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Move BTree Node utility methods into NodeUtil.mo
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,59 @@ | ||
| import AU "./ArrayUtil"; | ||
| import BS "./BinarySearch"; | ||
| import Types "./Types"; | ||
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| import Option "mo:base/Option"; | ||
| import Order "mo:base/Order"; | ||
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| module { | ||
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| /// Inserts element at the given index into a non-full leaf node | ||
| public func insertAtIndexOfNonFullNodeData<K, V>(data: Types.Data<K, V>, kvPair: (K, V), insertIndex: Nat): () { | ||
| let currentLastElementIndex: Nat = if (data.count == 0) { 0 } else { data.count - 1 }; | ||
| AU.insertAtPosition<(K, V)>(data.kvs, ?kvPair, insertIndex, currentLastElementIndex); | ||
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| // increment the count of data in this node since just inserted an element | ||
| data.count += 1; | ||
| }; | ||
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| /// Inserts two rebalanced (split) child halves into a non-full array of children. | ||
| public func insertRebalancedChild<K, V>(children: [var ?Types.Node<K, V>], rebalancedChildIndex: Nat, leftChildInsert: Types.Node<K, V>, rightChildInsert: Types.Node<K, V>): () { | ||
| // Note: BTree will always have an order >= 4, so this will never have negative Nat overflow | ||
| var j: Nat = children.size() - 2; | ||
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| // This is just a sanity check to ensure the children aren't already full (should split promote otherwise) | ||
| // TODO: Remove this check once confident | ||
| if (Option.isSome(children[j+1])) { assert false }; | ||
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| // Iterate backwards over the array and shift each element over to the right by one until the rebalancedChildIndex is hit | ||
| while (j > rebalancedChildIndex) { | ||
| children[j + 1] := children[j]; | ||
| j -= 1; | ||
| }; | ||
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| // Insert both the left and right rebalanced children (replacing the pre-split child) | ||
| children[j] := ?leftChildInsert; | ||
| children[j+1] := ?rightChildInsert; | ||
| }; | ||
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| /// Used when splitting the children of an internal node | ||
| /// | ||
| /// Takes in the rebalanced child index, as well as both halves of the rebalanced child and splits the children, inserting the left and right child halves appropriately | ||
| /// | ||
| /// For more context, see the documentation for the splitArrayAndInsertTwo method in ArrayUtils.mo | ||
| public func splitChildrenInTwoWithRebalances<K, V>( | ||
| children: [var ?Types.Node<K, V>], | ||
| rebalancedChildIndex: Nat, | ||
| leftChildInsert: Types.Node<K, V>, | ||
| rightChildInsert: Types.Node<K, V> | ||
| ): ([var ?Types.Node<K, V>], [var ?Types.Node<K, V>]) { | ||
| AU.splitArrayAndInsertTwo<Types.Node<K, V>>(children, rebalancedChildIndex, leftChildInsert, rightChildInsert); | ||
| }; | ||
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| /// Helper used to get the key index of of a key within a node | ||
| /// | ||
| /// for more, see the BinarySearch.binarySearchNode() documentation | ||
| public func getKeyIndex<K, V>(data: Types.Data<K, V>, compare: (K, K) -> Order.Order, key: K): BS.SearchResult { | ||
| BS.binarySearchNode<K, V>(data.kvs, compare, key, data.count); | ||
| }; | ||
| } |