Create pointer_iterator.h

include/preview/__iterator/pointer_iterator.h

@@ -0,0 +1,88 @@
+//
+// Created by yonggyulee on 2024. 10. 20.
+//
+
+#ifndef PREVIEW_ITERATOR_POINTER_ITERATOR_H_
+#define PREVIEW_ITERATOR_POINTER_ITERATOR_H_
+
+#include <cstddef>
+#include <type_traits>
+
+#include "preview/__iterator/detail/contiguous_iterator_tag.h"
+#include "preview/__iterator/iterator_tag.h"
+
+namespace preview {
+namespace detail {
+
+template<typename T, typename Tag = void>
+class pointer_iterator {
+ public:
+  using difference_type = std::ptrdiff_t;
+  using value_type      = std::remove_cv_t<T>;
+  using pointer         = T*;
+  using reference       = T&;
+  using iterator_category = std::random_access_iterator_tag;
+  using iterator_concept  = contiguous_iterator_tag;
+
+  pointer_iterator() = default;
+
+  constexpr pointer_iterator(pointer p)
+      : ptr_(p) {}
+
+  constexpr reference operator*() const noexcept { return *ptr_; }
+  constexpr pointer operator->() const noexcept { return ptr_; }
+
+  constexpr reference operator[](difference_type n) const noexcept {
+    return ptr_[n];
+  }
+
+  constexpr pointer_iterator& operator++() noexcept {
+    ++ptr_;
+    return *this;
+  }
+  constexpr pointer_iterator operator++(int) noexcept {
+    pointer_iterator temp{*this};
+    ++*this;
+    return temp;
+  }
+
+  constexpr pointer_iterator& operator--() noexcept {
+    --ptr_;
+    return *this;
+  }
+  constexpr pointer_iterator operator--(int) noexcept {
+    pointer_iterator temp{*this};
+    --*this;
+    return temp;
+  }
+
+  constexpr pointer_iterator& operator+=(difference_type n) const noexcept {
+    ptr_ += n;
+    return *this;
+  }
+
+  constexpr pointer_iterator& operator-=(difference_type n) const noexcept {
+    ptr_ -= n;
+    return *this;
+  }
+
+  friend constexpr bool operator==(pointer_iterator x, pointer_iterator y) noexcept { return x.ptr_ == y.ptr_; }
+  friend constexpr bool operator!=(pointer_iterator x, pointer_iterator y) noexcept { return x.ptr_ != y.ptr_; }
+  friend constexpr bool operator< (pointer_iterator x, pointer_iterator y) noexcept { return x.ptr_ <  y.ptr_; }
+  friend constexpr bool operator<=(pointer_iterator x, pointer_iterator y) noexcept { return x.ptr_ <= y.ptr_; }
+  friend constexpr bool operator> (pointer_iterator x, pointer_iterator y) noexcept { return x.ptr_ >  y.ptr_; }
+  friend constexpr bool operator>=(pointer_iterator x, pointer_iterator y) noexcept { return x.ptr_ >= y.ptr_; }
+
+  friend constexpr pointer_iterator operator+(pointer_iterator i, difference_type n) noexcept { return pointer_iterator{i.ptr_ + n}; }
+  friend constexpr pointer_iterator operator+(difference_type n, pointer_iterator i) noexcept { return pointer_iterator{i.ptr_ + n}; }
+  friend constexpr pointer_iterator operator-(pointer_iterator i, difference_type n) noexcept { return pointer_iterator{i.ptr_ - n}; }
+  friend constexpr difference_type operator-(pointer_iterator x, pointer_iterator y) noexcept { return x.ptr_ - y.ptr_; }
+
+ private:
+  pointer ptr_ = nullptr;
+};
+
+} // namespace detail
+} // namespace preview
+
+#endif // PREVIEW_ITERATOR_POINTER_ITERATOR_H_