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#ifndef PROTOZERO_DATA_VIEW_HPP
#define PROTOZERO_DATA_VIEW_HPP
/*****************************************************************************
protozero - Minimalistic protocol buffer decoder and encoder in C++.
This file is from https://github.com/mapbox/protozero where you can find more
documentation.
*****************************************************************************/
/**
* @file data_view.hpp
*
* @brief Contains the implementation of the data_view class.
*/
#include "config.hpp"
#include <algorithm>
#include <cstddef>
#include <cstring>
#include <string>
#include <utility>
namespace protozero {
#ifdef PROTOZERO_USE_VIEW
using data_view = PROTOZERO_USE_VIEW;
#else
/**
* Holds a pointer to some data and a length.
*
* This class is supposed to be compatible with the std::string_view
* that will be available in C++17.
*/
class data_view {
const char* m_data = nullptr;
std::size_t m_size = 0;
public:
/**
* Default constructor. Construct an empty data_view.
*/
constexpr data_view() noexcept = default;
/**
* Create data_view from pointer and size.
*
* @param ptr Pointer to the data.
* @param length Length of the data.
*/
constexpr data_view(const char* ptr, std::size_t length) noexcept
: m_data{ptr},
m_size{length} {
}
/**
* Create data_view from string.
*
* @param str String with the data.
*/
data_view(const std::string& str) noexcept // NOLINT(google-explicit-constructor, hicpp-explicit-conversions)
: m_data{str.data()},
m_size{str.size()} {
}
/**
* Create data_view from zero-terminated string.
*
* @param ptr Pointer to the data.
*/
data_view(const char* ptr) noexcept // NOLINT(google-explicit-constructor, hicpp-explicit-conversions)
: m_data{ptr},
m_size{std::strlen(ptr)} {
}
/**
* Swap the contents of this object with the other.
*
* @param other Other object to swap data with.
*/
void swap(data_view& other) noexcept {
using std::swap;
swap(m_data, other.m_data);
swap(m_size, other.m_size);
}
/// Return pointer to data.
constexpr const char* data() const noexcept {
return m_data;
}
/// Return length of data in bytes.
constexpr std::size_t size() const noexcept {
return m_size;
}
/// Returns true if size is 0.
constexpr bool empty() const noexcept {
return m_size == 0;
}
#ifndef PROTOZERO_STRICT_API
/**
* Convert data view to string.
*
* @pre Must not be default constructed data_view.
*
* @deprecated to_string() is not available in C++17 string_view so it
* should not be used to make conversion to that class easier
* in the future.
*/
std::string to_string() const {
protozero_assert(m_data);
return {m_data, m_size};
}
#endif
/**
* Convert data view to string.
*
* @pre Must not be default constructed data_view.
*/
explicit operator std::string() const {
protozero_assert(m_data);
return {m_data, m_size};
}
/**
* Compares the contents of this object with the given other object.
*
* @returns 0 if they are the same, <0 if this object is smaller than
* the other or >0 if it is larger. If both objects have the
* same size returns <0 if this object is lexicographically
* before the other, >0 otherwise.
*
* @pre Must not be default constructed data_view.
*/
int compare(data_view other) const noexcept {
assert(m_data && other.m_data);
const int cmp = std::memcmp(data(), other.data(),
std::min(size(), other.size()));
if (cmp == 0) {
if (size() == other.size()) {
return 0;
}
return size() < other.size() ? -1 : 1;
}
return cmp;
}
}; // class data_view
/**
* Swap two data_view objects.
*
* @param lhs First object.
* @param rhs Second object.
*/
inline void swap(data_view& lhs, data_view& rhs) noexcept {
lhs.swap(rhs);
}
/**
* Two data_view instances are equal if they have the same size and the
* same content.
*
* @param lhs First object.
* @param rhs Second object.
*/
inline constexpr bool operator==(const data_view lhs, const data_view rhs) noexcept {
return lhs.size() == rhs.size() &&
std::equal(lhs.data(), lhs.data() + lhs.size(), rhs.data());
}
/**
* Two data_view instances are not equal if they have different sizes or the
* content differs.
*
* @param lhs First object.
* @param rhs Second object.
*/
inline constexpr bool operator!=(const data_view lhs, const data_view rhs) noexcept {
return !(lhs == rhs);
}
/**
* Returns true if lhs.compare(rhs) < 0.
*
* @param lhs First object.
* @param rhs Second object.
*/
inline bool operator<(const data_view lhs, const data_view rhs) noexcept {
return lhs.compare(rhs) < 0;
}
/**
* Returns true if lhs.compare(rhs) <= 0.
*
* @param lhs First object.
* @param rhs Second object.
*/
inline bool operator<=(const data_view lhs, const data_view rhs) noexcept {
return lhs.compare(rhs) <= 0;
}
/**
* Returns true if lhs.compare(rhs) > 0.
*
* @param lhs First object.
* @param rhs Second object.
*/
inline bool operator>(const data_view lhs, const data_view rhs) noexcept {
return lhs.compare(rhs) > 0;
}
/**
* Returns true if lhs.compare(rhs) >= 0.
*
* @param lhs First object.
* @param rhs Second object.
*/
inline bool operator>=(const data_view lhs, const data_view rhs) noexcept {
return lhs.compare(rhs) >= 0;
}
#endif
} // end namespace protozero
#endif // PROTOZERO_DATA_VIEW_HPP
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