Subset.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
 
#ifndef META_OCEAN_BASE_SUBSET_H
#define META_OCEAN_BASE_SUBSET_H
 
#include "ocean/base/Base.h"
 
namespace Ocean
{
 
/**
 * This class implements subset functions.
 * @ingroup base
 */
class Subset
{
    private:
 
        /**
         * This helper class implements a subset functions.
         * @tparam TIndex Data type of the index elements
         */
        template <typename TIndex>
        class InternalSubset
        {
            public:
 
                /**
                 * Extracts a subset of a given set of objects by usage of an index vector holding the indices of all objects to be used.
                 * If the index data type is an uint8_t, than the (boolean != 0u) statement is used to use the corresponding object or not.<br>
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param indices Indices defining the subset to be extracted
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> subset(const std::vector<T>& objects, const std::vector<TIndex>& indices);
 
                /**
                 * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be used.
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param indices Indices defining the subset to be extracted
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> subset(const std::vector<T>& objects, const std::set<TIndex>& indices);
 
                /**
                 * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be not used.
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param indices Indices defining the inverted subset to be extracted
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> invertedSubset(const std::vector<T>& objects, const std::unordered_set<TIndex>& indices);
 
                /**
                 * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be not used.
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param indices Indices defining the inverted subset to be extracted
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> invertedSubset(const std::vector<T>& objects, const std::set<TIndex>& indices);
 
                /**
                 * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be used.
                 * If the index data type is an uint8_t, than the (boolean != 0u) statement is used to use the corresponding object or not.<br>
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param numberObjects Number of given objects
                 * @param indices Indices defining the subset to be extracted
                 * @param numberIndices Number of given indices
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> subset(const T* objects, const size_t numberObjects, const TIndex* indices, const size_t numberIndices);
 
                /**
                 * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be used.
                 * If the index data type is an uint8_t, than the (boolean != 0u) statement is used to use the corresponding object or not.<br>
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param numberObjects Number of given objects
                 * @param indices Indices defining the subset to be extracted
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> subset(const T* objects, const size_t numberObjects, const std::vector<TIndex>& indices);
 
                /**
                 * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be used.
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param numberObjects Number of given objects
                 * @param indices Indices defining the subset to be extracted
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> subset(const T* objects, const size_t numberObjects, const std::set<TIndex>& indices);
 
                /**
                 * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be not used.
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param numberObjects Number of given objects
                 * @param indices Indices defining the inverted subset to be extracted
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> invertedSubset(const T* objects, const size_t numberObjects, const std::unordered_set<TIndex>& indices);
 
                /**
                 * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be not used.
                 * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
                 * @param objects Entire set of objects from that a subset will be extracted
                 * @param numberObjects Number of given objects
                 * @param indices Indices defining the inverted subset to be extracted
                 * @return Resulting subset of the given objects
                 * @tparam T Data type of the objects
                 */
                template <typename T>
                static inline std::vector<T> invertedSubset(const T* objects, const size_t numberObjects, const std::set<TIndex>& indices);
 
                /**
                 * Converts object indices to an uint8_t vector holding statements for each object.
                 * @param indices Indices defining the subset of the objects, with range [0, numberObjects)
                 * @param numberObjects Number of objects that can be addressed by the indices
                 * @return Resulting (boolean != 0u) statements
                 * @tparam TContainer The container to be used, e.g., std::vector, std::set, std::unordred_set
                 * @tparam tValue Value for objects that are defined in the indices, the inverse value is applied otherwise
                 */
                template <typename TContainer, uint8_t tValue>
                static inline std::vector<uint8_t> indices2statements(const TContainer& indices, const size_t numberObjects);
 
                /**
                 * Converts object indices to an uint8_t vector holding statements for each object.
                 * @param indices Indices defining the subset of the objects, with range [0, numberObjects)
                 * @param numberIndices Number of provided indices
                 * @param numberObjects Number of objects that can be addressed by the indices
                 * @return Resulting boolean statements
                 * @tparam tValue Value for objects that are defined in the indices, the inverse value is applied otherwise
                 */
                template <uint8_t tValue>
                static inline std::vector<uint8_t> indices2statements(const TIndex* indices, const size_t numberIndices, const size_t numberObjects);
 
                /**
                 * Converts an uint8_t vector holding statements for each object into object indices.
                 * @param statements Boolean statement for each object
                 * @return Resulting object indices
                 * @tparam tValue Value for objects that will be defined in the indices
                 */
                template <uint8_t tValue>
                static inline std::vector<TIndex> statements2indices(const std::vector<uint8_t>& statements);
 
                /**
                 * Converts an uint8_t vector holding statements for each object into object indices.
                 * @param statements Boolean statement for each object
                 * @param numberStatements Number of statements
                 * @return Resulting object indices
                 * @tparam tValue Value for objects that will be defined in the indices
                 */
                template <uint8_t tValue>
                static inline std::vector<TIndex> statements2indices(const uint8_t* statements, const size_t numberStatements);
            };
 
    public:
 
        /**
         * Extracts a subset of a given set of objects by usage of an index vector holding the indices of all objects to be used.
         * If the index data type is an uint8_t, than the (boolean != 0u) statement is used to use the corresponding object or not.<br>
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param indices Indices defining the subset to be extracted
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> subset(const std::vector<T>& objects, const std::vector<TIndex>& indices);
 
        /**
         * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be used.
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param indices Indices defining the subset to be extracted
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> subset(const std::vector<T>& objects, const std::set<TIndex>& indices);
 
        /**
         * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be not used.
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param indices Indices defining the inverted subset to be extracted
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> invertedSubset(const std::vector<T>& objects, const std::unordered_set<TIndex>& indices);
 
        /**
         * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be not used.
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param indices Indices defining the inverted subset to be extracted
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> invertedSubset(const std::vector<T>& objects, const std::set<TIndex>& indices);
 
        /**
         * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be used.
         * If the index data type is an uint8_t, than the (boolean != 0u) statement is used to use the corresponding object or not.<br>
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param numberObjects Number of given objects
         * @param indices Indices defining the subset to be extracted
         * @param numberIndices Number of given indices
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> subset(const T* objects, const size_t numberObjects, const TIndex* indices, const size_t numberIndices);
 
        /**
         * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be used.
         * If the index data type is an uint8_t, than the (boolean != 0u) statement is used to use the corresponding object or not.<br>
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param numberObjects Number of given objects
         * @param indices Indices defining the subset to be extracted
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> subset(const T* objects, const size_t numberObjects, const std::vector<TIndex>& indices);
 
        /**
         * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be used.
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param numberObjects Number of given objects
         * @param indices Indices defining the subset to be extracted
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> subset(const T* objects, const size_t numberObjects, const std::set<TIndex>& indices);
 
        /**
         * Applies a subset to a vector of objects.
         * @param objects The entire set of objects on which the subset will be applied
         * @param begin Iterator to the first element of the subset
         * @param end Iterator to the end of the subset
         */
        template <typename TIndexIterator, typename T>
        static void applySubset(std::vector<T>& objects, const TIndexIterator& begin, const TIndexIterator& end);
 
        /**
         * Applies a subset to a vector of objects.
         * @param objects The entire set of objects on which the subset will be applied
         * @param indices The indices of the subset to be applied
         */
        template <typename TIndex, typename T>
        static inline void applySubset(std::vector<T>& objects, const std::vector<TIndex>& indices);
 
        /**
         * Applies a subset to a vector of objects.
         * @param objects The entire set of objects on which the subset will be applied
         * @param indices The indices of the subset to be applied, can be nullptr if numberIndices is 0
         * @param numberIndices The number of indices, with range [0, infinity)
         */
        template <typename TIndex, typename T>
        static inline void applySubset(std::vector<T>& objects, const TIndex* indices, const size_t numberIndices);
 
        /**
         * Extracts the indices that are not given within a set indices.
         * @param indices The set of given indices, the resulting indices will not contain any of these indices, can contain indices with range [0, maximalIndex]
         * @param numberElements The number of possible elements defining the entire range of possible indices: [0, numberElements)
         * @tparam TIndex Data type of the index elements
         */
        template <typename TIndex>
        static std::vector<TIndex> invertedIndices(const std::vector<TIndex>& indices, const size_t numberElements);
 
        /**
         * Extracts the indices that are not given within a set indices.
         * @param indices The set of given indices, the resulting indices will not contain any of these indices, can contain indices with range [0, maximalIndex]
         * @param numberElements The number of possible elements defining the entire range of possible indices: [0, numberElements)
         * @tparam TIndex Data type of the index elements
         */
        template <typename TIndex>
        static std::unordered_set<TIndex> invertedIndices(const std::unordered_set<TIndex>& indices, const size_t numberElements);
 
        /**
         * Extracts the indices that are not given within a set indices.
         * @param indices The set of given indices, the resulting indices will not contain any of these indices, can contain indices with range [0, maximalIndex]
         * @param numberElements The number of possible elements defining the entire range of possible indices: [0, numberElements)
         * @tparam TIndex Data type of the index elements
         */
        template <typename TIndex>
        static std::set<TIndex> invertedIndices(const std::set<TIndex>& indices, const size_t numberElements);
 
        /**
         * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be not used.
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param numberObjects Number of given objects
         * @param indices Indices defining the inverted subset to be extracted
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> invertedSubset(const T* objects, const size_t numberObjects, const std::unordered_set<TIndex>& indices);
 
        /**
         * Extracts a subset of a given set of objects by usage of a set of indices of all objects to be not used.
         * Beware: No range check is done! Thus, each index must not exceed the number of given objects.<br>
         * @param objects Entire set of objects from that a subset will be extracted
         * @param numberObjects Number of given objects
         * @param indices Indices defining the inverted subset to be extracted
         * @return Resulting subset of the given objects
         * @tparam TIndex Data type of the index elements
         * @tparam T Data type of the objects
         */
        template <typename TIndex, typename T>
        static inline std::vector<T> invertedSubset(const T* objects, const size_t numberObjects, const std::set<TIndex>& indices);
 
        /**
         * Converts object indices to an uint8_t vector holding statements for each object.
         * @param indices Indices defining the subset of the objects, with range [0, numberObjects)
         * @param numberObjects Number of objects that can be addressed by the indices
         * @return Resulting boolean statements
         * @tparam TIndex Data type of the index elements
         * @tparam tValue Value for objects that are defined in the indices, the inverse value is applied otherwise
         */
        template <typename TIndex, uint8_t tValue>
        static inline std::vector<uint8_t> indices2statements(const std::vector<TIndex>& indices, const size_t numberObjects);
 
        /**
         * Converts object indices to an uint8_t vector holding statements for each object.
         * @param indices Indices defining the subset of the objects, with range [0, numberObjects)
         * @param numberObjects Number of objects that can be addressed by the indices
         * @return Resulting boolean statements
         * @tparam TIndex Data type of the index elements
         * @tparam tValue Value for objects that are defined in the indices, the inverse value is applied otherwise
         */
        template <typename TIndex, uint8_t tValue>
        static inline std::vector<uint8_t> indices2statements(const std::set<TIndex>& indices, const size_t numberObjects);
 
        /**
         * Converts object indices to an uint8_t vector holding statements for each object.
         * @param indices Indices defining the subset of the objects, with range [0, numberObjects)
         * @param numberObjects Number of objects that can be addressed by the indices
         * @return Resulting boolean statements
         * @tparam TIndex Data type of the index elements
         * @tparam tValue Value for objects that are defined in the indices, the inverse value is applied otherwise
         */
        template <typename TIndex, uint8_t tValue>
        static inline std::vector<uint8_t> indices2statements(const std::unordered_set<TIndex>& indices, const size_t numberObjects);
 
        /**
         * Converts object indices to an uint8_t vector holding statements for each object.
         * @param indices Indices defining the subset of the objects, with range [0, numberObjects)
         * @param numberIndices Number of provided indices
         * @param numberObjects Number of objects that can be addressed by the indices
         * @return Resulting boolean statements
         * @tparam TIndex Data type of the index elements
         * @tparam tValue Value for objects that are defined in the indices, the inverse value is applied otherwise
         */
        template <typename TIndex, uint8_t tValue>
        static inline std::vector<uint8_t> indices2statements(const TIndex* indices, const size_t numberIndices, const size_t numberObjects);
 
        /**
         * Converts an uint8_t vector holding statements for each object into object indices.
         * @param statements Boolean statement for each object
         * @return Resulting object indices
         * @tparam TIndex Data type of the index elements
         * @tparam tValue Value for objects that will be defined in the indices
         */
        template <typename TIndex, uint8_t tValue>
        static inline std::vector<TIndex> statements2indices(const std::vector<uint8_t>& statements);
 
        /**
         * Converts an uint8_t vector holding statements for each object into object indices.
         * @param statements Boolean statement for each object
         * @param numberStatements Number of statements
         * @return Resulting object indices
         * @tparam TIndex Data type of the index elements
         * @tparam tValue Value for objects that will be defined in the indices
         */
        template <typename TIndex, uint8_t tValue>
        static inline std::vector<TIndex> statements2indices(const uint8_t* statements, const size_t numberStatements);
 
        /**
         * Determines corresponding element pairs from two sets of element maps.
         * Two elements correspond with each other if they have the same key.
         * @param elementMapA The first map of elements
         * @param elementMapB The second map of elements
         * @param elementsA The resulting elements from the first map which have a corresponding element in the second map
         * @param elementsB The resulting elements from the second map which have a corresponding element in the first map
         * @tparam TKey The data type of each key
         * @tparam TElement The data type of each element
         */
        template <typename TKey, typename TElement>
        static void correspondingElements(const std::map<TKey, TElement>& elementMapA, const std::map<TKey, TElement>& elementMapB, std::vector<TElement>& elementsA, std::vector<TElement>& elementsB);
 
        /**
         * Determines whether two (ordered) sets have at least one intersecting element.
         * Both input sets must be in ascending order.
         * @param firstA The iterator to the first element in the first set
         * @param endA The iterator to the (exclusive) element after the last element in the first set
         * @param firstB The iterator to the first element in the second set
         * @param endB The iterator to the (exclusive) element after the last element in the second set
         * @return True, if so
         */
        template <typename TIterator>
        static bool hasIntersectingElement(const TIterator& firstA, const TIterator& endA, const TIterator& firstB, const TIterator& endB);
 
        /**
         * Determines whether two (ordered) sets have at least one intersecting element.
         * @param setA The first set to check, can be empty
         * @param setB The second set to check, can be empty
         * @return True, if so
         */
        template <typename T>
        static inline bool hasIntersectingElement(const std::set<T>& setA, const std::set<T>& setB);
 
        /**
         * Determines whether two ordered vectors have at least one intersecting element.
         * @param sortedA The first vector to check, can be empty
         * @param sortedB The second vector to check, can be empty
         * @return True, if so
         */
        template <typename T>
        static inline bool hasIntersectingElement(const std::vector<T>& sortedA, const std::vector<T>& sortedB);
};
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::subset(const std::vector<T>& objects, const std::vector<TIndex>& indices)
{
    std::vector<T> result;
    result.reserve(indices.size());
 
    for (const TIndex& index : indices)
    {
        ocean_assert(size_t(index) < objects.size());
        result.push_back(objects[size_t(index)]);
    }
 
    return result;
}
 
template <>
template <typename T>
inline std::vector<T> Subset::InternalSubset<uint8_t>::subset(const std::vector<T>& objects, const std::vector<uint8_t>& indices)
{
    std::vector<T> result;
    result.reserve(indices.size());
 
    typename std::vector<T>::const_iterator iObject = objects.begin();
 
    for (const uint8_t index : indices)
    {
        if (index != 0u)
        {
            result.push_back(*iObject);
        }
 
        ++iObject;
    }
 
    return result;
}
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::subset(const std::vector<T>& objects, const std::set<TIndex>& indices)
{
    std::vector<T> result;
    result.reserve(indices.size());
 
    for (typename std::set<TIndex>::const_iterator i = indices.begin(); i != indices.end(); ++i)
    {
        ocean_assert(*i < objects.size());
        result.push_back(objects[size_t(*i)]);
    }
 
    return result;
}
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::invertedSubset(const std::vector<T>& objects, const std::unordered_set<TIndex>& indices)
{
    ocean_assert(objects.size() >= indices.size());
    ocean_assert((unsigned long long)(objects.size()) < (unsigned long long)(std::numeric_limits<TIndex>::max()));
 
    if (objects.size() == indices.size())
    {
#ifdef OCEAN_DEBUG
        for (const TIndex& index : indices)
        {
            ocean_assert(index < objects.size());
        }
#endif
 
        return std::vector<T>();
    }
 
    std::vector<T> result;
    result.reserve(objects.size() - indices.size());
 
    for (size_t n = 0u; n < objects.size(); ++n)
    {
        if (indices.find(TIndex(n)) == indices.cend())
        {
            result.push_back(objects[n]);
        }
    }
 
    return result;
}
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::invertedSubset(const std::vector<T>& objects, const std::set<TIndex>& indices)
{
    ocean_assert(objects.size() >= indices.size());
    ocean_assert((unsigned long long)(objects.size()) < (unsigned long long)(std::numeric_limits<TIndex>::max()));
 
    if (objects.size() == indices.size())
    {
#ifdef OCEAN_DEBUG
        for (const TIndex& index : indices)
        {
            ocean_assert(index < objects.size());
        }
#endif
 
        return std::vector<T>();
    }
 
    std::vector<T> result;
    result.reserve(objects.size() - indices.size());
 
    for (size_t n = 0u; n < objects.size(); ++n)
    {
        if (indices.find(TIndex(n)) == indices.cend())
        {
            result.push_back(objects[n]);
        }
    }
 
    return result;
}
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::subset(const T* objects, const size_t numberObjects, const TIndex* indices, const size_t numberIndices)
{
    std::vector<T> result;
    result.reserve(numberIndices);
 
    for (size_t n = 0; n < numberIndices; ++n)
    {
        ocean_assert_and_suppress_unused(indices[n] < numberObjects, numberObjects);
 
        result.push_back(objects[indices[n]]);
    }
 
    return result;
}
 
template <>
template <typename T>
inline std::vector<T> Subset::InternalSubset<uint8_t>::subset(const T* objects, const size_t numberObjects, const uint8_t* indices, const size_t numberIndices)
{
    ocean_assert_and_suppress_unused(numberIndices <= numberObjects, numberObjects);
 
    std::vector<T> result;
    result.reserve(numberIndices);
 
    for (size_t n = 0; n < numberIndices; ++n)
    {
        if (indices[n] != 0u)
        {
            result.push_back(objects[n]);
        }
    }
 
    return result;
}
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::subset(const T* objects, const size_t numberObjects, const std::vector<TIndex>& indices)
{
    return subset(objects, numberObjects, indices.data(), indices.size());
}
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::subset(const T* objects, const size_t numberObjects, const std::set<TIndex>& indices)
{
    std::vector<T> result;
    result.reserve(indices.size());
 
    for (const TIndex& index : indices)
    {
        ocean_assert_and_suppress_unused(index < numberObjects, numberObjects);
 
        result.push_back(objects[index]);
    }
 
    return result;
}
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::invertedSubset(const T* objects, const size_t numberObjects, const std::unordered_set<TIndex>& indices)
{
    ocean_assert(numberObjects >= indices.size());
    ocean_assert((unsigned long long)(numberObjects) < (unsigned long long)(std::numeric_limits<TIndex>::max()));
 
    if (numberObjects == indices.size())
    {
#ifdef OCEAN_DEBUG
        for (const TIndex& index : indices)
        {
            ocean_assert(indices < numberObjects);
        }
#endif
 
        return std::vector<T>();
    }
 
    std::vector<T> result;
    result.reserve(numberObjects - indices.size());
 
    for (size_t n = 0; n < numberObjects; ++n)
    {
        if (indices.find(TIndex(n)) == indices.cend())
        {
            result.push_back(objects[n]);
        }
    }
 
    return result;
}
 
template <typename TIndex>
template <typename T>
inline std::vector<T> Subset::InternalSubset<TIndex>::invertedSubset(const T* objects, const size_t numberObjects, const std::set<TIndex>& indices)
{
    ocean_assert(numberObjects >= indices.size());
    ocean_assert((unsigned long long)(numberObjects) < (unsigned long long)(std::numeric_limits<TIndex>::max()));
 
    if (numberObjects == indices.size())
    {
#ifdef OCEAN_DEBUG
        for (const TIndex& index : indices)
        {
            ocean_assert(index < numberObjects);
        }
#endif
 
        return std::vector<T>();
    }
 
    std::vector<T> result;
    result.reserve(numberObjects - indices.size());
 
    for (size_t n = 0; n < numberObjects; ++n)
    {
        if (indices.find(TIndex(n)) == indices.cend())
        {
            result.push_back(objects[n]);
        }
    }
 
    return result;
}
 
template <typename TIndex>
template <typename TContainer, uint8_t tValue>
inline std::vector<uint8_t> Subset::InternalSubset<TIndex>::indices2statements(const TContainer& indices, const size_t numberObjects)
{
    std::vector<uint8_t> result(numberObjects, !tValue);
 
    for (const TIndex& index : indices)
    {
        ocean_assert(index < result.size());
        result[index] = tValue;
    }
 
    return result;
}
 
template <typename TIndex>
template <uint8_t tValue>
inline std::vector<uint8_t> Subset::InternalSubset<TIndex>::indices2statements(const TIndex* indices, const size_t numberIndices, const size_t numberObjects)
{
    std::vector<uint8_t> result(numberObjects, !tValue);
 
    for (size_t n = 0; n < numberIndices; ++n)
    {
        ocean_assert(indices[n] < result.size());
        result[indices[n]] = tValue;
    }
 
    return result;
}
 
template <typename TIndex>
template <uint8_t tValue>
inline std::vector<TIndex> Subset::InternalSubset<TIndex>::statements2indices(const std::vector<uint8_t>& statements)
{
    std::vector<TIndex> result;
 
    for (size_t n = 0; n < statements.size(); ++n)
    {
        if (statements[n] == tValue)
        {
            result.push_back(TIndex(n));
        }
    }
 
    return result;
}
 
template <typename TIndex>
template <uint8_t tValue>
inline std::vector<TIndex> Subset::InternalSubset<TIndex>::statements2indices(const uint8_t* statements, const size_t numberStatements)
{
    std::vector<TIndex> result;
 
    for (size_t n = 0; n < numberStatements; ++n)
    {
        if (statements[n] == tValue)
        {
            result.push_back(TIndex(n));
        }
    }
 
    return result;
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::subset(const std::vector<T>& objects, const std::vector<TIndex>& indices)
{
    return InternalSubset<TIndex>::template subset<T>(objects, indices);
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::subset(const std::vector<T>& objects, const std::set<TIndex>& indices)
{
    return InternalSubset<TIndex>::template subset<T>(objects, indices);
}
 
template <typename TIndex>
std::vector<TIndex> Subset::invertedIndices(const std::vector<TIndex>& indices, const size_t numberElements)
{
    ocean_assert(indices.size() <= TIndex(numberElements));
 
    if (indices.size() == numberElements)
    {
#ifdef OCEAN_DEBUG
        const std::unordered_set<TIndex> indexSet(indices.begin(), indices.end());
        ocean_assert(indexSet.size() == indices.size());
 
        for (size_t n = 0; n < numberElements; ++n)
        {
            ocean_assert(indexSet.find(TIndex(n)) != indexSet.cend());
        }
#endif
 
        return std::vector<TIndex>();
    }
 
    const std::unordered_set<TIndex> indexSet(indices.begin(), indices.end());
    ocean_assert(indexSet.size() == indices.size());
 
    std::vector<TIndex> result;
    result.reserve(numberElements - indices.size());
 
    for (TIndex i = TIndex(0); i < TIndex(numberElements); ++i)
    {
        if (indexSet.find(i) == indexSet.cend())
        {
            result.push_back(i);
        }
    }
 
    return result;
}
 
template <typename TIndex>
std::unordered_set<TIndex> Subset::invertedIndices(const std::unordered_set<TIndex>& indices, const size_t numberElements)
{
    ocean_assert(indices.size() <= TIndex(numberElements));
 
    if (indices.size() == numberElements)
    {
#ifdef OCEAN_DEBUG
        for (size_t n = 0; n < numberElements; ++n)
        {
            ocean_assert(indices.find(TIndex(n)) != indices.end());
        }
#endif
 
        return std::unordered_set<TIndex>();
    }
 
    std::unordered_set<TIndex> result;
    result.reserve(numberElements - indices.size());
 
    for (TIndex i = TIndex(0); i < TIndex(numberElements); ++i)
    {
        if (indices.find(i) == indices.cend())
        {
            result.emplace(i);
        }
    }
 
    return result;
}
 
template <typename TIndex>
std::set<TIndex> Subset::invertedIndices(const std::set<TIndex>& indices, const size_t numberElements)
{
    ocean_assert(indices.size() <= TIndex(numberElements));
 
    if (indices.size() == numberElements)
    {
#ifdef OCEAN_DEBUG
        for (size_t n = 0; n < numberElements; ++n)
        {
            ocean_assert(indices.find(TIndex(n)) != indices.end());
        }
#endif
 
        return std::set<TIndex>();
    }
 
    std::set<TIndex> result;
 
    for (TIndex i = TIndex(0); i < TIndex(numberElements); ++i)
    {
        if (indices.find(i) == indices.cend())
        {
            result.insert(i);
        }
    }
 
    return result;
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::invertedSubset(const std::vector<T>& objects, const std::unordered_set<TIndex>& indices)
{
    return InternalSubset<TIndex>::template invertedSubset<T>(objects, indices);
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::invertedSubset(const std::vector<T>& objects, const std::set<TIndex>& indices)
{
    return InternalSubset<TIndex>::template invertedSubset<T>(objects, indices);
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::subset(const T* objects, const size_t numberObjects, const TIndex* indices, const size_t numberIndices)
{
    return InternalSubset<TIndex>::template subset<T>(objects, numberObjects, indices, numberIndices);
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::subset(const T* objects, const size_t numberObjects, const std::vector<TIndex>& indices)
{
    return InternalSubset<TIndex>::template subset<T>(objects, numberObjects, indices);
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::subset(const T* objects, const size_t numberObjects, const std::set<TIndex>& indices)
{
    return InternalSubset<TIndex>::template subset<T>(objects, numberObjects, indices);
}
 
template <typename TIndexIterator, typename T>
void Subset::applySubset(std::vector<T>& objects, const TIndexIterator& begin, const TIndexIterator& end)
{
    if (begin == end)
    {
        objects.clear();
        return;
    }
 
    size_t nIndex = 0;
 
    for (TIndexIterator iterator = begin; iterator < end; ++iterator)
    {
        objects[nIndex] = std::move(objects[*iterator]);
 
        ++nIndex;
    }
 
    objects.resize(nIndex);
}
 
template <typename TIndex, typename T>
void Subset::applySubset(std::vector<T>& objects, const std::vector<TIndex>& sortedIndices)
{
    applySubset(objects, sortedIndices.cbegin(), sortedIndices.cend());
}
 
template <typename TIndex, typename T>
void Subset::applySubset(std::vector<T>& objects, const TIndex* sortedIndices, const size_t numberSortedIndices)
{
    applySubset(objects, sortedIndices, sortedIndices + numberSortedIndices);
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::invertedSubset(const T* objects, const size_t numberObjects, const std::unordered_set<TIndex>& indices)
{
    return InternalSubset<TIndex>::template invertedSubset<T>(objects, numberObjects, indices);
}
 
template <typename TIndex, typename T>
inline std::vector<T> Subset::invertedSubset(const T* objects, const size_t numberObjects, const std::set<TIndex>& indices)
{
    return InternalSubset<TIndex>::template invertedSubset<T>(objects, numberObjects, indices);
}
 
template <typename TIndex, uint8_t tValue>
inline std::vector<uint8_t> Subset::indices2statements(const std::vector<TIndex>& indices, const size_t numberObjects)
{
    return InternalSubset<TIndex>::template indices2statements<std::vector<TIndex>, tValue>(indices, numberObjects);
}
 
template <typename TIndex, uint8_t tValue>
inline std::vector<uint8_t> Subset::indices2statements(const std::unordered_set<TIndex>& indices, const size_t numberObjects)
{
    return InternalSubset<TIndex>::template indices2statements<std::unordered_set<TIndex>, tValue>(indices, numberObjects);
}
 
template <typename TIndex, uint8_t tValue>
inline std::vector<uint8_t> Subset::indices2statements(const std::set<TIndex>& indices, const size_t numberObjects)
{
    return InternalSubset<TIndex>::template indices2statements<std::set<TIndex>, tValue>(indices, numberObjects);
}
 
template <typename TIndex, uint8_t tValue>
inline std::vector<uint8_t> Subset::indices2statements(const TIndex* indices, const size_t numberIndices, const size_t numberObjects)
{
    return InternalSubset<TIndex>::template indices2statements<tValue>(indices, numberIndices, numberObjects);
}
 
template <typename TIndex, uint8_t tValue>
inline std::vector<TIndex> Subset::statements2indices(const std::vector<uint8_t>& statements)
{
    return InternalSubset<TIndex>::template statements2indices<tValue>(statements);
}
 
template <typename TIndex, uint8_t tValue>
inline std::vector<TIndex> Subset::statements2indices(const uint8_t* statements, const size_t numberStatements)
{
    return InternalSubset<TIndex>::template statements2indices<tValue>(statements, numberStatements);
}
 
template <typename TKey, typename TElement>
void Subset::correspondingElements(const std::map<TKey, TElement>& elementMapA, const std::map<TKey, TElement>& elementMapB, std::vector<TElement>& elementsA, std::vector<TElement>& elementsB)
{
    elementsA.clear();
    elementsB.clear();
 
    // we expect that the map entries are sorted based on their keys
    ocean_assert(elementMapA.size() < 2 || elementMapA.cbegin()->first < elementMapA.crbegin()->first);
    ocean_assert(elementMapB.size() < 2 || elementMapB.cbegin()->first < elementMapB.crbegin()->first);
 
    typename std::map<TKey, TElement>::const_iterator iA = elementMapA.cbegin();
    typename std::map<TKey, TElement>::const_iterator iB = elementMapB.cbegin();
 
    while (iA != elementMapA.cend() && iB != elementMapB.cend())
    {
        // let's find elements with identical keys
 
        if (iA->first > iB->first)
        {
            ++iB;
        }
        else if (iA->first < iB->first)
        {
            ++iA;
        }
        else
        {
            ocean_assert(iA->first == iB->first);
 
            elementsA.emplace_back(iA->second);
            elementsB.emplace_back(iB->second);
 
            ++iA;
            ++iB;
        }
    }
}
 
template <typename TIterator>
bool Subset::hasIntersectingElement(const TIterator& firstA, const TIterator& endA, const TIterator& firstB, const TIterator& endB)
{
    if (firstA == endA || firstB == endB)
    {
        return false;
    }
 
#ifdef OCEAN_DEBUG
    TIterator debugLeftA = firstA;
    TIterator debugRightA = firstA;
    ++debugRightA;
 
    TIterator debugLeftB = firstB;
    TIterator debugRightB = firstB;
    ++debugRightB;
 
    while (debugRightA != endA && debugRightB != endB)
    {
        ocean_assert(*debugLeftA++ <= *debugRightA++);
        ocean_assert(*debugLeftB++ <= *debugRightB++);
    }
#endif
 
    TIterator lastA = endA;
    TIterator lastB = endB;
 
    if (*(--lastA) < *firstB || *(--lastB) < *firstA)
    {
        return false;
    }
 
    TIterator iA = firstA;
    TIterator iB = firstB;
 
    while (iA != endA && iB != endB)
    {
        if (*iA == *iB)
        {
            return true;
        }
 
        if (*iA < *iB)
        {
            ++iA;
        }
        else
        {
            ocean_assert(*iA > *iB);
            ++iB;
        }
    }
 
    return false;
}
 
template <typename T>
bool Subset::hasIntersectingElement(const std::set<T>& setA, const std::set<T>& setB)
{
    return hasIntersectingElement(setA.cbegin(), setA.cend(), setB.cbegin(), setB.cend());
}
 
template <typename T>
bool Subset::hasIntersectingElement(const std::vector<T>& sortedA, const std::vector<T>& sortedB)
{
    return hasIntersectingElement(sortedA.cbegin(), sortedA.cend(), sortedB.cbegin(), sortedB.cend());
}
 
}
 
#endif // META_OCEAN_BASE_SUBSET_H