diff --git a/mainwindow.cpp b/mainwindow.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..8d2adab6b15e58665815db9447ea56e7ce7a9196
--- /dev/null
+++ b/mainwindow.cpp
@@ -0,0 +1,194 @@
+#include <QErrorMessage>
+#include <QPushButton>
+#include <QFont>
+#include <QtXmlPatterns>
+#include <QContextMenuEvent>
+#include <parser.h>
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent)
+    : QMainWindow(parent), ui(new Ui::MainWindow), current_file(nullptr), current_pos(nullptr)
+{
+    ui->setupUi(this);
+    tree_widget = new QTreeWidget(this);
+    tree_widget->setHeaderLabel("Файлы");
+    tree_widget->setContextMenuPolicy(Qt::CustomContextMenu);
+    connect(tree_widget, SIGNAL(customContextMenuRequested(const QPoint&)), this, SLOT(slot_custom_menu(const QPoint&)));
+    menu_custom = new QMenu(this);
+    menu_custom->addAction("&Сделать действующим", this, SLOT(make_active()));
+    menu_custom->addAction("&Закрыть", this, SLOT(close_file()));
+    text_edit = new QTextEdit(this);
+    QMenu *menu = new QMenu("&Меню", this);
+    QPushButton *putton_download = new QPushButton("Загрузить Xquery запрос",this);
+    putton_download->setFont(*(new QFont("Times New Roman", 14, QFont::Bold)));
+    connect(putton_download, SIGNAL(clicked()), SLOT(open_query()));
+    QPushButton *putton = new QPushButton("Выполнить XQuery запрос",this);
+    putton->setFont(*(new QFont("Times New Roman", 14, QFont::Bold)));
+    connect(putton, SIGNAL(clicked()), SLOT(make_query()));
+    menu->addAction("&Открыть файл", this, SLOT(open_file()), Qt::CTRL + Qt::Key_O);
+    menu->addAction("&Закрыть все файлы", this, SLOT(clean_tree()));
+    menu->addAction("&Загрузить XQuery запрос", this, SLOT(open_query()), Qt::CTRL + Qt::Key_E);
+    menu->addSeparator();
+    menu->addAction("&Выход", this, SLOT(close_window()), Qt::CTRL + Qt::Key_Q);
+    ui->menubar->addMenu(menu);
+    dock = new QDockWidget("Результат выполнения запроса", this);
+    this->addDockWidget(Qt::DockWidgetArea::LeftDockWidgetArea, dock);
+    text_edit_dock = new QTextEdit(this);
+    text_edit_dock->setReadOnly(true);
+    dock->setWidget(text_edit_dock);
+    main_layout = new QGridLayout(this);
+    main_layout->addWidget(tree_widget, 0, 0, 5, 4);
+    main_layout->addWidget(text_edit, 5, 0, 5, 4);
+    main_layout->addWidget(putton, 16, 0, 1, 2);
+    main_layout->addWidget(putton_download, 16, 2, 1, 2);
+    main_layout->addWidget(dock, 10, 0, 5, 4);
+    main_widget = new QWidget(this);
+    main_widget->setLayout(main_layout);
+    setCentralWidget(main_widget);
+    setWindowTitle("XML reader");
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
+
+void MainWindow::close_window()
+{
+    QApplication::quit();
+}
+
+void MainWindow::clean_tree()
+{
+    if(current_file)
+    {
+        delete current_file;
+        current_file = nullptr;
+        current_pos = nullptr;
+    }
+    tree_widget->clear();
+}
+
+void MainWindow::make_query()
+{
+    if(current_file->open(QIODevice::ReadOnly))
+    {
+        QString query = text_edit->toPlainText();
+        QXmlQuery xml_query(QXmlQuery::XQuery10);
+        if(!xml_query.setFocus(current_file))
+             (new QErrorMessage(this))->showMessage("Выберите таблицу данных!");
+        xml_query.setQuery(query);
+        if (!xml_query.isValid())
+        {
+            current_file->close();
+            (new QErrorMessage(this))->showMessage("Ошибочный запрос!");
+        }
+        else
+        {
+            QString answer;
+            if (!xml_query.evaluateTo(&answer))
+            {
+                qDebug() << answer;
+                current_file->close();
+                (new QErrorMessage(this))->showMessage("Ошибка выполнения запроса!");
+            }
+            else
+            {
+                current_file->close();
+                text_edit_dock->setText(answer);
+                dock->show();
+            }
+        }
+    }
+
+}
+
+void MainWindow::open_file()
+{
+    QString filepath = QFileDialog::getOpenFileName(this, "Choose file", "File", "*.xml");
+    if(!filepath.isEmpty())
+    {
+        QFile file(filepath);
+        QXmlSimpleReader reader;
+        QString filename = filepath.section("/",-1,-1);
+        parser handler(tree_widget, filename);
+        QXmlInputSource source(&file);
+        reader.setContentHandler(&handler);
+        if (!reader.parse(source))
+            (new QErrorMessage(this))->showMessage("Не удаётся открыть файл!");
+        if(!current_file)
+        {
+            current_file = new QFile(filepath);
+            current_pos = tree_widget->itemAt(0, 0);
+            current_pos->setFont(0, QFont("Times New Roman", 14, QFont::Bold));
+        }
+    }
+}
+
+void MainWindow::open_query()
+{
+    QString filepath = QFileDialog::getOpenFileName(this, "Choose query-file", "File", "*.xq");
+    if (!filepath.isEmpty())
+    {
+        QFile file(filepath);
+        if (file.open(QIODevice::ReadOnly))
+        {
+            QString query = file.readAll();
+            file.close();
+            text_edit->setText(query);
+            make_query();
+        }
+        else
+        {
+            (new QErrorMessage(this))->showMessage("Не удаётся открыть файл!");
+        }
+    }
+}
+
+void MainWindow::slot_custom_menu(const QPoint& pos)
+{
+    if(tree_widget->currentItem() && !tree_widget->currentItem()->parent())
+        menu_custom->exec(QCursor::pos());
+}
+
+void MainWindow::make_active()
+{
+    QString current_filename =  current_file->fileName();
+    current_filename.resize(current_file->fileName().lastIndexOf('/') + 1);
+    current_filename += tree_widget->currentItem()->data(0,0).toString();
+    current_file->setFileName(current_filename);
+    current_pos->setFont(0, QFont("Times New Roman", 14));
+    tree_widget->currentItem()->setFont(0, QFont("Times New Roman", 14, QFont::Bold));
+    current_pos = tree_widget->currentItem();
+}
+
+void MainWindow::close_file()
+{
+    QString new_filename =  current_file->fileName();
+    new_filename.resize(current_file->fileName().lastIndexOf('/') + 1);
+    QModelIndex point;
+    if(tree_widget->currentIndex().row())
+        point = tree_widget->model()->index(tree_widget->currentIndex().row() - 1, tree_widget->currentIndex().column());
+    else
+        point = tree_widget->model()->index(tree_widget->currentIndex().row() + 1, tree_widget->currentIndex().column());
+    QString currnetActiveFile(tree_widget->currentItem()->text(0));
+    delete tree_widget->currentItem();
+    if(!point.isValid())
+    {
+        delete current_file;
+        current_file = nullptr;
+    }
+    else
+    {
+        tree_widget->setCurrentIndex(point);
+        new_filename += tree_widget->currentItem()->data(0,0).toString();
+        qDebug() << new_filename;
+        if(current_file->fileName().contains(currnetActiveFile))
+        {
+            current_file->setFileName(new_filename);
+            tree_widget->currentItem()->setFont(0, QFont("Times New Roman", 14, QFont::Bold));
+        }
+        current_pos = tree_widget->currentItem();
+    }
+}
\ No newline at end of file