1//===-- Standalone implementation of iterator -------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef LLVM_LIBC_SRC___SUPPORT_CPP_ITERATOR_H
10#define LLVM_LIBC_SRC___SUPPORT_CPP_ITERATOR_H
11
12#include "src/__support/CPP/type_traits/enable_if.h"
13#include "src/__support/CPP/type_traits/is_convertible.h"
14#include "src/__support/CPP/type_traits/is_same.h"
15#include "src/__support/macros/attributes.h"
16#include "src/__support/macros/config.h"
17
18namespace LIBC_NAMESPACE_DECL {
19namespace cpp {
20
21template <typename T> struct iterator_traits;
22template <typename T> struct iterator_traits<T *> {
23 using reference = T &;
24 using value_type = T;
25};
26
27template <typename Iter> class reverse_iterator {
28 Iter current;
29
30public:
31 using reference = typename iterator_traits<Iter>::reference;
32 using value_type = typename iterator_traits<Iter>::value_type;
33 using iterator_type = Iter;
34
35 LIBC_INLINE reverse_iterator() : current() {}
36 LIBC_INLINE constexpr explicit reverse_iterator(Iter it) : current(it) {}
37
38 template <typename Other,
39 cpp::enable_if_t<!cpp::is_same_v<Iter, Other> &&
40 cpp::is_convertible_v<const Other &, Iter>,
41 int> = 0>
42 LIBC_INLINE constexpr explicit reverse_iterator(const Other &it)
43 : current(it) {}
44
45 LIBC_INLINE friend constexpr bool operator==(const reverse_iterator &lhs,
46 const reverse_iterator &rhs) {
47 return lhs.base() == rhs.base();
48 }
49
50 LIBC_INLINE friend constexpr bool operator!=(const reverse_iterator &lhs,
51 const reverse_iterator &rhs) {
52 return lhs.base() != rhs.base();
53 }
54
55 LIBC_INLINE friend constexpr bool operator<(const reverse_iterator &lhs,
56 const reverse_iterator &rhs) {
57 return lhs.base() > rhs.base();
58 }
59
60 LIBC_INLINE friend constexpr bool operator<=(const reverse_iterator &lhs,
61 const reverse_iterator &rhs) {
62 return lhs.base() >= rhs.base();
63 }
64
65 LIBC_INLINE friend constexpr bool operator>(const reverse_iterator &lhs,
66 const reverse_iterator &rhs) {
67 return lhs.base() < rhs.base();
68 }
69
70 LIBC_INLINE friend constexpr bool operator>=(const reverse_iterator &lhs,
71 const reverse_iterator &rhs) {
72 return lhs.base() <= rhs.base();
73 }
74
75 LIBC_INLINE constexpr iterator_type base() const { return current; }
76
77 LIBC_INLINE constexpr reference operator*() const {
78 Iter tmp = current;
79 return *--tmp;
80 }
81 LIBC_INLINE constexpr reverse_iterator operator--() {
82 ++current;
83 return *this;
84 }
85 LIBC_INLINE constexpr reverse_iterator &operator++() {
86 --current;
87 return *this;
88 }
89 LIBC_INLINE constexpr reverse_iterator operator++(int) {
90 reverse_iterator tmp(*this);
91 --current;
92 return tmp;
93 }
94};
95
96} // namespace cpp
97} // namespace LIBC_NAMESPACE_DECL
98
99#endif // LLVM_LIBC_SRC___SUPPORT_CPP_ITERATOR_H
100