Delegate parts of CSequence to a non-template implementation

To reduce build time.

src/blackmisc/sequence.cpp

@@ -0,0 +1,31 @@
+/* Copyright (C) 2021
+ * swift project Community / Contributors
+ *
+ * This file is part of swift project. It is subject to the license terms in the LICENSE file found in the top-level
+ * directory of this distribution. No part of swift project, including this file, may be copied, modified, propagated,
+ * or distributed except according to the terms contained in the LICENSE file.
+ */
+
+//! \file
+
+#include "blackmisc/sequence.h"
+#include <numeric>
+
+namespace BlackMisc::Private
+{
+    QVector<int> findIndices(int size, const std::function<bool(int)> &predicate)
+    {
+        QVector<int> result(size);
+        std::iota(result.begin(), result.end(), 0);
+        result.erase(std::remove_if(result.begin(), result.end(), std::not_fn(predicate)), result.end());
+        return result;
+    }
+
+    QVector<int> sortIndices(int size, const std::function<bool(int, int)> &cmp)
+    {
+        QVector<int> result(size);
+        std::iota(result.begin(), result.end(), 0);
+        std::sort(result.begin(), result.end(), cmp);
+        return result;
+    }
+}