reorg to avoid circular import

src/pycalver/version.py

@@ -3,19 +3,98 @@
 #
 # Copyright (c) 2018 Manuel Barkhau (@mbarkhau) - MIT License
 # SPDX-License-Identifier: MIT
-"""Functions related to version string manipulation."""
+"""Functions related to version string manipulation.
 
+>>> version_info = PYCALVER_RE.match("v201712.0123-alpha").groupdict()
+>>> assert version_info == {
+...     "version" : "v201712.0123-alpha",
+...     "calver"  : "v201712",
+...     "year"    : "2017",
+...     "month"   : "12",
+...     "build"   : ".0123",
+...     "release" : "-alpha",
+... }
+>>>
+>>> version_info = PYCALVER_RE.match("v201712.0033").groupdict()
+>>> assert version_info == {
+...     "version" : "v201712.0033",
+...     "calver"  : "v201712",
+...     "year"    : "2017",
+...     "month"   : "12",
+...     "build"   : ".0033",
+...     "release" : None,
+... }
+"""
+
+import re
 import logging
 import pkg_resources
 import typing as typ
 import datetime as dt
 
 from . import lex_id
-from . import parse
 
 log = logging.getLogger("pycalver.version")
 
 
+# https://regex101.com/r/fnj60p/10
+PYCALVER_PATTERN = r"""
+\b
+(?P<version>
+    (?P<calver>
+       v                        # "v" version prefix
+       (?P<year>\d{4})
+       (?P<month>\d{2})
+    )
+    (?P<build>
+        \.                      # "." build nr prefix
+        \d{4,}
+    )
+    (?P<release>
+        \-                      # "-" release prefix
+        (?:alpha|beta|dev|rc|post)
+    )?
+)(?:\s|$)
+"""
+
+PYCALVER_RE: typ.Pattern[str] = re.compile(PYCALVER_PATTERN, flags=re.VERBOSE)
+
+
+class VersionInfo(typ.NamedTuple):
+    """Container for parsed version string."""
+
+    version       : str
+    pep440_version: str
+    calver        : str
+    year          : str
+    month         : str
+    build         : str
+    release       : typ.Optional[str]
+
+
+def parse_version_info(version_str: str) -> VersionInfo:
+    """Parse a PyCalVer string.
+
+    >>> vnfo = parse_version_info("v201712.0033-beta")
+    >>> assert vnfo == VersionInfo(
+    ...     version="v201712.0033-beta",
+    ...     pep440_version="201712.33b0",
+    ...     calver="v201712",
+    ...     year="2017",
+    ...     month="12",
+    ...     build=".0033",
+    ...     release="-beta",
+    ... )
+    """
+    match = PYCALVER_RE.match(version_str)
+    if match is None:
+        raise ValueError(f"Invalid PyCalVer string: {version_str}")
+
+    kwargs = match.groupdict()
+    kwargs['pep440_version'] = pycalver_to_pep440(kwargs['version'])
+    return VersionInfo(**kwargs)
+
+
 def current_calver() -> str:
     """Generate calver version string based on current date.
 
@@ -30,7 +109,7 @@ def incr(old_version: str, *, release: str = None) -> str:
     Old_version is assumed to be a valid calver string,
     already validated in pycalver.config.parse.
     """
-    old_ver = parse.parse_version_info(old_version)
+    old_ver = parse_version_info(old_version)
 
     new_calver = current_calver()