lib/pyasn1/pyasn1/type/tag.py

# ASN.1 types tags
from operator import getitem
from pyasn1 import error

tagClassUniversal = 0x00
tagClassApplication = 0x40
tagClassContext = 0x80
tagClassPrivate = 0xC0

tagFormatSimple = 0x00
tagFormatConstructed = 0x20

tagCategoryImplicit = 0x01
tagCategoryExplicit = 0x02
tagCategoryUntagged = 0x04

class Tag:
    def __init__(self, tagClass, tagFormat, tagId):
        if tagId < 0:
            raise error.PyAsn1Error(
                'Negative tag ID (%s) not allowed' % (tagId,)
                )
        self.__tag = (tagClass, tagFormat, tagId)
        self.uniq = (tagClass, tagId)
        self.__hashedUniqTag = hash(self.uniq)

    def __repr__(self):
        return '%s(tagClass=%s, tagFormat=%s, tagId=%s)' % (
            (self.__class__.__name__,) + self.__tag
            )
    # These is really a hotspot -- expose public "uniq" attribute to save on
    # function calls
    def __eq__(self, other): return self.uniq == other.uniq
    def __ne__(self, other): return self.uniq != other.uniq
    def __lt__(self, other): return self.uniq < other.uniq
    def __le__(self, other): return self.uniq <= other.uniq
    def __gt__(self, other): return self.uniq > other.uniq
    def __ge__(self, other): return self.uniq >= other.uniq
    def __hash__(self): return self.__hashedUniqTag
    def __getitem__(self, idx): return self.__tag[idx]
    def __and__(self, otherTag):
        (tagClass, tagFormat, tagId) = otherTag
        return self.__class__(
            self.__tag&tagClass, self.__tag&tagFormat, self.__tag&tagId
            )
    def __or__(self, otherTag):
        (tagClass, tagFormat, tagId) = otherTag
        return self.__class__(
            self.__tag[0]|tagClass,
            self.__tag[1]|tagFormat,
            self.__tag[2]|tagId
            )
    def asTuple(self): return self.__tag  # __getitem__() is slow
    
class TagSet:
    def __init__(self, baseTag=(), *superTags):
        self.__baseTag = baseTag
        self.__superTags = superTags
        self.__hashedSuperTags = hash(superTags)
        _uniq = ()
        for t in superTags:
            _uniq = _uniq + t.uniq
        self.uniq = _uniq
        self.__lenOfSuperTags = len(superTags)
        
    def __repr__(self):
        return '%s(%s)' % (
            self.__class__.__name__,
            ', '.join([repr(x) for x in self.__superTags])
            )

    def __add__(self, superTag):
        return self.__class__(
            self.__baseTag, *self.__superTags + (superTag,)
            )
    def __radd__(self, superTag):
        return self.__class__(
            self.__baseTag, *(superTag,) + self.__superTags
            )

    def tagExplicitly(self, superTag):
        tagClass, tagFormat, tagId = superTag
        if tagClass == tagClassUniversal:
            raise error.PyAsn1Error(
                'Can\'t tag with UNIVERSAL-class tag'
                )
        if tagFormat != tagFormatConstructed:
            superTag = Tag(tagClass, tagFormatConstructed, tagId)
        return self + superTag

    def tagImplicitly(self, superTag):
        tagClass, tagFormat, tagId = superTag
        if self.__superTags:
            superTag = Tag(tagClass, self.__superTags[-1][1], tagId)
        return self[:-1] + superTag

    def getBaseTag(self): return self.__baseTag
    def __getitem__(self, idx):
        if isinstance(idx, slice):
            return self.__class__(
               self.__baseTag, *getitem(self.__superTags, idx)
            )
        return self.__superTags[idx]
    def __eq__(self, other): return self.uniq == other.uniq
    def __ne__(self, other): return self.uniq != other.uniq
    def __lt__(self, other): return self.uniq < other.uniq
    def __le__(self, other): return self.uniq <= other.uniq
    def __gt__(self, other): return self.uniq > other.uniq
    def __ge__(self, other): return self.uniq >= other.uniq
    def __hash__(self): return self.__hashedSuperTags
    def __len__(self): return self.__lenOfSuperTags
    def isSuperTagSetOf(self, tagSet):
        if len(tagSet) < self.__lenOfSuperTags:
            return
        idx = self.__lenOfSuperTags - 1
        while idx >= 0:
            if self.__superTags[idx] != tagSet[idx]:
                return
            idx = idx - 1
        return 1
    
def initTagSet(tag): return TagSet(tag, tag)