1// Copyright 2014 the V8 project authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef V8_BASE_ITERATOR_H_ 6#define V8_BASE_ITERATOR_H_ 7 8#include <iterator> 9 10namespace v8 { 11namespace base { 12 13template <class Category, class Type, class Diff = std::ptrdiff_t, 14 class Pointer = Type*, class Reference = Type&> 15struct iterator { 16 using iterator_category = Category; 17 using value_type = Type; 18 using difference_type = Diff; 19 using pointer = Pointer; 20 using reference = Reference; 21}; 22 23// The intention of the base::iterator_range class is to encapsulate two 24// iterators so that the range defined by the iterators can be used like 25// a regular STL container (actually only a subset of the full container 26// functionality is available usually). 27template <typename ForwardIterator> 28class iterator_range { 29 public: 30 using iterator = ForwardIterator; 31 using const_iterator = ForwardIterator; 32 using pointer = typename std::iterator_traits<iterator>::pointer; 33 using reference = typename std::iterator_traits<iterator>::reference; 34 using value_type = typename std::iterator_traits<iterator>::value_type; 35 using difference_type = 36 typename std::iterator_traits<iterator>::difference_type; 37 38 iterator_range() : begin_(), end_() {} 39 iterator_range(ForwardIterator begin, ForwardIterator end) 40 : begin_(begin), end_(end) {} 41 42 iterator begin() { return begin_; } 43 iterator end() { return end_; } 44 const_iterator begin() const { return begin_; } 45 const_iterator end() const { return end_; } 46 const_iterator cbegin() const { return begin_; } 47 const_iterator cend() const { return end_; } 48 49 bool empty() const { return cbegin() == cend(); } 50 51 // Random Access iterators only. 52 reference operator[](difference_type n) { return begin()[n]; } 53 difference_type size() const { return cend() - cbegin(); } 54 55 private: 56 const_iterator const begin_; 57 const_iterator const end_; 58}; 59 60template <typename ForwardIterator> 61auto make_iterator_range(ForwardIterator begin, ForwardIterator end) { 62 return iterator_range<ForwardIterator>{begin, end}; 63} 64 65// {Reversed} returns a container adapter usable in a range-based "for" 66// statement for iterating a reversible container in reverse order. 67// 68// Example: 69// 70// std::vector<int> v = ...; 71// for (int i : base::Reversed(v)) { 72// // iterates through v from back to front 73// } 74template <typename T> 75auto Reversed(T& t) { // NOLINT(runtime/references): match {rbegin} and {rend} 76 return make_iterator_range(std::rbegin(t), std::rend(t)); 77} 78 79} // namespace base 80} // namespace v8 81 82#endif // V8_BASE_ITERATOR_H_ 83