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//
// immer: immutable data structures for C++
// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
//
// This software is distributed under the Boost Software License, Version 1.0.
// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
//
#pragma once
#include <immer/detail/hamts/champ.hpp>
#include <immer/detail/iterator_facade.hpp>
namespace immer {
namespace detail {
namespace hamts {
template <typename T, typename Hash, typename Eq, typename MP, bits_t B>
struct champ_iterator
: iterator_facade<champ_iterator<T, Hash, Eq, MP, B>,
std::forward_iterator_tag,
T,
const T&,
std::ptrdiff_t,
const T*>
{
using tree_t = champ<T, Hash, Eq, MP, B>;
using node_t = typename tree_t::node_t;
struct end_t
{};
champ_iterator() = default;
champ_iterator(const tree_t& v)
: depth_{0}
{
if (v.root->datamap()) {
cur_ = v.root->values();
end_ = v.root->values() + popcount(v.root->datamap());
} else {
cur_ = end_ = nullptr;
}
path_[0] = &v.root;
ensure_valid_();
}
champ_iterator(const tree_t& v, end_t)
: cur_{nullptr}
, end_{nullptr}
, depth_{0}
{
path_[0] = &v.root;
}
champ_iterator(const champ_iterator& other)
: cur_{other.cur_}
, end_{other.end_}
, depth_{other.depth_}
{
std::copy(other.path_, other.path_ + depth_ + 1, path_);
}
private:
friend iterator_core_access;
T* cur_;
T* end_;
count_t depth_;
node_t* const* path_[max_depth<B> + 1];
void increment()
{
++cur_;
ensure_valid_();
}
bool step_down()
{
if (depth_ < max_depth<B>) {
auto parent = *path_[depth_];
if (parent->nodemap()) {
++depth_;
path_[depth_] = parent->children();
auto child = *path_[depth_];
if (depth_ < max_depth<B>) {
if (child->datamap()) {
cur_ = child->values();
end_ = cur_ + popcount(child->datamap());
}
} else {
cur_ = child->collisions();
end_ = cur_ + child->collision_count();
}
return true;
}
}
return false;
}
bool step_right()
{
while (depth_ > 0) {
auto parent = *path_[depth_ - 1];
auto last = parent->children() + popcount(parent->nodemap());
auto next = path_[depth_] + 1;
if (next < last) {
path_[depth_] = next;
auto child = *path_[depth_];
if (depth_ < max_depth<B>) {
if (child->datamap()) {
cur_ = child->values();
end_ = cur_ + popcount(child->datamap());
}
} else {
cur_ = child->collisions();
end_ = cur_ + child->collision_count();
}
return true;
}
--depth_;
}
return false;
}
void ensure_valid_()
{
while (cur_ == end_) {
while (step_down())
if (cur_ != end_)
return;
if (!step_right()) {
// end of sequence
assert(depth_ == 0);
cur_ = end_ = nullptr;
return;
}
}
}
bool equal(const champ_iterator& other) const { return cur_ == other.cur_; }
const T& dereference() const { return *cur_; }
};
} // namespace hamts
} // namespace detail
} // namespace immer
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