def dup(self, position):
"""
Perform a DUP operation on the stack.
"""
idx = -1 * position
try:
self.push(self.values[idx])
except IndexError:
raise InsufficientStack("Insufficient stack items for DUP{0}".format(position))
def swap(self, position):
"""
Perform a SWAP operation on the stack.
"""
idx = -1 * position - 1
try:
self.values[-1], self.values[idx] = self.values[idx], self.values[-1]
except IndexError:
raise InsufficientStack("Insufficient stack items for SWAP{0}".format(position))
def pop(self, num_items=1, type_hint=None):
"""
Pop an item off thes stack.
Note: This function is optimized for speed over readability.
"""
try:
if num_items == 1:
return next(self._pop(num_items, type_hint))
else:
return tuple(self._pop(num_items, type_hint))
except IndexError:
raise InsufficientStack("No stack items")