def substituted_expression(e, env):
"""
Return an expression with all freely occurring identifiers in E
replaced by their corresponding value in ENV.
"""
from pltools import Environment
subst = Environment(env)
rewriter = VariableSubstitute(subst)
return rewriter.rewrite(e)
def __init__(self, globals=None, tvsupply=None):
# Record the global Python namespace (if any) in which code is
# defined. This maps identifiers to values; by convention
# Copperhead objects have a 'cu_type' slot that we will
# use for typing information.
#
# This dictionary should never be modified.
self.globals = globals or dict()
# Supply of unique type variable names: #tv0, #tv1, #tv2, ...
# They're known to be unique because they are illegal identifiers.
self._tvsupply = tvsupply or name_supply(['#tv'], drop_zero=False)
# The typings environment maps local identifiers to their
# corresponding types.
self.typings = Environment()
# Type variables associated with formal parameters, both in
# lambdas and procedures, are required to be monomorphic. This
# set records all introduced type variables that are known to be
# monomorphic. Since we make all internal variables unique, we
# only need a single set for this, rather than a hierarchical
# environment structure as with self.typings.
self.monomorphs = set()
# During inference, we accumulate a set of freely occurring
# identifiers. This set contains AST nodes, rather than names.
# Thus, multiple occurrences of a given name (e.g., 'x') may be
# found in this set if they occurred at separate source
# locations. For example, the expression 'x+x' will introduce
# two free occurrences, not one.
self.free_occurrences = set()
# The inference system builds up a set of assumptions about the
# types of identifiers occurring outside the current compilation
# unit and which have no known 'cu_type' attribute.
# This table provides a mapping from type variables created for
# free occurrences to the AST node at which they occur.
self.assumptions = dict()
def closure_conversion(ast, M):
'Perform closure conversion'
env = Environment(M.globals, __builtin__.__dict__)
return Front.closure_conversion(ast, env)
def free_variables(e, env={}):
'Generates all freely occurring identifiers in E not bound in ENV.'
from pltools import Environment
return FreeVariables(Environment(env)).visit(e)
