Fix prefix slicing on numbers and quoting in reserved expansion

tests/test_uritemplate.py

@@ -589,6 +589,14 @@ def test_no_mutate(self) -> None:
         t.expand(args, key=1)
         self.assertEqual(args, {})
 
+    def test_reserved_expansion_with_percent_escapes(self) -> None:
+        self.assertEqual(expand("{+var}", {"var": "a b%41"}), "a%20b%41")
+        self.assertEqual(expand("{#var}", {"var": "a b%41"}), "#a%20b%41")
+        self.assertEqual(
+            expand("{+path}", {"path": "/foo bar/baz%20qux"}),
+            "/foo%20bar/baz%20qux",
+        )
+
 
 class TestVariableModule(unittest.TestCase):
     def test_is_list_of_tuples(self) -> None:
@@ -663,6 +671,11 @@ def test_expand(self) -> None:
         # explicit testing for issue #53
         self.assertEqual(expand("{/zero}", self.context), "/0")
         self.assertEqual(expand("{/zero,a_float}", self.context), "/0/3.1415")
+        # explicit testing for issue #163
+        self.assertEqual(expand("{a_float:3}", self.context), "3.1")
+        self.assertEqual(expand("{?a_float:3}", self.context), "?a_float=3.1")
+        self.assertEqual(expand("{/a_float:3}", self.context), "/3.1")
+        self.assertEqual(expand("{;a_float:3}", self.context), ";a_float=3.1")
 
 
 if __name__ == "__main__":

uritemplate/variable.py

@@ -17,6 +17,7 @@
 
 import collections.abc
 import enum
+import re
 import string
 import typing as t
 import urllib.parse
@@ -38,6 +39,7 @@
 _GEN_DELIMS: t.Final[str] = ":/?#[]@"
 _SUB_DELIMS: t.Final[str] = "!$&'()*+,;="
 _RESERVED_CHARACTERS: t.Final[str] = f"{_GEN_DELIMS}{_SUB_DELIMS}"
+_PCT_ENCODED_RE: t.Final[t.Pattern[str]] = re.compile(r"(%[0-9a-fA-F]{2})")
 
 
 class Operator(enum.Enum):
@@ -150,9 +152,10 @@ def _always_quote(self, value: str) -> str:
         return quote(value, "")
 
     def _only_quote_unquoted_characters(self, value: str) -> str:
-        if urllib.parse.unquote(value) == value:
-            return quote(value, _RESERVED_CHARACTERS)
-        return value
+        parts = _PCT_ENCODED_RE.split(value)
+        for i in range(0, len(parts), 2):
+            parts[i] = quote(parts[i], _RESERVED_CHARACTERS)
+        return "".join(parts)
 
     def quote(self, value: t.Any) -> str:
         if not isinstance(value, (str, bytes)):
@@ -311,8 +314,7 @@ def _query_expansion(
                 return f"{name}={value}"
 
         if value:
-            value = t.cast(t.Text, value)
-            value = value[:prefix] if prefix else value
+            value = str(value)[:prefix] if prefix else value
             return f"{name}={_quote(value)}"
         return name + "="
 
@@ -364,8 +366,7 @@ def _label_path_expansion(
             )
             return expanded if expanded else None
 
-        value = t.cast(t.Text, value)
-        value = value[:prefix] if prefix else value
+        value = str(value)[:prefix] if prefix else value
         return self.operator.quote(value)
 
     def _semi_path_expansion(
@@ -413,8 +414,7 @@ def _semi_path_expansion(
                 )
                 return f"{name}={expanded}"
 
-        value = t.cast(t.Text, value)
-        value = value[:prefix] if prefix else value
+        value = str(value)[:prefix] if prefix else value
         if value:
             return f"{name}={self.operator.quote(value)}"
 
@@ -446,8 +446,7 @@ def _string_expansion(
                 for k, v in items
             )
 
-        value = t.cast(t.Text, value)
-        value = value[:prefix] if prefix else value
+        value = str(value)[:prefix] if prefix else value
         return self.operator.quote(value)
 
     def expand(