinaryIO
+
+
+class Unpacker:
+    @staticmethod
+    def from_bytes(data: bytes):
+        return Unpacker({}, BytesIO(data))
+
+    def __init__(self, formats: Dict[str, str], stream: BinaryIO, endianness: str = '>'):
+        self.formats = formats
+        self.stream = stream
+        self.endianness = endianness
+
+    def __getattribute__(self, item):
+        try:
+            return super(Unpacker, self).__getattribute__(item)
+        except AttributeError:
+            return self.unpack(item)
+
+    def __getitem__(self, item):
+        return self.unpack(item)
+
+    def unpack(self, item):
+        if item in self.formats:
+            fmt = self.formats.get(item)
+        else:
+            fmt = item
+
+        fmt = self.endianness + fmt
+
+        size = calcsize(fmt)
+        return unpack(fmt, self.stream.read(size))