Replace lxml with xml.etree.ElementTree (#346)

* Replace lxml with xml.etree.ElementTree
Replace iter() with iterfind()
Remove lxml from setup.py
Remove done FIXME Graffitti
Remove lxml from travis

* Replace wildcard iter via iter over every element to be python3.7 compatible

.travis.yml

@@ -22,7 +22,6 @@ jobs:
 install:
   - pip install python-dateutil
   - pip install pytz
-  - pip install lxml
   - pip install aiofiles
   - pip install aiosqlite
   - pip install pytest --upgrade

asyncua/common/structures.py

@@ -9,8 +9,7 @@ import logging
 # The next two imports are for generated code
 from datetime import datetime
 from enum import Enum, IntEnum, EnumMeta
-from lxml import objectify
-
+from xml.etree import ElementTree as ET
 from asyncua import ua
 
 from .structures104 import get_default_value, clean_name
@@ -119,19 +118,21 @@ class StructGenerator(object):
         self.model = []
 
     def make_model_from_string(self, xml):
-        obj = objectify.fromstring(xml)
+        obj = ET.fromstring(xml)
         self._make_model(obj)
 
     def make_model_from_file(self, path):
-        obj = objectify.parse(path)
+        obj = ET.parse(path)
         root = obj.getroot()
         self._make_model(root)
 
     def _make_model(self, root):
         enums = {}
-        for child in root.iter("{*}EnumeratedType"):
+        for child in root:
+            if child.tag.endswith("EnumeratedType"):
                 intenum = EnumType(child.get("Name"))
-            for xmlfield in child.iter("{*}EnumeratedValue"):
+                for xmlfield in child:
+                    if xmlfield.tag.endswith("EnumeratedValue"):
                         name = xmlfield.get("Name")
                         value = xmlfield.get("Value")
                         enumvalue = EnumeratedValue(name, value)
@@ -139,10 +140,13 @@ class StructGenerator(object):
                         enums[child.get("Name")] = value
                 self.model.append(intenum)
 
-        for child in root.iter("{*}StructuredType"):
+        for child in root:
+            if child.tag.endswith("StructuredType"):
                 struct = Struct(child.get("Name"))
                 array = False
-            for xmlfield in child.iter("{*}Field"):
+                # these lines can be reduced in >= Python3.8 with root.iterfind("{*}Field") and similar
+                for xmlfield in child:
+                    if xmlfield.tag.endswith("Field"):
                         name = xmlfield.get("Name")
                         if name.startswith("NoOf"):
                             array = True

asyncua/common/xmlparser.py

@@ -110,7 +110,6 @@ class XMLParser:
         self.logger = logging.getLogger(__name__)
         self._retag = re.compile(r"(\{.*\})(.*)")
         self.root = None
-        # FIXME: hard to get these xml namespaces with ElementTree, we may have to shift to lxml
         self.ns = {
             'base': "http://opcfoundation.org/UA/2011/03/UANodeSet.xsd",
             'uax': "http://opcfoundation.org/UA/2008/02/Types.xsd",

setup.py

@@ -15,7 +15,7 @@ setup(
     packages=find_packages(),
     provides=["asyncua"],
     license="GNU Lesser General Public License v3 or later",
-    install_requires=["aiofiles", "aiosqlite", "python-dateutil", "pytz", "lxml", 'cryptography'],
+    install_requires=["aiofiles", "aiosqlite", "python-dateutil", "pytz", 'cryptography'],
     classifiers=[
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",