tag parsing configurable through tag_regex

4 files changed, 111 insertions, 24 deletions

diff --git a/src/setuptools_scm/__init__.py b/src/setuptools_scm/__init__.py
index b256289..58dd929 100644
--- a/src/setuptools_scm/__init__.py
+++ b/src/setuptools_scm/__init__.py
@@ -5,13 +5,13 @@
 import os
 import sys
 
-from .utils import trace
+from .config import Configuration
+from .utils import trace, string_types
 from .version import format_version, meta
 from .discover import iter_matching_entrypoints
 
 PRETEND_KEY = "SETUPTOOLS_SCM_PRETEND_VERSION"
 
-
 TEMPLATES = {
     ".py": """\
 # coding: utf-8
@@ -22,9 +22,6 @@ version = {version!r}
     ".txt": "{version}",
 }
 
-PY3 = sys.version_info > (3,)
-string_types = (str,) if PY3 else (str, unicode)  # noqa
-
 
 def version_from_scm(root):
     return _version_from_entrypoint(root, "setuptools_scm.parse_scm")
@@ -99,6 +96,7 @@ def get_version(
     write_to=None,
     write_to_template=None,
     relative_to=None,
+    tag_regex=None,
     parse=None,
 ):
     """
@@ -107,11 +105,22 @@ def get_version(
     in the root of the repository to direct setuptools_scm to the
     root of the repository by supplying ``__file__``.
     """
+
     if relative_to:
         root = os.path.join(os.path.dirname(relative_to), root)
     root = os.path.abspath(root)
     trace("root", repr(root))
-
+    
+    config = Configuration()
+    config.root = root
+    config.version_scheme = version_scheme
+    config.local_scheme =  local_scheme
+    config.write_to =  write_to
+    config.write_to_template =  write_to_template
+    config.relative_to = relative_to
+    config.tag_regex = tag_regex
+    config.parse = parse
+    
     parsed_version = _do_parse(root, parse)
 
     if parsed_version:
diff --git a/src/setuptools_scm/config.py b/src/setuptools_scm/config.py
new file mode 100644
index 0000000..5107133
--- /dev/null
+++ b/src/setuptools_scm/config.py
@@ -0,0 +1,49 @@
+""" configuration """
+from __future__ import print_function, unicode_literals
+import re
+import warnings
+
+from .utils import singleton
+
+DEFAULT_TAG_REGEX = r'^(?P<prefix>\w+-)?(?P<version>v?\d+(?:\.\d+){0,2}[^\+]+)(?P<suffix>\+.*)?$'
+TAG_REGEX_EXPECTED_GROUPS = set(['prefix', 'version', 'suffix'])
+
+
+@singleton
+class Configuration(object):
+    """ Global Configuration single-instance class """
+
+    root = ''
+    version_scheme = ''
+    local_scheme = ''
+    write_to = ''
+    write_to_template = None
+    relative_to = None
+    parse = None
+    _tag_regex = None
+
+    def __init__(self):
+        self.root = '.'
+        self.version_scheme = "guess-next-dev"
+        self.local_scheme = "node-and-date"
+        self.tag_regex = DEFAULT_TAG_REGEX
+
+    @property
+    def tag_regex(self):
+        return self._tag_regex
+
+    @tag_regex.setter
+    def tag_regex(self, value):
+        if value is None:
+            value = DEFAULT_TAG_REGEX
+        regex = re.compile(value)
+
+        group_names = set(regex.groupindex.keys())
+        diff = TAG_REGEX_EXPECTED_GROUPS.difference(group_names)
+        if diff:
+            warnings.warn("expected match groups %s missing from regex '%s'" % (diff, regex.pattern))
+        diff = group_names.difference(TAG_REGEX_EXPECTED_GROUPS)
+        if diff:
+            warnings.warn("additional match groups %s found in regex '%s' (expected: %s)" % (diff, regex.pattern, TAG_REGEX_EXPECTED_GROUPS))
+
+        self._tag_regex = regex
diff --git a/src/setuptools_scm/utils.py b/src/setuptools_scm/utils.py
index e6b767c..5db87bf 100644
--- a/src/setuptools_scm/utils.py
+++ b/src/setuptools_scm/utils.py
@@ -14,6 +14,8 @@ import platform
 DEBUG = bool(os.environ.get("SETUPTOOLS_SCM_DEBUG"))
 IS_WINDOWS = platform.system() == "Windows"
 PY2 = sys.version_info < (3,)
+PY3 = sys.version_info > (3,)
+string_types = (str,) if PY3 else (str, unicode)  # noqa
 
 
 def trace(*k):
@@ -103,3 +105,18 @@ def has_command(name):
     if not res:
         warnings.warn("%r was not found" % name)
     return res
+
+
+def singleton(cls):
+    """ Class decorator to limit to a single global instance. """
+    instances = {}
+
+    def _get_instance(*args, **kwargs):
+        instance = instances.get(cls, None)
+        if instance is None:
+            instance = cls(*args, **kwargs)
+            instances[cls] = instance
+
+        return instance
+
+    return _get_instance
diff --git a/src/setuptools_scm/version.py b/src/setuptools_scm/version.py
index 5799f1a..85e02be 100644
--- a/src/setuptools_scm/version.py
+++ b/src/setuptools_scm/version.py
@@ -4,7 +4,8 @@ import warnings
 import re
 from itertools import chain, repeat, islice
 
-from .utils import trace
+from .config import Configuration
+from .utils import trace, string_types
 
 from pkg_resources import iter_entry_points
 
@@ -13,7 +14,6 @@ from pkg_resources import parse_version as pkg_parse_version
 SEMVER_MINOR = 2
 SEMVER_PATCH = 3
 SEMVER_LEN = 3
-TAG_PREFIX = re.compile(r"^\w+-(.*)")
 
 
 def _pad(iterable, size, padding=None):
@@ -21,6 +21,22 @@ def _pad(iterable, size, padding=None):
     return list(islice(padded, size))
 
 
+def _parse_version_tag(tag):
+    regex = Configuration().tag_regex
+    if isinstance(tag, string_types):
+        match = regex.match(tag)
+    else:
+        match = regex.match('%s' % tag)
+
+    if match:
+        result = match.groupdict()
+    else:
+        result = None
+
+    trace("'%s' parsed to %s" % (tag, result))
+    return result
+
+
 def _get_version_class():
     modern_version = pkg_parse_version("1.0")
     if isinstance(modern_version, tuple):
@@ -61,23 +77,19 @@ def tag_to_version(tag):
     take a tag that might be prefixed with a keyword and return only the version part
     """
     trace("tag", tag)
-    if "+" in tag:
-        warnings.warn("tag %r will be stripped of the local component" % tag)
-        tag = tag.split("+")[0]
-    # lstrip the v because of py2/py3 differences in setuptools
-    # also required for old versions of setuptools
-    prefix_match = TAG_PREFIX.match(tag)
-    if prefix_match is not None:
-        version = prefix_match.group(1)
-    else:
-        version = tag
+
+    tagdict = _parse_version_tag(tag)
+    if tagdict is None or len(tagdict['version']) < 1:
+        return None
+
+    version = tagdict['version']
     trace("version pre parse", version)
-    if VERSION_CLASS is None:
-        return version
-    version = pkg_parse_version(version)
-    trace("version", repr(version))
-    if isinstance(version, VERSION_CLASS):
-        return version
+
+    if VERSION_CLASS is not None:
+        version = pkg_parse_version(version)
+        trace("version", repr(version))
+    
+    return version
 
 
 def tags_to_versions(tags):