Meson: Flatten directory hierarchy

Keep tests/ and icons/ but put the rest into the toplevel.

The previous setup was so different from the rest of the bunch that
it regularly stuck out in maintenance tasks.

Change-Id: I69821be6268f69682353a388f6bb1fa343215303
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Alessandro Portale <alessandro.portale@qt.io>

src/plugins/mesonprojectmanager/common.h

@@ -0,0 +1,93 @@
+// Copyright (C) 2020 Alexis Jeandet.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
+
+#pragma once
+
+#include <QFile>
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QJsonObject>
+#include <QJsonValue>
+
+#include <optional>
+
+namespace MesonProjectManager {
+namespace Internal {
+
+template<typename T>
+inline T load(QJsonDocument &&doc);
+
+template<>
+inline QJsonArray load<QJsonArray>(QJsonDocument &&doc)
+{
+    return doc.array();
+}
+
+template<>
+inline QJsonObject load<QJsonObject>(QJsonDocument &&doc)
+{
+    return doc.object();
+}
+
+template<typename T>
+inline T load(const QJsonValueRef &ref);
+
+template<>
+inline QJsonArray load<QJsonArray>(const QJsonValueRef &ref)
+{
+    return ref.toArray();
+}
+
+template<>
+inline QJsonObject load<QJsonObject>(const QJsonValueRef &ref)
+{
+    return ref.toObject();
+}
+
+template<typename T>
+inline std::optional<T> load(const QString &jsonFile)
+{
+    QFile js(jsonFile);
+    js.open(QIODevice::ReadOnly | QIODevice::Text);
+    if (js.isOpen()) {
+        auto data = js.readAll();
+        return load<T>(QJsonDocument::fromJson(data));
+    }
+    return std::nullopt;
+}
+
+template<typename T>
+inline std::optional<T> get(const QJsonObject &obj, const QString &name);
+
+template<>
+inline std::optional<QJsonArray> get<QJsonArray>(const QJsonObject &obj, const QString &name)
+{
+    if (obj.contains(name)) {
+        auto child = obj[name];
+        if (child.isArray())
+            return child.toArray();
+    }
+    return std::nullopt;
+}
+
+template<>
+inline std::optional<QJsonObject> get<QJsonObject>(const QJsonObject &obj, const QString &name)
+{
+    if (obj.contains(name)) {
+        auto child = obj[name];
+        if (child.isObject())
+            return child.toObject();
+    }
+    return std::nullopt;
+}
+
+template<typename T, typename... Strings>
+inline std::optional<T> get(const QJsonObject &obj, const QString &firstPath, const Strings &...path)
+{
+    if (obj.contains(firstPath))
+        return get<T>(obj[firstPath].toObject(), path...);
+    return std::nullopt;
+}
+
+} // namespace Internal
+} // namespace MesonProjectManager