def _Closure(self, c):
closed_over_literal = any(
map(lambda x: not isinstance(x, S.Name), c.closed_over()))
if not closed_over_literal:
return c
#Find procedure being closed over
proc_name = c.body().id
proc = self.procedures[proc_name]
proc_args = proc.formals()
closed_args = c.closed_over()
#Construct new set of arguments, with literals closed over removed
replaced_args = proc_args[:-len(closed_args)]
replaced_closed_over = []
#Also record what replacements to make
replacement = {}
for orig_arg, closed_arg in zip(proc_args[-len(closed_args):],
closed_args):
if isinstance(closed_arg, S.Name):
replaced_args.append(orig_arg)
replaced_closed_over.append(closed_arg)
else:
replacement[orig_arg.id] = closed_arg
#If we are only closing over literals, we will return a name
#rather than a reduced closure. Check.
fully_opened = len(replacement) == len(closed_args)
replaced_stmts = [
S.substituted_expression(si, replacement) \
for si in proc.body()]
replaced_name = S.Name(proc_name + self.name_supply.next())
self.propagated.append(
S.Procedure(replaced_name, replaced_args, replaced_stmts))
if fully_opened:
return replaced_name
else:
return S.Closure(replaced_closed_over, replaced_name)
def _Procedure(self, ast):
binders = [v.id
for v in flatten(ast.variables)] # NOTE: this includes name
_ClosureRecursion._Procedure(self, ast)
# Take the free variable list, stick it in a set to make sure we don't
# duplicate a variable, and then put it back in a list to make sure
# it's got a defined ordering, which sets don't have
free = list(
set([
v for v in S.free_variables(ast.body(), binders)
if v in self.env
]))
if free:
bound = [S.Name("_K%d" % i) for i in range(len(free))]
ast.variables = ast.variables + bound
ast.parameters = S.substituted_expression(ast.parameters,
dict(zip(free, bound)))
# Transform recursive calls of this procedure within its own body.
recursive = _ClosureRecursion(self.env)
self.env[ast.name().id] = S.Closure(bound, ast.name())
ast.parameters = recursive.rewrite(ast.parameters)
# Register rewrite for calls to this procedure in later
# parts of the defining scope
self.env[ast.name().id] = S.Closure([S.Name(x) for x in free],
ast.name())
# else:
# self.locally_bound([ast.name()])
return ast
def _Lambda(self, e):
_ClosureRecursion._Lambda(self, e)
formals = [v.id for v in flatten(e.formals())]
# Take the free variable list, stick it in a set to make sure we don't
# duplicate a variable, and then put it back in a list to make sure
# it's got a defined ordering, which sets don't have
free = list(
set([
v for v in S.free_variables(e.body(), formals) if v in self.env
]))
if free:
bound = [S.Name("_K%d" % i) for i in range(len(free))]
body = S.substituted_expression(e.body(), dict(zip(free, bound)))
e.parameters = [body]
e.variables = e.variables + bound
return S.Closure([S.Name(x) for x in free], e)
else:
return e
def _Name(self, ast):
x = getattr(self.env, ast.id, None)
if ast.id in self.env and isinstance(self.env[ast.id], S.Closure):
return S.Closure(self.env[ast.id].variables, ast)
else:
return ast
