697 lines
22 KiB
Python
697 lines
22 KiB
Python
"""Classes to aid in working with the STIX 2 patterning language.
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"""
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import base64
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import binascii
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import datetime
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import re
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from .utils import parse_into_datetime
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def escape_quotes_and_backslashes(s):
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return s.replace(u'\\', u'\\\\').replace(u"'", u"\\'")
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def quote_if_needed(x):
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if isinstance(x, str):
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if x.find("-") != -1:
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if not x.startswith("'"):
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return "'" + x + "'"
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return x
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class _Constant(object):
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pass
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class StringConstant(_Constant):
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"""Pattern string constant
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Args:
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value (str): string value
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"""
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def __init__(self, value, from_parse_tree=False):
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self.needs_to_be_quoted = not from_parse_tree
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self.value = value
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def __str__(self):
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return "'%s'" % (escape_quotes_and_backslashes(self.value) if self.needs_to_be_quoted else self.value)
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class TimestampConstant(_Constant):
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"""Pattern timestamp constant
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Args:
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value (datetime.datetime OR str): if string, must be a timestamp string
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"""
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def __init__(self, value):
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try:
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self.value = parse_into_datetime(value)
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except Exception:
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raise ValueError("Must be a datetime object or timestamp string.")
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def __str__(self):
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return "t%s" % repr(self.value)
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class IntegerConstant(_Constant):
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"""Pattern interger constant
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Args:
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value (int): integer value
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"""
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def __init__(self, value):
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try:
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self.value = int(value)
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except Exception:
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raise ValueError("must be an integer.")
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def __str__(self):
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return "%s" % self.value
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class FloatConstant(_Constant):
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def __init__(self, value):
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try:
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self.value = float(value)
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except Exception:
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raise ValueError("must be a float.")
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def __str__(self):
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return "%s" % self.value
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class BooleanConstant(_Constant):
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"""Pattern boolean constant
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Args:
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value (str OR int):
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(str) 'true', 't' for True; 'false', 'f' for False
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(int) 1 for True; 0 for False
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"""
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def __init__(self, value):
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if isinstance(value, bool):
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self.value = value
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return
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trues = ['true', 't', '1']
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falses = ['false', 'f', '0']
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try:
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if value.lower() in trues:
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self.value = True
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return
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elif value.lower() in falses:
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self.value = False
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return
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except AttributeError:
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if value == 1:
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self.value = True
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return
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elif value == 0:
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self.value = False
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return
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raise ValueError("must be a boolean value.")
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def __str__(self):
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return str(self.value).lower()
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_HASH_REGEX = {
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"MD5": ("^[a-fA-F0-9]{32}$", "MD5"),
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"MD6": ("^[a-fA-F0-9]{32}|[a-fA-F0-9]{40}|[a-fA-F0-9]{56}|[a-fA-F0-9]{64}|[a-fA-F0-9]{96}|[a-fA-F0-9]{128}$", "MD6"),
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"RIPEMD160": ("^[a-fA-F0-9]{40}$", "RIPEMD-160"),
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"SHA1": ("^[a-fA-F0-9]{40}$", "SHA-1"),
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"SHA224": ("^[a-fA-F0-9]{56}$", "SHA-224"),
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"SHA256": ("^[a-fA-F0-9]{64}$", "SHA-256"),
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"SHA384": ("^[a-fA-F0-9]{96}$", "SHA-384"),
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"SHA512": ("^[a-fA-F0-9]{128}$", "SHA-512"),
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"SHA3224": ("^[a-fA-F0-9]{56}$", "SHA3-224"),
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"SHA3256": ("^[a-fA-F0-9]{64}$", "SHA3-256"),
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"SHA3384": ("^[a-fA-F0-9]{96}$", "SHA3-384"),
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"SHA3512": ("^[a-fA-F0-9]{128}$", "SHA3-512"),
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"SSDEEP": ("^[a-zA-Z0-9/+:.]{1,128}$", "ssdeep"),
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"WHIRLPOOL": ("^[a-fA-F0-9]{128}$", "WHIRLPOOL"),
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}
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class HashConstant(StringConstant):
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"""Pattern hash constant
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Args:
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value (str): hash value
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type (str): hash algorithm name. Supported hash algorithms:
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"MD5", "MD6", RIPEMD160", "SHA1", "SHA224", "SHA256",
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"SHA384", "SHA512", "SHA3224", "SHA3256", "SHA3384",
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"SHA3512", "SSDEEP", "WHIRLPOOL"
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"""
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def __init__(self, value, type):
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key = type.upper().replace('-', '')
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if key in _HASH_REGEX:
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vocab_key = _HASH_REGEX[key][1]
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if not re.match(_HASH_REGEX[key][0], value):
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raise ValueError("'%s' is not a valid %s hash" % (value, vocab_key))
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super(HashConstant, self).__init__(value)
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class BinaryConstant(_Constant):
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"""Pattern binary constant
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Args:
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value (str): base64 encoded string value
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"""
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def __init__(self, value, from_parse_tree=False):
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# support with or without a 'b'
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if from_parse_tree:
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m = re.match("^b'(.+)'$", value)
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if m:
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value = m.group(1)
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try:
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base64.b64decode(value)
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self.value = value
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except (binascii.Error, TypeError):
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raise ValueError("must contain a base64 encoded string")
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def __str__(self):
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return "b'%s'" % self.value
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class HexConstant(_Constant):
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"""Pattern hexadecimal constant
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Args:
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value (str): hexadecimal value
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"""
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def __init__(self, value, from_parse_tree=False):
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# support with or without an 'h'
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if not from_parse_tree and re.match('^([a-fA-F0-9]{2})+$', value):
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self.value = value
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else:
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m = re.match("^h'(([a-fA-F0-9]{2})+)'$", value)
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if m:
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self.value = m.group(1)
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else:
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raise ValueError("must contain an even number of hexadecimal characters")
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def __str__(self):
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return "h'%s'" % self.value
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class ListConstant(_Constant):
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"""Pattern list constant
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Args:
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value (list): list of values
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"""
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def __init__(self, values):
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# handle _Constants or make a _Constant
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self.value = [x if isinstance(x, _Constant) else make_constant(x) for x in values]
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def __str__(self):
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return "(" + ", ".join(["%s" % x for x in self.value]) + ")"
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def make_constant(value):
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"""Convert value to Pattern constant, best effort attempt
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at determining root value type and corresponding conversion
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Args:
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value: value to convert to Pattern constant
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"""
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if isinstance(value, _Constant):
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return value
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try:
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return parse_into_datetime(value)
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except ValueError:
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pass
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if isinstance(value, str):
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return StringConstant(value)
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elif isinstance(value, bool):
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return BooleanConstant(value)
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elif isinstance(value, int):
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return IntegerConstant(value)
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elif isinstance(value, float):
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return FloatConstant(value)
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elif isinstance(value, list):
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return ListConstant(value)
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else:
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raise ValueError("Unable to create a constant from %s" % value)
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class _ObjectPathComponent(object):
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@staticmethod
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def create_ObjectPathComponent(component_name):
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if component_name.endswith("_ref"):
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return ReferenceObjectPathComponent(component_name)
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elif component_name.find("[") != -1:
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parse1 = component_name.split("[")
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return ListObjectPathComponent(parse1[0], parse1[1][:-1])
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else:
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return BasicObjectPathComponent(component_name, False)
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def __str__(self):
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return quote_if_needed(self.property_name)
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class BasicObjectPathComponent(_ObjectPathComponent):
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"""Basic object path component (for an observation or expression)
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By "Basic", implies that the object path component is not a
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list, object reference or futher referenced property, i.e. terminal
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component
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Args:
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property_name (str): object property name
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is_key (bool): is dictionary key, default: False
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"""
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def __init__(self, property_name, is_key):
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self.property_name = property_name
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# TODO: set is_key to True if this component is a dictionary key
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# self.is_key = is_key
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class ListObjectPathComponent(_ObjectPathComponent):
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"""List object path component (for an observation or expression)
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Args:
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property_name (str): list object property name
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index (int): index of the list property's value that is specified
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"""
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def __init__(self, property_name, index):
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self.property_name = property_name
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self.index = index
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def __str__(self):
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return "%s[%s]" % (quote_if_needed(self.property_name), self.index)
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class ReferenceObjectPathComponent(_ObjectPathComponent):
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"""Reference object path component (for an observation or expression)
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Args:
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reference_property_name (str): reference object property name
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"""
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def __init__(self, reference_property_name):
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self.property_name = reference_property_name
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class ObjectPath(object):
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"""Pattern operand object (property) path
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Args:
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object_type_name (str): name of object type for corresponding object path component
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property_path (_ObjectPathComponent OR str): object path
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"""
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def __init__(self, object_type_name, property_path):
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self.object_type_name = object_type_name
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self.property_path = [
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x if isinstance(x, _ObjectPathComponent) else
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_ObjectPathComponent.create_ObjectPathComponent(x)
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for x in property_path
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]
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def __str__(self):
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return "%s:%s" % (self.object_type_name, ".".join(["%s" % quote_if_needed(x) for x in self.property_path]))
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def merge(self, other):
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"""Extend the object property with that of the supplied object property path"""
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self.property_path.extend(other.property_path)
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return self
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@staticmethod
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def make_object_path(lhs):
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"""Create ObjectPath from string encoded object path
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Args:
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lhs (str): object path of left-hand-side component of expression
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"""
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path_as_parts = lhs.split(":")
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return ObjectPath(path_as_parts[0], path_as_parts[1].split("."))
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class _PatternExpression(object):
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pass
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class _ComparisonExpression(_PatternExpression):
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"""Pattern Comparison Expression
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Args:
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operator (str): operator of comparison expression
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, operator, lhs, rhs, negated=False):
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if operator == "=" and isinstance(rhs, (ListConstant, list)):
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self.operator = "IN"
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else:
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self.operator = operator
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if isinstance(lhs, ObjectPath):
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self.lhs = lhs
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else:
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self.lhs = ObjectPath.make_object_path(lhs)
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if isinstance(rhs, _Constant):
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self.rhs = rhs
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else:
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self.rhs = make_constant(rhs)
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self.negated = negated
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self.root_type = self.lhs.object_type_name
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def __str__(self):
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if self.negated:
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return "%s NOT %s %s" % (self.lhs, self.operator, self.rhs)
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else:
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return "%s %s %s" % (self.lhs, self.operator, self.rhs)
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class EqualityComparisonExpression(_ComparisonExpression):
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"""Pattern Equality Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(EqualityComparisonExpression, self).__init__("=", lhs, rhs, negated)
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class GreaterThanComparisonExpression(_ComparisonExpression):
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"""Pattern Greater-than Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(GreaterThanComparisonExpression, self).__init__(">", lhs, rhs, negated)
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class LessThanComparisonExpression(_ComparisonExpression):
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"""Pattern Less-than Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(LessThanComparisonExpression, self).__init__("<", lhs, rhs, negated)
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class GreaterThanEqualComparisonExpression(_ComparisonExpression):
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"""Pattern Greater-Than-or-Equal-to Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(GreaterThanEqualComparisonExpression, self).__init__(">=", lhs, rhs, negated)
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class LessThanEqualComparisonExpression(_ComparisonExpression):
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"""Pattern Less-Than-or-Equal-to Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(LessThanEqualComparisonExpression, self).__init__("<=", lhs, rhs, negated)
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class InComparisonExpression(_ComparisonExpression):
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"""'in' Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(InComparisonExpression, self).__init__("IN", lhs, rhs, negated)
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class LikeComparisonExpression(_ComparisonExpression):
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"""'like' Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(LikeComparisonExpression, self).__init__("LIKE", lhs, rhs, negated)
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class MatchesComparisonExpression(_ComparisonExpression):
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"""'Matches' Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(MatchesComparisonExpression, self).__init__("MATCHES", lhs, rhs, negated)
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class IsSubsetComparisonExpression(_ComparisonExpression):
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""" 'is subset' Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(IsSubsetComparisonExpression, self).__init__("ISSUBSET", lhs, rhs, negated)
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class IsSupersetComparisonExpression(_ComparisonExpression):
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""" 'is super set' Comparison Expression
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Args:
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lhs (ObjectPath OR str): object path of left-hand-side component of expression
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rhs (ObjectPath OR str): object path of right-hand-side component of expression
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negated (bool): comparison expression negated. Default: False
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"""
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def __init__(self, lhs, rhs, negated=False):
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super(IsSupersetComparisonExpression, self).__init__("ISSUPERSET", lhs, rhs, negated)
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class _BooleanExpression(_PatternExpression):
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"""Boolean Pattern Expression
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Args:
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operator (str): boolean operator
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operands (list): boolean operands
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"""
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def __init__(self, operator, operands):
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self.operator = operator
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self.operands = []
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for arg in operands:
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if not hasattr(self, "root_type"):
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self.root_type = arg.root_type
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elif self.root_type and (self.root_type != arg.root_type) and operator == "AND":
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raise ValueError("All operands to an 'AND' expression must have the same object type")
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elif self.root_type and (self.root_type != arg.root_type):
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self.root_type = None
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self.operands.append(arg)
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def __str__(self):
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sub_exprs = []
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for o in self.operands:
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sub_exprs.append(str(o))
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return (" " + self.operator + " ").join(sub_exprs)
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class AndBooleanExpression(_BooleanExpression):
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"""'AND' Boolean Pattern Expression. Only use if both operands are of
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the same root object.
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Args:
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operands (list): AND operands
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"""
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def __init__(self, operands):
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super(AndBooleanExpression, self).__init__("AND", operands)
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class OrBooleanExpression(_BooleanExpression):
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"""'OR' Boolean Pattern Expression. Only use if both operands are of the same root object
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Args:
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operands (list): OR operands
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"""
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def __init__(self, operands):
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super(OrBooleanExpression, self).__init__("OR", operands)
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class ObservationExpression(_PatternExpression):
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"""Observation Expression
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Args:
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operand (str): observation expression operand
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"""
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def __init__(self, operand):
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self.operand = operand
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def __str__(self):
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return "[%s]" % self.operand
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class _CompoundObservationExpression(_PatternExpression):
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"""Compound Observation Expression
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Args:
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operator (str): compound observation operator
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operands (str): compound observation operands
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"""
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def __init__(self, operator, operands):
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self.operator = operator
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self.operands = operands
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def __str__(self):
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sub_exprs = []
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for o in self.operands:
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sub_exprs.append("%s" % o)
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return (" " + self.operator + " ").join(sub_exprs)
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class AndObservationExpression(_CompoundObservationExpression):
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"""'AND' Compound Observation Pattern Expression
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Args:
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operands (str): compound observation operands
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"""
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def __init__(self, operands):
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super(AndObservationExpression, self).__init__("AND", operands)
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class OrObservationExpression(_CompoundObservationExpression):
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"""Pattern 'OR' Compound Observation Expression
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Args:
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operands (str): compound observation operands
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"""
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def __init__(self, operands):
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super(OrObservationExpression, self).__init__("OR", operands)
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class FollowedByObservationExpression(_CompoundObservationExpression):
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"""Pattern 'Followed by' Compound Observation Expression
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Args:
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operands (str): compound observation operands
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"""
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def __init__(self, operands):
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super(FollowedByObservationExpression, self).__init__("FOLLOWEDBY", operands)
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class ParentheticalExpression(_PatternExpression):
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"""Pattern Parenthetical Observation Expression
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Args:
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exp (str): observation expression
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"""
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def __init__(self, exp):
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self.expression = exp
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if hasattr(exp, "root_type"):
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self.root_type = exp.root_type
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def __str__(self):
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return "(%s)" % self.expression
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class _ExpressionQualifier(_PatternExpression):
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pass
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class RepeatQualifier(_ExpressionQualifier):
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"""Pattern Repeat Qualifier
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Args:
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times_to_repeat (int): times the qualifiers is repeated
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"""
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def __init__(self, times_to_repeat):
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if isinstance(times_to_repeat, IntegerConstant):
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self.times_to_repeat = times_to_repeat
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elif isinstance(times_to_repeat, int):
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self.times_to_repeat = IntegerConstant(times_to_repeat)
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else:
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raise ValueError("%s is not a valid argument for a Repeat Qualifier" % times_to_repeat)
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def __str__(self):
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return "REPEATS %s TIMES" % self.times_to_repeat
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class WithinQualifier(_ExpressionQualifier):
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"""Pattern 'Within' Qualifier
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Args:
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number_of_seconds (int): seconds value for 'within' qualifier
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"""
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def __init__(self, number_of_seconds):
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if isinstance(number_of_seconds, IntegerConstant):
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self.number_of_seconds = number_of_seconds
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elif isinstance(number_of_seconds, int):
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self.number_of_seconds = IntegerConstant(number_of_seconds)
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else:
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raise ValueError("%s is not a valid argument for a Within Qualifier" % number_of_seconds)
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def __str__(self):
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return "WITHIN %s SECONDS" % self.number_of_seconds
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class StartStopQualifier(_ExpressionQualifier):
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"""Pattern Start/Stop Qualifier
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Args:
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start_time (TimestampConstant OR datetime.date): start timestamp for qualifier
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stop_time (TimestampConstant OR datetime.date): stop timestamp for qualifier
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"""
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def __init__(self, start_time, stop_time):
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if isinstance(start_time, TimestampConstant):
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self.start_time = start_time
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elif isinstance(start_time, datetime.date):
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self.start_time = TimestampConstant(start_time)
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else:
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raise ValueError("%s is not a valid argument for a Start/Stop Qualifier" % start_time)
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if isinstance(stop_time, TimestampConstant):
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self.stop_time = stop_time
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elif isinstance(stop_time, datetime.date):
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self.stop_time = TimestampConstant(stop_time)
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else:
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raise ValueError("%s is not a valid argument for a Start/Stop Qualifier" % stop_time)
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|
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def __str__(self):
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return "START %s STOP %s" % (self.start_time, self.stop_time)
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class QualifiedObservationExpression(_PatternExpression):
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"""Pattern Qualified Observation Expression
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Args:
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observation_expression (PatternExpression OR _CompoundObservationExpression OR ): pattern expression
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qualifier (_ExpressionQualifier): pattern expression qualifier
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"""
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def __init__(self, observation_expression, qualifier):
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self.observation_expression = observation_expression
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self.qualifier = qualifier
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def __str__(self):
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return "%s %s" % (self.observation_expression, self.qualifier)
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