#Premise
Premise
#The code
The code
#Restricting user input
Restricting user input
#Premise
#The code
#Restricting user input
Premise
The code
Restricting user input
C++ Calculator Simple postfix calculator app: efficiently keeping track of user input history
The calculator has a BackBack button (with a corresponding keyboard shortcut) that allows users to erase the previous input.
#The code All of the code works properly, but only parts of it are relevant to this question. I will post relevant snippets here to make things easier to understand.
All of the code works properly, but only parts of it are relevant to this question. I will post relevant snippets here to make things easier to understand.
If a user enters an operator, such as ++, they may enter a digit or opening parenthesis but may not enter another operator or closing parenthesis.
Notice that my mainwindow then has a private stack of States:QStack<State> history;
As the user provides input, the code creates a new State object and pushes it onto the stack. Here's the .cpp file (There are TODO statements for things I want to do in the future; please ignore those):
QStack<State> history;
As the user provides input, the code creates a new State object and pushes it onto the stack. Here's the .cpp file (there are TODO statements for things I want to do in the future; please ignore those):
##Edit 1
One idea that comes to mind is having each of the slot methods (e.g., on_digit_released() and on_binary_button_released()) check what character came before and proceeding accordingly. I think this would eliminate some of the memory workload, but it would also be a bit messier. Would the tradeofftrade-off be worth it?
C++ Calculator app: efficiently keeping track of user input history
The calculator has a Back button (with a corresponding keyboard shortcut) that allows users to erase the previous input.
#The code All of the code works properly, but only parts of it are relevant to this question. I will post relevant snippets here to make things easier to understand.
If a user enters an operator, such as +, they may enter a digit or opening parenthesis but may not enter another operator or closing parenthesis.
Notice that my mainwindow then has a private stack of States:QStack<State> history;
As the user provides input, the code creates a new State object and pushes it onto the stack. Here's the .cpp file (There are TODO statements for things I want to do in the future; please ignore those):
##Edit 1
One idea that comes to mind is having each of the slot methods (e.g., on_digit_released() and on_binary_button_released()) check what character came before and proceeding accordingly. I think this would eliminate some of the memory workload, but it would also be a bit messier. Would the tradeoff be worth it?
Simple postfix calculator app
The calculator has a Back button (with a corresponding keyboard shortcut) that allows users to erase the previous input.
#The code
All of the code works properly, but only parts of it are relevant to this question. I will post relevant snippets here to make things easier to understand.
If a user enters an operator, such as +, they may enter a digit or opening parenthesis but may not enter another operator or closing parenthesis.
Notice that my mainwindow then has a private stack of States:
QStack<State> history;
As the user provides input, the code creates a new State object and pushes it onto the stack. Here's the .cpp file (there are TODO statements for things I want to do in the future; please ignore those):
One idea that comes to mind is having each of the slot methods (e.g. on_digit_released() and on_binary_button_released()) check what character came before and proceeding accordingly. I think this would eliminate some of the memory workload, but it would also be a bit messier. Would the trade-off be worth it?
Updated code with new documentation. Some function bodies were changed. The code related to the question is fundamentally (functionally) the same.
Aleksandr Hovhannisyan
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#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "operator.h"
#include <QDebug> // debug output
#include <QChar>
#include <QShortcut> // keyboard input
#include <QKeySequence> // keyboard input
#include <QFont> // Qt fonts
// TODO add parentheses operations to calculator
/* Constructor for MainWindow objects. Connects all button signals
* to their appropriate private slots to handle user input and sets
* up some basic member variables.
*/
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
// Basic variable setups
ui->setupUi(this);
input = ui->labelInput;
reset();
// Connect digits' released() signals to on_digit_released
connect(ui->button0, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button1, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button2, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button3, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button4, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button5, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button6, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button7, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button8, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button9, SIGNAL(released()), this, SLOT(on_digit_released()));
// Connect binary operators' released() signals to on_binary_button_released
connect(ui->buttonPlus, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonMinus, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonTimes, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonDivide, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
// Shortcuts for math input via keyboard
// TODO potential memory leaks
QShortcut *shortcut0 = new QShortcut(QKeySequence("0"), this);
QShortcut *shortcut1 = new QShortcut(QKeySequence("1"), this);
QShortcut *shortcut2 = new QShortcut(QKeySequence("2"), this);
QShortcut *shortcut3 = new QShortcut(QKeySequence("3"), this);
QShortcut *shortcut4 = new QShortcut(QKeySequence("4"), this);
QShortcut *shortcut5 = new QShortcut(QKeySequence("5"), this);
QShortcut *shortcut6 = new QShortcut(QKeySequence("6"), this);
QShortcut *shortcut7 = new QShortcut(QKeySequence("7"), this);
QShortcut *shortcut8 = new QShortcut(QKeySequence("8"), this);
QShortcut *shortcut9 = new QShortcut(QKeySequence("9"), this);
QShortcut *shortcutDecimal = new QShortcut(QKeySequence("."), this);
QShortcut *shortcutPlus = new QShortcut(QKeySequence("+"), this);
QShortcut *shortcutMinus = new QShortcut(QKeySequence("-"), this);
QShortcut *shortcutTimes = new QShortcut(QKeySequence("SHIFT+8"), this);
QShortcut *shortcutDivide = new QShortcut(QKeySequence("/"), this);
QShortcut *shortcutOpenParenth = new QShortcut(QKeySequence("SHIFT+9"), this);
QShortcut *shortcutCloseParenth = new QShortcut(QKeySequence("SHIFT+0"), this);
QShortcut *shortcutEnter = new QShortcut(QKeySequence(Qt::Key_Return), this);
QShortcut *shortcutBackspace = new QShortcut(QKeySequence("Backspace"), this);
connect(shortcut0, SIGNAL(activated()), ui->button0, SLOT(click()));
connect(shortcut1, SIGNAL(activated()), ui->button1, SLOT(click()));
connect(shortcut2, SIGNAL(activated()), ui->button2, SLOT(click()));
connect(shortcut3, SIGNAL(activated()), ui->button3, SLOT(click()));
connect(shortcut4, SIGNAL(activated()), ui->button4, SLOT(click()));
connect(shortcut5, SIGNAL(activated()), ui->button5, SLOT(click()));
connect(shortcut6, SIGNAL(activated()), ui->button6, SLOT(click()));
connect(shortcut7, SIGNAL(activated()), ui->button7, SLOT(click()));
connect(shortcut8, SIGNAL(activated()), ui->button8, SLOT(click()));
connect(shortcut9, SIGNAL(activated()), ui->button9, SLOT(click()));
connect(shortcutDecimal, SIGNAL(activated()), ui->buttonDecimalPoint, SLOT(click()));
connect(shortcutPlus, SIGNAL(activated()), ui->buttonPlus, SLOT(click()));
connect(shortcutMinus, SIGNAL(activated()), ui->buttonMinus, SLOT(click()));
connect(shortcutTimes, SIGNAL(activated()), ui->buttonTimes, SLOT(click()));
connect(shortcutDivide, SIGNAL(activated()), ui->buttonDivide, SLOT(click()));
connect(shortcutOpenParenth, SIGNAL(activated()), ui->buttonOpenParenth, SLOT(click()));
connect(shortcutCloseParenth, SIGNAL(activated()), ui->buttonCloseParenth, SLOT(click()));
connect(shortcutEnter, SIGNAL(activated()), ui->buttonEquals, SLOT(click()));
connect(shortcutBackspace, SIGNAL(activated()), ui->buttonBack, SLOT(click()));
}
MainWindow::~MainWindow()
{
delete input;
delete ui;
}
/* Used by other functions whento checkingcheck if an operator was
* already applied directly before the current attempt at
* either evaluating the expression or adding auser's newinput operatortoken.
*/
bool MainWindow::operatorUsedDirectlyBefore() const
{
if(input->text().length() >= 2)
{
// Operators have a space after (e.g., " + "). Hence length()-2.
// If input is like "1 + 2", return false b/c " " is not operator.
return ((bool)operators.count(input->text().at(input->text().length()-21)));
}
return false;
}
/* WhenCalled when a user clicks any of the digit buttonbuttons is(0-9) pressed,or
its* textenters getsa relayeddigit from their keyboard (0-9). Appends the corresponding
* digit to inputthe labelinput.
*/
void MainWindow::on_digit_released()
{
State currentState = history.top();
if(currentState.digitAllowed)
{
QPushButton *button = (QPushButton*)sender();
history.push(State(true, true, false, true,
history.top().numOpenParenths,
history.top().numClosingParenths));
// Initial input is just a 0
if(input->text().length() == 1 && input->text()[0] == '0')
{
input->setText(input->text().replace(0, 1, button->text()));
}
// Otherwise, append the digit
else
{
input->setText(input->text().append(button->text()));
}
}
}
/* Called when a user clicks the '.' button or uses the keyboard
* shortcut '.' Appends a decimal point to the last digit that was
* entered.
*/
void MainWindow::on_buttonDecimalPoint_released()
{
// TODO prevent entry of multiple decimal points
if(!operatorUsedDirectlyBefore())
{
input->setText(input->text() + ".");
}
}
/* HandlesCalled functionalitywhen ofa negatinguser clicks the '±' button. Negates an input expression.
* Negating an expression appliesApplies the negative sign to the
* last number entered (if one exists).
* Negating a
* negative number will remove the negative sign. Negating the
* right operand of addition will change the '+' operator to subtraction.
* Similarly, negating the right operand of subtraction will change the
* '–' operator to addition.
*/
void MainWindow::on_buttonNegate_released()
{
if(operatorUsedDirectlyBefore()){ return; }
// Check if there are currently any operators in input
bool inputHasOperators = false;
for// If so, get the index of the last one (hence reverse traversal)
int iindexOfLastOperator = 0;-1;
for(int i <= input->text().length(); i++- 1; i >= 0; i--)
{
if(operators.count(input->text().at(i)) == 1)
{
inputHasOperators = true;
indexOfLastOperator = i;
break;
}
}
// InputIf expressionwe entered an operator and then tried to negate something
if(indexOfLastOperator == input->text().length()-1){ return; }
// Case 1: Input contains operators
if(inputHasOperators)
{
intQChar indexOfLastWhitespacelastOperator = input->text().lastIndexOfat(' 'indexOfLastOperator);
// If the number is negative andin partquestion ofis analready expressionnegative, w/undo opsit
if(input->text().at(indexOfLastWhitespace+1indexOfLastOperator+1) == '-')
{
input->setText(input->text().replace(indexOfLastWhitespace+1indexOfLastOperator+1, 1, ""));
}
// Otherwise,If justnot, alet's positivecheck numberwhat partkind of anoperator expressioncame w/before opsit
else
{
// If it was a plus, change that to a minus
if(lastOperator == '+')
{
input->setText(input->text().replace(indexOfLastOperator, 1, "–"));
}
// If it was a minus, change that to a plus
else if(lastOperator == '–')
{
input->setText(input->text().replace(indexOfLastOperator, 1, "+"));
}
// Otherwise, just negate the last number
else
{
input->setText(input->text().insert(indexOfLastWhitespace+1indexOfLastOperator+1, '-'));
}
}
}
// TODO or parenthetical expression?
// Case 2: No operators and already negative number
else if(input->text().at(0) == '-')
{
input->setText(input->text().replace(0, 1, ""));
}
// Case 3: No operators and positive number
else
{
input->setText(input->text().prepend("-"));
}
}
/* IfCalled thewhen a user pressesclicks any binary operation's button, like
* plus, minus, multiply(+, or divide-, this slot will be called
*, to/). insertInserts the appropriate operation into the current input.
*/
void MainWindow::on_binary_button_released()
{
QPushButton *button = (QPushButton*)sender();
State currentState = history.top();
if(currentState.operatorAllowed)
{
input->setText(input->text().append(button->text()));
history.push(State(true, false, true, false,
currentState.numOpenParenths,
currentState.numClosingParenths));
}
}
/* IfCalled thewhen a user releasesclicks the ='=' button, thenor theyuses wantthe keyboard
* theshortcut answer'Enter'. toChecks theirif the input tois beready calculatedfor evaluation.
* EmitsIf so, emits input_is_ready signal, toeffectively givehanding Calculatorits
* the input it needsstring to dothe itsCalculator jobfor processing.
*/
void MainWindow::on_buttonEquals_released()
{
State currentState = history.top();
if(!operatorUsedDirectlyBefore() &&
currentState.numOpenParenths == currentState.numClosingParenths)
{
emit input_is_ready(input->text());
}
}
/* Used to reset user input. Sets the input string to "0", clears its
* history, and applies all initial input restrictions.
*/
void MainWindow::reset()
{
input->setText("0");
history.clear();
history.push(State(true, true, false, false));
}
/* Pretty straightforward. Basically,Called ifwhen thea user *clicks pressesthe and'Clear' releasesbutton theor clearuses button,the thenkeyboard
* setshortcut the'Delete'. inputResets stringthe toinput. justSee 0MainWindow::reset().
*/
void MainWindow::on_buttonClear_released()
{
reset();
}
/* Called when a user clicks the 'Back' button or uses the
* keyboard shortcut 'Backspace'. Reverts the calculator to * its previous state of input,. Reapplies all appropriate input
* therebyrestrictions applyingthat allexisted appropriateprior restrictionsto deletion of the last token.
*/
void MainWindow::on_buttonBack_released()
{
// If the input is just a single digit, set it to 0
if(input->text().length() == 1)
{
input->setText("0");
}
// Otherwise, if we have 2 or more entries, remove last char
else
{
QString text = input->text();
input->setText(text.remove(text.length()-1, 1));
}
if(history.size() >= 2){ history.pop();}
}
void MainWindow::on_buttonRoot_released()
{
// TODO nth root
}
/* Called when a user pushes the '(' button or uses the
* keyboard shortcut SHIFT+9. Appends an opening parenthesis
* to the input. Disables entry of closing parentheses
* and operators directly afterwards.
*/
void MainWindow::on_buttonOpenParenth_released()
{
if(history.top().openParenthAllowed)
{
input->setText(input->text().append("("));
history.push(State(true, false, true, truefalse,
history.top().numOpenParenths+1,
history.top().numClosingParenths));
}
}
/* Called when a user pushes the ')' button or uses the
* keyboard shortcut SHIFT+0. Appends a closing parenthesis
* to the input. Disables entry of opening parentheses and
* digits directly afterwards.
*/
void MainWindow::on_buttonCloseParenth_released()
{
State currentState = history.top();
if(currentState.closingParenthAllowed &&
(currentState.numClosingParenths < currentState.numOpenParenths))
{
input->setText(input->text().append(")"));
history.push(State(false, true, false, true,
history.top().numOpenParenths,
history.top().numClosingParenths+1));
}
}
void MainWindow::on_buttonXSquared_released()
{
// TODO x squared
}
void MainWindow::on_buttonSqrt_released()
{
// TODO square root
}
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "operator.h"
#include <QDebug> // debug output
#include <QChar>
#include <QShortcut> // keyboard input
#include <QKeySequence> // keyboard input
#include <QFont> // Qt fonts
// TODO add parentheses operations to calculator
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
// Basic variable setups
ui->setupUi(this);
input = ui->labelInput;
reset();
// Connect digits' released() signals to on_digit_released
connect(ui->button0, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button1, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button2, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button3, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button4, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button5, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button6, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button7, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button8, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button9, SIGNAL(released()), this, SLOT(on_digit_released()));
// Connect binary operators' released() signals to on_binary_button_released
connect(ui->buttonPlus, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonMinus, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonTimes, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonDivide, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
// Shortcuts for math input via keyboard
// TODO potential memory leaks
QShortcut *shortcut0 = new QShortcut(QKeySequence("0"), this);
QShortcut *shortcut1 = new QShortcut(QKeySequence("1"), this);
QShortcut *shortcut2 = new QShortcut(QKeySequence("2"), this);
QShortcut *shortcut3 = new QShortcut(QKeySequence("3"), this);
QShortcut *shortcut4 = new QShortcut(QKeySequence("4"), this);
QShortcut *shortcut5 = new QShortcut(QKeySequence("5"), this);
QShortcut *shortcut6 = new QShortcut(QKeySequence("6"), this);
QShortcut *shortcut7 = new QShortcut(QKeySequence("7"), this);
QShortcut *shortcut8 = new QShortcut(QKeySequence("8"), this);
QShortcut *shortcut9 = new QShortcut(QKeySequence("9"), this);
QShortcut *shortcutDecimal = new QShortcut(QKeySequence("."), this);
QShortcut *shortcutPlus = new QShortcut(QKeySequence("+"), this);
QShortcut *shortcutMinus = new QShortcut(QKeySequence("-"), this);
QShortcut *shortcutTimes = new QShortcut(QKeySequence("SHIFT+8"), this);
QShortcut *shortcutDivide = new QShortcut(QKeySequence("/"), this);
QShortcut *shortcutOpenParenth = new QShortcut(QKeySequence("SHIFT+9"), this);
QShortcut *shortcutCloseParenth = new QShortcut(QKeySequence("SHIFT+0"), this);
QShortcut *shortcutEnter = new QShortcut(QKeySequence(Qt::Key_Return), this);
QShortcut *shortcutBackspace = new QShortcut(QKeySequence("Backspace"), this);
connect(shortcut0, SIGNAL(activated()), ui->button0, SLOT(click()));
connect(shortcut1, SIGNAL(activated()), ui->button1, SLOT(click()));
connect(shortcut2, SIGNAL(activated()), ui->button2, SLOT(click()));
connect(shortcut3, SIGNAL(activated()), ui->button3, SLOT(click()));
connect(shortcut4, SIGNAL(activated()), ui->button4, SLOT(click()));
connect(shortcut5, SIGNAL(activated()), ui->button5, SLOT(click()));
connect(shortcut6, SIGNAL(activated()), ui->button6, SLOT(click()));
connect(shortcut7, SIGNAL(activated()), ui->button7, SLOT(click()));
connect(shortcut8, SIGNAL(activated()), ui->button8, SLOT(click()));
connect(shortcut9, SIGNAL(activated()), ui->button9, SLOT(click()));
connect(shortcutDecimal, SIGNAL(activated()), ui->buttonDecimalPoint, SLOT(click()));
connect(shortcutPlus, SIGNAL(activated()), ui->buttonPlus, SLOT(click()));
connect(shortcutMinus, SIGNAL(activated()), ui->buttonMinus, SLOT(click()));
connect(shortcutTimes, SIGNAL(activated()), ui->buttonTimes, SLOT(click()));
connect(shortcutDivide, SIGNAL(activated()), ui->buttonDivide, SLOT(click()));
connect(shortcutOpenParenth, SIGNAL(activated()), ui->buttonOpenParenth, SLOT(click()));
connect(shortcutCloseParenth, SIGNAL(activated()), ui->buttonCloseParenth, SLOT(click()));
connect(shortcutEnter, SIGNAL(activated()), ui->buttonEquals, SLOT(click()));
connect(shortcutBackspace, SIGNAL(activated()), ui->buttonBack, SLOT(click()));
}
MainWindow::~MainWindow()
{
delete ui;
}
/* Used by other functions when checking if an operator was
* already applied directly before the current attempt at
* either evaluating the expression or adding a new operator.
*/
bool MainWindow::operatorUsedDirectlyBefore() const
{
if(input->text().length() >= 2)
{
// Operators have a space after (e.g., " + "). Hence length()-2.
// If input is like "1 + 2", return false b/c " " is not operator.
return ((bool)operators.count(input->text().at(input->text().length()-2)));
}
return false;
}
/* When a digit button is pressed, its text gets relayed to input label */
void MainWindow::on_digit_released()
{
State currentState = history.top();
if(currentState.digitAllowed)
{
QPushButton *button = (QPushButton*)sender();
history.push(State(true, true, false, true,
history.top().numOpenParenths,
history.top().numClosingParenths));
if(input->text().length() == 1 && input->text()[0] == '0')
{
input->setText(input->text().replace(0, 1, button->text()));
}
else
{
input->setText(input->text().append(button->text()));
}
}
}
void MainWindow::on_buttonDecimalPoint_released()
{
// TODO prevent entry of multiple decimal points
if(!operatorUsedDirectlyBefore())
{
input->setText(input->text() + ".");
}
}
/* Handles functionality of negating an input expression.
* Negating an expression applies the negative sign to the
* last number entered (if one exists). Negating a
* negative number will remove the negative sign.
*/
void MainWindow::on_buttonNegate_released()
{
if(operatorUsedDirectlyBefore()){ return; }
// Check if there are currently any operators in input
bool inputHasOperators = false;
for(int i = 0; i < input->text().length(); i++)
{
if(operators.count(input->text().at(i)) == 1)
{
inputHasOperators = true;
break;
}
}
// Input expression contains operators
if(inputHasOperators)
{
int indexOfLastWhitespace = input->text().lastIndexOf(' ');
// If the number is negative and part of an expression w/ ops
if(input->text().at(indexOfLastWhitespace+1) == '-')
{
input->setText(input->text().replace(indexOfLastWhitespace+1, 1, ""));
}
// Otherwise, just a positive number part of an expression w/ ops
else
{
input->setText(input->text().insert(indexOfLastWhitespace+1, '-'));
}
}
// TODO or parenthetical expression?
// No operators and already negative number
else if(input->text().at(0) == '-')
{
input->setText(input->text().replace(0, 1, ""));
}
// No operators and positive number
else
{
input->setText(input->text().prepend("-"));
}
}
/* If the user presses any binary operation's button, like
* plus, minus, multiply, or divide, this slot will be called
* to insert the appropriate operation into the current input.
*/
void MainWindow::on_binary_button_released()
{
QPushButton *button = (QPushButton*)sender();
State currentState = history.top();
if(currentState.operatorAllowed)
{
input->setText(input->text().append(button->text()));
history.push(State(true, false, true, false,
currentState.numOpenParenths,
currentState.numClosingParenths));
}
}
/* If the user releases the = button, then they want
* the answer to their input to be calculated.
* Emits input_is_ready signal to give Calculator
* the input it needs to do its job.
*/
void MainWindow::on_buttonEquals_released()
{
State currentState = history.top();
if(!operatorUsedDirectlyBefore() &&
currentState.numOpenParenths == currentState.numClosingParenths)
{
emit input_is_ready(input->text());
}
}
/*
*
*/
void MainWindow::reset()
{
input->setText("0");
history.clear();
history.push(State(true, true, false, false));
}
/* Pretty straightforward. Basically, if the user * presses and releases the clear button, then
* set the input string to just 0.
*/
void MainWindow::on_buttonClear_released()
{
reset();
}
/* Reverts the calculator to its previous state of input,
* thereby applying all appropriate restrictions.
*/
void MainWindow::on_buttonBack_released()
{
// If the input is just a single digit, set it to 0
if(input->text().length() == 1)
{
input->setText("0");
}
// Otherwise, if we have 2 or more entries, remove last char
else
{
QString text = input->text();
input->setText(text.remove(text.length()-1, 1));
}
if(history.size() >= 2){ history.pop();}
}
void MainWindow::on_buttonRoot_released()
{
// TODO nth root
}
void MainWindow::on_buttonOpenParenth_released()
{
if(history.top().openParenthAllowed)
{
input->setText(input->text().append("("));
history.push(State(true, false, true, true,
history.top().numOpenParenths+1,
history.top().numClosingParenths));
}
}
void MainWindow::on_buttonCloseParenth_released()
{
State currentState = history.top();
if(currentState.closingParenthAllowed &&
(currentState.numClosingParenths < currentState.numOpenParenths))
{
input->setText(input->text().append(")"));
history.push(State(false, true, false, true,
history.top().numOpenParenths,
history.top().numClosingParenths+1));
}
}
void MainWindow::on_buttonXSquared_released()
{
// TODO x squared
}
void MainWindow::on_buttonSqrt_released()
{
// TODO square root
}
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "operator.h"
#include <QDebug> // debug output
#include <QChar>
#include <QShortcut> // keyboard input
#include <QKeySequence> // keyboard input
#include <QFont> // Qt fonts
/* Constructor for MainWindow objects. Connects all button signals
* to their appropriate private slots to handle user input and sets
* up some basic member variables.
*/
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
// Basic variable setups
ui->setupUi(this);
input = ui->labelInput;
reset();
// Connect digits' released() signals to on_digit_released
connect(ui->button0, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button1, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button2, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button3, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button4, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button5, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button6, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button7, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button8, SIGNAL(released()), this, SLOT(on_digit_released()));
connect(ui->button9, SIGNAL(released()), this, SLOT(on_digit_released()));
// Connect binary operators' released() signals to on_binary_button_released
connect(ui->buttonPlus, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonMinus, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonTimes, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
connect(ui->buttonDivide, SIGNAL(released()),
this, SLOT(on_binary_button_released()));
// Shortcuts for math input via keyboard
// TODO potential memory leaks
QShortcut *shortcut0 = new QShortcut(QKeySequence("0"), this);
QShortcut *shortcut1 = new QShortcut(QKeySequence("1"), this);
QShortcut *shortcut2 = new QShortcut(QKeySequence("2"), this);
QShortcut *shortcut3 = new QShortcut(QKeySequence("3"), this);
QShortcut *shortcut4 = new QShortcut(QKeySequence("4"), this);
QShortcut *shortcut5 = new QShortcut(QKeySequence("5"), this);
QShortcut *shortcut6 = new QShortcut(QKeySequence("6"), this);
QShortcut *shortcut7 = new QShortcut(QKeySequence("7"), this);
QShortcut *shortcut8 = new QShortcut(QKeySequence("8"), this);
QShortcut *shortcut9 = new QShortcut(QKeySequence("9"), this);
QShortcut *shortcutDecimal = new QShortcut(QKeySequence("."), this);
QShortcut *shortcutPlus = new QShortcut(QKeySequence("+"), this);
QShortcut *shortcutMinus = new QShortcut(QKeySequence("-"), this);
QShortcut *shortcutTimes = new QShortcut(QKeySequence("SHIFT+8"), this);
QShortcut *shortcutDivide = new QShortcut(QKeySequence("/"), this);
QShortcut *shortcutOpenParenth = new QShortcut(QKeySequence("SHIFT+9"), this);
QShortcut *shortcutCloseParenth = new QShortcut(QKeySequence("SHIFT+0"), this);
QShortcut *shortcutEnter = new QShortcut(QKeySequence(Qt::Key_Return), this);
QShortcut *shortcutBackspace = new QShortcut(QKeySequence("Backspace"), this);
connect(shortcut0, SIGNAL(activated()), ui->button0, SLOT(click()));
connect(shortcut1, SIGNAL(activated()), ui->button1, SLOT(click()));
connect(shortcut2, SIGNAL(activated()), ui->button2, SLOT(click()));
connect(shortcut3, SIGNAL(activated()), ui->button3, SLOT(click()));
connect(shortcut4, SIGNAL(activated()), ui->button4, SLOT(click()));
connect(shortcut5, SIGNAL(activated()), ui->button5, SLOT(click()));
connect(shortcut6, SIGNAL(activated()), ui->button6, SLOT(click()));
connect(shortcut7, SIGNAL(activated()), ui->button7, SLOT(click()));
connect(shortcut8, SIGNAL(activated()), ui->button8, SLOT(click()));
connect(shortcut9, SIGNAL(activated()), ui->button9, SLOT(click()));
connect(shortcutDecimal, SIGNAL(activated()), ui->buttonDecimalPoint, SLOT(click()));
connect(shortcutPlus, SIGNAL(activated()), ui->buttonPlus, SLOT(click()));
connect(shortcutMinus, SIGNAL(activated()), ui->buttonMinus, SLOT(click()));
connect(shortcutTimes, SIGNAL(activated()), ui->buttonTimes, SLOT(click()));
connect(shortcutDivide, SIGNAL(activated()), ui->buttonDivide, SLOT(click()));
connect(shortcutOpenParenth, SIGNAL(activated()), ui->buttonOpenParenth, SLOT(click()));
connect(shortcutCloseParenth, SIGNAL(activated()), ui->buttonCloseParenth, SLOT(click()));
connect(shortcutEnter, SIGNAL(activated()), ui->buttonEquals, SLOT(click()));
connect(shortcutBackspace, SIGNAL(activated()), ui->buttonBack, SLOT(click()));
}
MainWindow::~MainWindow()
{
delete input;
delete ui;
}
/* Used by other functions to check if an operator was
* applied directly before the current user's input token.
*/
bool MainWindow::operatorUsedDirectlyBefore() const
{
return ((bool)operators.count(input->text().at(input->text().length()-1)));
}
/* Called when a user clicks any of the digit buttons (0-9) or
* enters a digit from their keyboard (0-9). Appends the corresponding
* digit to the input.
*/
void MainWindow::on_digit_released()
{
State currentState = history.top();
if(currentState.digitAllowed)
{
QPushButton *button = (QPushButton*)sender();
history.push(State(true, true, false, true,
history.top().numOpenParenths,
history.top().numClosingParenths));
// Initial input is just a 0
if(input->text().length() == 1 && input->text()[0] == '0')
{
input->setText(input->text().replace(0, 1, button->text()));
}
// Otherwise, append the digit
else
{
input->setText(input->text().append(button->text()));
}
}
}
/* Called when a user clicks the '.' button or uses the keyboard
* shortcut '.' Appends a decimal point to the last digit that was
* entered.
*/
void MainWindow::on_buttonDecimalPoint_released()
{
// TODO prevent entry of multiple decimal points
if(!operatorUsedDirectlyBefore())
{
input->setText(input->text() + ".");
}
}
/* Called when a user clicks the '±' button. Negates an input expression.
* Applies the negative sign to the last number entered (if one exists).
* Negating a negative number will remove the negative sign. Negating the
* right operand of addition will change the '+' operator to subtraction.
* Similarly, negating the right operand of subtraction will change the
* '–' operator to addition.
*/
void MainWindow::on_buttonNegate_released()
{
// Check if there are currently any operators in input
bool inputHasOperators = false;
// If so, get the index of the last one (hence reverse traversal)
int indexOfLastOperator = -1;
for(int i = input->text().length() - 1; i >= 0; i--)
{
if(operators.count(input->text().at(i)) == 1)
{
inputHasOperators = true;
indexOfLastOperator = i;
break;
}
}
// If we entered an operator and then tried to negate something
if(indexOfLastOperator == input->text().length()-1){ return; }
// Case 1: Input contains operators
if(inputHasOperators)
{
QChar lastOperator = input->text().at(indexOfLastOperator);
// If the number in question is already negative, undo it
if(input->text().at(indexOfLastOperator+1) == '-')
{
input->setText(input->text().replace(indexOfLastOperator+1, 1, ""));
}
// If not, let's check what kind of operator came before it
else
{
// If it was a plus, change that to a minus
if(lastOperator == '+')
{
input->setText(input->text().replace(indexOfLastOperator, 1, "–"));
}
// If it was a minus, change that to a plus
else if(lastOperator == '–')
{
input->setText(input->text().replace(indexOfLastOperator, 1, "+"));
}
// Otherwise, just negate the last number
else
{
input->setText(input->text().insert(indexOfLastOperator+1, '-'));
}
}
}
// TODO or parenthetical expression?
// Case 2: No operators and already negative number
else if(input->text().at(0) == '-')
{
input->setText(input->text().replace(0, 1, ""));
}
// Case 3: No operators and positive number
else
{
input->setText(input->text().prepend("-"));
}
}
/* Called when a user clicks any binary operation's button
* (+, -, *, /). Inserts the appropriate operation into input.
*/
void MainWindow::on_binary_button_released()
{
QPushButton *button = (QPushButton*)sender();
State currentState = history.top();
if(currentState.operatorAllowed)
{
input->setText(input->text().append(button->text()));
history.push(State(true, false, true, false,
currentState.numOpenParenths,
currentState.numClosingParenths));
}
}
/* Called when a user clicks the '=' button or uses the keyboard
* shortcut 'Enter'. Checks if the input is ready for evaluation.
* If so, emits input_is_ready signal, effectively handing its
* input string to the Calculator for processing.
*/
void MainWindow::on_buttonEquals_released()
{
State currentState = history.top();
if(!operatorUsedDirectlyBefore() &&
currentState.numOpenParenths == currentState.numClosingParenths)
{
emit input_is_ready(input->text());
}
}
/* Used to reset user input. Sets the input string to "0", clears its
* history, and applies all initial input restrictions.
*/
void MainWindow::reset()
{
input->setText("0");
history.clear();
history.push(State(true, true, false, false));
}
/* Called when a user clicks the 'Clear' button or uses the keyboard
* shortcut 'Delete'. Resets the input. See MainWindow::reset().
*/
void MainWindow::on_buttonClear_released()
{
reset();
}
/* Called when a user clicks the 'Back' button or uses the
* keyboard shortcut 'Backspace'. Reverts the calculator to * its previous state of input. Reapplies all appropriate input
* restrictions that existed prior to deletion of the last token.
*/
void MainWindow::on_buttonBack_released()
{
// If the input is just a single digit, set it to 0
if(input->text().length() == 1)
{
input->setText("0");
}
// Otherwise, if we have 2 or more entries, remove last char
else
{
QString text = input->text();
input->setText(text.remove(text.length()-1, 1));
}
if(history.size() >= 2){ history.pop();}
}
void MainWindow::on_buttonRoot_released()
{
// TODO nth root
}
/* Called when a user pushes the '(' button or uses the
* keyboard shortcut SHIFT+9. Appends an opening parenthesis
* to the input. Disables entry of closing parentheses
* and operators directly afterwards.
*/
void MainWindow::on_buttonOpenParenth_released()
{
if(history.top().openParenthAllowed)
{
input->setText(input->text().append("("));
history.push(State(true, false, true, false,
history.top().numOpenParenths+1,
history.top().numClosingParenths));
}
}
/* Called when a user pushes the ')' button or uses the
* keyboard shortcut SHIFT+0. Appends a closing parenthesis
* to the input. Disables entry of opening parentheses and
* digits directly afterwards.
*/
void MainWindow::on_buttonCloseParenth_released()
{
State currentState = history.top();
if(currentState.closingParenthAllowed &&
(currentState.numClosingParenths < currentState.numOpenParenths))
{
input->setText(input->text().append(")"));
history.push(State(false, true, false, true,
history.top().numOpenParenths,
history.top().numClosingParenths+1));
}
}
void MainWindow::on_buttonXSquared_released()
{
// TODO x squared
}
void MainWindow::on_buttonSqrt_released()
{
// TODO square root
}
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lang-cpp