RFC 7529 compatibility

CHANGES.rst

@@ -60,6 +60,9 @@ New features:
 
 - Test compatibility with Python 3.12
 - Add function ``icalendar.use_pytz()``.
+- Allows selecting components with ``walk(select=func)`` where ``func`` takes a
+  component and returns ``True`` or ``False``.
+- Add compatibility to :rfc:`7529`, adding ``vMonth`` and ``vSkip``
 
 Bug fixes:
 

docs/usage.rst

@@ -7,6 +7,23 @@ standard in RFC 5545.
 It should be fully compliant, but it is possible to generate and parse invalid
 files if you really want to.
 
+Compatibility
+-------------
+
+This package is compatible with the following standards:
+
+- :rfc:`5545`
+- :rfc:`7529`
+
+We do not claim compatibility to:
+
+- :rfc:`2445` - which is obsoleted by :rfc:`5545`
+- :rfc:`6886`
+- :rfc:`7953`
+- :rfc:`7986`
+- :rfc:`9073`
+- :rfc:`9074`
+- :rfc:`9253`
 
 File structure
 --------------

src/icalendar/cal.py

@@ -275,23 +275,29 @@ def add_component(self, component):
         """
         self.subcomponents.append(component)
 
-    def _walk(self, name):
+    def _walk(self, name, select):
         """Walk to given component.
         """
         result = []
-        if name is None or self.name == name:
+        if (name is None or self.name == name) and select(self):
             result.append(self)
         for subcomponent in self.subcomponents:
-            result += subcomponent._walk(name)
+            result += subcomponent._walk(name, select)
         return result
 
-    def walk(self, name=None):
+    def walk(self, name=None, select=lambda c: True):
         """Recursively traverses component and subcomponents. Returns sequence
         of same. If name is passed, only components with name will be returned.
+
+        :param name: The name of the component or None such as ``VEVENT``.
+        :param select: A function that takes the component as first argument
+          and returns True/False.
+        :returns: A list of components that match.
+        :rtype: list[Component]
         """
         if name is not None:
             name = name.upper()
-        return self._walk(name)
+        return self._walk(name, select)
 
     #####################
     # Generation

src/icalendar/parser_tools.py

@@ -1,10 +1,11 @@
-from typing import Any
+from typing import Any, Union
 
 SEQUENCE_TYPES = (list, tuple)
 DEFAULT_ENCODING = 'utf-8'
+ICAL_TYPE = Union[str, bytes]
 
 
-def from_unicode(value: Any, encoding='utf-8') -> bytes:
+def from_unicode(value: ICAL_TYPE, encoding='utf-8') -> bytes:
     """
     Converts a value to bytes, even if it already is bytes
     :param value: The value to convert
@@ -21,7 +22,7 @@ def from_unicode(value: Any, encoding='utf-8') -> bytes:
     return value
 
 
-def to_unicode(value, encoding='utf-8'):
+def to_unicode(value: ICAL_TYPE, encoding='utf-8') -> str:
     """Converts a value to unicode, even if it is already a unicode string.
     """
     if isinstance(value, str):
@@ -34,7 +35,7 @@ def to_unicode(value, encoding='utf-8'):
     return value
 
 
-def data_encode(data, encoding=DEFAULT_ENCODING):
+def data_encode(data: Union[ICAL_TYPE, dict, list], encoding=DEFAULT_ENCODING) -> bytes:
     """Encode all datastructures to the given encoding.
     Currently unicode strings, dicts and lists are supported.
     """

src/icalendar/prop.py

@@ -44,18 +44,18 @@
 from icalendar.parser import Parameters
 from icalendar.parser import escape_char
 from icalendar.parser import unescape_char
-from icalendar.parser_tools import DEFAULT_ENCODING
-from icalendar.parser_tools import SEQUENCE_TYPES
-from icalendar.parser_tools import to_unicode
-from icalendar.parser_tools import from_unicode
+from icalendar.parser_tools import (
+    DEFAULT_ENCODING, SEQUENCE_TYPES, to_unicode, from_unicode, ICAL_TYPE
+)
 
 import base64
 import binascii
 from .timezone import tzp
 import re
 import time as _time
 
-from typing import Optional
+from typing import Optional, Union
+from enum import Enum, auto
 
 
 DURATION_REGEX = re.compile(r'([-+]?)P(?:(\d+)W)?(?:(\d+)D)?'
@@ -126,6 +126,29 @@ def from_ical(cls, ical):
             raise ValueError(f"Expected 'TRUE' or 'FALSE'. Got {ical}")
 
 
+class vText(str):
+    """Simple text.
+    """
+
+    def __new__(cls, value, encoding=DEFAULT_ENCODING):
+        value = to_unicode(value, encoding=encoding)
+        self = super().__new__(cls, value)
+        self.encoding = encoding
+        self.params = Parameters()
+        return self
+
+    def __repr__(self) -> str:
+        return f"vText({self.to_ical()!r})"
+
+    def to_ical(self) -> bytes:
+        return escape_char(self).encode(self.encoding)
+
+    @classmethod
+    def from_ical(cls, ical:ICAL_TYPE):
+        ical_unesc = unescape_char(ical)
+        return cls(ical_unesc)
+
+
 class vCalAddress(str):
     """This just returns an unquoted string.
     """
@@ -176,11 +199,11 @@ def __new__(cls, *args, **kwargs):
         self.params = Parameters()
         return self
 
-    def to_ical(self):
+    def to_ical(self) -> bytes:
         return str(self).encode('utf-8')
 
     @classmethod
-    def from_ical(cls, ical):
+    def from_ical(cls, ical:ICAL_TYPE):
         try:
             return cls(ical)
         except Exception:
@@ -610,6 +633,92 @@ def from_ical(cls, ical):
             raise ValueError(f'Expected frequency, got: {ical}')
 
 
+class vMonth(int):
+    """The number of the month for recurrence.
+
+    In :rfc:`5545`, this is just an int.
+    In :rfc:`7529`, this can be followed by `L` to indicate a leap month.
+
+        >>> vMonth(1) # first month January
+        vMonth('1')
+        >>> vMonth("5L") # leap month in Hebrew calendar
+        vMonth('5L')
+        >>> vMonth(1).leap
+        False
+        >>> vMonth("5L").leap
+        True
+
+    Definition from RFC::
+
+        type-bymonth = element bymonth {
+           xsd:positiveInteger |
+           xsd:string
+        }
+    """
+    def __new__(cls, month:Union[str, int]):
+        if isinstance(month, vMonth):
+            return cls(month.to_ical().decode())
+        if isinstance(month, str):
+            if month.isdigit():
+                month_index = int(month)
+                leap = False
+            else:
+                if not month[-1] == "L" and month[:-1].isdigit():
+                    raise ValueError(f"Invalid month: {month!r}")
+                month_index = int(month[:-1])
+                leap = True
+        else:
+            leap = False
+            month_index = int(month)
+        self = super().__new__(cls, month_index)
+        self.leap = leap
+        self.params = Parameters()
+        return self
+
+    def to_ical(self) -> bytes:
+        """The ical representation."""
+        return str(self).encode('utf-8')
+
+    @classmethod
+    def from_ical(cls, ical: str):
+        return cls(ical)
+
+    def leap():
+        doc = "Whether this is a leap month."
+        def fget(self) -> bool:
+            return self._leap
+        def fset(self, value:bool) -> None:
+            self._leap = value
+        return locals()
+    leap = property(**leap())
+
+
+    def __repr__(self) -> str:
+        """repr(self)"""
+        return f"{self.__class__.__name__}({str(self)!r})"
+
+    def __str__(self) -> str:
+        """str(self)"""
+        return f"{int(self)}{'L' if self.leap else ''}"
+
+
+class vSkip(vText, Enum):
+    """Skip values for RRULE.
+
+    These are defined in :rfc:`7529`.
+
+    OMIT  is the default value.
+    """
+
+    OMIT = "OMIT"
+    FORWARD = "FORWARD"
+    BACKWARD = "BACKWARD"
+
+    def __reduce_ex__(self, _p):
+        """For pickling."""
+        return self.__class__, (self._name_,)
+
+
 class vRecur(CaselessDict):
     """Recurrence definition.
     """
@@ -619,10 +728,10 @@ class vRecur(CaselessDict):
 
     # Mac iCal ignores RRULEs where FREQ is not the first rule part.
     # Sorts parts according to the order listed in RFC 5545, section 3.3.10.
-    canonical_order = ("FREQ", "UNTIL", "COUNT", "INTERVAL",
+    canonical_order = ("RSCALE", "FREQ", "UNTIL", "COUNT", "INTERVAL",
                        "BYSECOND", "BYMINUTE", "BYHOUR", "BYDAY", "BYWEEKDAY",
                        "BYMONTHDAY", "BYYEARDAY", "BYWEEKNO", "BYMONTH",
-                       "BYSETPOS", "WKST")
+                       "BYSETPOS", "WKST", "SKIP")
 
     types = CaselessDict({
         'COUNT': vInt,
@@ -633,16 +742,20 @@ class vRecur(CaselessDict):
         'BYWEEKNO': vInt,
         'BYMONTHDAY': vInt,
         'BYYEARDAY': vInt,
-        'BYMONTH': vInt,
+        'BYMONTH': vMonth,
         'UNTIL': vDDDTypes,
         'BYSETPOS': vInt,
         'WKST': vWeekday,
         'BYDAY': vWeekday,
         'FREQ': vFrequency,
         'BYWEEKDAY': vWeekday,
+        'SKIP': vSkip,
     })
 
     def __init__(self, *args, **kwargs):
+        for k, v in kwargs.items():
+            if not isinstance(v, SEQUENCE_TYPES):
+                kwargs[k] = [v]
         super().__init__(*args, **kwargs)
         self.params = Parameters()
 
@@ -667,7 +780,7 @@ def parse_type(cls, key, values):
         return [parser.from_ical(v) for v in values.split(',')]
 
     @classmethod
-    def from_ical(cls, ical):
+    def from_ical(cls, ical: str):
         if isinstance(ical, cls):
             return ical
         try:
@@ -680,34 +793,13 @@ def from_ical(cls, ical):
                     # FREQ=YEARLY;BYMONTH=11;BYDAY=1SU;
                     continue
                 recur[key] = cls.parse_type(key, vals)
-            return dict(recur)
-        except Exception:
+            return cls(recur)
+        except ValueError:
+            raise
+        except:
             raise ValueError(f'Error in recurrence rule: {ical}')
 
 
-class vText(str):
-    """Simple text.
-    """
-
-    def __new__(cls, value, encoding=DEFAULT_ENCODING):
-        value = to_unicode(value, encoding=encoding)
-        self = super().__new__(cls, value)
-        self.encoding = encoding
-        self.params = Parameters()
-        return self
-
-    def __repr__(self):
-        return f"vText('{self.to_ical()!r}')"
-
-    def to_ical(self):
-        return escape_char(self).encode(self.encoding)
-
-    @classmethod
-    def from_ical(cls, ical):
-        ical_unesc = unescape_char(ical)
-        return cls(ical_unesc)
-
-
 class vTime(TimeBase):
     """Render and generates iCalendar time format.
     """

src/icalendar/tests/calendars/rfc_7529.ics

@@ -0,0 +1,29 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+PRODID://RESEARCH IN MOTION//BIS 3.0
+METHOD:REQUEST
+BEGIN:VEVENT
+UID:4.3.1
+DTSTART;VALUE=DATE:20130210
+RRULE:RSCALE=CHINESE;FREQ=YEARLY
+SUMMARY:Chinese New Year
+END:VEVENT
+BEGIN:VEVENT
+UID:4.3.2
+DTSTART;VALUE=DATE:20130906
+RRULE:RSCALE=ETHIOPIC;FREQ=MONTHLY;BYMONTH=13
+SUMMARY:First day of 13th month
+END:VEVENT
+BEGIN:VEVENT
+UID:4.3.3
+DTSTART;VALUE=DATE:20140208
+RRULE:RSCALE=HEBREW;FREQ=YEARLY;BYMONTH=5L;BYMONTHDAY=8;SKIP=FORWARD
+SUMMARY:Anniversary
+END:VEVENT
+BEGIN:VEVENT
+UID:4.3.4
+DTSTART;VALUE=DATE:20120229
+RRULE:RSCALE=GREGORIAN;FREQ=YEARLY;SKIP=FORWARD
+SUMMARY:Anniversary
+END:VEVENT
+END:VCALENDAR