Put the include depenency table into a separate class, and cache it when possible.

src/libs/cplusplus/DependencyTable.h

@@ -0,0 +1,65 @@
+/**************************************************************************
+**
+** This file is part of Qt Creator
+**
+** Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).
+**
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** Commercial Usage
+**
+** Licensees holding valid Qt Commercial licenses may use this file in
+** accordance with the Qt Commercial License Agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Nokia.
+**
+** 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.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at http://qt.nokia.com/contact.
+**
+**************************************************************************/
+
+#ifndef DEPENDENCYTABLE_H
+#define DEPENDENCYTABLE_H
+
+#include <CPlusPlusForwardDeclarations.h>
+
+#include <QtCore/QBitArray>
+#include <QtCore/QHash>
+#include <QtCore/QString>
+#include <QtCore/QStringList>
+#include <QtCore/QVector>
+
+namespace CPlusPlus {
+
+class Snapshot;
+
+class CPLUSPLUS_EXPORT DependencyTable
+{
+public:
+    bool isValidFor(const Snapshot &snapshot) const;
+
+    QStringList filesDependingOn(const QString &fileName) const;
+    QHash<QString, QStringList> dependencyTable() const;
+
+    void build(const Snapshot &snapshot);
+
+private:
+    QHash<QString, QStringList> includesPerFile;
+    QVector<QString> files;
+    QHash<QString, int> fileIndex;
+    QHash<int, QList<int> > includes;
+    QVector<QBitArray> includeMap;
+};
+
+} // namespace CPlusPlus
+
+#endif // DEPENDENCYTABLE_H