about summary refs log tree commit diff
path: root/immer/experimental/detail/dvektor_impl.hpp
blob: 81dbbc59f5f34fe7f97f73acd980d8069d100d9a (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
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
//
// 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/heap/heap_policy.hpp>
#include <immer/refcount/enable_intrusive_ptr.hpp>
#include <immer/refcount/refcount_policy.hpp>

#include <boost/intrusive_ptr.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <boost/smart_ptr/intrusive_ref_counter.hpp>

#include <cassert>
#include <limits>

namespace immer {
namespace detail {
namespace dvektor {

constexpr auto fast_log2(std::size_t x)
{
    return x == 0 ? 0 : sizeof(std::size_t) * 8 - 1 - __builtin_clzl(x);
}

template <int B, typename T = std::size_t>
constexpr T branches = T{1} << B;

template <int B, typename T = std::size_t>
constexpr T mask = branches<B, T> - 1;

template <int B, typename T = std::size_t>
constexpr auto
    max_depth = fast_log2(std::numeric_limits<std::size_t>::max()) / B;

template <typename T, int B, typename MP>
struct node;

template <typename T, int B, typename MP>
using node_ptr = boost::intrusive_ptr<node<T, B, MP>>;

template <typename T, int B>
using leaf_node = std::array<T, 1 << B>;

template <typename T, int B, typename MP>
using inner_node = std::array<node_ptr<T, B, MP>, 1 << B>;

template <typename T, int B, typename MP>
struct node
    : enable_intrusive_ptr<node<T, B, MP>, typename MP::refcount>
    , enable_optimized_heap_policy<node<T, B, MP>, typename MP::heap>
{
    using leaf_node_t  = leaf_node<T, B>;
    using inner_node_t = inner_node<T, B, MP>;

    enum
    {
        leaf_kind,
        inner_kind
    } kind;

    union data_t
    {
        leaf_node_t leaf;
        inner_node_t inner;
        data_t(leaf_node_t n)
            : leaf(std::move(n))
        {}
        data_t(inner_node_t n)
            : inner(std::move(n))
        {}
        ~data_t() {}
    } data;

    ~node()
    {
        switch (kind) {
        case leaf_kind:
            data.leaf.~leaf_node_t();
            break;
        case inner_kind:
            data.inner.~inner_node_t();
            break;
        }
    }

    node(leaf_node<T, B> n)
        : kind{leaf_kind}
        , data{std::move(n)}
    {}

    node(inner_node<T, B, MP> n)
        : kind{inner_kind}
        , data{std::move(n)}
    {}

    inner_node_t& inner() &
    {
        assert(kind == inner_kind);
        return data.inner;
    }
    const inner_node_t& inner() const&
    {
        assert(kind == inner_kind);
        return data.inner;
    }
    inner_node_t&& inner() &&
    {
        assert(kind == inner_kind);
        return std::move(data.inner);
    }

    leaf_node_t& leaf() &
    {
        assert(kind == leaf_kind);
        return data.leaf;
    }
    const leaf_node_t& leaf() const&
    {
        assert(kind == leaf_kind);
        return data.leaf;
    }
    leaf_node_t&& leaf() &&
    {
        assert(kind == leaf_kind);
        return std::move(data.leaf);
    }
};

template <typename T, int B, typename MP, typename... Ts>
auto make_node(Ts&&... xs) -> boost::intrusive_ptr<node<T, B, MP>>
{
    return new node<T, B, MP>(std::forward<Ts>(xs)...);
}

template <typename T, int B, typename MP>
struct ref
{
    using inner_t    = inner_node<T, B, MP>;
    using leaf_t     = leaf_node<T, B>;
    using node_t     = node<T, B, MP>;
    using node_ptr_t = node_ptr<T, B, MP>;

    unsigned depth;
    std::array<node_ptr_t, max_depth<B>> display;

    template <typename... Ts>
    static auto make_node(Ts&&... xs)
    {
        return dvektor::make_node<T, B, MP>(std::forward<Ts>(xs)...);
    }

    const T& get_elem(std::size_t index, std::size_t xr) const
    {
        auto display_idx = fast_log2(xr) / B;
        auto node        = display[display_idx].get();
        auto shift       = display_idx * B;
        while (display_idx--) {
            node = node->inner()[(index >> shift) & mask<B>].get();
            shift -= B;
        }
        return node->leaf()[index & mask<B>];
    }

    node_ptr_t null_slot_and_copy_inner(node_ptr_t& node, std::size_t idx)
    {
        auto& n = node->inner();
        auto x  = node_ptr_t{};
        x.swap(n[idx]);
        return copy_of_inner(x);
    }

    node_ptr_t null_slot_and_copy_leaf(node_ptr_t& node, std::size_t idx)
    {
        auto& n = node->inner();
        auto x  = node_ptr_t{};
        x.swap(n[idx]);
        return copy_of_leaf(x);
    }

    node_ptr_t copy_of_inner(const node_ptr_t& n)
    {
        return make_node(n->inner());
    }

    node_ptr_t copy_of_leaf(const node_ptr_t& n)
    {
        return make_node(n->leaf());
    }

    void stabilize(std::size_t index)
    {
        auto shift = B;
        for (auto i = 1u; i < depth; ++i) {
            display[i] = copy_of_inner(display[i]);
            display[i]->inner()[(index >> shift) & mask<B>] = display[i - 1];
            shift += B;
        }
    }

    void goto_pos_writable_from_clean(std::size_t old_index,
                                      std::size_t index,
                                      std::size_t xr)
    {
        assert(depth);
        auto d = depth - 1;
        if (d == 0) {
            display[0] = copy_of_leaf(display[0]);
        } else {
            IMMER_UNREACHABLE;
            display[d] = copy_of_inner(display[d]);
            auto shift = B * d;
            while (--d) {
                display[d] = null_slot_and_copy_inner(
                    display[d + 1], (index >> shift) & mask<B>);
                shift -= B;
            }
            display[0] =
                null_slot_and_copy_leaf(display[1], (index >> B) & mask<B>);
        }
    }

    void goto_pos_writable_from_dirty(std::size_t old_index,
                                      std::size_t new_index,
                                      std::size_t xr)
    {
        assert(depth);
        if (xr < (1 << B)) {
            display[0] = copy_of_leaf(display[0]);
        } else {
            auto display_idx = fast_log2(xr) / B;
            auto shift       = B;
            for (auto i = 1u; i <= display_idx; ++i) {
                display[i] = copy_of_inner(display[i]);
                display[i]->inner()[(old_index >> shift) & mask<B>] =
                    display[i - 1];
                shift += B;
            }
            for (auto i = display_idx - 1; i > 0; --i) {
                shift -= B;
                display[i] = null_slot_and_copy_inner(
                    display[i + 1], (new_index >> shift) & mask<B>);
            }
            display[0] =
                null_slot_and_copy_leaf(display[1], (new_index >> B) & mask<B>);
        }
    }

    void goto_fresh_pos_writable_from_clean(std::size_t old_index,
                                            std::size_t new_index,
                                            std::size_t xr)
    {
        auto display_idx = fast_log2(xr) / B;
        if (display_idx > 0) {
            auto shift = display_idx * B;
            if (display_idx == depth) {
                display[display_idx] = make_node(inner_t{});
                display[display_idx]->inner()[(old_index >> shift) & mask<B>] =
                    display[display_idx - 1];
                ++depth;
            }
            while (--display_idx) {
                auto node = display[display_idx + 1]
                                ->inner()[(new_index >> shift) & mask<B>];
                display[display_idx] =
                    node ? std::move(node) : make_node(inner_t{});
            }
            display[0] = make_node(leaf_t{});
        }
    }

    void goto_fresh_pos_writable_from_dirty(std::size_t old_index,
                                            std::size_t new_index,
                                            std::size_t xr)
    {
        stabilize(old_index);
        goto_fresh_pos_writable_from_clean(old_index, new_index, xr);
    }

    void goto_next_block_start(std::size_t index, std::size_t xr)
    {
        auto display_idx = fast_log2(xr) / B;
        auto shift       = display_idx * B;
        if (display_idx > 0) {
            display[display_idx - 1] =
                display[display_idx]->inner()[(index >> shift) & mask<B>];
            while (--display_idx)
                display[display_idx - 1] = display[display_idx]->inner()[0];
        }
    }

    void goto_pos(std::size_t index, std::size_t xr)
    {
        auto display_idx = fast_log2(xr) / B;
        auto shift       = display_idx * B;
        if (display_idx) {
            do {
                display[display_idx - 1] =
                    display[display_idx]->inner()[(index >> shift) & mask<B>];
                shift -= B;
            } while (--display_idx);
        }
    }
};

template <typename T, int B, typename MP>
struct impl
{
    using inner_t    = inner_node<T, B, MP>;
    using leaf_t     = leaf_node<T, B>;
    using node_t     = node<T, B, MP>;
    using node_ptr_t = node_ptr<T, B, MP>;
    using ref_t      = ref<T, B, MP>;

    std::size_t size;
    std::size_t focus;
    bool dirty;
    ref_t p;

    template <typename... Ts>
    static auto make_node(Ts&&... xs)
    {
        return dvektor::make_node<T, B, MP>(std::forward<Ts>(xs)...);
    }

    void goto_pos_writable(std::size_t old_index,
                           std::size_t new_index,
                           std::size_t xr)
    {
        if (dirty) {
            p.goto_pos_writable_from_dirty(old_index, new_index, xr);
        } else {
            p.goto_pos_writable_from_clean(old_index, new_index, xr);
            dirty = true;
        }
    }

    void goto_fresh_pos_writable(std::size_t old_index,
                                 std::size_t new_index,
                                 std::size_t xr)
    {
        if (dirty) {
            p.goto_fresh_pos_writable_from_dirty(old_index, new_index, xr);
        } else {
            p.goto_fresh_pos_writable_from_clean(old_index, new_index, xr);
            dirty = true;
        }
    }

    impl push_back(T value) const
    {
        if (size) {
            auto block_index = size & ~mask<B>;
            auto lo          = size & mask<B>;
            if (size != block_index) {
                auto s = impl{size + 1, block_index, dirty, p};
                s.goto_pos_writable(focus, block_index, focus ^ block_index);
                s.p.display[0]->leaf()[lo] = std::move(value);
                return s;
            } else {
                auto s = impl{size + 1, block_index, dirty, p};
                s.goto_fresh_pos_writable(
                    focus, block_index, focus ^ block_index);
                s.p.display[0]->leaf()[lo] = std::move(value);
                return s;
            }
        } else {
            return impl{
                1, 0, false, {1, {{make_node(leaf_t{{std::move(value)}})}}}};
        }
    }

    const T& get(std::size_t index) const
    {
        return p.get_elem(index, index ^ focus);
    }

    template <typename FnT>
    impl update(std::size_t idx, FnT&& fn) const
    {
        auto s = impl{size, idx, dirty, p};
        s.goto_pos_writable(focus, idx, focus ^ idx);
        auto& v = s.p.display[0]->leaf()[idx & mask<B>];
        v       = fn(std::move(v));
        return s;
    }

    impl assoc(std::size_t idx, T value) const
    {
        return update(idx, [&](auto&&) { return std::move(value); });
    }
};

template <typename T, int B, typename MP>
const impl<T, B, MP> empty = {0, 0, false, ref<T, B, MP>{1, {}}};

template <typename T, int B, typename MP>
struct iterator
    : boost::iterator_facade<iterator<T, B, MP>,
                             T,
                             boost::random_access_traversal_tag,
                             const T&>
{
    struct end_t
    {};

    iterator() = default;

    iterator(const impl<T, B, MP>& v)
        : p_{v.p}
        , i_{0}
        , base_{0}
    {
        if (v.dirty)
            p_.stabilize(v.focus);
        p_.goto_pos(0, 0 ^ v.focus);
        curr_ = p_.display[0]->leaf().begin();
    }

    iterator(const impl<T, B, MP>& v, end_t)
        : p_{v.p}
        , i_{v.size}
        , base_{(v.size - 1) & ~mask<B>}
    {
        if (v.dirty)
            p_.stabilize(v.focus);
        p_.goto_pos(base_, base_ ^ v.focus);
        curr_ = p_.display[0]->leaf().begin() + (i_ - base_);
    }

private:
    friend class boost::iterator_core_access;
    using leaf_iterator = typename leaf_node<T, B>::const_iterator;

    ref<T, B, MP> p_;
    std::size_t i_;
    std::size_t base_;
    leaf_iterator curr_;

    void increment()
    {
        ++i_;
        if (i_ - base_ < branches<B>) {
            ++curr_;
        } else {
            auto new_base = base_ + branches<B>;
            p_.goto_next_block_start(new_base, base_ ^ new_base);
            base_ = new_base;
            curr_ = p_.display[0]->leaf().begin();
        }
    }

    void decrement()
    {
        assert(i_ > 0);
        --i_;
        if (i_ >= base_) {
            --curr_;
        } else {
            auto new_base = base_ - branches<B>;
            p_.goto_pos(new_base, base_ ^ new_base);
            base_ = new_base;
            curr_ = std::prev(p_.display[0]->leaf().end());
        }
    }

    void advance(std::ptrdiff_t n)
    {
        i_ += n;
        if (i_ <= base_ && i_ - base_ < branches<B>) {
            curr_ += n;
        } else {
            auto new_base = i_ & ~mask<B>;
            p_.goto_pos(new_base, base_ ^ new_base);
            base_ = new_base;
            curr_ = p_.display[0]->leaf().begin() + (i_ - base_);
        }
    }

    bool equal(const iterator& other) const { return i_ == other.i_; }

    std::ptrdiff_t distance_to(const iterator& other) const
    {
        return other.i_ > i_ ? static_cast<std::ptrdiff_t>(other.i_ - i_)
                             : -static_cast<std::ptrdiff_t>(i_ - other.i_);
    }

    const T& dereference() const { return *curr_; }
};

} /* namespace dvektor */
} /* namespace detail */
} /* namespace immer */