commit 0a2681233c1d7ae87d140ba351d06b9468b24ecc
Author: Aadhavan Srinivasan <aadhavan@twomorecents.org>
Date:   Sun Nov 26 10:50:25 2023 -0500

    First commit

diff --git a/calculator.py b/calculator.py
new file mode 100644
index 0000000..c84afea
--- /dev/null
+++ b/calculator.py
@@ -0,0 +1,91 @@
+import re
+from parse import *
+
+# Regular expression that checks for valid characters in an expression
+valid_chars = '[0-9.\(\)+-\/*]'
+
+def raise_error(error_code):
+
+	# List of error codes:
+	# 0 - Invalid characters found in expression
+	# 1 - Unclosed parantheses
+
+	match error_code:
+		case 0:
+			print("You have invalid characters in your expression.")
+		case 1:
+			print("You have an unclosed parantheses in your expression.")
+	
+	main() # Re-enter main loop
+
+def check_errors(expr):
+	# Check if number of opening parantheses is equal to number of closing parantheses
+	num_open_pars = 0
+	num_close_pars = 0
+	for val in expr:
+		num_open_pars += 1 if val == '('
+		num_close_pars += 1 if val == ')'
+		if num_open_pars != num_close_pars:
+			raise_error(2) 
+		
+
+
+def evaluate(subexpr): # Evaluate a tokenized expression, that contains no parantheses
+
+	subexpr = [element for element in subexpr if element != ''] # Remove empty characters in the expression
+
+	print(subexpr)
+
+	if (len(subexpr) == 1):
+		return float(subexpr[0])
+
+	if '/' in subexpr:
+		index = subexpr.index('/')
+		subexpr[index] = float(subexpr[index-1]) / float(subexpr[index+1])
+		subexpr[index-1] = ''
+		subexpr[index+1] = ''
+	elif '*' in subexpr:
+		index = subexpr.index('*')
+		subexpr[index] = float(subexpr[index-1]) * float(subexpr[index+1])
+		subexpr[index-1] = ''
+		subexpr[index+1] = ''
+	elif '+' in subexpr:
+		index = subexpr.index('+')
+		subexpr[index] = float(subexpr[index-1]) + float(subexpr[index+1])
+		subexpr[index-1] = ''
+		subexpr[index+1] = ''
+	elif '-' in subexpr:
+		index = subexpr.index('-')
+		subexpr[index] = float(subexpr[index-1]) - float(subexpr[index+1])
+		subexpr[index-1] = ''
+		subexpr[index+1] = ''
+			
+	print(subexpr)
+
+	return evaluate(subexpr)
+
+def find_inner(subexpr):
+	print("expr: "  + subexpr)
+
+	subexpr = parse(subexpr)
+
+	for index,val in enumerate(subexpr):
+		if '(' in val or ')' in val:
+			subexpr[index] = find_inner(val[1:len(val)-1])
+
+
+	subexpr_string = ''.join(subexpr)
+	print("New expr: " + subexpr_string)
+	if not '(' in subexpr_string and not ')' in subexpr_string:
+		return str(evaluate(subexpr))
+
+	
+
+def main():
+	while True:
+		expr = input()
+		check_for_errors(expr)
+		expr = find_inner(expr)
+		print(expr)
+
+main()
diff --git a/parse.py b/parse.py
new file mode 100644
index 0000000..3ca6e30
--- /dev/null
+++ b/parse.py
@@ -0,0 +1,38 @@
+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])
+
+		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)
+			temp_string = ""
+
+		elif expr[index] == '(':
+			num_par = 1
+			temp_string += expr[index]
+			index += 1
+			while num_par != 0 and index < len(expr):
+				temp_string += expr[index]
+				if expr[index] == '(':
+					num_par += 1
+				if expr[index] == ')':
+					num_par -= 1
+				index += 1
+
+			tokenized.append(temp_string)
+			temp_string = ""
+
+
+		index += 1
+
+	return tokenized