Program Listing for File span.h

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#pragma once

#include <algorithm>
#include <array>
#include "utility/assert.h"
#include <cstddef>
#include <cstring>
#include <vector>

namespace gpa {
namespace playback {
namespace detail {

template<typename T>
class Span
{
public:
    inline Span() = default;

    inline Span(std::nullptr_t)
    {
    }

    inline Span(T& data)
        : mData{&data}
        , mCount{1}
    {
    }

    inline Span(T* data, size_t count)
        : mData{count ? data : nullptr}
        , mCount{data ? count : 0}
    {
    }

    template<size_t Count>
    inline Span(std::array<T, Count>& container)
        : mData{Count ? container.data() : nullptr}
        , mCount{Count}
    {
    }

    inline Span(std::vector<T>& container)
        : mData{!container.empty() ? container.data() : nullptr}
        , mCount{container.size()}
    {
    }

    inline T const& operator[](size_t index) const
    {
        GPA_CHECK_RET(!empty() && "operator[] called on empty Span<>", GPA_DUMMY);
        GPA_CHECK_RET(index < mCount && "Array subscript is out of range", GPA_DUMMY);
        return mData[index];
    }

    inline T& operator[](size_t index)
    {
        GPA_CHECK_RET(!empty() && "operator[] called on empty Span<>", GPA_DUMMY);
        GPA_CHECK_RET(index < mCount && "Array subscript is out of range", GPA_DUMMY);
        return mData[index];
    }

    inline T const* begin() const
    {
        return mData;
    }

    inline T* begin()
    {
        return mData;
    }

    inline T const* end() const
    {
        return mData + mCount;
    }

    inline T* end()
    {
        return mData + mCount;
    }

    inline T const& front() const
    {
        GPA_CHECK_RET(!empty() && "front() called on empty Span<>", GPA_DUMMY);
        return operator[](0);
    }

    inline T& front()
    {
        GPA_CHECK_RET(!empty() && "front() called on empty Span<>", GPA_DUMMY);
        return operator[](0);
    }

    inline T const& back() const
    {
        GPA_CHECK_RET(!empty() && "back() called on empty Span<>", GPA_DUMMY);
        return operator[](mCount - 1);
    }

    inline T& back()
    {
        GPA_CHECK_RET(!empty() && "back() called on empty Span<>", GPA_DUMMY);
        return operator[](mCount - 1);
    }

    inline bool empty() const
    {
        return !mData;
    }

    inline size_t size() const
    {
        return mCount;
    }

    inline size_t size_bytes() const
    {
        return mCount * sizeof(T);
    }

    inline void clear()
    {
        mData = nullptr;
        mCount = 0;
    }

    inline T const* data() const
    {
        return mData;
    }

    inline T* data()
    {
        return mData;
    }

private:
    T* mData{nullptr};
    size_t mCount{0};
};

template<typename T>
inline bool operator==(Span<T> const& lhs, Span<T> const& rhs)
{
    return std::equal(lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
}

template<typename T>
inline bool operator!=(Span<T> const& lhs, Span<T> const& rhs)
{
    return !(lhs == rhs);
}

template<typename T>
inline bool operator<(Span<T> const& lhs, Span<T> const& rhs)
{
    return std::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
}

template<typename T>
inline Span<T const> MakeSpan(T const* pData, size_t count)
{
    return pData && count ? Span<T const>(pData, count) : Span<T const>{};
}

template<typename T>
inline Span<T> MakeSpan(T* pData, size_t count)
{
    return pData && count ? Span<T>(pData, count) : Span<T>{};
}

inline Span<char const> MakeSpan(char const* cStr)
{
    return cStr ? Span<char const>(cStr, strlen(cStr) + 1) : Span<char const>{};
}

inline Span<char> MakeSpan(char* cStr)
{
    return cStr ? Span<char>(cStr, strlen(cStr) + 1) : Span<char>{};
}

}  // namespace detail
}  // namespace playback
}  // namespace gpa