expression_compiler.py

from AbstractDataTypes import Queue, Stack

OPERATORS = {"+": 1, "-": 1, "*": 2, "/": 2, "%": 2, "**": 3}
OPEN_PARENTHESIS = "("
CLOSE_PARENTHESIS = ")"

def to_postfix(infix):
    infix = Queue(infix.strip().split())
    stack = Stack()
    postfix = str()

    while infix.size != 0:
        char = infix.dequeue()
        if char.isalpha() or char.isnumeric():
            postfix += char
            postfix += " "
        elif char == OPEN_PARENTHESIS:
            stack.push(char)
        elif char == CLOSE_PARENTHESIS:
            while stack.peek() != OPEN_PARENTHESIS:
                postfix += stack.pop()
                postfix += " "
            stack.pop()
        else:
            while stack.size > 0 and stack.peek() != OPEN_PARENTHESIS and OPERATORS[stack.peek()] >= OPERATORS[char]:
                postfix += stack.pop()
                postfix += " "
            stack.push(char)

        if infix.size == 0 and stack.size > 0:
            while stack.size != 0:
                postfix += stack.pop()
                postfix += " "

    return postfix[:-1]

def evaluate(postfix, variables={}):
    stack = Stack()
    postfix = Queue(postfix.strip().split())

    while postfix.size != 0:
        char = postfix.dequeue()
        if char.isalpha() or char.isnumeric():
            stack.push(eval(char, variables, locals()))
        else:
            operand_1 = stack.pop()
            operand_2 = stack.pop()
            answer = eval(f"operand_2 {char} operand_1", variables, locals())
            stack.push(answer)
    return stack.pop()