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linedance-app/venv/lib/python3.12/site-packages/sklearn/utils/_heap.pyx

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+from cython cimport floating
+
+from sklearn.utils._typedefs cimport intp_t
+
+
+cdef inline int heap_push(
+    floating* values,
+    intp_t* indices,
+    intp_t size,
+    floating val,
+    intp_t val_idx,
+) noexcept nogil:
+    """Push a tuple (val, val_idx) onto a fixed-size max-heap.
+
+    The max-heap is represented as a Structure of Arrays where:
+     - values is the array containing the data to construct the heap with
+     - indices is the array containing the indices (meta-data) of each value
+
+    Notes
+    -----
+    Arrays are manipulated via a pointer to there first element and their size
+    as to ease the processing of dynamically allocated buffers.
+
+    For instance, in pseudo-code:
+
+        values = [1.2, 0.4, 0.1],
+        indices = [42, 1, 5],
+        heap_push(
+            values=values,
+            indices=indices,
+            size=3,
+            val=0.2,
+            val_idx=4,
+        )
+
+    will modify values and indices inplace, giving at the end of the call:
+
+        values  == [0.4, 0.2, 0.1]
+        indices == [1, 4, 5]
+
+    """
+    cdef:
+        intp_t current_idx, left_child_idx, right_child_idx, swap_idx
+
+    # Check if val should be in heap
+    if val >= values[0]:
+        return 0
+
+    # Insert val at position zero
+    values[0] = val
+    indices[0] = val_idx
+
+    # Descend the heap, swapping values until the max heap criterion is met
+    current_idx = 0
+    while True:
+        left_child_idx = 2 * current_idx + 1
+        right_child_idx = left_child_idx + 1
+
+        if left_child_idx >= size:
+            break
+        elif right_child_idx >= size:
+            if values[left_child_idx] > val:
+                swap_idx = left_child_idx
+            else:
+                break
+        elif values[left_child_idx] >= values[right_child_idx]:
+            if val < values[left_child_idx]:
+                swap_idx = left_child_idx
+            else:
+                break
+        else:
+            if val < values[right_child_idx]:
+                swap_idx = right_child_idx
+            else:
+                break
+
+        values[current_idx] = values[swap_idx]
+        indices[current_idx] = indices[swap_idx]
+
+        current_idx = swap_idx
+
+    values[current_idx] = val
+    indices[current_idx] = val_idx
+
+    return 0