Meson build plugin initial support

Most basic project management is implemented:
- Project config/build
- Build options accessible to user
- Lists most build targets
- Meson and Ninja added to kit setup
- Basic project file tree with files known by Meson
- Some basic meson and ninja process output parsing
- Some project templates

Missing features, that will come later:
- Configurable project tree layout
- Locators for Meson
- Build importer
- Access to Machine files for better user fine tuning
- ...

Fixes: QTCREATORBUG-18117
Change-Id: I2811e71562c113fb0fc6b6177bcf0698fa71ef63
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/mesonprojectmanager/settings/tools/kitaspect/toolkitaspectwidget.cpp

@@ -0,0 +1,144 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 Alexis Jeandet.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#include "toolkitaspectwidget.h"
+#include "coreplugin/icore.h"
+#include "mesonpluginconstants.h"
+#include "mesontoolkitaspect.h"
+#include "ninjatoolkitaspect.h"
+#include "utils/qtcassert.h"
+
+namespace MesonProjectManager {
+namespace Internal {
+ToolKitAspectWidget::ToolKitAspectWidget(ProjectExplorer::Kit *kit,
+                                         const ProjectExplorer::KitAspect *ki,
+                                         ToolType type)
+    : ProjectExplorer::KitAspectWidget(kit, ki)
+    , m_toolsComboBox{new QComboBox}
+    , m_manageButton(new QPushButton(KitAspectWidget::msgManage()))
+    , m_type{type}
+{
+    m_toolsComboBox->setSizePolicy(QSizePolicy::Ignored,
+                                   m_toolsComboBox->sizePolicy().verticalPolicy());
+    m_toolsComboBox->setEnabled(false);
+    m_toolsComboBox->setToolTip(ki->description());
+    loadTools();
+
+    m_manageButton->setContentsMargins(0, 0, 0, 0);
+    connect(m_manageButton, &QPushButton::clicked, this, [this]() {
+        Core::ICore::showOptionsDialog(Constants::SettingsPage::TOOLS_ID, buttonWidget());
+    });
+
+    connect(MesonTools::instance(),
+            &MesonTools::toolAdded,
+            this,
+            &ToolKitAspectWidget::addTool);
+    connect(MesonTools::instance(),
+            &MesonTools::toolRemoved,
+            this,
+            &ToolKitAspectWidget::removeTool);
+    connect(m_toolsComboBox,
+            qOverload<int>(&QComboBox::currentIndexChanged),
+            this,
+            &ToolKitAspectWidget::setCurrentToolIndex);
+}
+
+ToolKitAspectWidget::~ToolKitAspectWidget()
+{
+    delete m_toolsComboBox;
+    delete m_manageButton;
+}
+
+void ToolKitAspectWidget::addTool(const MesonTools::Tool_t &tool)
+{
+    QTC_ASSERT(tool, return );
+    if (isCompatible(tool))
+        this->m_toolsComboBox->addItem(tool->name(), tool->id().toSetting());
+}
+
+void ToolKitAspectWidget::removeTool(const MesonTools::Tool_t &tool)
+{
+    QTC_ASSERT(tool, return );
+    if (!isCompatible(tool))
+        return;
+    const int index = indexOf(tool->id());
+    QTC_ASSERT(index >= 0, return );
+    if (index == m_toolsComboBox->currentIndex())
+        setToDefault();
+    m_toolsComboBox->removeItem(index);
+}
+
+void ToolKitAspectWidget::setCurrentToolIndex(int index)
+{
+    const Core::Id id = Core::Id::fromSetting(m_toolsComboBox->itemData(index));
+    if (m_type == ToolType::Meson)
+        MesonToolKitAspect::setMesonTool(m_kit, id);
+    else
+        NinjaToolKitAspect::setNinjaTool(m_kit, id);
+}
+
+int ToolKitAspectWidget::indexOf(const Core::Id &id)
+{
+    for (int i = 0; i < m_toolsComboBox->count(); ++i) {
+        if (id == Core::Id::fromSetting(m_toolsComboBox->itemData(i)))
+            return i;
+    }
+    return -1;
+}
+
+bool ToolKitAspectWidget::isCompatible(const MesonTools::Tool_t &tool)
+{
+    return (m_type == ToolType::Meson && MesonTools::isMesonWrapper(tool))
+           || (m_type == ToolType::Ninja && MesonTools::isNinjaWrapper(tool));
+}
+
+void ToolKitAspectWidget::loadTools()
+{
+    std::for_each(std::cbegin(MesonTools::tools()),
+                  std::cend(MesonTools::tools()),
+                  [this](const MesonTools::Tool_t &tool) { addTool(tool); });
+    refresh();
+    m_toolsComboBox->setEnabled(m_toolsComboBox->count());
+}
+
+void ToolKitAspectWidget::setToDefault()
+{
+    const MesonTools::Tool_t autoDetected = [this]() {
+        if (m_type == ToolType::Meson)
+            return std::dynamic_pointer_cast<ToolWrapper>(MesonTools::mesonWrapper());
+        return std::dynamic_pointer_cast<ToolWrapper>(MesonTools::ninjaWrapper());
+    }();
+
+    if (autoDetected) {
+        const auto index = indexOf(autoDetected->id());
+        m_toolsComboBox->setCurrentIndex(index);
+        setCurrentToolIndex(index);
+    } else {
+        m_toolsComboBox->setCurrentIndex(0);
+        setCurrentToolIndex(0);
+    }
+}
+} // namespace Internal
+} // namespace MesonProjectManager