"""
===============================================================================
ENGR 13300 Fall 2023

Program Description
	This is the function that parses the expression. It goes through the expression, and produces a list of 'tokens', where each token represents a part of the expression. For example, '3 + 2' would yield the tokens '3', '+' and '2'. It then returns the list of tokens.
Assignment Information
    Assignment:     Individual Project
    Author:         Aadhavan Srinivasan, srini193@purdue.edu
    Team ID:        LC3 - 19


Contributor:    Name, login@purdue [repeat for each]
    My contributor(s) helped me:
    [ ] understand the assignment expectations without
        telling me how they will approach it.
    [ ] understand different ways to think about a solution
        without helping me plan my solution.
    [ ] think through the meaning of a specific error or
        bug present in my code without looking at my code.
    Note that if you helped somebody else with their code, you
    have to list that person as a contributor here as well.
    
ACADEMIC INTEGRITY STATEMENT
I have not used source code obtained from any other unauthorized
source, either modified or unmodified. Neither have I provided
access to my code to another. The project I am submitting
is my own original work.
===============================================================================
"""
def parse(expr):

	opers = ['+', '-', '*', '/', '=']

	num_par = 0
	tokenized = []
	temp_string = ""
	index = 0
	while index < len(expr):
		if expr[index] in opers:
			tokenized.append(expr[index])
			index += 1

		elif expr[index].isdigit() or expr[index] == '.':
			while (index < len(expr)) and (expr[index].isdigit() or expr[index] == '.'):
				temp_string += expr[index]
				index += 1
			tokenized.append(temp_string)

		elif expr[index] == '(':
			num_par = 1
			temp_string += expr[index]
			index += 1
			while index < len(expr) and num_par != 0:
				temp_string += expr[index]
				if expr[index] == '(':
					num_par += 1
				if expr[index] == ')':
					num_par -= 1
				index += 1

			tokenized.append(temp_string)

		elif expr[index].isalpha(): # If you encounter a variable
			temp_string += expr[index]
			index += 1
			while index < len(expr) and expr[index].isalpha():
				temp_string += expr[index]
				index += 1
			tokenized.append(temp_string)

		else:
			index += 1

		temp_string = ""

	return tokenized