laforge has submitted this change. ( https://gerrit.osmocom.org/c/pysim/+/37620?usp=email )

Change subject: pySim.tlv: Add convenience methods to IE class ......................................................................

pySim.tlv: Add convenience methods to IE class

The new methods allow programmatic resolution of nested IEs from a parent, assuming there's only one child of a given type (which is often but not always the case).

Change-Id: Ic95b74437647ae8d4bf3cdc481832afb622e3cf0 --- M pySim/tlv.py 1 file changed, 32 insertions(+), 1 deletion(-)

Approvals: fixeria: Looks good to me, but someone else must approve laforge: Looks good to me, approved Jenkins Builder: Verified

diff --git a/pySim/tlv.py b/pySim/tlv.py index 6dc5301..ed3be5d 100644 --- a/pySim/tlv.py +++ b/pySim/tlv.py @@ -19,7 +19,7 @@ import inspect import abc import re -from typing import List, Tuple +from typing import List, Tuple, Optional

from pySim.utils import bertlv_encode_len, bertlv_parse_len, bertlv_encode_tag, bertlv_parse_tag from pySim.utils import comprehensiontlv_encode_tag, comprehensiontlv_parse_tag @@ -189,6 +189,24 @@ self.children = [] return super().from_bytes(do, context=context)

+ def child_by_name(self, name: str) -> Optional['IE']: + """Return a child IE instance of given snake-case/json type name. This only works in case + there is no more than one child IE of the given type.""" + children = list(filter(lambda c: camel_to_snake(type(c).__name__) == name, self.children)) + if len(children) > 1: + raise KeyError('There are multiple children of class %s' % name) + elif len(children) == 1: + return children[0] + + def child_by_type(self, cls) -> Optional['IE']: + """Return a child IE instance of given type (class). This only works in case + there is no more than one child IE of the given type.""" + children = list(filter(lambda c: isinstance(c, cls), self.children)) + if len(children) > 1: + raise KeyError('There are multiple children of class %s' % cls) + elif len(children) == 1: + return children[0] +

class TLV_IE(IE): """Abstract base class for various TLV type Information Elements."""