[text] implement 'parse_query_list()'

gallery_dl/text.py

@@ -238,7 +238,10 @@ def parse_float(value, default=0.0):
 
 
 def parse_query(qs):
-    """Parse a query string into key-value pairs"""
+    """Parse a query string into name-value pairs
+
+    Ignore values whose name has been seen before
+    """
     if not qs:
         return {}
 
@@ -255,6 +258,34 @@ def parse_query(qs):
     return result
 
 
+def parse_query_list(qs):
+    """Parse a query string into name-value pairs
+
+    Combine values of duplicate names into lists
+    """
+    if not qs:
+        return {}
+
+    result = {}
+    try:
+        for name_value in qs.split("&"):
+            name, eq, value = name_value.partition("=")
+            if eq:
+                name = unquote(name.replace("+", " "))
+                value = unquote(value.replace("+", " "))
+                if name in result:
+                    rvalue = result[name]
+                    if isinstance(rvalue, list):
+                        rvalue.append(value)
+                    else:
+                        result[name] = [rvalue, value]
+                else:
+                    result[name] = value
+    except Exception:
+        pass
+    return result
+
+
 if sys.hexversion < 0x30c0000:
     # Python <= 3.11
     def parse_timestamp(ts, default=None):

test/test_text.py

@@ -413,6 +413,28 @@ class TestText(unittest.TestCase):
         for value in INVALID:
             self.assertEqual(f(value), {})
 
+    def test_parse_query_list(self, f=text.parse_query_list):
+        # standard usage
+        self.assertEqual(f(""), {})
+        self.assertEqual(f("foo=1"), {"foo": "1"})
+        self.assertEqual(f("foo=1&bar=2"), {"foo": "1", "bar": "2"})
+
+        # missing value
+        self.assertEqual(f("bar"), {})
+        self.assertEqual(f("foo=1&bar"), {"foo": "1"})
+        self.assertEqual(f("foo=1&bar&baz=3"), {"foo": "1", "baz": "3"})
+
+        # keys with identical names
+        self.assertEqual(f("foo=1&foo=2"), {"foo": ["1", "2"]})
+        self.assertEqual(
+            f("foo=1&bar=2&foo=3&bar=4&foo=5"),
+            {"foo": ["1", "3", "5"], "bar": ["2", "4"]},
+        )
+
+        # invalid arguments
+        for value in INVALID:
+            self.assertEqual(f(value), {})
+
     def test_parse_timestamp(self, f=text.parse_timestamp):
         null = util.datetime_utcfromtimestamp(0)
         value = util.datetime_utcfromtimestamp(1555816235)