def forward_transfer(gen_sym, in_env, statement):
if isinstance(statement, ast.Assign):
target = statement.targets[0].id
result, gen_sym = peval_expression(statement.value, gen_sym, in_env.known_values())
new_values=dict(in_env.values)
for name in result.mutated_bindings:
new_values[name] = Value(undefined=True)
if result.fully_evaluated:
new_value = Value(value=result.value)
else:
new_value = Value(undefined=True)
new_values[target] = new_value
out_env = Environment(values=new_values)
new_exprs = [CachedExpression(path=['value'], node=result.node)]
return gen_sym, out_env, new_exprs, result.temp_bindings
elif isinstance(statement, (ast.Expr, ast.Return)):
result, gen_sym = peval_expression(statement.value, gen_sym, in_env.known_values())
new_values=dict(in_env.values)
for name in result.mutated_bindings:
new_values[name] = Value(undefined=True)
new_exprs = [CachedExpression(path=['value'], node=result.node)]
out_env = Environment(values=new_values)
return gen_sym, out_env, new_exprs, result.temp_bindings
elif isinstance(statement, ast.If):
result, gen_sym = peval_expression(statement.test, gen_sym, in_env.known_values())
new_values=dict(in_env.values)
for name in result.mutated_bindings:
new_values[name] = Value(undefined=True)
out_env = Environment(values=new_values)
new_exprs = [CachedExpression(path=['test'], node=result.node)]
return gen_sym, out_env, new_exprs, result.temp_bindings
else:
return gen_sym, in_env, [], {}
def check_peval_expression(source, bindings, expected_source,
fully_evaluated=False, expected_value=None, expected_temp_bindings=None):
source_tree = expression_ast(source)
# In some cases we need to enforce the expected node,
# because it cannot be obtained by parsing
# (e.g. "-5" is parsed as "UnaryOp(op=USub(), Num(n=5))", not as "Num(n=-5)").
# But we expect the latter from a fully evaluated expression.
if isinstance(expected_source, str):
expected_tree = expression_ast(expected_source)
else:
expected_tree = expected_source
gen_sym = GenSym()
result, gen_sym = peval_expression(source_tree, gen_sym, bindings)
assert_ast_equal(result.node, expected_tree)
assert result.fully_evaluated == fully_evaluated
if fully_evaluated:
assert result.value == expected_value
if expected_temp_bindings is not None:
for key, val in expected_temp_bindings.items():
assert key in result.temp_bindings
assert result.temp_bindings[key] == expected_temp_bindings[key]
def test_generator_exp():
# Need to do this manually, since we can't compare generator expressions
# without changing their state.
source_tree = expression_ast("(x + 1 for x in range(a))")
expected_tree = expression_ast("__peval_temp_2")
bindings = dict(a=10, range=range)
gen_sym = GenSym()
result, gen_sym = peval_expression(source_tree, gen_sym, bindings)
assert_ast_equal(result.node, expected_tree)
assert result.fully_evaluated
expected_genexp = (x + 1 for x in range(10))
assert type(result.value) == type(expected_genexp)
assert list(result.value) == list(expected_genexp)
# Since the binding contained the reference to the same genexp,
# and we destroyed it, we need to do the evaluation again
# in order to check the binding as well
gen_sym = GenSym()
result, gen_sym = peval_expression(source_tree, gen_sym, bindings)
expected_genexp = (x + 1 for x in range(10))
assert '__peval_temp_2' in result.temp_bindings
binding = result.temp_bindings['__peval_temp_2']
assert type(binding) == type(expected_genexp)
assert list(binding) == list(expected_genexp)
check_peval_expression(
'(x + 1 for x in range(a))', dict(a=10), '(x + 1 for x in range(10))')
