refs #338 Topological sorting algorithm, to be used for sorting CLogPattern.

samples/blackmisc/main.cpp

@@ -14,6 +14,7 @@
 #include "samplesjson.h"
 #include "samplesvariant.h"
 #include "samplesperformance.h"
+#include "samplesalgorithm.h"
 #include "blackmisc/blackmiscfreefunctions.h"
 #include "blackmisc/pqallquantities.h"
 
@@ -40,6 +41,7 @@ int main(int argc, char *argv[])
         qDebug() << "4 .. Metadata";
         qDebug() << "5 .. Variant";
         qDebug() << "6 .. Performance";
+        qDebug() << "7 .. Algorithms";
         qDebug() << "-----";
         qDebug() << "x .. Bye";
         QTextStream qtin(stdin);
@@ -51,6 +53,7 @@ int main(int argc, char *argv[])
         else if (s.startsWith("4")) { CSamplesMetadata::samples(); }
         else if (s.startsWith("5")) { CSamplesVariant::samples(); }
         else if (s.startsWith("6")) { CSamplesPerformance::samples(); }
+        else if (s.startsWith("7")) { CSamplesAlgorithm::samples(); }
         else if (s.startsWith("x")) { break; }
     }
     while (true);

samples/blackmisc/samplesalgorithm.cpp

@@ -0,0 +1,42 @@
+/* Copyright (C) 2014
+ * 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 and at http://www.swift-project.org/license.html. 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.
+ */
+
+#include "samplesalgorithm.h"
+#include "blackmisc/algorithm.h"
+#include <QDebug>
+#include <QString>
+
+namespace BlackMiscTest
+{
+
+    /*
+     * Samples
+     */
+    int CSamplesAlgorithm::samples()
+    {
+        QStringList src { "a1", "a2", "a3", "b1", "b2", "b3", "c1", "c2", "c3" };
+        std::random_shuffle(src.begin(), src.end());
+        qDebug() << src;
+        qDebug() << "topologicallySortedInsert";
+        QStringList dst;
+        int count = 0;
+        auto cmp = [ & ](const QString &a, const QString &b) { count++; return a[0] == b[0] && a[1] < b[1]; };
+        for (const auto &s : src) { BlackMisc::topologicallySortedInsert(dst, s, cmp); }
+        qDebug() << count << "comparisons";
+        qDebug() << dst;
+        qDebug() << "topologicalSort";
+        count = 0;
+        BlackMisc::topologicalSort(dst.begin(), dst.end(), cmp);
+        qDebug() << count << "comparisons";
+        qDebug() << dst;
+
+        return 0;
+    }
+
+} // namespace

samples/blackmisc/samplesalgorithm.h

@@ -0,0 +1,26 @@
+/* Copyright (C) 2014
+ * 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 and at http://www.swift-project.org/license.html. 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
+
+#ifndef BLACKMISCTEST_SAMPLESALGORITHM_H
+#define BLACKMISCTEST_SAMPLESALGORITHM_H
+
+namespace BlackMiscTest
+{
+    //! Samples for our algorithms
+    class CSamplesAlgorithm
+    {
+    public:
+        //! Run the samples
+        static int samples();
+    };
+} // namespace
+
+#endif

src/blackmisc/algorithm.h

@@ -0,0 +1,79 @@
+/* Copyright (C) 2014
+ * 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 and at http://www.swift-project.org/license.html. 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
+
+#ifndef BLACKMISC_ALGORITHM_H
+#define BLACKMISC_ALGORITHM_H
+
+#include <QtGlobal>
+#include <algorithm>
+#include <iterator>
+
+namespace BlackMisc
+{
+    /*!
+     * Topological sorting algorithm.
+     *
+     * \param begin      Begin iterator of the range to sort.
+     * \param end        End iterator of the range to sort.
+     * \param comparator A binary function which defines a less-than relation between elements of the range.
+     *                   The ordering it induces must be a partial ordering, which is a more relaxed requirement
+     *                   than the strict weak ordering required by most standard sorting algorithms.
+     *
+     * \see https://en.wikipedia.org/wiki/Topological_sorting
+     * \see https://en.wikipedia.org/wiki/Partial_ordering
+     */
+    template <typename I, typename F>
+    void topologicalSort(I begin, I end, F comparator)
+    {
+        using value_type = typename std::iterator_traits<I>::value_type;
+        auto part = begin;
+        while (part != end)
+        {
+            auto newPart = std::partition(part, end, [ = ](const value_type &a)
+            {
+                return std::none_of(part, end, [ =, &a ](const value_type &b)
+                {
+                    return comparator(b, a);
+                });
+            });
+            Q_ASSERT_X(newPart != part, "BlackMisc::topologicalSort", "Cyclic less-than relation detected (not a partial ordering)");
+            part = newPart;
+        }
+    }
+
+    /*!
+     * Insert an element into a sequential container while preserving the topological ordering of the container.
+     *
+     * \param container  A sequential container.
+     * \param value      The value to insert.
+     * \param comparator A binary function which defines a less-than relation between elements of the container.
+     *                   The ordering it induces must be a partial ordering, which is a more relaxed requirement
+     *                   than the strict weak ordering required by most standard sorting algorithms.
+     *
+     * \see https://en.wikipedia.org/wiki/Topological_sorting
+     * \see https://en.wikipedia.org/wiki/Partial_ordering
+     */
+    template <typename C, typename T, typename F>
+    void topologicallySortedInsert(C &container, T &&value, F comparator)
+    {
+        using value_type = typename C::value_type;
+        using reverse = std::reverse_iterator<typename C::iterator>;
+        auto rit = std::find_if(reverse(container.end()), reverse(container.begin()), [ =, &value ](const value_type &lhs)
+        {
+            return comparator(lhs, value);
+        });
+        Q_ASSERT_X(std::none_of(rit, reverse(container.begin()), [ =, &value ](const value_type &rhs) { return comparator(value, rhs); }),
+            "BlackMisc::topologicallySortedInsert", "Cyclic less-than relation detected (not a partial ordering)");
+        container.insert(rit.base(), std::forward<T>(value));
+    }
+}
+
+#endif