Calculator: Use KeypadValue class instead of double

Calculator now uses the KeypadValue class instead of double in
its internal calculations. By not constantly converting to
double back-and-forth, we do not use precision simply by, for
example, negating a number. This fixes #7484.

6 files changed, 43 insertions, 57 deletions

diff --git a/Userland/Applications/Calculator/Calculator.cpp b/Userland/Applications/Calculator/Calculator.cpp
index a0972927a5..d55fdb5719 100644
--- a/Userland/Applications/Calculator/Calculator.cpp
+++ b/Userland/Applications/Calculator/Calculator.cpp
@@ -5,6 +5,7 @@
  */
 
 #include "Calculator.h"
+#include "KeypadValue.h"
 #include <AK/Assertions.h>
 #include <AK/Math.h>
 
@@ -16,9 +17,9 @@ Calculator::~Calculator()
 {
 }
 
-double Calculator::begin_operation(Operation operation, double argument)
+KeypadValue Calculator::begin_operation(Operation operation, KeypadValue argument)
 {
-    double res = 0.0;
+    KeypadValue res = 0;
 
     switch (operation) {
     case Operation::None:
@@ -33,30 +34,30 @@ double Calculator::begin_operation(Operation operation, double argument)
         return argument;
 
     case Operation::Sqrt:
-        if (argument < 0.0) {
+        if (argument < 0) {
             m_has_error = true;
             return argument;
         }
-        res = AK::sqrt(argument);
+        res = KeypadValue { AK::sqrt((double)argument) };
         clear_operation();
         break;
     case Operation::Inverse:
-        if (argument == 0.0) {
+        if (argument == 0) {
             m_has_error = true;
             return argument;
         }
-        res = 1 / argument;
+        res = KeypadValue { 1.0 / (double)argument };
         clear_operation();
         break;
     case Operation::Percent:
-        res = argument * 0.01;
+        res = argument * KeypadValue { 1, 2 }; // also known as `KeypadValue{0.01}`
         break;
     case Operation::ToggleSign:
         res = -argument;
         break;
 
     case Operation::MemClear:
-        m_mem = 0.0;
+        m_mem = 0;
         res = argument;
         break;
     case Operation::MemRecall:
@@ -67,7 +68,7 @@ double Calculator::begin_operation(Operation operation, double argument)
         res = argument;
         break;
     case Operation::MemAdd:
-        m_mem += argument;
+        m_mem = m_mem + argument; //avoids the need for operator+=()
         res = m_mem;
         break;
     }
@@ -75,9 +76,9 @@ double Calculator::begin_operation(Operation operation, double argument)
     return res;
 }
 
-double Calculator::finish_operation(double argument)
+KeypadValue Calculator::finish_operation(KeypadValue argument)
 {
-    double res = 0.0;
+    KeypadValue res = 0;
 
     switch (m_operation_in_progress) {
     case Operation::None:
@@ -93,11 +94,11 @@ double Calculator::finish_operation(double argument)
         res = m_saved_argument * argument;
         break;
     case Operation::Divide:
-        if (argument == 0.0) {
+        if (argument == 0) {
             m_has_error = true;
             return argument;
         }
-        res = m_saved_argument / argument;
+        res = KeypadValue { (double)m_saved_argument / (double)argument };
         break;
 
     case Operation::Sqrt:
@@ -118,6 +119,6 @@ double Calculator::finish_operation(double argument)
 void Calculator::clear_operation()
 {
     m_operation_in_progress = Operation::None;
-    m_saved_argument = 0.0;
+    m_saved_argument = 0;
     clear_error();
 }
diff --git a/Userland/Applications/Calculator/Calculator.h b/Userland/Applications/Calculator/Calculator.h
index c5a92325a4..1ca9fca5c0 100644
--- a/Userland/Applications/Calculator/Calculator.h
+++ b/Userland/Applications/Calculator/Calculator.h
@@ -6,6 +6,8 @@
 
 #pragma once
 
+#include "KeypadValue.h"
+
 // This type implements the regular calculator
 // behavior, such as performing arithmetic
 // operations and providing a memory cell.
@@ -36,8 +38,8 @@ public:
         MemAdd
     };
 
-    double begin_operation(Operation, double);
-    double finish_operation(double);
+    KeypadValue begin_operation(Operation, KeypadValue);
+    KeypadValue finish_operation(KeypadValue);
 
     bool has_error() const { return m_has_error; }
 
@@ -46,7 +48,7 @@ public:
 
 private:
     Operation m_operation_in_progress { Operation::None };
-    double m_saved_argument { 0.0 };
-    double m_mem { 0.0 };
+    KeypadValue m_saved_argument { (i64)0 };
+    KeypadValue m_mem { (i64)0 };
     bool m_has_error { false };
 };
diff --git a/Userland/Applications/Calculator/CalculatorWidget.cpp b/Userland/Applications/Calculator/CalculatorWidget.cpp
index 6ef4b73d50..0343c20886 100644
--- a/Userland/Applications/Calculator/CalculatorWidget.cpp
+++ b/Userland/Applications/Calculator/CalculatorWidget.cpp
@@ -7,6 +7,7 @@
  */
 
 #include "CalculatorWidget.h"
+#include "KeypadValue.h"
 #include <Applications/Calculator/CalculatorGML.h>
 #include <LibGUI/Button.h>
 #include <LibGUI/Label.h>
@@ -96,8 +97,8 @@ CalculatorWidget::CalculatorWidget()
 
     m_equals_button = *find_descendant_of_type_named<GUI::Button>("equal_button");
     m_equals_button->on_click = [this](auto) {
-        double argument = m_keypad.value();
-        double res = m_calculator.finish_operation(argument);
+        KeypadValue argument = m_keypad.value();
+        KeypadValue res = m_calculator.finish_operation(argument);
         m_keypad.set_value(res);
         update_display();
     };
@@ -110,8 +111,8 @@ CalculatorWidget::~CalculatorWidget()
 void CalculatorWidget::add_operation_button(GUI::Button& button, Calculator::Operation operation)
 {
     button.on_click = [this, operation](auto) {
-        double argument = m_keypad.value();
-        double res = m_calculator.begin_operation(operation, argument);
+        KeypadValue argument = m_keypad.value();
+        KeypadValue res = m_calculator.begin_operation(operation, argument);
         m_keypad.set_value(res);
         update_display();
     };
@@ -130,7 +131,7 @@ String CalculatorWidget::get_entry()
     return m_entry->text();
 }
 
-void CalculatorWidget::set_entry(double value)
+void CalculatorWidget::set_entry(KeypadValue value)
 {
     m_keypad.set_value(value);
     update_display();
diff --git a/Userland/Applications/Calculator/CalculatorWidget.h b/Userland/Applications/Calculator/CalculatorWidget.h
index ae5e6d399e..b18570a733 100644
--- a/Userland/Applications/Calculator/CalculatorWidget.h
+++ b/Userland/Applications/Calculator/CalculatorWidget.h
@@ -9,6 +9,7 @@
 
 #include "Calculator.h"
 #include "Keypad.h"
+#include "KeypadValue.h"
 #include <AK/Vector.h>
 #include <LibGUI/Widget.h>
 
@@ -17,7 +18,7 @@ class CalculatorWidget final : public GUI::Widget {
 public:
     virtual ~CalculatorWidget() override;
     String get_entry();
-    void set_entry(double);
+    void set_entry(KeypadValue);
 
 private:
     CalculatorWidget();
diff --git a/Userland/Applications/Calculator/Keypad.cpp b/Userland/Applications/Calculator/Keypad.cpp
index 243a895f11..9422e467dc 100644
--- a/Userland/Applications/Calculator/Keypad.cpp
+++ b/Userland/Applications/Calculator/Keypad.cpp
@@ -6,6 +6,8 @@
  */
 
 #include "Keypad.h"
+#include "KeypadValue.h"
+#include <AK/Math.h>
 #include <AK/StringBuilder.h>
 
 Keypad::Keypad()
@@ -97,51 +99,29 @@ void Keypad::type_backspace()
     }
 }
 
-double Keypad::value() const
+KeypadValue Keypad::value() const
 {
-    double res = 0.0;
-
-    u64 frac = m_frac_value.value();
-    for (int i = 0; i < m_frac_length; i++) {
-        u8 digit = frac % 10;
-        res += digit;
-        res /= 10.0;
-        frac /= 10;
-    }
-
-    res += m_int_value.value();
+    KeypadValue frac_part = { (i64)m_frac_value.value(), m_frac_length };
+    KeypadValue int_part = { (i64)m_int_value.value() };
+    KeypadValue res = int_part + frac_part;
     if (m_negative)
         res = -res;
-
     return res;
 }
 
-void Keypad::set_value(double value)
+void Keypad::set_value(KeypadValue value)
 {
     m_state = State::External;
 
-    if (value < 0.0) {
+    if (value.m_value < 0) {
         m_negative = true;
         value = -value;
     } else
         m_negative = false;
 
-    m_int_value = value;
-    value -= m_int_value.value();
-
-    m_frac_value = 0;
-    m_frac_length = 0;
-    while (value != 0) {
-        value *= 10.0;
-        int digit = value;
-        m_frac_value *= 10;
-        m_frac_value += digit;
-        m_frac_length++;
-        value -= digit;
-
-        if (m_frac_length > 6)
-            break;
-    }
+    m_int_value = value.m_value / (u64)AK::pow(10.0, (double)value.m_decimal_places);
+    m_frac_value = value.m_value % (u64)AK::pow(10.0, (double)value.m_decimal_places);
+    m_frac_length = value.m_decimal_places;
 }
 
 String Keypad::to_string() const
diff --git a/Userland/Applications/Calculator/Keypad.h b/Userland/Applications/Calculator/Keypad.h
index d090f6ff5c..7d10115942 100644
--- a/Userland/Applications/Calculator/Keypad.h
+++ b/Userland/Applications/Calculator/Keypad.h
@@ -6,6 +6,7 @@
 
 #pragma once
 
+#include "KeypadValue.h"
 #include <AK/String.h>
 
 // This type implements number typing and
@@ -22,8 +23,8 @@ public:
     void type_decimal_point();
     void type_backspace();
 
-    double value() const;
-    void set_value(double);
+    KeypadValue value() const;
+    void set_value(KeypadValue);
 
     String to_string() const;