XML Converter

Summary

Base functionality for matching and converting XML trees is implemented.

See: #145 (closed)

This should be reviewed and merged relatively soon. Follow-up issues will be created for the following tasks:

• user and API documentation (#159)
• design and implement more unit tests (#160)
• integration tests (#161)
• issue for creating attribute node converter and completing the text node converter (#158 (closed))

Focus

Have a look at #145 (closed) and check whether the requirements are met.

Test Environment

There are unit tests.

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• Up-to-date JSON schema (or not necessary)
• Appropriate user and developer documentation (or not necessary)
  • How do I use the software? Assume "stupid" users.
  • How do I develop or debug the software? Assume novice developers.
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md (or not necessary)
• Appropriate user and developer documentation (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there specifications? Are they satisfied?

For further good practices have a look at our review guidelines.

src/caoscrawler/structure_elements.py

@@ -24,6 +24,7 @@
 #
 
 import warnings
+import lxml.etree
 
 
 class StructureElement(object):
@@ -167,3 +168,53 @@ class DictDictElement(DictElement):
     def __init__(self, *args, **kwargs):
         warnings.warn(DeprecationWarning("This class is depricated. Please use DictElement."))
         super().__init__(*args, **kwargs)
+
+
+class XMLTagElement(StructureElement):
+    """
+    Stores elements of an XML tree.
+    """
+
+    def __init__(self, element: lxml.etree.Element):
+        super().__init__(element.getroottree().getelementpath(element))
+        self.tag = element
+
+
+class XMLTextNode(StructureElement):
+    """
+    Stores text nodes of XML trees.
+    """
+
+    def __init__(self, element: lxml.etree.Element):
+        """
+        Initializes this XML text node.
+
+        Please note that, although syntactically similar, it is semantically
+        different from TextElement:
+        - TextElements have a meaningful name, e.g. a key in a key-value pair. This name can
+          be matched using the match_name entry.
+        - XMLTextNodes just have a text and the name is just for identifying the structure element.
+          They can only be matched using the match entry in the XMLTextNodeConverter.
+        """
+        super().__init__(element.getroottree().getelementpath(element) + "/text()")
+        self.tag = element
+        self.value = element.text
+
+
+class XMLAttributeNode(StructureElement):
+    """
+    Stores text nodes of XML trees.
+    """
+
+    def __init__(self, element: lxml.etree.Element,
+                 key: str):
+        """
+        Initializes this XML attribute node.
+
+        element: The xml tree element containing the attribute.
+        key: The key which identifies the attribute in the list of attributes.
+        """
+        super().__init__(element.getroottree().getelementpath(element) + "@" + key)
+        self.value = element.attrib[key]
+        self.key = key
+        self.tag = element