def do_prepare(self):
argspec = inspect.getargspec(self.expr_fn)
check_multiple([
(len(argspec.args)
in (1, 2), 'Invalid collection iteration lambda: only one '
'or two parameters expected'),
(not argspec.varargs and not argspec.keywords,
'Invalid collection iteration lambda: no *args or **kwargs'),
(not argspec.defaults,
'Invalid collection iteration lambda: No default values allowed '
'for arguments')
])
self.requires_index = len(argspec.args) == 2
self.element_var = AbstractVariable(
names.Name("Item_{}".format(next(CollectionExpression._counter))),
source_name=names.Name.from_lower(argspec.args[0]))
if self.requires_index:
self.index_var = AbstractVariable(
names.Name('I'),
type=LongType,
create_local=True,
source_name=names.Name.from_lower(argspec.args[1]))
expr = self.expr_fn(self.index_var, self.element_var)
else:
expr = self.expr_fn(self.element_var)
self.expr = unsugar(expr)
def do_prepare(self):
# When this expression does not come from our Python DSL (see the
# initialize method above), the sub-expression is ready to use: do not
# try to expand the function.
if self.expr is not None:
return
argspec = inspect.getargspec(self.expr_fn)
check_multiple([
(len(argspec.args) in (1, 2),
'Invalid collection iteration lambda: only one '
'or two parameters expected'),
(not argspec.varargs and not argspec.keywords,
'Invalid collection iteration lambda: no *args or **kwargs'),
(not argspec.defaults,
'Invalid collection iteration lambda: No default values allowed '
'for arguments')
])
if len(argspec.args) == 2:
self.requires_index = True
index_var_pos = 0
item_var_pos = 1
else:
self.requires_index = False
index_var_pos = None
item_var_pos = 0
# Get the name of the loop variable from the DSL. But don't when we
# have a "default" one, such as for using the ".filter" combinator. In
# this case, it's up to ".filter"'s special implementation to get the
# name from the filter function.
source_name = (None if self.expr_fn == collection_expr_identity else
names.Name.from_lower(argspec.args[item_var_pos]))
self.element_var = AbstractVariable(
names.Name("Item_{}".format(next(CollectionExpression._counter))),
source_name=source_name
)
if self.requires_index:
self.index_var = AbstractVariable(
names.Name('I'), type=T.Int,
source_name=names.Name.from_lower(argspec.args[index_var_pos])
)
expr = self.expr_fn(self.index_var, self.element_var)
else:
expr = self.expr_fn(self.element_var)
self.expr = unsugar(expr)
def do_prepare(self):
# If this Then was created using create_from exprs, there is no lambda
# expansion to do.
if self.then_expr:
return
argspec = inspect.getargspec(self.then_fn)
check_source_language(
len(argspec.args) == 1 and not argspec.varargs
and not argspec.keywords and not argspec.defaults,
'Invalid lambda for Then expression: exactly one parameter is'
' required, without a default value')
self.var_expr = AbstractVariable(names.Name("Var_Expr"),
create_local=True,
source_name=names.Name(
argspec.args[0]))
self.then_expr = unsugar(self.then_fn(self.var_expr))
def prepare_iter_function(
self,
what: str,
expr_fn: Union[Callable[[AbstractExpression], AbstractExpression],
Callable[[AbstractExpression, AbstractExpression],
AbstractExpression]]
) -> AbstractExpression:
"""
Validate an iteration function, whether it only takes the iteration
element or also the iteration index.
Return the abstract expression to evaluate for each iteration.
:param what: Purpose of this function. Used for diagnostics.
:param expr_fn: Function to prepare.
"""
check_type(
expr_fn,
types.FunctionType,
"{what} passed to a collection expression must be a lambda or a"
" function"
)
argspec = inspect.getargspec(expr_fn)
check_multiple([
(len(argspec.args) in (1, 2),
'Invalid collection iteration lambda: only one'
' or two parameters expected'),
(not argspec.varargs and not argspec.keywords,
'Invalid collection iteration lambda: no *args or **kwargs'),
(not argspec.defaults,
'Invalid collection iteration lambda: No default values allowed'
' for arguments')
])
# Get source names for the iteration variables
index_required = False
index_varname: Optional[str] = None
element_varname: Optional[str] = None
if len(argspec.args) == 2:
index_required = True
self.requires_index = True
index_varname = argspec.args[0]
element_varname = argspec.args[1]
else:
element_varname = argspec.args[0]
# We are interested in names from user sources: disregard names from
# the default functions function we define here.
if expr_fn in builtin_collection_functions:
index_varname = None
element_varname = None
# Make sure we have an iteration element variable
self.element_var = self.create_iteration_var(
self.element_var, "Item", element_varname
)
# Expand the function. If the index is required, make sure we have an
# iteration variable for it.
if index_required:
self.index_var = self.create_iteration_var(
self.index_var, "Index", index_varname, T.Int
)
expr = expr_fn(self.index_var, self.element_var) # type: ignore
else:
expr = expr_fn(self.element_var) # type: ignore
return unsugar(expr)
