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 | |
34 | STATIC 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 | |
41 | STATIC 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 | |
56 | STATIC 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 | |
73 | STATIC 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 | } |
79 | STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_uheapq_heappush_obj, mod_uheapq_heappush); |
80 | |
81 | STATIC 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 | } |
95 | STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_uheapq_heappop_obj, mod_uheapq_heappop); |
96 | |
97 | STATIC 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 | } |
104 | STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_uheapq_heapify_obj, mod_uheapq_heapify); |
105 | |
106 | #if !MICROPY_ENABLE_DYNRUNTIME |
107 | STATIC 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 | |
114 | STATIC MP_DEFINE_CONST_DICT(mp_module_uheapq_globals, mp_module_uheapq_globals_table); |
115 | |
116 | const 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 | |