allow separator between dev and num, ie, "dev.23"

According to the regular expression in Appendix B of the specification for
Version Specifiers:

https://packaging.python.org/en/latest/specifications/version-specifiers/#appendix-parsing-version-strings-with-regular-expressionsversion-specifiers/

... a separator character ('-', '_', or '.') is allowed between the word
"dev" and the optional number:

```
(?P<dev>                     # dev release
    [-_\.]?
    (?P<dev_l>dev)
    [-_\.]?
(?P<dev_n>[0-9]+)?
)?
```

Fixes RazerM#33

src/parver/_parse.py

@@ -43,8 +43,8 @@
     post = sep? post_tag pre_post_num?
     post_implicit = "-" int
     post_tag = "post" / "rev" / "r"
+    dev = sep? "dev" pre_post_num?
     pre_post_num = sep? int
-    dev = sep? "dev" int?
     local = "+" local_part (sep local_part)*
     local_part = alpha / int
     sep = dot / "-" / "_"
@@ -175,20 +175,30 @@ def visit_post_implicit(
     def visit_dev(self, node: Node, children: SemanticActionResults) -> segment.Dev:
         num: Union[ImplicitZero, int] = IMPLICIT_ZERO
         sep: Union[Separator, None, UnsetType] = UNSET
+        sep2: Union[Separator, None, UnsetType] = UNSET
 
         for token in children:
-            if sep is UNSET:
-                if isinstance(token, Sep):
-                    sep = token.value
-                else:
-                    num = token
-            else:
+            if isinstance(token, Sep):
+                assert sep is UNSET
+                sep = token.value
+            elif isinstance(token, int):
+                # we should only get an int if there's no sep2 - if there is,
+                # we should get a tuple
+                assert sep2 is UNSET
+                sep2 = None
                 num = token
+            elif isinstance(token, tuple):
+                assert len(token) == 2
+                sep2 = token[0].value
+                num = token[1]
+            else:
+                raise AssertionError(f"unknown dev child token type: {token!r}")
 
+        # if there is a dev segment at all, the first sep is always known
         if isinstance(sep, UnsetType):
             sep = None
 
-        return segment.Dev(value=num, sep=sep)
+        return segment.Dev(value=num, sep=sep, sep2=sep2)
 
     def visit_local(self, node: Node, children: SemanticActionResults) -> segment.Local:
         return segment.Local("".join(str(getattr(c, "value", c)) for c in children))

src/parver/_segments.py

@@ -46,6 +46,7 @@ class Post:
 class Dev:
     value: Union[ImplicitZero, int] = attr.ib()
     sep: Optional[Separator] = attr.ib()
+    sep2: Union[Separator, UnsetType, None] = attr.ib()
 
 
 @attr.s(slots=True)

src/parver/_version.py

@@ -167,6 +167,9 @@ class Version:
     :param dev_sep: Specify an alternate separator before the development
         release segment. The normal form is ``'.'``.
 
+    :param dev_sep2: Specify an alternate separator between the identifier and
+        number. The normal form is `None`.
+
     :param post_tag: Specify alternate post release identifier `rev` or `r`.
         May be `None` to signify an `implicit post release`_.
 
@@ -258,6 +261,10 @@ class Version:
 
         The separator before the develepment release identifier.
 
+    .. attribute:: dev_sep2
+
+        The separator between the development release identifier and number.
+
     .. attribute:: post_tag
 
         If this :class:`Version` instance represents a post release, this
@@ -322,6 +329,9 @@ class Version:
     dev_sep: Optional[Separator] = attr.ib(
         default=UNSET, validator=validate_sep_or_unset
     )
+    dev_sep2: Union[Separator, UnsetType, None] = attr.ib(
+        default=UNSET, validator=validate_sep_or_unset
+    )
     post_tag: Optional[PostTag] = attr.ib(default=UNSET, validator=validate_post_tag)
 
     epoch_implicit: bool = attr.ib(default=False, init=False)
@@ -429,10 +439,15 @@ def _validate_dev(self, set_: Callable[[str, Any], None]) -> None:
         elif self.dev is None:
             if self.dev_sep is not UNSET:
                 raise ValueError("Cannot set dev_sep without dev.")
+            if self.dev_sep2 is not UNSET:
+                raise ValueError("Cannot set dev_sep2 without dev.")
 
         if self.dev_sep is UNSET:
             set_("dev_sep", None if self.dev is None else ".")
 
+        if self.dev_sep2 is UNSET:
+            set_("dev_sep2", None)
+
     @classmethod
     def parse(cls, version: str, strict: bool = False) -> "Version":
         """
@@ -479,6 +494,7 @@ def parse(cls, version: str, strict: bool = False) -> "Version":
             elif isinstance(s, segment.Dev):
                 kwargs["dev"] = s.value
                 kwargs["dev_sep"] = s.sep
+                kwargs["dev_sep2"] = s.sep2
             elif isinstance(s, segment.Local):
                 kwargs["local"] = s.value
             elif isinstance(s, segment.V):
@@ -534,6 +550,8 @@ def __str__(self) -> str:
             if self.dev_sep is not None:
                 parts.append(self.dev_sep)
             parts.append("dev")
+            if self.dev_sep2:
+                parts.append(self.dev_sep2)
             if not self.dev_implicit:
                 parts.append(str(self.dev))
 
@@ -663,6 +681,7 @@ def _attrs_as_init(self) -> Dict[str, Any]:
         if self.dev is None:
             del d["dev"]
             del d["dev_sep"]
+            del d["dev_sep2"]
 
         return d
 
@@ -681,6 +700,7 @@ def replace(
         post_sep1: Union[Separator, None, UnsetType] = UNSET,
         post_sep2: Union[Separator, None, UnsetType] = UNSET,
         dev_sep: Union[Separator, None, UnsetType] = UNSET,
+        dev_sep2: Union[Separator, None, UnsetType] = UNSET,
         post_tag: Union[PostTag, None, UnsetType] = UNSET,
     ) -> "Version":
         """Return a new :class:`Version` instance with the same attributes,
@@ -702,6 +722,7 @@ def replace(
             post_sep1=post_sep1,
             post_sep2=post_sep2,
             dev_sep=dev_sep,
+            dev_sep2=dev_sep2,
             post_tag=post_tag,
         )
         kwargs = {k: v for k, v in kwargs.items() if v is not UNSET}
@@ -726,6 +747,7 @@ def replace(
 
         if kwargs.get("dev", UNSET) is None:
             d.pop("dev_sep", None)
+            d.pop("dev_sep2", None)
 
         d.update(kwargs)
         return Version(**d)

tests/strategies.py

@@ -105,7 +105,11 @@ def dev(draw, strict=False):
 
     blank = just("")
 
-    num_part = num_str
+    sep2 = separator(strict=strict, optional=True)
+    if strict:
+        sep2 = blank
+
+    num_part = sep2.map(lambda s: s + draw(num_str))
     if not strict:
         num_part = one_of(blank, num_part)