503 lines
13 KiB
Python
503 lines
13 KiB
Python
import operator
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import os
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import abc
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import pyparsing as pp
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from .. import utils
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from . import generators, exceptions
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class Settings:
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def __init__(
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self,
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is_client = False,
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staticdir = None,
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unconstrained_file_access = False,
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request_host = None,
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websocket_key = None
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):
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self.staticdir = staticdir
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self.unconstrained_file_access = unconstrained_file_access
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self.request_host = request_host
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self.websocket_key = websocket_key
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self.is_client = is_client
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Sep = pp.Optional(pp.Literal(":")).suppress()
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v_integer = pp.Word(pp.nums)\
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.setName("integer")\
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.setParseAction(lambda toks: int(toks[0]))
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v_literal = pp.MatchFirst(
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[
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pp.QuotedString(
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"\"",
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unquoteResults=True,
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multiline=True
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),
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pp.QuotedString(
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"'",
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unquoteResults=True,
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multiline=True
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),
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]
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)
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v_naked_literal = pp.MatchFirst(
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[
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v_literal,
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pp.Word("".join(i for i in pp.printables if i not in ",:\n@\'\""))
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]
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)
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class Token(object):
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"""
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A token in the specification language. Tokens are immutable. The token
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classes have no meaning in and of themselves, and are combined into
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Components and Actions to build the language.
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"""
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__metaclass__ = abc.ABCMeta
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@classmethod
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def expr(klass): # pragma: no cover
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"""
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A parse expression.
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"""
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return None
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@abc.abstractmethod
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def spec(self): # pragma: no cover
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"""
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A parseable specification for this token.
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"""
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return None
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@property
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def unique_name(self):
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"""
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Controls uniqueness constraints for tokens. No two tokens with the
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same name will be allowed. If no uniquness should be applied, this
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should be None.
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"""
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return self.__class__.__name__
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def resolve(self, settings, msg):
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"""
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Resolves this token to ready it for transmission. This means that
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the calculated offsets of actions are fixed.
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settings: a language.Settings instance
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msg: The containing message
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"""
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return self
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def __repr__(self):
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return self.spec()
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class _TokValueLiteral(Token):
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def __init__(self, val):
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self.val = val.decode("string_escape")
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def get_generator(self, settings):
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return self.val
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def freeze(self, settings):
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return self
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class TokValueLiteral(_TokValueLiteral):
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"""
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A literal with Python-style string escaping
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"""
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@classmethod
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def expr(klass):
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e = v_literal.copy()
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return e.setParseAction(klass.parseAction)
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@classmethod
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def parseAction(klass, x):
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v = klass(*x)
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return v
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def spec(self):
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inner = self.val.encode("string_escape")
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inner = inner.replace(r"\'", r"\x27")
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return "'" + inner + "'"
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class TokValueNakedLiteral(_TokValueLiteral):
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@classmethod
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def expr(klass):
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e = v_naked_literal.copy()
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return e.setParseAction(lambda x: klass(*x))
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def spec(self):
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return self.val.encode("string_escape")
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class TokValueGenerate(Token):
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def __init__(self, usize, unit, datatype):
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if not unit:
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unit = "b"
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self.usize, self.unit, self.datatype = usize, unit, datatype
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def bytes(self):
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return self.usize * utils.SIZE_UNITS[self.unit]
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def get_generator(self, settings):
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return generators.RandomGenerator(self.datatype, self.bytes())
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def freeze(self, settings):
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g = self.get_generator(settings)
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return TokValueLiteral(g[:].encode("string_escape"))
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@classmethod
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def expr(klass):
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e = pp.Literal("@").suppress() + v_integer
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u = reduce(
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operator.or_,
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[pp.Literal(i) for i in utils.SIZE_UNITS.keys()]
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).leaveWhitespace()
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e = e + pp.Optional(u, default=None)
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s = pp.Literal(",").suppress()
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s += reduce(
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operator.or_,
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[pp.Literal(i) for i in generators.DATATYPES.keys()]
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)
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e += pp.Optional(s, default="bytes")
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return e.setParseAction(lambda x: klass(*x))
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def spec(self):
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s = "@%s"%self.usize
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if self.unit != "b":
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s += self.unit
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if self.datatype != "bytes":
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s += ",%s"%self.datatype
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return s
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class TokValueFile(Token):
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def __init__(self, path):
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self.path = str(path)
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@classmethod
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def expr(klass):
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e = pp.Literal("<").suppress()
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e = e + v_naked_literal
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return e.setParseAction(lambda x: klass(*x))
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def freeze(self, settings):
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return self
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def get_generator(self, settings):
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if not settings.staticdir:
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raise exceptions.FileAccessDenied("File access disabled.")
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s = os.path.expanduser(self.path)
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s = os.path.normpath(
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os.path.abspath(os.path.join(settings.staticdir, s))
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)
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uf = settings.unconstrained_file_access
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if not uf and not s.startswith(settings.staticdir):
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raise exceptions.FileAccessDenied(
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"File access outside of configured directory"
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)
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if not os.path.isfile(s):
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raise exceptions.FileAccessDenied("File not readable")
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return generators.FileGenerator(s)
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def spec(self):
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return "<'%s'"%self.path.encode("string_escape")
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TokValue = pp.MatchFirst(
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[
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TokValueGenerate.expr(),
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TokValueFile.expr(),
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TokValueLiteral.expr()
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]
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)
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TokNakedValue = pp.MatchFirst(
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[
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TokValueGenerate.expr(),
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TokValueFile.expr(),
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TokValueLiteral.expr(),
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TokValueNakedLiteral.expr(),
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]
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)
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TokOffset = pp.MatchFirst(
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[
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v_integer,
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pp.Literal("r"),
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pp.Literal("a")
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]
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)
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class _Component(Token):
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"""
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A value component of the primary specification of an message.
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Components produce byte values desribe the bytes of the message.
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"""
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def values(self, settings): # pragma: no cover
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"""
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A sequence of values, which can either be strings or generators.
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"""
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pass
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def string(self, settings=None):
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"""
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A string representation of the object.
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"""
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return "".join(i[:] for i in self.values(settings or {}))
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class KeyValue(_Component):
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"""
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A key/value pair.
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klass.preamble: leader
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"""
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def __init__(self, key, value):
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self.key, self.value = key, value
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@classmethod
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def expr(klass):
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e = pp.Literal(klass.preamble).suppress()
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e += TokValue
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e += pp.Literal("=").suppress()
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e += TokValue
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return e.setParseAction(lambda x: klass(*x))
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def spec(self):
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return "%s%s=%s"%(self.preamble, self.key.spec(), self.value.spec())
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def freeze(self, settings):
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return self.__class__(
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self.key.freeze(settings), self.value.freeze(settings)
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)
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class CaselessLiteral(_Component):
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"""
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A caseless token that can take only one value.
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"""
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def __init__(self, value):
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self.value = value
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@classmethod
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def expr(klass):
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spec = pp.CaselessLiteral(klass.TOK)
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spec = spec.setParseAction(lambda x: klass(*x))
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return spec
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def values(self, settings):
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return self.TOK
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def spec(self):
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return self.TOK
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def freeze(self, settings):
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return self
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class OptionsOrValue(_Component):
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"""
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Can be any of a specified set of options, or a value specifier.
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"""
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preamble = ""
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options = []
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def __init__(self, value):
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# If it's a string, we were passed one of the options, so we lower-case
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# it to be canonical. The user can specify a different case by using a
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# string value literal.
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self.option_used = False
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if isinstance(value, basestring):
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for i in self.options:
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# Find the exact option value in a case-insensitive way
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if i.lower() == value.lower():
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self.option_used = True
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value = TokValueLiteral(i)
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break
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self.value = value
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@classmethod
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def expr(klass):
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parts = [pp.CaselessLiteral(i) for i in klass.options]
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m = pp.MatchFirst(parts)
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spec = m | TokValue.copy()
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spec = spec.setParseAction(lambda x: klass(*x))
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if klass.preamble:
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spec = pp.Literal(klass.preamble).suppress() + spec
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return spec
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def values(self, settings):
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return [
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self.value.get_generator(settings)
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]
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def spec(self):
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s = self.value.spec()
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if s[1:-1].lower() in self.options:
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s = s[1:-1].lower()
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return "%s%s"%(self.preamble, s)
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def freeze(self, settings):
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return self.__class__(self.value.freeze(settings))
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class Integer(_Component):
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def __init__(self, value):
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self.value = str(value)
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@classmethod
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def expr(klass):
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e = v_integer.copy()
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return e.setParseAction(lambda x: klass(*x))
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def values(self, settings):
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return self.value
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def spec(self):
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return "%s"%(self.value)
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def freeze(self, settings):
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return self
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class Value(_Component):
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"""
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A value component lead by an optional preamble.
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"""
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preamble = ""
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def __init__(self, value):
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self.value = value
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@classmethod
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def expr(klass):
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e = (TokValue | TokNakedValue)
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if klass.preamble:
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e = pp.Literal(klass.preamble).suppress() + e
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return e.setParseAction(lambda x: klass(*x))
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def values(self, settings):
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return [self.value.get_generator(settings)]
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def spec(self):
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return "%s%s"%(self.preamble, self.value.spec())
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def freeze(self, settings):
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return self.__class__(self.value.freeze(settings))
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class FixedLengthValue(Value):
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"""
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A value component lead by an optional preamble.
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"""
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preamble = ""
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length = None
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def __init__(self, value):
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Value.__init__(self, value)
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lenguess = None
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try:
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lenguess = len(value.get_generator(Settings()))
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except exceptions.RenderError:
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pass
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# This check will fail if we know the length upfront
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if lenguess is not None and lenguess != self.length:
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raise exceptions.RenderError(
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"Invalid value length: '%s' is %s bytes, should be %s."%(
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self.spec(),
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lenguess,
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self.length
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)
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)
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def values(self, settings):
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ret = Value.values(self, settings)
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l = sum(len(i) for i in ret)
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# This check will fail if we don't know the length upfront - i.e. for
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# file inputs
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if l != self.length:
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raise exceptions.RenderError(
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"Invalid value length: '%s' is %s bytes, should be %s."%(
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self.spec(),
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l,
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self.length
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)
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)
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return ret
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class Boolean(_Component):
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"""
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A boolean flag.
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name = true
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-name = false
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"""
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name = ""
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def __init__(self, value):
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self.value = value
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@classmethod
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def expr(klass):
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e = pp.Optional(pp.Literal("-"), default=True)
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e += pp.Literal(klass.name).suppress()
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def parse(s, loc, toks):
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val = True
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if toks[0] == "-":
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val = False
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return klass(val)
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return e.setParseAction(parse)
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def spec(self):
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return "%s%s"%("-" if not self.value else "", self.name)
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class IntField(_Component):
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"""
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An integer field, where values can optionally specified by name.
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"""
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names = {}
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max = 16
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preamble = ""
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def __init__(self, value):
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self.origvalue = value
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self.value = self.names.get(value, value)
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if self.value > self.max:
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raise exceptions.ParseException(
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"Value can't exceed %s"%self.max, 0, 0
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)
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@classmethod
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def expr(klass):
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parts = [pp.CaselessLiteral(i) for i in klass.names.keys()]
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m = pp.MatchFirst(parts)
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spec = m | v_integer.copy()
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spec = spec.setParseAction(lambda x: klass(*x))
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if klass.preamble:
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spec = pp.Literal(klass.preamble).suppress() + spec
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return spec
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def values(self, settings):
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return [str(self.value)]
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def spec(self):
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return "%s%s"%(self.preamble, self.origvalue)
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