def bind_partial(self, *args, **kwds):
"""
Binds the provided positional and keyword arguments
and returns a new ``Function`` object with an updated signature.
"""
# We only need the signature, so clean the function body before eval'ing.
empty_func = self.replace(tree=replace_fields(self.tree, body=[ast.Pass()]))
signature = inspect.signature(empty_func.eval())
bargs = signature.bind_partial(*args, **kwds)
# Remove the bound arguments from the function AST
bound_argnames = set(bargs.arguments.keys())
new_tree = filter_function_def(self.tree, bound_argnames)
# Add assignments for bound parameters
assignments = []
gen_sym = GenSym.for_tree(new_tree)
new_bindings = {}
for name, value in bargs.arguments.items():
node, gen_sym, binding = reify_unwrapped(value, gen_sym)
new_bindings.update(binding)
assignments.append(ast.Assign(targets=[ast.Name(id=name, ctx=ast.Store())], value=node))
new_globals = dict(self.globals)
new_globals.update(new_bindings)
new_tree = replace_fields(new_tree, body=assignments + new_tree.body)
return Function(new_tree, new_globals, self.closure_vals, self._compiler_flags)
def test_replace_fields():
node = ast.Name(id='x', ctx=ast.Load())
new_node = replace_fields(node, id='y')
assert new_node is not node
assert new_node.id == 'y' and type(new_node.ctx) == ast.Load
new_node = replace_fields(node, id='x')
# no new object is created if the new value is the same as the old value
assert new_node is node
assert new_node.id == 'x' and type(new_node.ctx) == ast.Load
def handle_YieldFrom(state, node, ctx):
state, result = _peval_expression(state, node.value, ctx)
# We cannot evaluate a yield expression,
# so just wrap whatever we've got in a node and return.
state, new_value = map_reify(state, result)
return state, replace_fields(node, value=new_value)
def increment(node, walk_field, **kwds):
if isinstance(node, ast.Assign):
return replace_fields(node, targets=node.targets, value=walk_field(node.value))
elif isinstance(node, ast.Num):
return ast.Num(n=node.n + 1)
else:
return node
def _handle_loop(node, state, ctx, visit_after, visiting_after, walk_field, **_):
if not visiting_after:
# Need to traverse fields explicitly since for the purposes of _replace_returns(),
# the body of `orelse` field is not inside a loop.
state = state.update(loop_nesting_ctr=state.loop_nesting_ctr + 1)
state, new_body = walk_field(state, node.body, block_context=True)
state = state.update(loop_nesting_ctr=state.loop_nesting_ctr - 1)
state, new_orelse = walk_field(state, node.orelse, block_context=True)
visit_after()
return state, replace_fields(node, body=new_body, orelse=new_orelse)
else:
# If there was a return inside a loop, append a conditional break
# to propagate the return otside all nested loops
if state.return_inside_a_loop:
new_nodes = [
node,
ast.If(
test=ast.Name(id=ctx.return_flag_var),
body=[ast.Break()],
orelse=[])]
else:
new_nodes = node
# if we are at root level, reset the return-inside-a-loop flag
if state.loop_nesting_ctr == 0:
state = state.update(return_inside_a_loop=False)
return state, new_nodes
def remove_simple_assignments(node):
"""
Remove one assigment of the form `<variable> = <variable>` at a time,
touching only the top level statements of the block.
"""
remaining_nodes = list(node.body)
new_nodes = []
while len(remaining_nodes) > 0:
cur_node = remaining_nodes.pop(0)
if type(cur_node) == ast.Assign:
can_remove, dest_name, src_name = _can_remove_assignment(cur_node, remaining_nodes)
if can_remove:
remaining_nodes = replace_name(
remaining_nodes, ctx=dict(dest_name=dest_name, src_name=src_name))
else:
new_nodes.append(cur_node)
else:
new_nodes.append(cur_node)
if len(new_nodes) == len(node.body):
return node
return replace_fields(node, body=new_nodes)
def peval_comprehension(state, node, ctx):
accum_cls = {
ast.ListComp: ListAccumulator,
ast.GeneratorExp: GeneratorExpAccumulator,
ast.SetComp: SetAccumulator,
ast.DictComp: DictAccumulator,
}
# variables from generators temporary mask bindings
target_names = set()
for generator in node.generators:
if type(generator.target) == ast.Name:
target_names.add(generator.target.id)
else:
target_names.update([elt.id for elt in generator.target.elts])
# pre-evaluate the expression
elt_bindings = dict(ctx.bindings)
for name in target_names:
if name in elt_bindings:
del elt_bindings[name]
elt_ctx = ctx.update(bindings=elt_bindings)
if type(node) == ast.DictComp:
elt = ast.Tuple(elts=[node.key, node.value])
else:
elt = node.elt
state, new_elt = _peval_expression(state, elt, elt_ctx)
try:
state, container = _peval_comprehension(
state, accum_cls[type(node)], new_elt, node.generators, ctx)
evaluated = True
except CannotEvaluateComprehension:
evaluated = False
if evaluated:
return state, KnownValue(value=container)
else:
state, new_elt = map_reify(state, new_elt)
state, new_generators = _peval_comprehension_generators(state, node.generators, ctx)
if type(node) == ast.DictComp:
key, value = new_elt.elts
return state, replace_fields(node, key=key, value=value, generators=new_generators)
else:
return state, replace_fields(node, elt=new_elt, generators=new_generators)
def handle_Attribute(state, node, ctx):
state, result = _peval_expression(state, node.value, ctx)
if is_known_value(result):
success, attr = try_get_attribute(result.value, node.attr)
if success:
return state, KnownValue(value=attr)
state, new_value = map_reify(state, result)
return state, replace_fields(node, value=new_value)
def handle_Slice(state, node, ctx):
state, results = map_peval_expression(state, (node.lower, node.upper, node.step), ctx)
# how do we handle None values in nodes? Technically, they are known values
if all_known_values_or_none(results):
lower, upper, step = [result if result is None else result.value for result in results]
return state, KnownValue(value=slice(lower, upper, step))
state, new_nodes = map_reify(state, results)
new_node = replace_fields(node, lower=new_nodes[0], upper=new_nodes[1], step=new_nodes[2])
return state, new_node
def remove_unreachable_statements(node, walk_field, **kwds):
for attr in ('body', 'orelse'):
if hasattr(node, attr):
old_list = getattr(node, attr)
new_list = filter_block(old_list)
if new_list is not old_list:
new_list = walk_field(new_list, block_context=True)
kwds = {attr: new_list}
node = replace_fields(node, **kwds)
return node
def names_and_incremented_nums(node, state, walk_field, **kwds):
if isinstance(node, ast.Assign):
value_node, state = walk_field(node.value, state)
new_node = replace_fields(node, targets=node.targets, value=value_node)
new_state = state.update(objs=state.objs.add(node.targets[0].id))
return new_node, new_state
elif isinstance(node, ast.Num):
return ast.Num(n=node.n + 1), state.update(objs=state.objs.add(node.n))
else:
return node, state
def handle_Set(state, node, ctx):
state, elts = map_peval_expression(state, node.elts, ctx)
can_eval = all_known_values(elts)
if can_eval:
new_set = set(elt.value for elt in elts)
return state, KnownValue(value=new_set)
else:
state, new_elts = map_reify(state, elts)
return state, replace_fields(node, elts=new_elts)
def handle_Dict(state, node, ctx):
state, pairs = map_peval_expression(state, zip(node.keys, node.values), ctx)
can_eval = all_known_values(pairs)
if can_eval:
new_dict = dict((key.value, value.value) for key, value in pairs)
return state, KnownValue(value=new_dict)
else:
state, keys_values = map_reify(state, zip(*pairs))
new_node = replace_fields(node, keys=list(keys_values[0]), values=list(keys_values[1]))
return state, new_node
def replace_by_path(obj, path, new_value):
if len(path) > 1:
if isinstance(ptr, str):
sub_obj = getattr(obj, ptr)
elif isinstance(ptr, int):
sub_obj = obj[ptr]
new_value = replace_by_path(sub_obj, path[1:], new_value)
ptr = path[0]
if isinstance(ptr, str):
return replace_fields(obj, **{ptr: new_value})
elif isinstance(ptr, int):
return obj[:ptr] + [new_value] + obj[ptr+1:]
def handle_Subscript(state, node, ctx):
state, value_result = _peval_expression(state, node.value, ctx)
state, slice_result = _peval_expression(state, node.slice, ctx)
if is_known_value(value_result) and is_known_value(slice_result):
success, elem = try_call_method(
value_result.value, '__getitem__', args=(slice_result.value,))
if success:
return state, KnownValue(value=elem)
state, new_value = map_reify(state, value_result)
state, new_slice = map_reify(state, slice_result)
if type(new_slice) not in (ast.Index, ast.Slice, ast.ExtSlice):
new_slice = ast.Index(value=new_slice)
return state, replace_fields(node, value=new_value, slice=new_slice)
def handle_IfExp(state, node, ctx):
state, test_value = _peval_expression(state, node.test, ctx)
if is_known_value(test_value):
success, bool_value = try_call(bool, args=(test_value.value,))
if success:
taken_node = node.body if bool_value else node.orelse
return _peval_expression(state, taken_node, ctx)
state, new_body = _peval_expression(state, node.body, ctx)
state, new_orelse = _peval_expression(state, node.orelse, ctx)
state, new_body_node = map_reify(state, new_body)
state, new_orelse_node = map_reify(state, new_orelse)
return state, replace_fields(
node, test=test_value, body=new_body_node, orelse=new_orelse_node)
def from_object(cls, func, ignore_decorators=False):
"""
Creates a ``Function`` object from an evaluated function.
"""
src = getsource(func)
tree = ast.parse(src).body[0]
if ignore_decorators:
tree = replace_fields(tree, decorator_list=[])
global_values = func.__globals__
closure_vals = get_closure(func)
scope = analyze_scope(tree)
func_name = func.__name__
# Builtins can be either a dict or a module
builtins = global_values["__builtins__"]
if not isinstance(builtins, dict):
builtins = dict(vars(builtins))
globals_ = {}
for name in scope.globals:
if name == func_name:
globals_[name] = func
elif name in global_values:
globals_[name] = global_values[name]
elif name in builtins:
globals_[name] = builtins[name]
elif name in closure_vals:
continue
else:
raise NameError(name)
compiler_flags = func.__code__.co_flags
# We only need the flags corresponding to future features.
# Also, these are the only ones supported by compile().
compiler_flags = compiler_flags & FUTURE_FLAGS
return cls(tree, globals_, closure_vals, compiler_flags)
def handle_Name(node, ctx, **_):
if type(node.ctx) == ast.Load and node.id == ctx.dest_name:
return replace_fields(node, id=ctx.src_name)
else:
return node
def handle_ExtSlice(state, node, ctx):
state, results = map_peval_expression(state, node.dims, ctx)
if all_known_values(results):
return state, KnownValue(value=tuple(result.value for result in results))
state, new_nodes = map_reify(state, results)
return state, replace_fields(node, dims=new_nodes)
def mangle_outer_functions(node, **kwds):
if isinstance(node, ast.FunctionDef):
return replace_fields(node, name='__' + node.name)
else:
return node
def mangle_all_functions(node, walk_field, **kwds):
if isinstance(node, ast.FunctionDef):
return replace_fields(
node, name='__' + node.name, body=walk_field(node.body, block_context=True))
else:
return node
