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/* -*- mode: c++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
Copyright (C) 2000, 2001, 2002, 2003 RiskMap srl
This file is part of QuantLib, a free-software/open-source library
for financial quantitative analysts and developers - http://quantlib.org/
QuantLib is free software: you can redistribute it and/or modify it
under the terms of the QuantLib license. You should have received a
copy of the license along with this program; if not, please email
<quantlib-dev@lists.sf.net>. The license is also available online at
<https://www.quantlib.org/license.shtml>.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the license for more details.
*/
/*! \file steppingiterator.hpp
\brief Iterator advancing in constant steps
*/
#ifndef quantlib_stepping_iterator_hpp
#define quantlib_stepping_iterator_hpp
#include <ql/errors.hpp>
#include <ql/types.hpp>
#include <iterator>
#include <type_traits>
namespace QuantLib {
//! Iterator advancing in constant steps
/*! This iterator advances an underlying random-access iterator in
steps of \f$ n \f$ positions, where \f$ n \f$ is a positive
integer given upon construction.
*/
#ifdef __cpp_concepts
template <std::random_access_iterator Iterator>
#else
template <class Iterator>
#endif
class step_iterator { // NOLINT(cppcoreguidelines-special-member-functions)
private:
Iterator base_{};
// a Size would mess up integer division in distance_to
BigInteger step_{};
public:
using iterator_category = typename std::iterator_traits<Iterator>::iterator_category;
using difference_type = typename std::iterator_traits<Iterator>::difference_type;
using value_type = typename std::iterator_traits<Iterator>::value_type;
using pointer = typename std::iterator_traits<Iterator>::pointer;
using reference = typename std::iterator_traits<Iterator>::reference;
step_iterator() = default;
explicit step_iterator(const Iterator& base, Size step)
: base_(base), step_(static_cast<BigInteger>(step)) {}
template <class OtherIterator>
step_iterator(const step_iterator<OtherIterator>& i,
std::enable_if_t<std::is_convertible_v
<OtherIterator, Iterator>>* = nullptr)
: base_(i.base_), step_(static_cast<BigInteger>(i.step())) {}
Size step() const { return static_cast<Size>(this->step_); }
step_iterator& operator=(const step_iterator& other) = default;
step_iterator& operator++() {
base_ += step_;
return *this;
}
step_iterator operator++(int) {
auto tmp = *this;
base_ += step_;
return tmp;
}
reference operator*() const {
return *base_;
}
step_iterator& operator--() {
base_ -= step_;
return *this;
}
step_iterator operator--(int) {
auto tmp = *this;
base_ -= step_;
return tmp;
}
step_iterator& operator+=(Size n) {
base_ += n * step_;
return *this;
}
step_iterator& operator-=(Size n) {
base_ -= n * step_;
return *this;
}
reference operator[](Size n) const {
return *(base_ + n * step_);
}
friend step_iterator operator+(const step_iterator& i, Size n) {
return step_iterator(i.base_ + n * i.step_, i.step_);
}
friend step_iterator operator+(Size n, const step_iterator& i) {
return step_iterator(i.base_ + n * i.step_, i.step_);
}
friend step_iterator operator-(const step_iterator& i, Size n) {
return step_iterator(i.base_ - n * i.step_, i.step_);
}
friend difference_type operator-(const step_iterator& lhs, const step_iterator& rhs) {
#ifdef QL_EXTRA_SAFETY_CHECKS
QL_REQUIRE(lhs.step_ == rhs.step_, "step_iterators with different step cannot be added or subtracted");
#endif
return (lhs.base_ - rhs.base_) / lhs.step_;
}
friend bool operator==(const step_iterator& lhs, const step_iterator& rhs) {
return lhs.base_ == rhs.base_ && lhs.step_ == rhs.step_;
}
friend bool operator!=(const step_iterator& lhs, const step_iterator& rhs) {
return lhs.base_ != rhs.base_ || lhs.step_ != rhs.step_;
}
friend bool operator<(const step_iterator& lhs, const step_iterator& rhs) {
#ifdef QL_EXTRA_SAFETY_CHECKS
QL_REQUIRE(lhs.step_ == rhs.step_, "step_iterators with different step cannot be compared");
#endif
return lhs.base_ < rhs.base_;
}
friend bool operator>(const step_iterator& lhs, const step_iterator& rhs) {
#ifdef QL_EXTRA_SAFETY_CHECKS
QL_REQUIRE(lhs.step_ == rhs.step_, "step_iterators with different step cannot be compared");
#endif
return lhs.base_ > rhs.base_;
}
friend bool operator<=(const step_iterator& lhs, const step_iterator& rhs) {
#ifdef QL_EXTRA_SAFETY_CHECKS
QL_REQUIRE(lhs.step_ == rhs.step_, "step_iterators with different step cannot be compared");
#endif
return lhs.base_ <= rhs.base_;
}
friend bool operator>=(const step_iterator& lhs, const step_iterator& rhs) {
#ifdef QL_EXTRA_SAFETY_CHECKS
QL_REQUIRE(lhs.step_ == rhs.step_, "step_iterators with different step cannot be compared");
#endif
return lhs.base_ >= rhs.base_;
}
};
//! helper function to create step iterators
/*! \relates step_iterator */
template <class Iterator>
step_iterator<Iterator> make_step_iterator(Iterator it, Size step) {
return step_iterator<Iterator>(it,step);
}
}
#endif
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