Utils: Add FilePath::watch

Change-Id: I1e5706f22aaa072c68b97496896cfa6d244d9849
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/devicefileaccess.cpp

@@ -17,9 +17,11 @@
 #endif
 
 #include <QCoreApplication>
+#include <QFileSystemWatcher>
 #include <QOperatingSystemVersion>
 #include <QRandomGenerator>
 #include <QRegularExpression>
+#include <QStandardPaths>
 #include <QStorageInfo>
 #include <QTemporaryFile>
 
@@ -33,7 +35,6 @@
 #include <qplatformdefs.h>
 #endif
 
-#include <QStandardPaths>
 #include <algorithm>
 #include <array>
 
@@ -389,6 +390,13 @@ expected_str<FilePath> DeviceFileAccess::createTempFile(const FilePath &filePath
         Tr::tr("createTempFile is not implemented for \"%1\".").arg(filePath.toUserOutput()));
 }
 
+Utils::expected_str<std::unique_ptr<FilePathWatcher>> DeviceFileAccess::watch(
+    const FilePath &path) const
+{
+    Q_UNUSED(path);
+    return make_unexpected(Tr::tr("watch is not implemented."));
+}
+
 // DesktopDeviceFileAccess
 
 DesktopDeviceFileAccess::~DesktopDeviceFileAccess() = default;
@@ -767,6 +775,29 @@ expected_str<FilePath> DesktopDeviceFileAccess::createTempFile(const FilePath &f
     return filePath.withNewPath(file.fileName());
 }
 
+class DesktopFilePathWatcher : public FilePathWatcher
+{
+    QFileSystemWatcher m_watcher;
+
+public:
+    DesktopFilePathWatcher(const FilePath &path) {
+        connect(&m_watcher, &QFileSystemWatcher::fileChanged, this, [this, path] {
+            emit pathChanged(path);
+        });
+        connect(&m_watcher, &QFileSystemWatcher::directoryChanged, this, [this, path] {
+            emit pathChanged(path);
+        });
+
+        m_watcher.addPath(path.path());
+    }
+};
+
+Utils::expected_str<std::unique_ptr<FilePathWatcher>> DesktopDeviceFileAccess::watch(
+    const FilePath &path) const
+{
+    return std::make_unique<DesktopFilePathWatcher>(path);
+}
+
 QDateTime DesktopDeviceFileAccess::lastModified(const FilePath &filePath) const
 {
     return QFileInfo(filePath.path()).lastModified();