Utils: Improve FileUtils::commonPath

Make it a worthy FilePath-based counterpart of Utils::commonPath.
With tests.

Change-Id: I68bae129c5d9d9dd3e46dfa6093e229f8ca0aee1
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>

src/libs/utils/fileutils.cpp

@@ -385,6 +385,52 @@ static QByteArray fileIdWin(HANDLE fHandle)
 }
 #endif
 
+FilePath FileUtils::commonPath(const FilePaths &paths)
+{
+    if (paths.isEmpty())
+        return {};
+
+    if (paths.count() == 1)
+        return paths.constFirst();
+
+    const FilePath &first = paths.constFirst();
+    const FilePaths others = paths.mid(1);
+    FilePath result;
+
+    // Common scheme
+    const QString &commonScheme = first.scheme();
+    auto sameScheme = [&commonScheme] (const FilePath &fp) {
+        return commonScheme == fp.scheme();
+    };
+    if (!allOf(others, sameScheme))
+        return result;
+    result.setScheme(commonScheme);
+
+    // Common host
+    const QString &commonHost = first.host();
+    auto sameHost = [&commonHost] (const FilePath &fp) {
+        return commonHost == fp.host();
+    };
+    if (!allOf(others, sameHost))
+        return result;
+    result.setHost(commonHost);
+
+    // Common path
+    QString commonPath;
+    auto sameBasePath = [&commonPath] (const FilePath &fp) {
+        return QString(fp.path() + '/').startsWith(commonPath);
+    };
+    const QStringList pathSegments = first.path().split('/');
+    for (const QString &segment : pathSegments) {
+        commonPath += segment + '/';
+        if (!allOf(others, sameBasePath))
+            return result;
+        result.setPath(commonPath.chopped(1));
+    }
+
+    return result;
+}
+
 QByteArray FileUtils::fileId(const FilePath &fileName)
 {
     QByteArray result;

src/libs/utils/fileutils.h

@@ -134,6 +134,7 @@ public:
     static bool isRelativePath(const QString &fileName);
     static bool isAbsolutePath(const QString &fileName) { return !isRelativePath(fileName); }
     static FilePath commonPath(const FilePath &oldCommonPath, const FilePath &fileName);
+    static FilePath commonPath(const FilePaths &paths);
     static QByteArray fileId(const FilePath &fileName);
     static FilePath homePath();
 

tests/auto/utils/fileutils/tst_fileutils.cpp

@@ -66,6 +66,8 @@ private slots:
     void linkFromString();
     void pathAppended_data();
     void pathAppended();
+    void commonPath_data();
+    void commonPath();
 
     void asyncLocalCopy();
 
@@ -590,6 +592,46 @@ void tst_fileutils::pathAppended_data()
     QTest::newRow("u4") << "a/b" << "c/d" << "a/b/c/d";
 }
 
+void tst_fileutils::commonPath()
+{
+    QFETCH(FilePaths, list);
+    QFETCH(FilePath, expected);
+
+    const FilePath result = FileUtils::commonPath(list);
+
+    QCOMPARE(expected.toString(), result.toString());
+}
+
+void tst_fileutils::commonPath_data()
+{
+    QTest::addColumn<FilePaths>("list");
+    QTest::addColumn<FilePath>("expected");
+
+    const FilePath p1 = FilePath::fromString("c:/Program Files(x86)");
+    const FilePath p2 = FilePath::fromString("c:/Program Files(x86)/Ide");
+    const FilePath p3 = FilePath::fromString("c:/Program Files(x86)/Ide/Qt Creator");
+    const FilePath p4 = FilePath::fromString("c:/Program Files");
+    const FilePath p5 = FilePath::fromString("c:");
+
+    const FilePath url1 = FilePath::fromString("http://127.0.0.1/./");
+    const FilePath url2 = FilePath::fromString("https://127.0.0.1/./");
+    const FilePath url3 = FilePath::fromString("http://www.qt.io/./");
+    const FilePath url4 = FilePath::fromString("https://www.qt.io/./");
+    const FilePath url5 = FilePath::fromString("https://www.qt.io/ide/");
+    const FilePath url6 = FilePath::fromString("http:///./");
+
+    QTest::newRow("Zero paths") << FilePaths{} << FilePath();
+    QTest::newRow("Single path") << FilePaths{ p1 } << p1;
+    QTest::newRow("3 identical paths") << FilePaths{ p1, p1, p1 } << p1;
+    QTest::newRow("3 paths, common path") << FilePaths{ p1, p2, p3 } << p1;
+    QTest::newRow("3 paths, no common path") << FilePaths{ p1, p2, p4 } << p5;
+    QTest::newRow("3 paths, first is part of second") << FilePaths{ p4, p1, p3 } << p5;
+    QTest::newRow("Common scheme") << FilePaths{ url1, url3 } << url6;
+    QTest::newRow("Different scheme") << FilePaths{ url1, url2 } << FilePath();
+    QTest::newRow("Common host") << FilePaths{ url4, url5 } << url4;
+    QTest::newRow("Different host") << FilePaths{ url1, url3 } << url6;
+}
+
 void tst_fileutils::asyncLocalCopy()
 {
     const FilePath orig = FilePath::fromString(rootPath).pathAppended("x/y/fileToCopy.txt");