1/* Copyright 2016-2019 Joaquin M Lopez Munoz.
2 * Distributed under the Boost Software License, Version 1.0.
3 * (See accompanying file LICENSE_1_0.txt or copy at
4 * http://www.boost.org/LICENSE_1_0.txt)
5 *
6 * See http://www.boost.org/libs/poly_collection for library home page.
7 */
8
9#ifndef BOOST_POLY_COLLECTION_DETAIL_STRIDE_ITERATOR_HPP
10#define BOOST_POLY_COLLECTION_DETAIL_STRIDE_ITERATOR_HPP
11
12#if defined(_MSC_VER)
13#pragma once
14#endif
15
16#include <boost/detail/workaround.hpp>
17#include <boost/iterator/iterator_facade.hpp>
18#include <type_traits>
19
20namespace boost{
21
22namespace poly_collection{
23
24namespace detail{
25
26/* random-access iterator to Value elements laid out stride *chars* apart */
27
28template<typename Value>
29class stride_iterator:
30 public boost::iterator_facade<
31 stride_iterator<Value>,
32 Value,
33 boost::random_access_traversal_tag
34 >
35{
36public:
37 stride_iterator()=default;
38 stride_iterator(Value* p,std::size_t stride)noexcept:p{p},stride_{stride}{}
39 stride_iterator(const stride_iterator&)=default;
40 stride_iterator& operator=(const stride_iterator&)=default;
41
42 template<
43 typename NonConstValue,
44 typename std::enable_if<
45 std::is_same<Value,const NonConstValue>::value>::type* =nullptr
46 >
47 stride_iterator(const stride_iterator<NonConstValue>& x)noexcept:
48 p{x.p},stride_{x.stride_}{}
49
50 template<
51 typename NonConstValue,
52 typename std::enable_if<
53 std::is_same<Value,const NonConstValue>::value>::type* =nullptr
54 >
55 stride_iterator& operator=(const stride_iterator<NonConstValue>& x)noexcept
56 {
57 p=x.p;stride_=x.stride_;
58 return *this;
59 }
60
61 /* interoperability with [Derived]Value* */
62
63 stride_iterator& operator=(Value* p_)noexcept{p=p_;return *this;}
64 operator Value*()const noexcept{return p;}
65
66 template<
67 typename DerivedValue,
68 typename std::enable_if<
69 std::is_base_of<Value,DerivedValue>::value&&
70 (std::is_const<Value>::value||!std::is_const<DerivedValue>::value)
71 >::type* =nullptr
72 >
73 explicit stride_iterator(DerivedValue* x)noexcept:
74 p{x},stride_{sizeof(DerivedValue)}{}
75
76#if BOOST_WORKAROUND(BOOST_GCC_VERSION,>=40900)||\
77 BOOST_WORKAROUND(BOOST_CLANG,>=1)&&\
78 (__clang_major__>3 || __clang_major__==3 && __clang_minor__ >= 8)
79/* https://github.com/boostorg/poly_collection/issues/15 */
80
81#define BOOST_POLY_COLLECTION_NO_SANITIZE
82
83/* UBSan seems not to be supported in some environments */
84#if defined(BOOST_GCC_VERSION)
85#pragma GCC diagnostic push
86#pragma GCC diagnostic ignored "-Wattributes"
87#elif defined(BOOST_CLANG)
88#pragma clang diagnostic push
89#pragma clang diagnostic ignored "-Wattributes"
90#endif
91#endif
92
93 template<
94 typename DerivedValue,
95 typename std::enable_if<
96 std::is_base_of<Value,DerivedValue>::value&&
97 (!std::is_const<Value>::value||std::is_const<DerivedValue>::value)
98 >::type* =nullptr
99 >
100#if defined(BOOST_POLY_COLLECTION_NO_SANITIZE)
101 __attribute__((no_sanitize("undefined")))
102#endif
103 explicit operator DerivedValue*()const noexcept
104 {return static_cast<DerivedValue*>(p);}
105
106#if defined(BOOST_POLY_COLLECTION_NO_SANITIZE)
107#if defined(BOOST_GCC_VERSION)
108#pragma GCC diagnostic pop
109#elif defined(BOOST_CLANG)
110#pragma clang diagnostic pop
111#endif
112
113#undef BOOST_POLY_COLLECTION_NO_SANITIZE
114#endif
115
116 std::size_t stride()const noexcept{return stride_;}
117
118private:
119 template<typename>
120 friend class stride_iterator;
121
122 using char_pointer=typename std::conditional<
123 std::is_const<Value>::value,
124 const char*,
125 char*
126 >::type;
127
128 static char_pointer char_ptr(Value* p)noexcept
129 {return reinterpret_cast<char_pointer>(p);}
130 static Value* value_ptr(char_pointer p)noexcept
131 {return reinterpret_cast<Value*>(p);}
132
133 friend class boost::iterator_core_access;
134
135 Value& dereference()const noexcept{return *p;}
136 bool equal(const stride_iterator& x)const noexcept{return p==x.p;}
137 void increment()noexcept{p=value_ptr(p: char_ptr(p)+stride_);}
138 void decrement()noexcept{p=value_ptr(p: char_ptr(p)-stride_);}
139 template<typename Integral>
140 void advance(Integral n)noexcept
141 {p=value_ptr(p: char_ptr(p)+n*(std::ptrdiff_t)stride_);}
142 std::ptrdiff_t distance_to(const stride_iterator& x)const noexcept
143 {return (char_ptr(p: x.p)-char_ptr(p))/(std::ptrdiff_t)stride_;}
144
145 Value* p;
146 std::size_t stride_;
147};
148
149} /* namespace poly_collection::detail */
150
151} /* namespace poly_collection */
152
153} /* namespace boost */
154
155#endif
156

source code of boost/libs/poly_collection/include/boost/poly_collection/detail/stride_iterator.hpp