qt-creator/src/libs/utils/smallstringview.h

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** Copyright (C) 2016 The Qt Company Ltd.
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#pragma once

#include "smallstringiterator.h"

#include <QtGlobal>

#include <cstring>
#include <string>

namespace Utils {

class SmallStringView
{
public:
    using const_iterator = Internal::SmallStringIterator<std::random_access_iterator_tag, const char>;
    using const_reverse_iterator = std::reverse_iterator<const_iterator>;
    using size_type = std::size_t;

    template<size_type Size>
    constexpr
    SmallStringView(const char(&string)[Size]) noexcept
        : m_pointer(string),
          m_size(Size - 1)
    {
        static_assert(Size >= 1, "Invalid string literal! Length is zero!");
    }

    template<typename Type,
             typename = std::enable_if_t<std::is_pointer<Type>::value>
             >
    SmallStringView(Type characterPointer) noexcept
        : m_pointer(characterPointer),
          m_size(std::strlen(characterPointer))
    {
        static_assert(!std::is_array<Type>::value, "Input type is array and not char pointer!");
    }

    constexpr
    SmallStringView(const char *const string, const size_type size) noexcept
        : m_pointer(string),
          m_size(size)
    {
    }

    static
    SmallStringView fromUtf8(const char *const characterPointer)
    {
        return SmallStringView(characterPointer, std::strlen(characterPointer));
    }

    constexpr
    const char *data() const
    {
        return m_pointer;
    }

    constexpr
    size_type size() const
    {
        return m_size;
    }

    constexpr
    size_type isEmpty() const
    {
        return m_size == 0;
    }

    const_iterator begin() const noexcept
    {
        return data();
    }

    const_iterator end() const noexcept
    {
        return data() + size();
    }

    const_reverse_iterator rbegin() const noexcept
    {
        return const_reverse_iterator(end() - static_cast<std::size_t>(1));
    }

    const_reverse_iterator rend() const noexcept
    {
        return const_reverse_iterator(begin() - static_cast<std::size_t>(1));
    }

    operator std::string() const
    {
        return std::string(data(), size());
    }

    bool startsWith(SmallStringView subStringToSearch) const noexcept
    {
        if (size() >= subStringToSearch.size())
            return !std::memcmp(m_pointer, subStringToSearch.data(), subStringToSearch.size());

        return false;
    }

    bool startsWith(char characterToSearch) const noexcept
    {
        return m_pointer[0] == characterToSearch;
    }

private:
    const char *m_pointer;
    size_type m_size;
};

inline
bool operator==(const SmallStringView& first, const SmallStringView& second) noexcept
{
    return first.size() == second.size() && std::memcmp(first.data(), second.data(), first.size()) == 0;
}

inline
bool operator!=(const SmallStringView& first, const SmallStringView& second) noexcept
{
    return !(first == second);
}

} // namespace Utils