pycalc/parse.py

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