Handle parameters in data urls (follow up PR)

data_url/__init__.py

@@ -1,5 +1,6 @@
 import re
 import base64
+from urllib.parse import unquote, quote
 
 DATA_URL_RE = re.compile(
     r"""
@@ -39,7 +40,7 @@ def construct_data_url(mime_type, base64_encoded, data):
     return data_url.url
 
 class DataURL:
-    URL_FORMAT = "data:{mime_type}{encoded},{data}"
+    URL_FORMAT = "data:{mime_type}{parameters}{encoded},{data}"
     ENCODING_STRING = ";base64"
 
     @classmethod
@@ -119,6 +120,14 @@ def __parse_url(self):
         if match:
             self._is_base64_encoded = match.group('encoded') is not None
             self._mime_type = match.group("MIME") or ""
+            params = match.group("parameters")
+            if params:
+                self._parameters = {}
+                for pair in params.split(";"):
+                    if pair:
+                        name, value = pair.split("=", 1)
+                        self._parameters[name] = unquote(value)
+
             raw_data = match.group('data')
             if self._is_base64_encoded:
                 self._data = base64.b64decode(raw_data)
@@ -130,8 +139,9 @@ def __parse_url(self):
     def __construct_url(self):
         """Constructs an actual data URL string from class attributes."""
         return self.URL_FORMAT.format(
-            mime_type=self._mime_type,
-            encoded=self.ENCODING_STRING if self._is_base64_encoded else "",
+            mime_type=self.mime_type,
+            parameters=";" + ";".join([f"{name}={quote(value)}" for name, value in self.parameters.items()]) if self.parameters else "",
+            encoded=self.ENCODING_STRING if self.is_base64_encoded else "",
             data=self.encoded_data
         )
 
@@ -164,3 +174,10 @@ def encoded_data(self):
         if self._is_base64_encoded:
             return base64.b64encode(self._data).decode('utf-8')
         return self._data
+
+    @property
+    def parameters(self):
+        """Attribute / Value parameters."""
+        if not hasattr(self, '_parameters'):
+            self._parameters = {}
+        return self._parameters

test/test_url.py

@@ -5,6 +5,9 @@
 from data_url import *
 
 class TestUrlCreation(unittest.TestCase):
+    example_url = "data:image/png;hello=world;name=two%20words;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=="
+    example_data = "iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=="
+
     # TODO tests with characters that need percent encoding
     def test_construct_data_url_string(self):
         mime_type = "text/plain"
@@ -64,6 +67,19 @@ def test_non_compliant_url(self):
         url = DataURL.from_url("not a url")
         assert url is None
 
+    def test_url_with_parameters(self):
+        url = DataURL.from_url(self.example_url)
+        self.assertEqual(url.mime_type, "image/png")
+        self.assertEqual(url.is_base64_encoded, True)
+        self.assertDictEqual(url.parameters, {"hello": "world", "name": "two words"})
+
+    def test_url_assembly_with_parameters(self):
+        url = DataURL.from_data("image/png", True, self.example_data)
+        url.parameters["hello"] = "world"
+        url.parameters["name"] = "two words"
+        self.assertEqual(str(url), self.example_url)
+
+
 class TestFromData(unittest.TestCase):
     def test_typing(self):
         with self.assertRaises(Exception) as context:
@@ -172,3 +188,10 @@ def run_assertions(self):
 
         self.assertEqual(self.url.is_base64_encoded, self.base64_encoded)
         self.assertEqual(self.expected_url, self.url.url)
+
+class TestFromUrl(unittest.TestCase):
+    def test_from_urls(self):
+        test_str = "data:image/png;charset=USASCII;name=file.png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=="
+        url = DataURL.from_url(test_str)
+        self.assertEqual(len(url.parameters), 2)
+        self.assertDictEqual(url.parameters, {"charset": "USASCII", "name": "file.png"})