def test_simple_function(self):
expression = "sin 5"
computed_token_list = tokenize(expression)
postfix_token_list = infix_to_postfix(computed_token_list)
token_list = [
tokens.OperandToken(5),
tokens.SinFunctionToken(),
]
self.assertListEqual(postfix_token_list, token_list)
def test_simple_operator(self):
expression = "2 + 1"
computed_token_list = tokenize(expression)
postfix_token_list = infix_to_postfix(computed_token_list)
token_list = [
tokens.OperandToken(2),
tokens.OperandToken(1),
tokens.PlusOperatorToken(),
]
self.assertListEqual(postfix_token_list, token_list)
def test_parenthesis(self):
expression = "2 * (1 + 5)"
computed_token_list = tokenize(expression)
postfix_token_list = infix_to_postfix(computed_token_list)
token_list = [
tokens.OperandToken(2),
tokens.OperandToken(1),
tokens.OperandToken(5),
tokens.PlusOperatorToken(),
tokens.ProductOperatorToken()
]
self.assertListEqual(postfix_token_list, token_list)
def test_multiple_operators_reversed(self):
expression = "2 * 1 + 5"
computed_token_list = tokenize(expression)
postfix_token_list = infix_to_postfix(computed_token_list)
token_list = [
tokens.OperandToken(2),
tokens.OperandToken(1),
tokens.ProductOperatorToken(),
tokens.OperandToken(5),
tokens.PlusOperatorToken(),
]
self.assertListEqual(postfix_token_list, token_list)
def evaluate(input, is_postfix=False):
input = input.strip()
if not input:
raise RuntimeError("Missing expression")
logger.debug("Evaluating input '%s'", input)
# Tokenize the input
token_list = tokenize(input)
logger.debug("Tokens:")
for tok in token_list:
logger.debug(" %r", tok)
# In Postfix notation, make sure there are no parenthesis, variables or equal signs
if is_postfix:
for tok in token_list:
if isinstance(
tok,
(tokens.OpenParenthesisToken, tokens.CloseParenthesisToken)):
raise RuntimeError(
"Parenthesis are not allowed in postfix expressions")
if isinstance(tok, (tokens.EqualSignToken, tokens.VariableToken)):
raise RuntimeError(
"Equations cannot be written in postfix notation")
# Decide whether it's an expression or an equation
is_equation = False
# For equations, convert the equal sign into a "minus" sign and surround the RHS of the equation in parenthesis
for i, tok in enumerate(token_list):
if isinstance(tok, tokens.EqualSignToken):
logger.debug("Detected equation")
is_equation = True
token_list.pop(i)
token_list.insert(i, tokens.MinusOperatorToken())
token_list.insert(i + 1, tokens.OpenParenthesisToken())
token_list.append(tokens.CloseParenthesisToken())
break
# Equation testing
if is_equation:
# Make sure there are variables if it's an equation
for i, tok in enumerate(token_list):
if isinstance(tok, tokens.VariableToken):
break
else:
raise RuntimeError("Incorrect equation: missing variable")
# Make sure there are no more equal signs
if len([x for x in token_list
if isinstance(x, tokens.EqualSignToken)]):
raise RuntimeError(
"Incorrect equation: more than one equal sign found")
# Make sure all variables are the same
if len(
set([
x.value
for x in token_list if isinstance(x, tokens.VariableToken)
])) > 1:
raise RuntimeError("Only one variable allowed")
# Make sure there are no variables if it's not an equation
if not is_equation:
for i, tok in enumerate(token_list):
if isinstance(tok, tokens.VariableToken):
raise RuntimeError(
"Variable '{}' found in non-equation".format(tok.value))
if not is_postfix:
# Even if it's not postfix, run a dumb detection algorithm just to make sure
for i, tok in enumerate(token_list[:-1]):
if isinstance(tok, tokens.OperandToken) and isinstance(
token_list[i + 1], tokens.OperandToken):
logger.debug("Expression already in postfix")
is_postfix = True
break
if not is_postfix:
logger.debug("Converting to postfix")
token_list = infix_to_postfix(token_list)
logger.debug("Tokens in postfix:")
for tok in token_list:
logger.debug(" %r", tok)
stack = []
logger.debug("Evaluating token list:")
for tok in token_list:
logger.debug("")
logger.debug("Stack: %r", stack)
logger.debug("%r", tok)
node = None
if tokens.is_operand(tok):
node = EquationNode(constant=tok.value)
elif tokens.is_variable(tok):
node = EquationNode(coefficient=1)
elif tokens.is_constant(tok):
node = EquationNode(constant=tok.value)
else:
if tokens.is_operator(tok):
try:
second_operand = stack.pop()
first_operand = stack.pop()
except IndexError:
raise RuntimeError("Bad expression, missing operands")
logger.debug(" Oper A: %r", first_operand)
logger.debug(" Oper B: %r", second_operand)
if isinstance(tok, tokens.PlusOperatorToken):
constant = None
coefficient = None
if first_operand.constant is not None:
constant = first_operand.constant
if second_operand.constant is not None:
if constant is None: constant = 0
constant += second_operand.constant
if first_operand.coefficient is not None:
coefficient = first_operand.coefficient
if second_operand.coefficient is not None:
if coefficient is None: coefficient = 0
coefficient += second_operand.coefficient
node = EquationNode(coefficient=coefficient,
constant=constant)
elif isinstance(tok, tokens.MinusOperatorToken):
constant = None
coefficient = None
if first_operand.constant is not None:
constant = first_operand.constant
if second_operand.constant is not None:
if constant is None: constant = 0
constant -= second_operand.constant
if first_operand.coefficient is not None:
coefficient = first_operand.coefficient
if second_operand.coefficient is not None:
if coefficient is None: coefficient = 0
coefficient -= second_operand.coefficient
node = EquationNode(coefficient=coefficient,
constant=constant)
elif isinstance(tok, tokens.ProductOperatorToken):
constant = None
coefficient = None
if first_operand.has_constant():
if second_operand.has_constant():
if constant is None: constant = 0
constant += first_operand.constant * second_operand.constant
if second_operand.has_coef():
if coefficient is None: coefficient = 0
coefficient += first_operand.constant * second_operand.coefficient
if first_operand.has_coef():
if second_operand.has_constant():
if coefficient is None: coefficient = 0
coefficient += first_operand.coefficient * second_operand.constant
if second_operand.has_coef():
raise RuntimeError(
"Unsupported expression, can't have exponential variables"
)
node = EquationNode(coefficient=coefficient,
constant=constant)
elif isinstance(tok, tokens.DivisionOperatorToken):
constant = None
coefficient = None
if first_operand.has_constant():
if second_operand.has_constant():
if constant is None: constant = 0
constant += first_operand.constant / second_operand.constant
if second_operand.has_coef():
raise RuntimeError(
"Unsupported expression, non-linear equations are not supported"
)
if first_operand.has_coef():
if second_operand.has_constant():
if coefficient is None: coefficient = 0
coefficient += first_operand.coefficient / second_operand.constant
if second_operand.has_coef():
raise RuntimeError(
"Unsupported expression, can't have exponential variables"
)
node = EquationNode(coefficient=coefficient,
constant=constant)
elif tokens.is_function(tok):
try:
operand = stack.pop()
except IndexError as e:
raise RuntimeError(
"Missing value for trigonometric function")
# Functions are only allowed in simple expressions, not in equations, so there should be no coeffs.
if operand.has_coef():
raise RuntimeError("Function not allowed in equations")
# Make sure there's a value to work with
if not operand.has_constant():
raise RuntimeError(
"Missing value for trigonometric function")
if tokens.is_trigonometric(tok):
node = EquationNode(constant=tok.oper(operand.constant))
elif isinstance(tok, tokens.LnFunctionToken):
node = EquationNode(
constant=math.log(operand.constant, math.e))
elif isinstance(tok, tokens.LogFunctionToken):
base = 10
if tok.has_custom_base:
base = stack.pop().constant
node = EquationNode(
constant=math.log(operand.constant, base))
if node is not None:
logger.debug("Pushing to stack: %r", node)
stack.append(node)
logger.debug("Final stack %r", stack)
arred = lambda x, n: x * (10**n) // 1 / (10**n)
logger.info("Input: {}".format(input))
if is_equation:
value = -stack[-1].constant / stack[-1].coefficient
value = arred(value, 10)
logger.info("x = {}".format(value))
else:
value = stack[-1].constant
value = arred(value, 10)
logger.info(value)
return value
def test_missing_right_parenthesis(self):
expression = "2 * (1 + 5"
computed_token_list = tokenize(expression)
with self.assertRaises(RuntimeError):
postfix_token_list = infix_to_postfix(computed_token_list)