Deduplicate the import resolution algorithm

We will need it in various other places, too.

Change-Id: I61c55f88b66ab85448ae8fff125fe34108532fc4
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

3 files changed, 191 insertions, 2 deletions

diff --git a/src/qml/qmldirparser/qmldirparser.pri b/src/qml/qmldirparser/qmldirparser.pri
index fefe2e75be..3923208e4a 100644
--- a/src/qml/qmldirparser/qmldirparser.pri
+++ b/src/qml/qmldirparser/qmldirparser.pri
@@ -2,7 +2,9 @@ INCLUDEPATH += $$PWD
 INCLUDEPATH += $$OUT_PWD
 
 HEADERS += \
-    $$PWD/qqmldirparser_p.h
+    $$PWD/qqmldirparser_p.h \
+    $$PWD/qqmlimportresolver_p.h
 
 SOURCES += \
-    $$PWD/qqmldirparser.cpp
+    $$PWD/qqmldirparser.cpp \
+    $$PWD/qqmlimportresolver.cpp
diff --git a/src/qml/qmldirparser/qqmlimportresolver.cpp b/src/qml/qmldirparser/qqmlimportresolver.cpp
new file mode 100644
index 0000000000..d427706140
--- /dev/null
+++ b/src/qml/qmldirparser/qqmlimportresolver.cpp
@@ -0,0 +1,122 @@
+/****************************************************************************
+**
+** Copyright (C) 2020 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** 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-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qqmlimportresolver_p.h"
+
+QT_BEGIN_NAMESPACE
+
+enum ImportVersion { FullyVersioned, PartiallyVersioned, Unversioned };
+
+/*!
+    Forms complete paths to a module, from a list of base paths,
+    a module URI and version specification.
+
+    For example, QtQml.Models 2.0:
+    - base/QtQml/Models.2.0
+    - base/QtQml.2.0/Models
+    - base/QtQml/Models.2
+    - base/QtQml.2/Models
+    - base/QtQml/Models
+*/
+QStringList qQmlResolveImportPaths(const QString &uri, const QStringList &basePaths,
+                                   QTypeRevision version)
+{
+    static const QLatin1Char Slash('/');
+    static const QLatin1Char Backslash('\\');
+
+    const QVector<QStringRef> parts = uri.splitRef(QLatin1Char('.'), Qt::SkipEmptyParts);
+
+    QStringList importPaths;
+    // fully & partially versioned parts + 1 unversioned for each base path
+    importPaths.reserve(2 * parts.count() + 1);
+
+    auto versionString = [](QTypeRevision version, ImportVersion mode)
+    {
+        if (mode == FullyVersioned) {
+            // extension with fully encoded version number (eg. MyModule.3.2)
+            return QString::fromLatin1(".%1.%2").arg(version.majorVersion())
+                    .arg(version.minorVersion());
+        }
+        if (mode == PartiallyVersioned) {
+            // extension with encoded version major (eg. MyModule.3)
+            return QString::fromLatin1(".%1").arg(version.majorVersion());
+        }
+        // else extension without version number (eg. MyModule)
+        return QString();
+    };
+
+    auto joinStringRefs = [](const QVector<QStringRef> &refs, const QChar &sep) {
+        QString str;
+        for (auto it = refs.cbegin(); it != refs.cend(); ++it) {
+            if (it != refs.cbegin())
+                str += sep;
+            str += *it;
+        }
+        return str;
+    };
+
+    const ImportVersion initial = (version.hasMinorVersion())
+            ? FullyVersioned
+            : (version.hasMajorVersion() ? PartiallyVersioned : Unversioned);
+    for (int mode = initial; mode <= Unversioned; ++mode) {
+        const QString ver = versionString(version, ImportVersion(mode));
+
+        for (const QString &path : basePaths) {
+            QString dir = path;
+            if (!dir.endsWith(Slash) && !dir.endsWith(Backslash))
+                dir += Slash;
+
+            // append to the end
+            importPaths += dir + joinStringRefs(parts, Slash) + ver;
+
+            if (mode != Unversioned) {
+                // insert in the middle
+                for (int index = parts.count() - 2; index >= 0; --index) {
+                    importPaths += dir + joinStringRefs(parts.mid(0, index + 1), Slash)
+                            + ver + Slash
+                            + joinStringRefs(parts.mid(index + 1), Slash);
+                }
+            }
+        }
+    }
+
+    return importPaths;
+}
+
+QT_END_NAMESPACE
diff --git a/src/qml/qmldirparser/qqmlimportresolver_p.h b/src/qml/qmldirparser/qqmlimportresolver_p.h
new file mode 100644
index 0000000000..bfc0592bf8
--- /dev/null
+++ b/src/qml/qmldirparser/qqmlimportresolver_p.h
@@ -0,0 +1,65 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQml module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** 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-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QQMLIMPORTRESOLVER_P_H
+#define QQMLIMPORTRESOLVER_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qglobal.h>
+#include <QtCore/qstring.h>
+#include <QtCore/qversionnumber.h>
+
+QT_BEGIN_NAMESPACE
+
+QStringList qQmlResolveImportPaths(const QString &uri, const QStringList &basePaths,
+                                   QTypeRevision version);
+
+QT_END_NAMESPACE
+
+#endif // QQMLIMPORTRESOLVER_P_H