initial commit after bringing over cleaned up code and testing some examples

daemon/core/misc/structutils.py

@@ -0,0 +1,44 @@
+from core.misc import log
+
+logger = log.get_logger(__name__)
+
+
+def pack_values(clazz, packers):
+    """
+    Pack values for a given legacy class.
+
+    :param class clazz: class that will provide a pack method
+    :param list packers: a list of tuples that are used to pack values and transform them
+    :return: packed data string of all values
+    """
+
+    # iterate through tuples of values to pack
+    data = ""
+    for packer in packers:
+        # check if a transformer was provided for valid values
+        transformer = None
+        if len(packer) == 2:
+            tlv_type, value = packer
+        elif len(packer) == 3:
+            tlv_type, value, transformer = packer
+        else:
+            raise RuntimeError("packer had more than 3 arguments")
+
+        # convert unicode to normal str for packing
+        if isinstance(value, unicode):
+            value = str(value)
+
+        # only pack actual values and avoid packing empty strings
+        # protobuf defaults to empty strings and does no imply a value to set
+        if value is None or (isinstance(value, str) and not value):
+            continue
+
+        # transform values as needed
+        if transformer:
+            value = transformer(value)
+
+        # pack and add to existing data
+        logger.info("packing: %s - %s", tlv_type, value)
+        data += clazz.pack(tlv_type.value, value)
+
+    return data