cpp-common/bt2c: add `bt2c::PrioHeap` (C++ version of `bt_heap_` C API)

[babeltrace.git] / src / lib / prio-heap / prio-heap.c

diff --git a/src/lib/prio-heap/prio-heap.c b/src/lib/prio-heap/prio-heap.c
deleted file mode 100644 (file)
index d137aed..0000000
--- a/src/lib/prio-heap/prio-heap.c
+++ /dev/null
@@ -1,220 +0,0 @@
-/*
- * SPDX-License-Identifier: MIT
- *
- * Copyright 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * Static-sized priority heap containing pointers. Based on CLRS,
- * chapter 6.
- */
-
-#include "common/macros.h"
-#include "common/assert.h"
-#include <errno.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "prio-heap.h"
-
-#ifdef DEBUG_HEAP
-void check_heap(const struct ptr_heap *heap)
-{
-       size_t i;
-
-       if (!heap->len)
-               return;
-
-       for (i = 1; i < heap->len; i++)
-               BT_ASSERT_DBG(!heap->gt(heap->ptrs[i], heap->ptrs[0]));
-}
-#endif
-
-static
-size_t parent(size_t i)
-{
-       return (i - 1) >> 1;
-}
-
-static
-size_t left(size_t i)
-{
-       return (i << 1) + 1;
-}
-
-static
-size_t right(size_t i)
-{
-       return (i << 1) + 2;
-}
-
-/*
- * Copy of heap->ptrs pointer is invalid after heap_grow.
- */
-static
-int heap_grow(struct ptr_heap *heap, size_t new_len)
-{
-       void **new_ptrs;
-
-       if (G_LIKELY(heap->alloc_len >= new_len))
-               return 0;
-
-       heap->alloc_len = bt_max_t(size_t, new_len, heap->alloc_len << 1);
-       new_ptrs = calloc(heap->alloc_len, sizeof(void *));
-       if (G_UNLIKELY(!new_ptrs))
-               return -ENOMEM;
-       if (G_LIKELY(heap->ptrs))
-               memcpy(new_ptrs, heap->ptrs, heap->len * sizeof(void *));
-       free(heap->ptrs);
-       heap->ptrs = new_ptrs;
-       return 0;
-}
-
-static
-int heap_set_len(struct ptr_heap *heap, size_t new_len)
-{
-       int ret;
-
-       ret = heap_grow(heap, new_len);
-       if (G_UNLIKELY(ret))
-               return ret;
-       heap->len = new_len;
-       return 0;
-}
-
-int bt_heap_init(struct ptr_heap *heap, size_t alloc_len,
-             int gt(void *a, void *b))
-{
-       heap->ptrs = NULL;
-       heap->len = 0;
-       heap->alloc_len = 0;
-       heap->gt = gt;
-       /*
-        * Minimum size allocated is 1 entry to ensure memory allocation
-        * never fails within bt_heap_replace_max.
-        */
-       return heap_grow(heap, bt_max_t(size_t, 1, alloc_len));
-}
-
-void bt_heap_free(struct ptr_heap *heap)
-{
-       free(heap->ptrs);
-}
-
-static void heapify(struct ptr_heap *heap, size_t i)
-{
-       void **ptrs = heap->ptrs;
-       size_t l, r, largest;
-
-       for (;;) {
-               void *tmp;
-
-               l = left(i);
-               r = right(i);
-               if (l < heap->len && heap->gt(ptrs[l], ptrs[i]))
-                       largest = l;
-               else
-                       largest = i;
-               if (r < heap->len && heap->gt(ptrs[r], ptrs[largest]))
-                       largest = r;
-               if (G_UNLIKELY(largest == i))
-                       break;
-               tmp = ptrs[i];
-               ptrs[i] = ptrs[largest];
-               ptrs[largest] = tmp;
-               i = largest;
-       }
-       check_heap(heap);
-}
-
-void *bt_heap_replace_max(struct ptr_heap *heap, void *p)
-{
-       void *res;
-
-       if (G_UNLIKELY(!heap->len)) {
-               (void) heap_set_len(heap, 1);
-               heap->ptrs[0] = p;
-               check_heap(heap);
-               return NULL;
-       }
-
-       /* Replace the current max and heapify */
-       res = heap->ptrs[0];
-       heap->ptrs[0] = p;
-       heapify(heap, 0);
-       return res;
-}
-
-int bt_heap_insert(struct ptr_heap *heap, void *p)
-{
-       void **ptrs;
-       size_t pos;
-       int ret;
-
-       ret = heap_set_len(heap, heap->len + 1);
-       if (G_UNLIKELY(ret))
-               return ret;
-       ptrs = heap->ptrs;
-       pos = heap->len - 1;
-       while (pos > 0 && heap->gt(p, ptrs[parent(pos)])) {
-               /* Move parent down until we find the right spot */
-               ptrs[pos] = ptrs[parent(pos)];
-               pos = parent(pos);
-       }
-       ptrs[pos] = p;
-       check_heap(heap);
-       return 0;
-}
-
-void *bt_heap_remove(struct ptr_heap *heap)
-{
-       switch (heap->len) {
-       case 0:
-               return NULL;
-       case 1:
-               (void) heap_set_len(heap, 0);
-               return heap->ptrs[0];
-       }
-       /* Shrink, replace the current max by previous last entry and heapify */
-       heap_set_len(heap, heap->len - 1);
-       /* len changed. previous last entry is at heap->len */
-       return bt_heap_replace_max(heap, heap->ptrs[heap->len]);
-}
-
-void *bt_heap_cherrypick(struct ptr_heap *heap, void *p)
-{
-       size_t pos, len = heap->len;
-
-       for (pos = 0; pos < len; pos++)
-               if (G_UNLIKELY(heap->ptrs[pos] == p))
-                       goto found;
-       return NULL;
-found:
-       if (G_UNLIKELY(heap->len == 1)) {
-               (void) heap_set_len(heap, 0);
-               check_heap(heap);
-               return heap->ptrs[0];
-       }
-       /* Replace p with previous last entry and heapify. */
-       heap_set_len(heap, heap->len - 1);
-       /* len changed. previous last entry is at heap->len */
-       heap->ptrs[pos] = heap->ptrs[heap->len];
-       heapify(heap, pos);
-       return p;
-}
-
-int bt_heap_copy(struct ptr_heap *dst, struct ptr_heap *src)
-{
-       int ret;
-
-       ret = bt_heap_init(dst, src->alloc_len, src->gt);
-       if (ret < 0)
-               goto end;
-
-       ret = heap_set_len(dst, src->len);
-       if (ret < 0)
-               goto end;
-
-       memcpy(dst->ptrs, src->ptrs, src->len * sizeof(void *));
-
-end:
-       return ret;
-}