def duplicate_stack_item(self, pos: int = 0):
"""
Duplicates the item n back in the stack
:param pos: index of the variable
"""
# n = 1 -> duplicates stack top item
# n = 0 -> value varies in runtime
if pos >= 0:
opcode: Opcode = Opcode.get_dup(pos)
if opcode is Opcode.PICK and pos > 0:
self.convert_literal(pos - 1)
self._stack.pop()
op_info = OpcodeInfo.get_info(opcode)
self.__insert1(op_info)
self._stack.append(self._stack[-pos])
def _compare_values(self) -> List[Tuple[Opcode, bytes]]:
from boa3.neo.vm.type.Integer import Integer
jmp_place_holder = (Opcode.JMP, b'\x01')
test_if_are_equal = [
(Opcode.OVER, b''),
(Opcode.OVER, b''),
(Opcode.EQUAL, b''), # if str1 == str2:
Opcode.get_jump_and_data(Opcode.JMPIFNOT, 4),
(Opcode.PUSH1, b''),
jmp_place_holder, # go to final test
]
get_limit_index = [
(Opcode.OVER, b''), # limit = min((len(str1), len(str2))
(Opcode.SIZE, b''),
(Opcode.OVER, b''),
(Opcode.SIZE, b''),
(Opcode.MIN, b''),
(Opcode.PUSH0, b''), # index = 0
]
while_body_before_compare = [
(Opcode.PUSH3, b''), # value1 = str1[index]
(Opcode.get_dup(3), b''),
(Opcode.OVER, b''),
(Opcode.PICKITEM, b''),
(Opcode.OVER, b''),
(Opcode.PUSH4, b''), # value2 = str2[index]
(Opcode.get_dup(4), b''),
(Opcode.SWAP, b''),
(Opcode.PICKITEM, b''),
]
while_body_compare = [
(Opcode.OVER, b''),
(Opcode.OVER, b''),
(Opcode.JMPEQ, Integer(7).to_byte_array(
signed=True)), # if value1 != value2 jmp to end
(Opcode.GT, b''),
(Opcode.NIP, b''),
(Opcode.NIP, b''),
jmp_place_holder, # jmp to end
]
while_body_after_compare = [
(Opcode.DROP, b''),
(Opcode.DROP, b''),
(Opcode.INC, b''), # index++
]
while_full_body = while_body_before_compare + while_body_compare + while_body_after_compare
while_bytes_size = get_bytes_count(while_full_body)
get_limit_index.append(
Opcode.get_jump_and_data(Opcode.JMP, while_bytes_size, True))
while_condition = [(Opcode.OVER, b''), (Opcode.OVER, b'')]
while_condition_bytes_size = get_bytes_count(while_condition)
while_condition.append(
Opcode.get_jump_and_data(
Opcode.JMPGT, -while_bytes_size - while_condition_bytes_size))
while_else_body = [
(Opcode.DROP, b''),
(Opcode.DROP, b''),
(Opcode.OVER, b''), # if len(str1) > len(str2) jmp to end
(Opcode.SIZE, b''),
(Opcode.OVER, b''),
(Opcode.SIZE, b''),
(Opcode.GT, b''),
]
everything_after_while_check = while_body_after_compare + while_condition + while_else_body
jmp_while_check = Opcode.get_jump_and_data(
Opcode.JMP, get_bytes_count(everything_after_while_check), True)
while_body_compare[-1] = jmp_while_check
everything_after_equal_check = (get_limit_index +
while_body_before_compare +
while_body_compare +
everything_after_while_check)
jmp_test_equal = Opcode.get_jump_and_data(
Opcode.JMP, get_bytes_count(everything_after_equal_check), True)
test_if_are_equal[-1] = jmp_test_equal
final_test = [
(Opcode.JMPIF, Integer(4).to_byte_array(
signed=True)), # if condition is not True
(Opcode.DROP, b''), # remove str1 <=> return str2
(Opcode.JMP, Integer(3).to_byte_array(signed=True)), # else
(Opcode.NIP, b'') # remove str2 <=> return str1
]
return (test_if_are_equal + everything_after_equal_check + final_test)
