def join(cls, a: 'Variable', b: 'Variable') -> 'Variable':
"""
Return a Variable whose values and def sites are the
unions of the inputs value and def site sets.
"""
vals = ssle.join(a, b)
sites = ssle.join(a.def_sites, b.def_sites)
if vals.is_top:
return cls.top(def_sites=sites)
return cls(values=vals, def_sites=sites)
def bottom(
cls,
name=VAR_DEFAULT_NAME,
def_sites: ssle = ssle.bottom()) -> 'Variable':
"""
Return a Variable with Bottom value, and optionally set its name.
Args:
name: the name of the new variable.
def_sites: a set of locations where this variable was possibly defined.
"""
return cls(values=cls._bottom_val(), name=name, def_sites=def_sites)
def top(
cls,
name=VAR_DEFAULT_NAME,
def_sites: ssle = ssle.bottom()) -> 'Variable':
"""
Return a Variable with Top value, and optionally set its name.
Args:
name: the name of the new variable.
def_sites: a set of locations where this variable was possibly defined.
"""
result = cls(name=name, def_sites=def_sites)
result.value = cls._top_val()
return result
def arith_op(cls,
opname: str,
args: t.Iterable['Variable'],
name=VAR_RESULT_NAME) -> 'Variable':
"""
Apply the named arithmetic operation to the given Variables' values
in all permutations, and return a Variable containing the result.
Args:
opname: the EVM operation to apply.
args: a sequence of Variables whose length matches the
arity of the specified operation.
name: the name of the result Variable.
"""
result = ssle.cartesian_map(getattr(cls, opname), args)
return cls(values=result, name=name)
def __init__(self,
values: t.Iterable = None,
name: str = VAR_DEFAULT_NAME,
def_sites: ssle = ssle.bottom()):
"""
Args:
values: the set of values this variable could take.
name: the name that uniquely identifies this variable.
def_sites: a set of locations (TACLocRefs) where this variable
was possibly defined.
"""
# Make sure the input values are not out of range.
mod = [] if values is None else [v % self.CARDINALITY for v in values]
super().__init__(value=mod)
self.name = name
self.def_sites = def_sites
def __init__(self,
name: str,
payload=None,
def_sites: ssle = ssle.bottom()):
"""
Args:
name: the name of the new MetaVariable
payload: some information to carry along with this MetaVariable.
def_sites: a set of locations where this variable was possibly defined.
"""
super().__init__(values=self._bottom_val(),
name=name,
def_sites=def_sites)
self.value = self._top_val()
"""
The value of this MetaVariable.
MetaVariables are taken to have unconstrained value sets.
"""
self.payload = payload
def values(self) -> ssle:
"""
Return the set of values this location may contain.
Generically, this set is unconstrained.
"""
return ssle.top()
def __new_metavar(n: int, def_sites: ssle = ssle.bottom()) -> MetaVariable:
"""Return a MetaVariable with the given payload and a corresponding name."""
return MetaVariable(name="S{}".format(n),
payload=n,
def_sites=def_sites)