1 files changed, 124 insertions, 0 deletions
diff --git a/extmod/modheapq.c b/extmod/modheapq.c
new file mode 100644
index 0000000000..79a12c2b9c
--- /dev/null
+++ b/extmod/modheapq.c
@@ -0,0 +1,124 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/objlist.h"
+#include "py/runtime.h"
+
+#if MICROPY_PY_HEAPQ
+
+// the algorithm here is modelled on CPython's heapq.py
+
+STATIC mp_obj_list_t *heapq_get_heap(mp_obj_t heap_in) {
+    if (!mp_obj_is_type(heap_in, &mp_type_list)) {
+        mp_raise_TypeError(MP_ERROR_TEXT("heap must be a list"));
+    }
+    return MP_OBJ_TO_PTR(heap_in);
+}
+
+STATIC void heapq_heap_siftdown(mp_obj_list_t *heap, mp_uint_t start_pos, mp_uint_t pos) {
+    mp_obj_t item = heap->items[pos];
+    while (pos > start_pos) {
+        mp_uint_t parent_pos = (pos - 1) >> 1;
+        mp_obj_t parent = heap->items[parent_pos];
+        if (mp_binary_op(MP_BINARY_OP_LESS, item, parent) == mp_const_true) {
+            heap->items[pos] = parent;
+            pos = parent_pos;
+        } else {
+            break;
+        }
+    }
+    heap->items[pos] = item;
+}
+
+STATIC void heapq_heap_siftup(mp_obj_list_t *heap, mp_uint_t pos) {
+    mp_uint_t start_pos = pos;
+    mp_uint_t end_pos = heap->len;
+    mp_obj_t item = heap->items[pos];
+    for (mp_uint_t child_pos = 2 * pos + 1; child_pos < end_pos; child_pos = 2 * pos + 1) {
+        // choose right child if it's <= left child
+        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) {
+            child_pos += 1;
+        }
+        // bubble up the smaller child
+        heap->items[pos] = heap->items[child_pos];
+        pos = child_pos;
+    }
+    heap->items[pos] = item;
+    heapq_heap_siftdown(heap, start_pos, pos);
+}
+
+STATIC mp_obj_t mod_heapq_heappush(mp_obj_t heap_in, mp_obj_t item) {
+    mp_obj_list_t *heap = heapq_get_heap(heap_in);
+    mp_obj_list_append(heap_in, item);
+    heapq_heap_siftdown(heap, 0, heap->len - 1);
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_2(mod_heapq_heappush_obj, mod_heapq_heappush);
+
+STATIC mp_obj_t mod_heapq_heappop(mp_obj_t heap_in) {
+    mp_obj_list_t *heap = heapq_get_heap(heap_in);
+    if (heap->len == 0) {
+        mp_raise_msg(&mp_type_IndexError, MP_ERROR_TEXT("empty heap"));
+    }
+    mp_obj_t item = heap->items[0];
+    heap->len -= 1;
+    heap->items[0] = heap->items[heap->len];
+    heap->items[heap->len] = MP_OBJ_NULL; // so we don't retain a pointer
+    if (heap->len) {
+        heapq_heap_siftup(heap, 0);
+    }
+    return item;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_heapq_heappop_obj, mod_heapq_heappop);
+
+STATIC mp_obj_t mod_heapq_heapify(mp_obj_t heap_in) {
+    mp_obj_list_t *heap = heapq_get_heap(heap_in);
+    for (mp_uint_t i = heap->len / 2; i > 0;) {
+        heapq_heap_siftup(heap, --i);
+    }
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(mod_heapq_heapify_obj, mod_heapq_heapify);
+
+#if !MICROPY_ENABLE_DYNRUNTIME
+STATIC const mp_rom_map_elem_t mp_module_heapq_globals_table[] = {
+    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_heapq) },
+    { MP_ROM_QSTR(MP_QSTR_heappush), MP_ROM_PTR(&mod_heapq_heappush_obj) },
+    { MP_ROM_QSTR(MP_QSTR_heappop), MP_ROM_PTR(&mod_heapq_heappop_obj) },
+    { MP_ROM_QSTR(MP_QSTR_heapify), MP_ROM_PTR(&mod_heapq_heapify_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(mp_module_heapq_globals, mp_module_heapq_globals_table);
+
+const mp_obj_module_t mp_module_heapq = {
+    .base = { &mp_type_module },
+    .globals = (mp_obj_dict_t *)&mp_module_heapq_globals,
+};
+
+MP_REGISTER_MODULE(MP_QSTR_heapq, mp_module_heapq);
+#endif
+
+#endif // MICROPY_PY_HEAPQ