| 1 | from .attribute import Attribute |
|---|
| 2 | import sys |
|---|
| 3 | import struct |
|---|
| 4 | import logging |
|---|
| 5 | |
|---|
| 6 | # initialize logger |
|---|
| 7 | logger = logging.getLogger(__name__) |
|---|
| 8 | |
|---|
| 9 | class AttributeGroup(object): |
|---|
| 10 | """An AttributeGroup consists of an attribute-group-tag, followed |
|---|
| 11 | by a sequence of Attributes. According to RFC 2565, 'Within an |
|---|
| 12 | attribute-sequence, if two attributes have the same name, the |
|---|
| 13 | first occurrence MUST be ignored.', so we can effectively treat |
|---|
| 14 | this as an ordered dictionary. |
|---|
| 15 | |
|---|
| 16 | """ |
|---|
| 17 | |
|---|
| 18 | def __init__(self, tag=None, attributes=[]): |
|---|
| 19 | """Initialize an AttributeGroup. An AttributeGroup can be |
|---|
| 20 | initialized in three ways: |
|---|
| 21 | |
|---|
| 22 | AttributeGroup() |
|---|
| 23 | AttributeGroup(tag) |
|---|
| 24 | AttributeGroup(tag, attributes) |
|---|
| 25 | |
|---|
| 26 | Arguments: |
|---|
| 27 | |
|---|
| 28 | tag -- a signed char, holds the tag of the |
|---|
| 29 | attribute group |
|---|
| 30 | |
|---|
| 31 | attributes -- a list of attributes |
|---|
| 32 | |
|---|
| 33 | """ |
|---|
| 34 | |
|---|
| 35 | if tag is not None and not isinstance(tag, int): |
|---|
| 36 | raise ValueError("tag must be a character") |
|---|
| 37 | |
|---|
| 38 | self.tag = tag |
|---|
| 39 | self.attributes = [] |
|---|
| 40 | self.extend(attributes) |
|---|
| 41 | |
|---|
| 42 | def __cmp__(self, other): |
|---|
| 43 | eq = self.tag == other.tag |
|---|
| 44 | for a1, a2 in zip(self.attributes, other.attributes): |
|---|
| 45 | eq = eq and (a1 == a2) |
|---|
| 46 | return 0 if eq else 1 |
|---|
| 47 | |
|---|
| 48 | def __getitem__(self, name): |
|---|
| 49 | """Returns a list of attributes which have name 'name'. |
|---|
| 50 | |
|---|
| 51 | """ |
|---|
| 52 | |
|---|
| 53 | attribute = filter(lambda x: x.name == name, self.attributes) |
|---|
| 54 | if attribute: |
|---|
| 55 | return attribute[0] |
|---|
| 56 | else: |
|---|
| 57 | raise KeyError("Attribute %r not found" % name) |
|---|
| 58 | |
|---|
| 59 | def __contains__(self, name): |
|---|
| 60 | return len(filter(lambda x: x.name == name, self.attributes)) |
|---|
| 61 | |
|---|
| 62 | def __iter__(self): |
|---|
| 63 | return (a.name for a in self.attributes) |
|---|
| 64 | |
|---|
| 65 | iterkeys = __iter__ |
|---|
| 66 | |
|---|
| 67 | def __setitem__(self, name, attribute): |
|---|
| 68 | """Sets an attribute in the attribute group. Note that the key |
|---|
| 69 | is ignored and the attribute is queried for its name. |
|---|
| 70 | |
|---|
| 71 | """ |
|---|
| 72 | |
|---|
| 73 | return self.append(attribute) |
|---|
| 74 | |
|---|
| 75 | def __delitem__(self, name): |
|---|
| 76 | self.attributes = filter(lambda x: x.name != name, |
|---|
| 77 | self.attributes) |
|---|
| 78 | |
|---|
| 79 | def append(self, attribute): |
|---|
| 80 | return self.extend([attribute]) |
|---|
| 81 | |
|---|
| 82 | def extend(self, attributes): |
|---|
| 83 | """Sets the attributes for the attribute group. |
|---|
| 84 | |
|---|
| 85 | """ |
|---|
| 86 | |
|---|
| 87 | for a in attributes: |
|---|
| 88 | if not isinstance(a, Attribute): |
|---|
| 89 | raise ValueError("attribute must be of type Attribute") |
|---|
| 90 | |
|---|
| 91 | for a in attributes: |
|---|
| 92 | # XXX: Instead of replacing the attribute, do we want to |
|---|
| 93 | # append the value to the attribute here? |
|---|
| 94 | del self[a.name] |
|---|
| 95 | self.attributes.append(a) |
|---|
| 96 | |
|---|
| 97 | @property |
|---|
| 98 | def packed_value(self): |
|---|
| 99 | """Convert the AttributeGroup to binary. |
|---|
| 100 | |
|---|
| 101 | """ |
|---|
| 102 | |
|---|
| 103 | # convert the tag to binary |
|---|
| 104 | tag = struct.pack('>b', self.tag) |
|---|
| 105 | |
|---|
| 106 | # convert each of the attributes to binary |
|---|
| 107 | attributes = [a.packed_value for a in self.attributes] |
|---|
| 108 | |
|---|
| 109 | # concatenate everything and return |
|---|
| 110 | return tag + ''.join(attributes) |
|---|
| 111 | |
|---|
| 112 | def __repr__(self): |
|---|
| 113 | return '<IPPAttributeGroup (%r, %r)>' % (self.tag, self.attributes) |
|---|
