From bd0ec9e0955dacde283c68fcd0924e474e8c6024 Mon Sep 17 00:00:00 2001
From: "Zed A. Shaw" <zed.shaw@gmail.com>
Date: Tue, 6 May 2025 10:43:11 -0400
Subject: [PATCH] Making an FSM work better for the calulator.

---
 demos/calc.cpp | 82 +++++++++++++++++++++++++++++++++-----------------
 1 file changed, 55 insertions(+), 27 deletions(-)

diff --git a/demos/calc.cpp b/demos/calc.cpp
index 01c5ffc..df4c6bf 100644
--- a/demos/calc.cpp
+++ b/demos/calc.cpp
@@ -19,23 +19,19 @@ const std::unordered_map<string, wstring> LABELS {
     {"btn2", L"2"}, {"btn3", L"3"}, {"btn4", L"4"},
     {"btn5", L"5"}, {"btn6", L"6"}, {"btn7", L"7"},
     {"btn8", L"8"}, {"btn9", L"9"}, {"mult", L"*"},
-    {"minus", L"-"}, {"plus", L"+"}, {"neg", L"!"},
-    {"div", L"/"}, {"eq", L"="}
-    };
+    {"minus", L"-"}, {"plus", L"+"}, {"neg", L"±"},
+    {"div", L"/"}, {"eq", L"="} };
 
 enum class Event {
-  NUMBER=0,
-  OP=1,
-  CLR=2,
-  NOT=3,
-  EQ=4
+  NUMBER, ADD, SUB, MUL,
+  DIV, CLR, NOT, EQ,
 };
 
 enum class State {
-  START=0,
-  CALCULATING=1,
-  CLEARED=3,
-  DISPLAYED=4
+  START,
+  CALCULATING,
+  CLEARED,
+  DISPLAYED
 };
 
 
@@ -60,17 +56,39 @@ struct Calculator : DeadSimpleFSM<State, Event> {
   }
 
   void CALCULATING(Event ev, wchar_t op) {
-    if(ev == Event::NUMBER) {
-      input += op;
-    } else if(ev == Event::OP) {
-
-    } else if(ev == Event::NOT) {
+    using enum Event;
 
-    } else if(ev == Event::EQ) {
-
-    } else if(ev == Event::CLR) {
-      input = L"";
-      state(State::CLEARED);
+    switch(ev) {
+      case NUMBER:
+        input += op;
+        break;
+      case ADD:
+        value += std::stof(input);
+        input = L"";
+        break;
+      case SUB:
+        value -= std::stof(input);
+        input = L"";
+        break;
+      case MUL:
+        value *= std::stof(input);
+        input = L"";
+        break;
+      case DIV:
+        value /= std::stof(input);
+        input = L"";
+        break;
+      case NOT:
+        value = std::stof(input) * -1;
+        input = L"";
+        break;
+      case EQ:
+        value = std::stof(input);
+        break;
+      case CLR:
+        input = L"";
+        state(State::CLEARED);
+        break;
     }
   }
 
@@ -134,6 +152,8 @@ struct CalculatorUI {
   }
 
   void handle_button(wchar_t op) {
+    using enum Event;
+
     switch(op) {
       case L'0':
       case L'1':
@@ -145,20 +165,28 @@ struct CalculatorUI {
       case L'7':
       case L'8':
       case L'9':
-        $fsm.event(Event::NUMBER, op);
+        $fsm.event(NUMBER, op);
         break;
       case L'*':
+        $fsm.event(MUL, op);
+        break;
       case L'-':
+        $fsm.event(SUB, op);
+        break;
       case L'+':
+        $fsm.event(ADD, op);
+        break;
       case L'/':
-      case L'!':
-        $fsm.event(Event::OP, op);
+        $fsm.event(DIV, op);
+        break;
+      case L'±':
+        $fsm.event(NOT, op);
         break;
       case L'=':
-        $fsm.event(Event::EQ, op);
+        $fsm.event(EQ, op);
         break;
       case L'C':
-        $fsm.event(Event::CLR, op);
+        $fsm.event(CLR, op);
         break;
     }