Update calculator.py

Adds new constants to represent operators and calculator buttons.

Adds a new function for setting the entire equation at once.

Also implements the previously unimplemented 'CE' and 'AC' buttons.

Author: self-init

calculator/api/calculator.py

@@ -1,3 +1,17 @@
+from enum import Enum
+
+class Operator(Enum):
+    ADD = "+"
+    SUBTRACT = "-"
+    MULTIPLY = "x"
+    DIVIDE = "/"
+
+ALL_CLEAR = "AC"
+CLEAR_ENTRY = "CE"
+FLIP_SIGN = "+/-"
+DECIMAL = "."
+EQ_SIGN = "="
+
 class Calculator:
     def __init__(self):
         self.equation_first = ""
@@ -8,26 +22,51 @@ def __init__(self):
     def input_button(self, button: str):
         if button.isdigit():
             self.add_digit(button)
-        elif button in ["+", "-", "/", "x"]:
+        elif button in set(item.value for item in Operator):
             self.set_operator(button)
-        elif button == "=":
+        elif button == EQ_SIGN:
             if self.current_part == "last":
                 self.solve()
-        elif button == ".":
+        elif button == DECIMAL:
             self.add_decimal()
-        elif button == "+/-":
+        elif button == FLIP_SIGN:
             self.flip_sign()
+        elif button == ALL_CLEAR:
+            self.all_clear()
+        elif button == CLEAR_ENTRY:
+            self.clear_entry()
 
+    def set_equation(self, first_part: str | float| int, operator: Operator = None, second_part: str | float | int = ""):
+        self.equation_first = str(first_part)
+        self.equation_type = operator or ""
+        self.equation_last = str(second_part)
+        if operator == None:
+            self.current_part = "first"
+        else:
+            self.current_part = "last"
+    
+    def clear_entry(self):
+        if self.current_part == "first":
+            self.equation_first = self.equation_first[:-1]
+        elif self.current_part == "last":
+            if self.equation_last == "":
+                self.equation_type = ""
+                self.current_part = "first"
+            else:
+                self.equation_last = self.equation_last[:-1]
+    
+    def all_clear(self):
+        self.set_equation("")
+
     def add_digit(self, digit):
         if self.current_part == "first":
             self.equation_first += digit
         elif self.current_part == "last":
             self.equation_last += digit
 
-    def set_operator(self, operator):
+    def set_operator(self, operator: Operator):
         self.equation_type = operator
-        if self.current_part == "first":
-            self.current_part = "last"
+        self.current_part = "last"
 
     def flip_sign(self):
         if self.current_part == "first":