Move cycle detection into its own class.

It has the characteristics of a visitor, so let's make
it one.
Also introduce test case.

Change-Id: Ibfe14ca71268f73afe5e524fa1a15b3ab67058f1
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/src/lib/buildgraph/cycledetector.h b/src/lib/buildgraph/cycledetector.h
new file mode 100644
index 000000000..ff5023fb8
--- /dev/null
+++ b/src/lib/buildgraph/cycledetector.h
@@ -0,0 +1,60 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/legal
+**
+** This file is part of the Qt Build Suite.
+**
+** 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 Digia.  For licensing terms and
+** conditions see http://qt.digia.com/licensing.  For further information
+** use the contact form at http://qt.digia.com/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 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Digia gives you certain additional
+** rights.  These rights are described in the Digia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+****************************************************************************/
+#ifndef CYCLEDETECTOR_H
+#define CYCLEDETECTOR_H
+
+#include "artifactvisitor.h"
+
+#include <QSet>
+
+namespace qbs {
+namespace Internal {
+
+class CycleDetector : public ArtifactVisitor
+{
+public:
+    CycleDetector();
+
+    void visitProject(const BuildProject::ConstPtr &project);
+    void visitArtifact(Artifact *artifact);
+
+private:
+    void doVisit(Artifact *artifact);
+
+    QList<Artifact *> cycle(Artifact *doubleEntry);
+
+    QSet<Artifact *> m_allArtifacts;
+    QSet<Artifact *> m_artifactsInCurrentPath;
+    Artifact *m_parent;
+};
+
+} // namespace Internal
+} // namespace qbs
+
+#endif // CYCLEDETECTOR_H