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#include <QtWidgets>

#include <cmath>

#include "button.h"
#include "calculator.h"

//! [0]
Calculator::Calculator(QWidget* parent)
  : QWidget(parent)
{
    sumInMemory = 0.0;
    sumSoFar = 0.0;
    factorSoFar = 0.0;
    waitingForOperand = true;
    //! [0]

    //! [1]
    display = new QLineEdit("0");
    //! [1] //! [2]
    display->setReadOnly(true);
    display->setAlignment(Qt::AlignRight);
    display->setMaxLength(15);

    QFont font = display->font();
    font.setPointSize(font.pointSize() + 8);
    display->setFont(font);
    //! [2]

    //! [4]
    for (int i = 0; i < NumDigitButtons; ++i) {
        digitButtons[i] =
          createButton(QString::number(i), SLOT(digitClicked()));
    }

    Button* pointButton = createButton(".", SLOT(pointClicked()));
    Button* changeSignButton =
      createButton("\302\261", SLOT(changeSignClicked()));

    Button* backspaceButton =
      createButton("Backspace", SLOT(backspaceClicked()));
    Button* clearButton = createButton("Clear", SLOT(clear()));
    Button* clearAllButton = createButton("Clear All", SLOT(clearAll()));

    Button* clearMemoryButton = createButton("MC", SLOT(clearMemory()));
    Button* readMemoryButton = createButton("MR", SLOT(readMemory()));
    Button* setMemoryButton = createButton("MS", SLOT(setMemory()));
    Button* addToMemoryButton = createButton("M+", SLOT(addToMemory()));

    Button* divisionButton =
      createButton("\303\267", SLOT(multiplicativeOperatorClicked()));
    Button* timesButton =
      createButton("\303\227", SLOT(multiplicativeOperatorClicked()));
    Button* minusButton = createButton("-", SLOT(additiveOperatorClicked()));
    Button* plusButton = createButton("+", SLOT(additiveOperatorClicked()));

    Button* squareRootButton =
      createButton("Sqrt", SLOT(unaryOperatorClicked()));
    Button* powerButton =
      createButton("x\302\262", SLOT(unaryOperatorClicked()));
    Button* reciprocalButton =
      createButton("1/x", SLOT(unaryOperatorClicked()));
    Button* equalButton = createButton("=", SLOT(equalClicked()));
    //! [4]

    //! [5]
    QGridLayout* mainLayout = new QGridLayout;
    //! [5] //! [6]
    mainLayout->setSizeConstraint(QLayout::SetFixedSize);
    mainLayout->addWidget(display, 0, 0, 1, 6);
    mainLayout->addWidget(backspaceButton, 1, 0, 1, 2);
    mainLayout->addWidget(clearButton, 1, 2, 1, 2);
    mainLayout->addWidget(clearAllButton, 1, 4, 1, 2);

    mainLayout->addWidget(clearMemoryButton, 2, 0);
    mainLayout->addWidget(readMemoryButton, 3, 0);
    mainLayout->addWidget(setMemoryButton, 4, 0);
    mainLayout->addWidget(addToMemoryButton, 5, 0);

    for (int i = 1; i < NumDigitButtons; ++i) {
        int row = ((9 - i) / 3) + 2;
        int column = ((i - 1) % 3) + 1;
        mainLayout->addWidget(digitButtons[i], row, column);
    }

    mainLayout->addWidget(digitButtons[0], 5, 1);
    mainLayout->addWidget(pointButton, 5, 2);
    mainLayout->addWidget(changeSignButton, 5, 3);

    mainLayout->addWidget(divisionButton, 2, 4);
    mainLayout->addWidget(timesButton, 3, 4);
    mainLayout->addWidget(minusButton, 4, 4);
    mainLayout->addWidget(plusButton, 5, 4);

    mainLayout->addWidget(squareRootButton, 2, 5);
    mainLayout->addWidget(powerButton, 3, 5);
    mainLayout->addWidget(reciprocalButton, 4, 5);
    mainLayout->addWidget(equalButton, 5, 5);
    setLayout(mainLayout);

    setWindowTitle("Calculator");
}
//! [6]

//! [7]
void Calculator::digitClicked()
{
    Button* clickedButton = qobject_cast<Button*>(sender());
    int digitValue = clickedButton->text().toInt();
    if (display->text() == "0" && digitValue == 0.0)
        return;

    if (waitingForOperand) {
        display->clear();
        waitingForOperand = false;
    }
    display->setText(display->text() + QString::number(digitValue));
}
//! [7]

//! [8]
void Calculator::unaryOperatorClicked()
//! [8] //! [9]
{
    Button* clickedButton = qobject_cast<Button*>(sender());
    QString clickedOperator = clickedButton->text();
    double operand = display->text().toDouble();
    double result = 0.0;

    if (clickedOperator == "Sqrt") {
        if (operand < 0.0) {
            abortOperation();
            return;
        }
        result = std::sqrt(operand);
    } else if (clickedOperator == "x\302\262") {
        result = std::pow(operand, 2.0);
    } else if (clickedOperator == "1/x") {
        if (operand == 0.0) {
            abortOperation();
            return;
        }
        result = 1.0 / operand;
    }
    display->setText(QString::number(result));
    waitingForOperand = true;
}
//! [9]

//! [10]
void Calculator::additiveOperatorClicked()
//! [10] //! [11]
{
    Button* clickedButton = qobject_cast<Button*>(sender());
    QString clickedOperator = clickedButton->text();
    double operand = display->text().toDouble();

    //! [11] //! [12]
    if (!pendingMultiplicativeOperator.isEmpty()) {
        //! [12] //! [13]
        if (!calculate(operand, pendingMultiplicativeOperator)) {
            abortOperation();
            return;
        }
        display->setText(QString::number(factorSoFar));
        operand = factorSoFar;
        factorSoFar = 0.0;
        pendingMultiplicativeOperator.clear();
    }

    //! [13] //! [14]
    if (!pendingAdditiveOperator.isEmpty()) {
        //! [14] //! [15]
        if (!calculate(operand, pendingAdditiveOperator)) {
            abortOperation();
            return;
        }
        display->setText(QString::number(sumSoFar));
    } else {
        sumSoFar = operand;
    }

    //! [15] //! [16]
    pendingAdditiveOperator = clickedOperator;
    //! [16] //! [17]
    waitingForOperand = true;
}
//! [17]

//! [18]
void Calculator::multiplicativeOperatorClicked()
{
    Button* clickedButton = qobject_cast<Button*>(sender());
    QString clickedOperator = clickedButton->text();
    double operand = display->text().toDouble();

    if (!pendingMultiplicativeOperator.isEmpty()) {
        if (!calculate(operand, pendingMultiplicativeOperator)) {
            abortOperation();
            return;
        }
        display->setText(QString::number(factorSoFar));
    } else {
        factorSoFar = operand;
    }

    pendingMultiplicativeOperator = clickedOperator;
    waitingForOperand = true;
}
//! [18]

//! [20]
void Calculator::equalClicked()
{
    double operand = display->text().toDouble();

    if (!pendingMultiplicativeOperator.isEmpty()) {
        if (!calculate(operand, pendingMultiplicativeOperator)) {
            abortOperation();
            return;
        }
        operand = factorSoFar;
        factorSoFar = 0.0;
        pendingMultiplicativeOperator.clear();
    }
    if (!pendingAdditiveOperator.isEmpty()) {
        if (!calculate(operand, pendingAdditiveOperator)) {
            abortOperation();
            return;
        }
        pendingAdditiveOperator.clear();
    } else {
        sumSoFar = operand;
    }

    display->setText(QString::number(sumSoFar));
    sumSoFar = 0.0;
    waitingForOperand = true;
}
//! [20]

//! [22]
void Calculator::pointClicked()
{
    if (waitingForOperand)
        display->setText("0");
    if (!display->text().contains('.'))
        display->setText(display->text() + ".");
    waitingForOperand = false;
}
//! [22]

//! [24]
void Calculator::changeSignClicked()
{
    QString text = display->text();
    double value = text.toDouble();

    if (value > 0.0) {
        text.prepend("-");
    } else if (value < 0.0) {
        text.remove(0, 1);
    }
    display->setText(text);
}
//! [24]

//! [26]
void Calculator::backspaceClicked()
{
    if (waitingForOperand)
        return;

    QString text = display->text();
    text.chop(1);
    if (text.isEmpty()) {
        text = "0";
        waitingForOperand = true;
    }
    display->setText(text);
}
//! [26]

//! [28]
void Calculator::clear()
{
    if (waitingForOperand)
        return;

    display->setText("0");
    waitingForOperand = true;
}
//! [28]

//! [30]
void Calculator::clearAll()
{
    sumSoFar = 0.0;
    factorSoFar = 0.0;
    pendingAdditiveOperator.clear();
    pendingMultiplicativeOperator.clear();
    display->setText("0");
    waitingForOperand = true;
}
//! [30]

//! [32]
void Calculator::clearMemory()
{
    sumInMemory = 0.0;
}

void Calculator::readMemory()
{
    display->setText(QString::number(sumInMemory));
    waitingForOperand = true;
}

void Calculator::setMemory()
{
    equalClicked();
    sumInMemory = display->text().toDouble();
}

void Calculator::addToMemory()
{
    equalClicked();
    sumInMemory += display->text().toDouble();
}
//! [32]
//! [34]
Button* Calculator::createButton(const QString& text, const char* member)
{
    Button* button = new Button(text);
    connect(button, SIGNAL(clicked()), this, member);
    return button;
}
//! [34]

//! [36]
void Calculator::abortOperation()
{
    clearAll();
    display->setText("####");
}
//! [36]

//! [38]
bool Calculator::calculate(double rightOperand, const QString& pendingOperator)
{
    if (pendingOperator == "+") {
        sumSoFar += rightOperand;
    } else if (pendingOperator == "-") {
        sumSoFar -= rightOperand;
    } else if (pendingOperator == "\303\227") {
        factorSoFar *= rightOperand;
    } else if (pendingOperator == "\303\267") {
        if (rightOperand == 0.0)
            return false;
        factorSoFar /= rightOperand;
    }
    return true;
}
//! [38]
