about summary refs log tree commit diff
path: root/immer/detail/hamts/champ_iterator.hpp
blob: 72673b41be03ef4440c317c7778491dc6101e2d9 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
//
// 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