Core/Utils: Moved rng functions to separate header and added utility functions to select a random element from a container where each element can have different chance of being selected

(cherry picked from commit ae20b2ab561bc07d85f443ae914bc597c9d6ac6e)
(cherry picked from commit 921d893c2a82eb6ac0762bf7001df87911b44611)
(cherry picked from commit 9ab10d6e680ca835d1dfdfbceb9f18f330f994fc)
(cherry picked from commit 00c878e73a8c6b8ce3339d224ab5611df3bbd07c)
(cherry picked from commit ff9c999334d87acc3fcea9737753c30b7f1abe25)
(cherry picked from commit bc94bacce404401a480b6871eaa7bc38d766014c)
(cherry picked from commit d5b0ffbe9b0c07beb8d0dfc52a6532c2da805285)

1 files changed, 165 insertions, 0 deletions

diff --git a/src/common/Utilities/Containers.h b/src/common/Utilities/Containers.h
new file mode 100644
index 00000000000..f3e9432ca4c
--- /dev/null
+++ b/src/common/Utilities/Containers.h
@@ -0,0 +1,165 @@
+/*
+ * Copyright (C) 2008-2016 TrinityCore <http://www.trinitycore.org/>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef TRINITY_CONTAINERS_H
+#define TRINITY_CONTAINERS_H
+
+#include "Define.h"
+#include "Random.h"
+#include <algorithm>
+#include <functional>
+#include <list>
+#include <vector>
+
+namespace Trinity
+{
+    namespace Containers
+    {
+        template<class T>
+        void RandomResizeList(std::list<T> &list, uint32 size)
+        {
+            size_t list_size = list.size();
+
+            while (list_size > size)
+            {
+                typename std::list<T>::iterator itr = list.begin();
+                std::advance(itr, urand(0, list_size - 1));
+                list.erase(itr);
+                --list_size;
+            }
+        }
+
+        template<class T, class Predicate>
+        void RandomResizeList(std::list<T> &list, Predicate& predicate, uint32 size)
+        {
+            //! First use predicate filter
+            std::list<T> listCopy;
+            for (typename std::list<T>::iterator itr = list.begin(); itr != list.end(); ++itr)
+                if (predicate(*itr))
+                    listCopy.push_back(*itr);
+
+            if (size)
+                RandomResizeList(listCopy, size);
+
+            list = listCopy;
+        }
+
+        /*
+         * Select a random element from a container.
+         *
+         * Note: container cannot be empty
+         */
+        template <class C>
+        typename C::value_type const& SelectRandomContainerElement(C const& container)
+        {
+            typename C::const_iterator it = container.begin();
+            std::advance(it, urand(0, container.size() - 1));
+            return *it;
+        }
+
+        /*
+         * Select a random element from a container where each element has a different chance to be selected.
+         *
+         * @param container Container to select an element from
+         * @param weights Chances of each element to be selected, must be in the same order as elements in container.
+         *                Caller is responsible for checking that sum of all weights is greater than 0.
+         *
+         * Note: container cannot be empty
+         */
+        template <class C>
+        typename C::const_iterator SelectRandomWeightedContainerElement(C const& container, std::vector<double> weights)
+        {
+            Trinity::discrete_distribution_param<uint32> ddParam(weights.begin(), weights.end());
+            std::discrete_distribution<uint32> dd(ddParam);
+            typename C::const_iterator it = container.begin();
+            std::advance(it, dd(SFMTEngine::Instance()));
+            return it;
+        }
+
+        /*
+         * Select a random element from a container where each element has a different chance to be selected.
+         *
+         * @param container Container to select an element from
+         * @param weightExtractor Function retrieving chance of each element in container, expected to take an element of the container and returning a double
+         *
+         * Note: container cannot be empty
+         */
+        template <class C, class Fn>
+        typename C::const_iterator SelectRandomWeightedContainerElement(C const& container, Fn weightExtractor)
+        {
+            std::vector<double> weights;
+            weights.reserve(container.size());
+            double weightSum = 0.0;
+            for (auto itr = container.begin(); itr != container.end(); ++itr)
+            {
+                double weight = weightExtractor(*itr);
+                weights.push_back(weight);
+                weightSum += weight;
+            }
+            if (weightSum <= 0.0)
+                weights.assign(container.size(), 1.0);
+
+            return SelectRandomWeightedContainerElement(container, weights);
+        }
+
+        /**
+        * @fn bool Trinity::Containers::Intersects(Iterator first1, Iterator last1, Iterator first2, Iterator last2)
+        *
+        * @brief Checks if two SORTED containers have a common element
+        *
+        * @param first1 Iterator pointing to start of the first container
+        * @param last1 Iterator pointing to end of the first container
+        * @param first2 Iterator pointing to start of the second container
+        * @param last2 Iterator pointing to end of the second container
+        *
+        * @return true if containers have a common element, false otherwise.
+        */
+        template<class Iterator1, class Iterator2>
+        bool Intersects(Iterator1 first1, Iterator1 last1, Iterator2 first2, Iterator2 last2)
+        {
+            while (first1 != last1 && first2 != last2)
+            {
+                if (*first1 < *first2)
+                    ++first1;
+                else if (*first2 < *first1)
+                    ++first2;
+                else
+                    return true;
+            }
+
+            return false;
+        }
+
+        template<class K, class V, template<class, class, class...> class M, class... Rest>
+        void MultimapErasePair(M<K, V, Rest...>& multimap, K const& key, V const& value)
+        {
+            auto range = multimap.equal_range(key);
+            for (auto itr = range.first; itr != range.second;)
+            {
+                if (itr->second == value)
+                    itr = multimap.erase(itr);
+                else
+                    ++itr;
+            }
+        }
+
+    }
+    //! namespace Containers
+}
+//! namespace Trinity
+
+#endif //! #ifdef TRINITY_CONTAINERS_H