Add more flexible parsing and formating

src/pycalver/parse.py

@@ -5,50 +5,14 @@
 # SPDX-License-Identifier: MIT
 """Parse PyCalVer strings from files."""
 
-import re
 import logging
 import typing as typ
 
+from . import patterns
+
 log = logging.getLogger("pycalver.parse")
 
 
-VALID_RELEASE_VALUES = ("alpha", "beta", "dev", "rc", "post", "final")
-
-
-PATTERN_ESCAPES = [
-    ("\u005c", "\u005c\u005c"),
-    ("-"     , "\u005c-"),
-    ("."     , "\u005c."),
-    ("+"     , "\u005c+"),
-    ("*"     , "\u005c*"),
-    ("{"     , "\u005c{{"),
-    ("}"     , "\u005c}}"),
-    ("["     , "\u005c["),
-    ("]"     , "\u005c]"),
-    ("("     , "\u005c("),
-    (")"     , "\u005c)"),
-]
-
-# NOTE (mb 2018-09-03): These are matchers for parts, which are
-#   used in the patterns, they're not for validation. This means
-#   that they may find strings, which are not valid pycalver
-#   strings, when parsed in their full context. For such cases,
-#   the patterns should be expanded.
-
-
-RE_PATTERN_PARTS = {
-    'pep440_version': r"\d{6}\.[1-9]\d*(a|b|dev|rc|post)?\d*",
-    'version'       : r"v\d{6}\.\d{4,}(\-(alpha|beta|dev|rc|post|final))?",
-    'calver'        : r"v\d{6}",
-    'year'          : r"\d{4}",
-    'month'         : r"\d{2}",
-    'build'         : r"\.\d{4,}",
-    'build_no'      : r"\d{4,}",
-    'release'       : r"(\-(alpha|beta|dev|rc|post|final))?",
-    'release_tag'   : r"(alpha|beta|dev|rc|post|final)?",
-}
-
-
 class PatternMatch(typ.NamedTuple):
     """Container to mark a version string in a file."""
 
@@ -62,26 +26,10 @@ class PatternMatch(typ.NamedTuple):
 PatternMatches = typ.Iterable[PatternMatch]
 
 
-def compile_pattern(pattern: str) -> typ.Pattern[str]:
-    pattern_tmpl = pattern
-
-    for char, escaped in PATTERN_ESCAPES:
-        pattern_tmpl = pattern_tmpl.replace(char, escaped)
-
-    # undo escaping only for valid part names
-    for part_name in RE_PATTERN_PARTS.keys():
-        pattern_tmpl = pattern_tmpl.replace(
-            "\u005c{{" + part_name + "\u005c}}", "{" + part_name + "}"
-        )
-
-    pattern_str = pattern_tmpl.format(**RE_PATTERN_PARTS)
-    return re.compile(pattern_str)
-
-
 def _iter_for_pattern(lines: typ.List[str], pattern: str) -> PatternMatches:
     # The pattern is escaped, so that everything besides the format
     # string variables is treated literally.
-    pattern_re = compile_pattern(pattern)
+    pattern_re = patterns.compile_pattern(pattern)
 
     for lineno, line in enumerate(lines):
         match = pattern_re.search(line)
@@ -93,12 +41,12 @@ def iter_matches(lines: typ.List[str], patterns: typ.List[str]) -> PatternMatche
     """Iterate over all matches of any pattern on any line.
 
     >>> lines = ["__version__ = 'v201712.0002-alpha'"]
-    >>> patterns = ["{version}", "{pep440_version}"]
+    >>> patterns = ["{pycalver}", "{pep440_pycalver}"]
     >>> matches = list(iter_matches(lines, patterns))
     >>> assert matches[0] == PatternMatch(
     ...     lineno = 0,
     ...     line   = "__version__ = 'v201712.0002-alpha'",
-    ...     pattern= "{version}",
+    ...     pattern= "{pycalver}",
     ...     span   = (15, 33),
     ...     match  = "v201712.0002-alpha",
     ... )