Add Buffer.pack_slot()

CHANGES.rst

@@ -4,7 +4,8 @@ Changelog
 master
 ------
 
-- Nothing yet
+- Added ``Buffer.pack_slot()`` method.
+- Added tests for slot packing and unpacking.
 
 v0.8
 ----

docs/data_types/buffers.rst

@@ -32,5 +32,6 @@ a byte string. A reference to the :class:`Buffer` class is available from
 .. automethod:: Buffer.pack_varint
 .. automethod:: Buffer.pack_uuid
 .. automethod:: Buffer.pack_position
+.. automethod:: Buffer.pack_slot
 .. automethod:: Buffer.pack_nbt
 .. automethod:: Buffer.pack_chunk_section

quarry/types/buffer.py

@@ -326,7 +326,28 @@ def pack_twos_comp(bits, number):
             pack_twos_comp(26, z))))
 
     @classmethod
-    def pack_nbt(cls, tag):
+    def pack_slot(cls, id=-1, count=1, damage=0, tag=None):
+        """
+        Packs a slot.
+        """
+
+        if id == -1:
+            return cls.pack('h', id)
+
+        return cls.pack('hbh', id, count, damage) + cls.pack_nbt(tag)
+
+    @classmethod
+    def pack_nbt(cls, tag=None):
+        """
+        Packs an NBT tag
+        """
+
+        if tag is None:
+            # slower but more obvious:
+            #   from quarry.types import nbt
+            #   tag = nbt.TagRoot({})
+            return "\x00"
+
         return tag.to_bytes()
 
     @classmethod

quarry/types/nbt.py

@@ -26,6 +26,9 @@ def to_obj(self):
     def __repr__(self):
         return "%s(%r)" % (type(self).__name__, self.value)
 
+    def __cmp__(self, other):
+        return cmp(self.to_obj(), other.to_obj())
+
 
 class _DataTag(_Tag):
     fmt = None

tests/types/test_buffer.py

@@ -1,6 +1,7 @@
 import pytest
 
 from quarry.types.buffer import Buffer, BufferUnderrun
+from quarry.types.nbt import *
 from quarry.types.uuid import UUID
 
 pack_unpack_vectors = [
@@ -34,6 +35,33 @@
     (2147483647, b"\xFF\xFF\xFF\xFF\x07"),
     (-2147483648, b"\x80\x80\x80\x80\x08"),
 ]
+slot_vectors = [
+    # Empty slot
+    ({'id': -1}, '\xFF\xFF'),
+
+    # 20 stone blocks
+    ({'id': 276, 'count': 20, 'damage': 0, 'tag': TagRoot({})},
+
+        '\x01\x14' # ID
+        '\x14'     # Count
+        '\x00\x00' # Damage
+        '\x00'),   # NBT
+
+    # Sharpness 4 diamond sword
+    ({'id': 276, 'count': 1, 'damage': 0, 'tag': TagRoot({u'': TagCompound({
+        u'ench': TagList([
+             TagCompound({
+                u'id': TagShort(16),
+                u'lvl': TagShort(4)})])})})},  # hmm
+
+        '\x01\x14' # ID
+        '\x01'     # Count
+        '\x00\x00' # Damage
+        '\x0A\x00\x00\x09\x00\x04ench\n\x00\x00\x00\x01' # NBT container start
+        '\x02\x00\x03lvl\x00\x04'                        # Enchantment level
+        '\x02\x00\x02id\x00\x10'                         # Enchantment type
+        '\x00\x00'),                                     # NBT container end
+]
 
 def test_add():
     buffer = Buffer()
@@ -100,6 +128,13 @@ def test_unpack_uuid():
     buffer.add(uuid_vector)
     assert buffer.unpack_uuid().to_bytes() == uuid_vector
 
+def test_unpack_slot():
+    buffer = Buffer()
+    for value, data in slot_vectors:
+        buffer.add(data)
+        assert buffer.unpack_slot() == value
+        assert len(buffer) == 0
+
 def test_pack():
     for fmt, data, values in pack_unpack_vectors:
         if not isinstance(values, tuple):
@@ -120,4 +155,8 @@ def test_pack_varint():
         assert Buffer.pack_varint(value, signed=True) == data
 
 def test_pack_uuid():
-    assert Buffer.pack_uuid(UUID.from_bytes(uuid_vector)) == uuid_vector
+    assert Buffer.pack_uuid(UUID.from_bytes(uuid_vector)) == uuid_vector
+
+def test_pack_slot():
+    for value, data in slot_vectors:
+        assert Buffer.pack_slot(**value) == data