1/*
2 * This file is part of the MicroPython project, http://micropython.org/
3 *
4 * The MIT License (MIT)
5 *
6 * Copyright (c) 2014 Damien P. George
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24 * THE SOFTWARE.
25 */
26
27#include "py/objlist.h"
28#include "py/runtime.h"
29
30#if MICROPY_PY_UHEAPQ
31
32// the algorithm here is modelled on CPython's heapq.py
33
34STATIC mp_obj_list_t *uheapq_get_heap(mp_obj_t heap_in) {
35 if (!mp_obj_is_type(heap_in, &mp_type_list)) {
36 mp_raise_TypeError(MP_ERROR_TEXT("heap must be a list"));
37 }
38 return MP_OBJ_TO_PTR(heap_in);
39}
40
41STATIC void uheapq_heap_siftdown(mp_obj_list_t *heap, mp_uint_t start_pos, mp_uint_t pos) {
42 mp_obj_t item = heap->items[pos];
43 while (pos > start_pos) {
44 mp_uint_t parent_pos = (pos - 1) >> 1;
45 mp_obj_t parent = heap->items[parent_pos];
46 if (mp_binary_op(MP_BINARY_OP_LESS, item, parent) == mp_const_true) {
47 heap->items[pos] = parent;
48 pos = parent_pos;
49 } else {
50 break;
51 }
52 }
53 heap->items[pos] = item;
54}
55
56STATIC void uheapq_heap_siftup(mp_obj_list_t *heap, mp_uint_t pos) {
57 mp_uint_t start_pos = pos;
58 mp_uint_t end_pos = heap->len;
59 mp_obj_t item = heap->items[pos];
60 for (mp_uint_t child_pos = 2 * pos + 1; child_pos < end_pos; child_pos = 2 * pos + 1) {
61 // choose right child if it's <= left child
62 if (child_pos + 1 < end_pos && mp_binary_op(MP_BINARY_OP_LESS, heap->items[child_pos], heap->items[child_pos + 1]) == mp_const_false) {
63 child_pos += 1;
64 }
65 // bubble up the smaller child
66 heap->items[pos] = heap->items[child_pos];
67 pos = child_pos;
68 }
69 heap->items[pos] = item;
70 uheapq_heap_siftdown(heap, start_pos, pos);
71}
72
73STATIC mp_obj_t mod_uheapq_heappush(mp_obj_t heap_in, mp_obj_t item) {
74 mp_obj_list_t *heap = uheapq_get_heap(heap_in);
75 mp_obj_list_append(heap_in, item);
76 uheapq_heap_siftdown(heap, 0, heap->len - 1);
77 return mp_const_none;
78}
79STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_uheapq_heappush_obj, mod_uheapq_heappush);
80
81STATIC mp_obj_t mod_uheapq_heappop(mp_obj_t heap_in) {
82 mp_obj_list_t *heap = uheapq_get_heap(heap_in);
83 if (heap->len == 0) {
84 mp_raise_msg(&mp_type_IndexError, MP_ERROR_TEXT("empty heap"));
85 }
86 mp_obj_t item = heap->items[0];
87 heap->len -= 1;
88 heap->items[0] = heap->items[heap->len];
89 heap->items[heap->len] = MP_OBJ_NULL; // so we don't retain a pointer
90 if (heap->len) {
91 uheapq_heap_siftup(heap, 0);
92 }
93 return item;
94}
95STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_uheapq_heappop_obj, mod_uheapq_heappop);
96
97STATIC mp_obj_t mod_uheapq_heapify(mp_obj_t heap_in) {
98 mp_obj_list_t *heap = uheapq_get_heap(heap_in);
99 for (mp_uint_t i = heap->len / 2; i > 0;) {
100 uheapq_heap_siftup(heap, --i);
101 }
102 return mp_const_none;
103}
104STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_uheapq_heapify_obj, mod_uheapq_heapify);
105
106#if !MICROPY_ENABLE_DYNRUNTIME
107STATIC const mp_rom_map_elem_t mp_module_uheapq_globals_table[] = {
108 { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_uheapq) },
109 { MP_ROM_QSTR(MP_QSTR_heappush), MP_ROM_PTR(&mod_uheapq_heappush_obj) },
110 { MP_ROM_QSTR(MP_QSTR_heappop), MP_ROM_PTR(&mod_uheapq_heappop_obj) },
111 { MP_ROM_QSTR(MP_QSTR_heapify), MP_ROM_PTR(&mod_uheapq_heapify_obj) },
112};
113
114STATIC MP_DEFINE_CONST_DICT(mp_module_uheapq_globals, mp_module_uheapq_globals_table);
115
116const mp_obj_module_t mp_module_uheapq = {
117 .base = { &mp_type_module },
118 .globals = (mp_obj_dict_t *)&mp_module_uheapq_globals,
119};
120#endif
121
122#endif // MICROPY_PY_UHEAPQ
123