def _return_from_function(config: Configuration) -> None:
"""
Helper function for when the control flow for a frame exits.
"""
valn = tuple(config.pop_operand() for _ in range(config.frame_arity))
# discard all of the current labels before popping the frame.
while config.has_active_label:
config.pop_label()
config.pop_frame()
if config.has_active_frame:
config.extend_operands(valn)
else:
config.extend_results(valn)
def _br(config: Configuration, label_idx: LabelIdx) -> None:
"""
Helper function for the BR, BR_IF, and BR_TABLE opcodes.
"""
label = config.get_label_by_idx(label_idx)
# take any return values off of the stack before popping labels
valn = tuple(config.pop_operand() for _ in range(label.arity))
if label.is_loop:
# For loops we keep the label which represents the loop on the stack
# since the continuation of a loop is beginning back at the beginning
# of the loop itself.
for _ in range(label_idx):
config.pop_label()
config.seek_to_instruction_idx(0)
else:
for _ in range(label_idx + 1):
config.pop_label()
# put return values back on the stack.
config.extend_operands(valn)
def _exit_block(config: Configuration) -> None:
"""
Helper function for when the control flow for a label exits.
"""
label = config.pop_label()
config.extend_operands(label.operand_stack)