Add support for parsing XML files (#51)

* Add support for parsing XML files

* Add sample.xml test

* lint

data/sample.xml

@@ -0,0 +1,14 @@
+<library>
+   <book>
+      <title>The Fellowship of the Ring</title>
+      <publication-year>1954</publication-year>
+   </book>
+   <book>
+      <title>The Two Towers</title>
+      <publication-year>1954</publication-year>
+   </book>
+   <book>
+      <title>The Return of the King</title>
+      <publication-year>1955</publication-year>
+   </book>
+</library>

dataflows/processors/load.py

@@ -1,11 +1,68 @@
 import os
 
 from datapackage import Package, Resource
+from tabulator.parser import Parser
+from tabulator.helpers import reset_stream
 from .. import DataStreamProcessor
 from ..base.schema_validator import schema_validator
 from ..helpers.resource_matcher import ResourceMatcher
 
 
+class XMLParser(Parser):
+    options = []
+
+    def __init__(self, loader, force_parse, **options):
+        self.__loader = loader
+        self.__force_parse = force_parse
+        self.__extended_rows = None
+        self.__encoding = None
+        self.__chars = None
+
+    def open(self, source, encoding=None):
+        self.close()
+        self.__chars = self.__loader.load(source, encoding=encoding)
+        self.__encoding = getattr(self.__chars, 'encoding', encoding)
+        if self.__encoding:
+            self.__encoding.lower()
+        self.reset()
+
+    def close(self):
+        if not self.closed:
+            self.__chars.close()
+
+    def reset(self):
+        reset_stream(self.__chars)
+        self.__extended_rows = self.__iter_extended_rows()
+
+    @property
+    def closed(self):
+        return self.__chars is None or self.__chars.closed
+
+    @property
+    def encoding(self):
+        return self.__encoding
+
+    @property
+    def extended_rows(self):
+        return self.__extended_rows
+
+    # Private
+
+    def __iter_extended_rows(self):
+        from xml.etree.ElementTree import parse
+        from xmljson import parker
+
+        parsed = parker.data(parse(self.__chars).getroot())
+        elements = list(parsed.values())
+        if len(elements) > 0:
+            elements = elements[0]
+        else:
+            elements = []
+        for row_number, row in enumerate(elements, start=1):
+            keys, values = zip(*(row.items()))
+            yield (row_number, list(keys), list(values))
+
+
 class load(DataStreamProcessor):
 
     def __init__(self, load_source, name=None, resources=None, validate=False, strip=True, **options):
@@ -50,6 +107,8 @@ def process_datapackage(self, dp: Package):
                 descriptor['format'] = self.options.get('format')
                 if 'encoding' in self.options:
                     descriptor['encoding'] = self.options['encoding']
+                if descriptor['format'] == 'xml' or self.load_source.endswith('.xml'):
+                    self.options.setdefault('custom_parsers', {})['xml'] = XMLParser
                 self.options.setdefault('ignore_blank_headers', True)
                 self.options.setdefault('headers', 1)
                 self.res = Resource(descriptor,

setup.py

@@ -29,6 +29,7 @@ def read(*paths):
     'inquirer',
     'tabulate',
     'tableschema-sql',
+    'xmljson',
 ]
 SPEEDUP_REQUIRES = [
     'plyvel',

tests/test_lib.py

@@ -535,4 +535,15 @@ def func(row):
         {'a': 3, 'b': 4}, 
         {'a': 5, 'b': 6}
     ]
-    assert len(dp.resources[0].schema.fields) == 2
+    assert len(dp.resources[0].schema.fields) == 2
+
+def test_load_xml():
+    from dataflows import Flow, load
+
+    results, dp, stats = Flow(load('data/sample.xml')).results()
+
+    assert results[0] == [
+        {'publication-year': 1954, 'title': 'The Fellowship of the Ring'}, 
+        {'publication-year': 1954, 'title': 'The Two Towers'}, 
+        {'publication-year': 1955, 'title': 'The Return of the King'}
+    ]