Array STL

Arrays STL各种实现代码。 《C++标准程序库》

/* 
2015.4
an STL container (as wrapper) for arrays of constant size.

*/

#pragma warning(disable : 4996)
#include <iostream>
#include <cstddef>
#include <stdexcept>
#include <algorithm>    //transform()
#include <functional>    //negate<>()
#include <assert.h>

namespace boost 
{

    template<class T, std::size_t N>
    class array
    {
    private:
        T elems[N];    // fixed-size array of elements of type T

    public:
        // type definitions
        typedef T              value_type;
        typedef T*             iterator;
        typedef const T*       const_iterator;
        typedef T&             reference;
        typedef const T&       const_reference;
        typedef std::size_t    size_type;
        typedef std::ptrdiff_t difference_type;

        // iterator support
        iterator        begin()       { return elems; }
        const_iterator  begin() const { return elems; }
        const_iterator cbegin() const { return elems; }

        iterator        end()       { return elems + N; }
        const_iterator  end() const { return elems + N; }
        const_iterator cend() const { return elems + N; }

        // reverse iterator support
        typedef std::reverse_iterator<iterator> reverse_iterator;
        typedef std::reverse_iterator<const_iterator> const_reverse_iterator;

        reverse_iterator rbegin() { return reverse_iterator(end()); }
        const_reverse_iterator rbegin() const
        {
            return const_reverse_iterator(end());
        }
        const_reverse_iterator crbegin() const 
        {
            return const_reverse_iterator(end());
        }

        reverse_iterator rend() { return reverse_iterator(begin()); }
        const_reverse_iterator rend() const 
        {
            return const_reverse_iterator(begin());
        }
        const_reverse_iterator crend() const 
        {
            return const_reverse_iterator(begin());
        }

        // operator[]
        reference operator[](size_type i)
        {
            //assert(i < N);
            return elems[i];
        }

        const_reference operator[](size_type i) const
        {
            //assert(i < N);
            return elems[i];
        }

        // at() with range check
        reference at(size_type i) { rangecheck(i); return elems[i]; }
        const_reference at(size_type i) const { rangecheck(i); return elems[i]; }

        // front() and back()
        reference front()
        {
            return elems[0];
        }

        const_reference front() const
        {
            return elems[0];
        }

        reference back()
        {
            return elems[N - 1];
        }

        const_reference back() const
        {
            return elems[N - 1];
        }

        // size is constant
        static size_type size() { return N; }
        
        static bool empty() { return false; }
        static size_type max_size() { return N; }
        enum { static_size = N };

        // swap (note: linear complexity)
        void swap(array<T, N>& y)
        {
            for (size_type i = 0; i < N; ++i)
                boost::swap(elems[i], y.elems[i]);
        }

        // direct access to data (read-only)
        const T* data() const { return elems; }
        T* data() { return elems; }

        // use array as C array (direct read/write access to data)
        T* c_array() { return elems; }

        // assignment with type conversion
        template <typename T2>
        array<T, N>& operator= (const array<T2, N>& rhs)
        {
            std::copy(rhs.begin(), rhs.end(), begin());
            return *this;
        }

        // assign one value to all elements
        void assign(const T& value) { fill(value); }    // A synonym for fill
        void fill(const T& value)
        {
            std::fill_n(begin(), size(), value);
        }

        // check range (may be private because it is static)
        static void rangecheck(size_type i)
        {
            if (i >= size()) 
            {
                std::out_of_range e("array<>: index out of range");
                boost::throw_exception(e);
            }
        }

    };//class array

    // comparisons
    template<class T, std::size_t N>
    bool operator== (const array<T, N>& x, const array<T, N>& y)
    {
        return std::equal(x.begin(), x.end(), y.begin());
    }
    template<class T, std::size_t N>
    bool operator< (const array<T, N>& x, const array<T, N>& y)
    {
        return std::lexicographical_compare(x.begin(), x.end(), y.begin(), y.end());
    }
    template<class T, std::size_t N>
    bool operator!= (const array<T, N>& x, const array<T, N>& y)
    {
        return !(x == y);
    }
    template<class T, std::size_t N>
    bool operator> (const array<T, N>& x, const array<T, N>& y) 
    {
        return y<x;
    }
    template<class T, std::size_t N>
    bool operator<= (const array<T, N>& x, const array<T, N>& y)
    {
        return !(y<x);
    }
    template<class T, std::size_t N>
    bool operator>= (const array<T, N>& x, const array<T, N>& y) 
    {
        return !(x<y);
    }

    // global swap()
    template<class T, std::size_t N>
    inline void swap(array<T, N>& x, array<T, N>& y) 
    {
        x.swap(y);    //use from <algorithm>  
    }

} /* namespace boost */


/*
Test:
*/
int main()
{
    using namespace boost;
    using namespace std;

    array<int, 10> a;
    for (unsigned int i = 0; i < a.size(); ++i)
    {
        a[i] = i+1;
    }    

    //1 2 3 4...10
    for (int* pos = a.begin(); pos != a.end(); ++pos)
        cout << *pos << ' ';
    cout << endl;

    //10 9 8...1
    reverse(a.begin(), a.end());
    for (int* pos = a.begin(); pos != a.end(); ++pos)
        cout << *pos << ' ';
    cout << endl;

    //-10 -9 -8...-1
    transform(a.begin(), a.end(),    //source
        a.begin(),                    //destination
        negate<int>());                //operation
    for (int* pos = a.begin(); pos != a.end(); ++pos)
        cout << *pos << ' ';
    cout << endl;

    return 0;
}