path: root/src/include/array

/* IBM_PROLOG_BEGIN_TAG                                                   */
/* This is an automatically generated prolog.                             */
/*                                                                        */
/* $Source: src/include/array $                                           */
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/* OpenPOWER HostBoot Project                                             */
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/* Contributors Listed Below - COPYRIGHT 2016,2019                        */
/* [+] International Business Machines Corp.                              */
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/* Licensed under the Apache License, Version 2.0 (the "License");        */
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/* IBM_PROLOG_END_TAG                                                     */
#ifndef stl_array
#define stl_array

/**
 * @file array
 * @brief simple stl array template class declaration.
 */

#include <stddef.h>

#if !defined( __STDC_LIMIT_MACROS)
#define __STDC_LIMIT_MACROS
#endif
#include <stdint.h>
#include <algorithm>

namespace std
{
    template <class T, size_t N >
    struct array {
        // types:
        typedef T&                               reference;
        typedef const T&                         const_reference;
        typedef T *                              iterator;
        typedef const T *                        const_iterator;
        typedef size_t                           size_type;
        typedef ptrdiff_t                        difference_type;
        typedef T                                value_type;
        typedef T*                               pointer;
        typedef const T*                         const_pointer;

/*  Not supporting for now
        typedef reverse_iterator<iterator>       reverse_iterator;
        typedef reverse_iterator<const_iterator> const_reverse_iterator;
*/

        T elems[N ? N : 1]; // exposition only

        // no explicit construct/copy/destroy for aggregate type

        /**
         * Assigns the given value to all elements in the container.
         * @param[in] the value to assign to the elements
         * @pre None.
         * @post None.
         */
        void fill(const T& value)
        {
            fill_n(begin(), N, value);
        }

        /**
         * Exchanges the contents of the container with those of other.
         * @param[in] container to exchange the contents with
         * @pre Does not cause iterators and references to associate with the
         *      other container.
         * @post None.
         */
        void swap(array<T, N>& other)
        {
            std::swap(elems, other.elems);
        }

        // iterators:

        /**
         * Returns an iterator to the first element of the container.
         * @return iterator to the first element
         * @pre If the container is empty, the returned iterator will be equal
         *      to end().
         * @post None.
         */
        iterator begin()
        {
            return iterator(&elems[0]);
        }

        /**
         * Returns a const_iterator to the first element of the container.
         * @return const_iterator to the first element
         * @pre If the container is empty, the returned iterator will be equal
         *      to end().
         * @post None.
         */
        constexpr const_iterator begin() const
        {
            return const_iterator(&elems[0]);
        }

        /**
         * Returns a const_iterator to the first element of the container.
         * @return const_iterator to the first element
         * @pre If the container is empty, the returned iterator will be equal
         *      to end().
         * @post None.
         */
        constexpr const_iterator cbegin() const
        {
            return const_iterator(&elems[0]);
        }

        /**
         * Returns an iterator to the element following the last element of the
         * container.
         * @return iterator to the element following the last element.
         * @pre This element acts as a placeholder; attempting to access it
         *      results in undefined behavior.
         * @post None.
         */
        iterator end()
        {
            return iterator(&elems[N]);
        }

        /**
         * Returns an const_iterator to the element following the last element
         * of the container.
         * @return const_iterator to the element following the last element.
         * @pre This element acts as a placeholder; attempting to access it
         *      results in undefined behavior.
         * @post None.
         */
        constexpr const_iterator end() const
        {
            return const_iterator(&elems[N]);
        }

        /**
         * Returns an const_iterator to the element following the last element
         * of the container.
         * @return const_iterator to the element following the last element.
         * @pre This element acts as a placeholder; attempting to access it
         *      results in undefined behavior.
         * @post None.
         */
        constexpr const_iterator cend() const
        {
            return const_iterator(&elems[N]);
        }

/*  Not supporting for now
        reverse_iterator        rbegin();
        const_reverse_iterator  rbegin() const;
        reverse_iterator        rend();
        const_reverse_iterator  rend() const;
        const_reverse_iterator  crbegin() const;
        const_reverse_iterator  crend() const;
*/

        // capacity:

        /**
         * Returns the number of elements in the container
         * @return The number of elements in the container.
         * @pre None.
         * @post None.
         */
        constexpr size_type size() const
        {
            return N;
        }

        /**
         * Returns the maximum number of elements the container is able to hold
         * due to system or library implementation limitations,
         * @return Maximum number of elements.
         * @pre Because each std::array<T, N> is a fixed-size container, the
         *      value returned by max_size equals N (which is also the value
         *      returned by size)
         * @post None.
         */
        constexpr size_type max_size()
        {
            return size();
        }

        /**
         * Checks if the container has no elements
         * @return true if the container is empty, false otherwise
         * @pre None.
         * @post None.
         */
        constexpr bool empty()
        {
            return (N == 0);
        }

        // element access:

        /**
         * Returns a reference to the element at specified location pos.
         * No bounds checking is performed.
         * @param[in] position of the element to return
         * @return Reference to the requested element.
         * @pre Unlike std::map::operator[], this operator never inserts a new
         *      element into the container.
         * @post None.
         */
        reference operator[](size_type n)
        {
            return elems[n];
        }

        /**
         * Returns a const_reference to the element at specified location pos.
         * No bounds checking is performed.
         * @param[in] position of the element to return
         * @return const_reference to the requested element.
         * @pre None.
         * @post None.
         */
        const_reference operator[](size_type n) const
        {
            return elems[n];
        }

        /**
         * Returns a reference to the element at specified location pos, with
         * bounds checking. Will assert if pos is not within the range of the
         * container
         * @param[in] position of the element to return
         * @return reference to the requested element.
         * @pre None.
         * @post None.
         */
        reference at(size_type n)
        {
            assert(n < size());
            return elems[n];
        }

        /**
         * Returns a const_reference to the element at specified location pos,
         * with bounds checking. Will assert if pos is not within the range of
         * the container
         * @param[in] position of the element to return
         * @return const_reference to the requested element.
         * @pre None.
         * @post None.
         */
        const_reference at(size_type n) const
        {
            assert(n < size());
            return elems[n];
        }

        /**
         * Returns a reference to the first element in the container. Calling
         * front on an empty container is undefined.
         * @return reference to the first element
         * @pre For a container c, the expression c.front() is equivalent to
         *      *c.begin().
         * @post None.
         */
        reference front()
        {
            return *begin();
        }

        /**
         * Returns a const_reference to the first element in the container.
         * Calling front on an empty container is undefined.
         * @return const_reference to the first element
         * @pre For a container c, the expression c.front() is equivalent to
         *      *c.begin().
         * @post None.
         */
        constexpr const_reference front() const
        {
            return *begin();
        }

        /**
         * Returns reference to the last element in the container.
         * Calling back on an empty container is undefined.
         * @return Reference to the last element.
         * @pre For a container c, the expression return c.back(); is equivalent
         *      to { auto tmp = c.end(); --tmp; return *tmp; }
         * @post None.
         */
        reference back()
        {
            return N ? *(end() - 1) : *end();
        }

        /**
         * Returns const_reference to the last element in the container.
         * Calling back on an empty container is undefined.
         * @return const_reference to the last element.
         * @pre For a container c, the expression return c.back(); is equivalent
         *      to { auto tmp = c.end(); --tmp; return *tmp; }
         * @post None.
         */
        constexpr const_reference back() const
        {
            return N ? *(end() - 1) : *end();
        }

        /**
         * Returns pointer to the underlying array serving as element storage.
         * Calling back on an empty container is undefined.
         * @return Pointer to the underlying element storage.
         *         For non-empty containers, returns &front()
         * @pre The pointer is such that range [data(); data() + size()) is
         *      always a valid range, even if the container is empty (data() is
         *      not dereferenceable in that case).
         * @post None.
         */
        T * data()
        {
            return &front();
        }

        /**
         * Returns const pointer to the underlying array serving as element
         * storage. Calling back on an empty container is undefined.
         * @return const_pointer to the underlying element storage.
         *         For non-empty containers, returns &front()
         * @pre The pointer is such that range [data(); data() + size()) is
         *      always a valid range, even if the container is empty (data() is
         *      not dereferenceable in that case).
         * @post None.
         */
        constexpr const T * data() const
        {
            return &front();
        }
    };

    /**
     * Compare the contents of two containers - overload operator==
     * @return true if the contents of the containers are equal, false otherwise
     * @pre None.
     * @post None.
     */
    template <class T, size_t N, size_t M=N>
    inline bool operator==(const array<T,N>& lhs, const array<T,M>& rhs)
    {
        static_assert(N==M, "std::arrays must be of the same size when using "
                            "overloaded compare operators");
        return std::equal(lhs.begin(), lhs.end(), rhs.begin());
    }

    /**
     * Compare the contents of two containers - overload operator!=
     * @return true if the contents of the containers are not equal, false
     *         otherwise
     * @pre None.
     * @post None.
     */
    template <class T, size_t N, size_t M=N>
    inline bool operator!=(const array<T,N>& lhs, const array<T,M>& rhs)
    {
        static_assert(N==M, "std::arrays must be of the same size when using "
                            "overloaded compare operators");
        return !(lhs == rhs);
    }

    /**
     * Compare the contents of two containers - overload operator<
     * @return true if the contents of the lhs are lexicographically less than
     *         the contents of rhs, false otherwise
     * @pre None.
     * @post None.
     */
    template <class T, size_t N, size_t M=N>
    inline bool operator<(const array<T,N>& lhs, const array<T,M>& rhs)
    {
        static_assert(N==M, "std::arrays must be of the same size when using overloaded compare operators");
        return std::lexicographical_compare(lhs.begin(), lhs.end(),
                                            rhs.begin(), rhs.end());
    }

    /**
     * Compare the contents of two containers - overload operator<=
     * @return true if the contents of the lhs are lexicographically less than
     *         or equal the contents of rhs, false otherwise
     * @pre None.
     * @post None.
     */
    template <class T, size_t N, size_t M=N>
    inline bool operator<=(const array<T,N>& lhs, const array<T,M>& rhs)
    {
        static_assert(N==M, "std::arrays must be of the same size when using overloaded compare operators");
        return (lhs < rhs) || (lhs == rhs);
    }

    /**
     * Compare the contents of two containers - overload operator>
     * @return true if the contents of the lhs are lexicographically greater
     *         than the contents of rhs, false otherwise
     * @pre None.
     * @post None.
     */
    template <class T, size_t N, size_t M=N>
    inline bool operator>(const array<T,N>& lhs, const array<T,M>& rhs)
    {
        static_assert(N==M, "std::arrays must be of the same size when using overloaded compare operators");
        return !(lhs < rhs) && !(lhs == rhs);
    }

    /**
     * Compare the contents of two containers - overload operator>=
     * @return true if the contents of the lhs are lexicographically greater
     *         than or equal the contents of rhs, false otherwise
     * @pre None.
     * @post None.
     */
    template <class T, size_t N, size_t M=N>
    inline bool operator>=(const array<T,N>& lhs, const array<T,M>& rhs)
    {
        static_assert(N==M, "std::arrays must be of the same size when using overloaded compare operators");
        return !(lhs < rhs);
    }

    /**
     * Specializes the std::swap algorithm for std::array. Swaps the contents of
     * lhs and rhs. Calls lhs.swap(rhs)
     * @param[in] container whose contents to swap
     * @param[in] container whose contents to swap
     * @pre None.
     * @post None.
     */
    template <class T, size_t N>
    inline void swap(array<T,N>& lhs, array<T,N>& rhs)
    {
        lhs.swap(rhs);
    }

    /**
     * Extracts the Ith element element from the array.
     * @param[in] array whose contents to extract
     * @return A reference to the Ith element of a.
     * @pre I must be an integer value in range [0, N). This is enforced at
     *      compile time as opposed to at() or operator[].
     * @post None.
     */
    template <size_t I, class T, size_t N>
    inline constexpr T& get(array<T, N>& a)
    {
        static_assert( ( I>=0 && I<N ), "std::get trying to access element out of range");
        return a[I];
    }

    /**
     * Extracts the Ith element element from the array.
     * @param[in] array whose contents to extract
     * @return A const reference to the Ith element of a.
     * @pre I must be an integer value in range [0, N). This is enforced at
     *      compile time as opposed to at() or operator[].
     * @post None.
     */
    template <size_t I, class T, size_t N>
    inline constexpr const T& get(const array<T, N>& a)
    {
        static_assert( ( I>=0 && I<N ), "std::get trying to access element out of range");
        return a[I];
    }

    /**
     * Extracts the Ith element element from the array.
     * @param[in] array whose contents to extract
     * @return An rvalue reference to the Ith element of a.
     * @pre I must be an integer value in range [0, N). This is enforced at
     *      compile time as opposed to at() or operator[].
     * @post None.
     */
    template <size_t I, class T, size_t N>
    inline constexpr T&& get(array<T, N>&& a)
    {
        static_assert( ( I>=0 && I<N ), "std::get trying to access element out of range");
        return a[I];
    }

/*  Not supporting for now
    template <class T> class tuple_size;
    template <size_t I, class T> class tuple_element;
    template <class T, size_t N> struct tuple_size<array<T, N> >;
    template <size_t I, class T, size_t N> struct tuple_element<I, array<T, N> >;
*/

}

#endif