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byterator.hpp
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318 lines (285 loc) · 10.5 KB
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#pragma once
#include <stdx/bit.hpp>
#include <stdx/memory.hpp>
#include <stdx/type_traits.hpp>
#include <stdx/utility.hpp>
#include <cstddef>
#include <cstring>
#include <functional>
#include <iterator>
#include <type_traits>
// NOLINTBEGIN(modernize-use-constraints)
namespace stdx {
inline namespace v1 {
namespace detail {
template <typename It>
constexpr auto is_byteratorish_v =
std::is_base_of_v<std::random_access_iterator_tag,
typename std::iterator_traits<It>::iterator_category> and
std::is_trivially_copyable_v<typename std::iterator_traits<It>::value_type>;
template <typename It>
constexpr auto iterator_value_type()
-> decltype(*std::declval<typename std::iterator_traits<It>::pointer>());
template <typename It>
using iterator_value_t =
std::remove_reference_t<decltype(iterator_value_type<It>())>;
} // namespace detail
template <typename T> class byterator {
using byte_t =
stdx::conditional_t<std::is_const_v<T>, std::byte const, std::byte>;
byte_t *ptr;
[[nodiscard]] friend constexpr auto operator==(byterator const &x,
byterator const &y) -> bool {
return x.ptr == y.ptr;
}
template <typename It,
std::enable_if_t<std::is_same_v<detail::iterator_value_t<It>, T>,
int> = 0>
[[nodiscard]] friend constexpr auto operator==(byterator const &x, It y)
-> bool {
return static_cast<void const *>(x.ptr) ==
static_cast<void const *>(stdx::to_address(y));
}
#if __cpp_impl_three_way_comparison >= 201907L
[[nodiscard]] friend constexpr auto operator<=>(byterator const &x,
byterator const &y) {
return x.ptr <=> y.ptr;
}
template <typename It,
std::enable_if_t<std::is_same_v<detail::iterator_value_t<It>, T>,
int> = 0>
[[nodiscard]] friend constexpr auto operator<=>(byterator const &x, It y) {
return static_cast<void const *>(x.ptr) <=>
static_cast<void const *>(stdx::to_address(y));
}
#else
template <typename It>
[[nodiscard]] friend constexpr auto operator==(It x, byterator const &y)
-> bool {
return y == x;
}
[[nodiscard]] friend constexpr auto operator!=(byterator const &x,
byterator const &y) -> bool {
return not(x == y);
}
template <typename It>
[[nodiscard]] friend constexpr auto operator!=(byterator const &x, It y)
-> bool {
return not(x == y);
}
template <typename It>
[[nodiscard]] friend constexpr auto operator!=(It x, byterator const &y)
-> bool {
return y != x;
}
[[nodiscard]] friend constexpr auto operator<(byterator const &x,
byterator const &y) -> bool {
return std::less{}(x.ptr, y.ptr);
}
template <typename It,
std::enable_if_t<std::is_same_v<detail::iterator_value_t<It>, T>,
int> = 0>
[[nodiscard]] friend constexpr auto operator<(byterator const &x, It y)
-> bool {
return std::less{}(static_cast<void const *>(x.ptr),
static_cast<void const *>(stdx::to_address(y)));
}
template <typename It,
std::enable_if_t<std::is_same_v<detail::iterator_value_t<It>, T>,
int> = 0>
[[nodiscard]] friend constexpr auto operator<(It x, byterator const &y)
-> bool {
return std::less{}(static_cast<void const *>(stdx::to_address(x)),
static_cast<void const *>(y.ptr));
}
[[nodiscard]] friend constexpr auto operator<=(byterator const &x,
byterator const &y) -> bool {
return not(y < x);
}
template <typename It>
[[nodiscard]] friend constexpr auto operator<=(byterator const &x, It y)
-> bool {
return not(y < x);
}
template <typename It>
[[nodiscard]] friend constexpr auto operator<=(It x, byterator const &y)
-> bool {
return not(y < x);
}
[[nodiscard]] friend constexpr auto operator>(byterator const &x,
byterator const &y) -> bool {
return y < x;
}
template <typename It>
[[nodiscard]] friend constexpr auto operator>(byterator const &x, It y)
-> bool {
return y < x;
}
template <typename It>
[[nodiscard]] friend constexpr auto operator>(It x, byterator const &y)
-> bool {
return y < x;
}
[[nodiscard]] friend constexpr auto operator>=(byterator const &x,
byterator const &y) -> bool {
return not(x < y);
}
template <typename It>
[[nodiscard]] friend constexpr auto operator>=(byterator const &x, It y)
-> bool {
return not(x < y);
}
template <typename It>
[[nodiscard]] friend constexpr auto operator>=(It x, byterator const &y)
-> bool {
return not(x < y);
}
#endif
public:
using difference_type = std::ptrdiff_t;
using value_type = std::byte;
using pointer = value_type *;
using reference = value_type &;
using iterator_category = std::random_access_iterator_tag;
template <typename It,
std::enable_if_t<detail::is_byteratorish_v<It>, int> = 0>
explicit byterator(It it) : ptr(bit_cast<byte_t *>(stdx::to_address(it))) {}
[[nodiscard]] constexpr auto operator->() const -> byte_t * { return ptr; }
[[nodiscard]] constexpr auto operator*() const -> byte_t & { return *ptr; }
constexpr auto operator++() -> byterator & {
++ptr;
return *this;
}
[[nodiscard]] constexpr auto operator++(int) -> byterator {
auto tmp = *this;
++(*this);
return tmp;
}
constexpr auto operator--() -> byterator & {
--ptr;
return *this;
}
[[nodiscard]] constexpr auto operator--(int) -> byterator {
auto tmp = *this;
--(*this);
return tmp;
}
constexpr auto operator+=(difference_type d) -> byterator & {
ptr += d;
return *this;
}
constexpr auto operator-=(difference_type d) -> byterator & {
ptr -= d;
return *this;
}
constexpr auto advance(difference_type d) -> byterator & {
ptr += d;
return *this;
}
[[nodiscard]] friend constexpr auto operator+(byterator i,
difference_type d)
-> byterator {
i += d;
return i;
}
[[nodiscard]] friend constexpr auto operator+(difference_type d,
byterator i) -> byterator {
i += d;
return i;
}
[[nodiscard]] friend constexpr auto operator-(byterator i,
difference_type d)
-> byterator {
i -= d;
return i;
}
[[nodiscard]] friend constexpr auto operator-(byterator x, byterator y)
-> difference_type {
return x.ptr - y.ptr;
}
[[nodiscard]] constexpr auto operator[](difference_type n) -> byte_t & {
return ptr[n];
}
[[nodiscard]] constexpr auto operator[](difference_type n) const
-> byte_t const & {
return ptr[n];
}
template <typename V = std::uint8_t, typename R = V,
std::enable_if_t<std::is_trivially_copyable_v<V>, int> = 0>
[[nodiscard]] auto peek() -> R {
V v;
std::memcpy(std::addressof(v), ptr, sizeof(V));
return static_cast<R>(v);
}
template <typename V = std::uint8_t> auto advance() -> decltype(auto) {
return advance(sizeof(V));
}
template <typename V = std::uint8_t, typename R = V,
std::enable_if_t<std::is_trivially_copyable_v<V>, int> = 0>
[[nodiscard]] auto read() -> R {
R ret = peek<V, R>();
advance<V>();
return ret;
}
template <typename V,
std::enable_if_t<std::is_trivially_copyable_v<remove_cvref_t<V>>,
int> = 0>
auto write(V &&v) -> void {
using R = remove_cvref_t<V>;
std::memcpy(ptr, std::addressof(v), sizeof(R));
advance<R>();
}
template <typename V = std::uint8_t> [[nodiscard]] auto peeku8() {
return peek<std::uint8_t, V>();
}
template <typename V = std::uint8_t> auto advanceu8() -> decltype(auto) {
return advance<std::uint8_t>();
}
template <typename V = std::uint8_t> [[nodiscard]] auto readu8() {
return read<std::uint8_t, V>();
}
template <typename V> [[nodiscard]] auto writeu8(V &&v) {
return write(static_cast<std::uint8_t>(std::forward<V>(v)));
}
template <typename V = std::uint16_t> [[nodiscard]] auto peeku16() {
return peek<std::uint16_t, V>();
}
template <typename V = std::uint16_t> auto advanceu16() -> decltype(auto) {
return advance<std::uint16_t>();
}
template <typename V = std::uint16_t> [[nodiscard]] auto readu16() {
return read<std::uint16_t, V>();
}
template <typename V> [[nodiscard]] auto writeu16(V &&v) {
return write(static_cast<std::uint16_t>(std::forward<V>(v)));
}
template <typename V = std::uint32_t> [[nodiscard]] auto peeku32() {
return peek<std::uint32_t, V>();
}
template <typename V = std::uint32_t> auto advanceu32() -> decltype(auto) {
return advance<std::uint32_t>();
}
template <typename V = std::uint32_t> [[nodiscard]] auto readu32() {
return read<std::uint32_t, V>();
}
template <typename V> [[nodiscard]] auto writeu32(V &&v) {
return write(static_cast<std::uint32_t>(std::forward<V>(v)));
}
template <typename V = std::uint64_t> [[nodiscard]] auto peeku64() {
return peek<std::uint64_t, V>();
}
template <typename V = std::uint64_t> auto advanceu64() -> decltype(auto) {
return advance<std::uint64_t>();
}
template <typename V = std::uint64_t> [[nodiscard]] auto readu64() {
return read<std::uint64_t, V>();
}
template <typename V> [[nodiscard]] auto writeu64(V &&v) {
return write(static_cast<std::uint64_t>(std::forward<V>(v)));
}
};
template <typename It, std::enable_if_t<detail::is_byteratorish_v<It>, int> = 0>
byterator(It) -> byterator<detail::iterator_value_t<It>>;
} // namespace v1
} // namespace stdx
// NOLINTEND(modernize-use-constraints)