def find_operations(expression_string):
operations = list()
for character_position, character in enumerate(expression_string):
if Sign.is_operation_sign(character_position, expression_string):
operation = OperationFactory.create(character,
character_position)
operations.append(operation)
return operations
def find_first_sign_position_in_string(string):
character_position = 0
for character in string:
if Sign.is_sign(character):
return character_position
else:
character_position += 1
raise ValueError("No sign in string")
def find_left_operand_position(function_string, sign_position):
left_sign_or_end_position = SignFinder.find_left_sign_or_end_position(
function_string, sign_position)
if left_sign_or_end_position == 0:
return left_sign_or_end_position
if Sign.is_sign_of_negative_operand(left_sign_or_end_position,
function_string):
return left_sign_or_end_position
return left_sign_or_end_position + 1
def find_left_sign_or_end_position(function_string, sign_position):
left_substring = function_string[:sign_position]
if Sign.contains_sign(left_substring):
reversed_left_substring = left_substring[::-1]
first_sign_position_in_reversed_left_substring = (
SignFinder.find_first_sign_position_in_string(reversed_left_substring)
)
left_sign_position = (
SignFinder.get_string_position_from_left_substring_position(
first_sign_position_in_reversed_left_substring, sign_position
)
)
return left_sign_position
else:
end_position = 0
return end_position
def find_right_sign_or_end_position(function_string, sign_position):
sign_position_tail = sign_position + 1
right_substring = function_string[sign_position_tail:]
if Sign.contains_operation_sign(right_substring):
first_operation_sign_position_in_right_substring = (
SignFinder.find_first_operation_sign_position_in_string(right_substring)
)
right_sign_position = (
SignFinder.get_string_position_from_right_substring_position(
first_operation_sign_position_in_right_substring, sign_position
)
)
return right_sign_position
else:
end_position = len(function_string)
return end_position
def find_first_operation_sign_position_in_string(function_string):
for character_position, character in enumerate(function_string):
if Sign.is_operation_sign(character_position, function_string):
return character_position
raise ValueError("No sign in string")
def test_is_sign_when_sign_given(sign):
assert Sign.is_sign(sign) is True
def test_is_operation_sign_returns_false_for_negative_operand_sign(sign_position, expression_string):
assert Sign.is_operation_sign(sign_position, expression_string) is False