@rimbu/sorted
Version:
Immutable SortedMap and SortedSet implementations for TypeScript
879 lines • 36.8 kB
JavaScript
import { Arr, RimbuError } from '@rimbu/base';
import { EmptyBase, NonEmptyBase } from '@rimbu/collection-types/map-custom';
import { IndexRange, OptLazy, TraverseState } from '@rimbu/common';
import { Stream } from '@rimbu/stream';
import { SortedIndex } from './index.mjs';
/**
* Base implementation used for empty sorted collections.<br/>
* <br/>
* Provides the index‑based operations used by `SortedMap` / `SortedSet`
* instances when they are empty and always returns the given fallback value.
*/
export class SortedEmpty extends EmptyBase {
min(otherwise) {
return OptLazy(otherwise);
}
max(otherwise) {
return OptLazy(otherwise);
}
getAtIndex(index, otherwise) {
return OptLazy(otherwise);
}
take() {
return this;
}
drop() {
return this;
}
sliceIndex() {
return this;
}
}
/**
* Abstract base class for non‑empty sorted collections.<br/>
* <br/>
* It exposes the common index‑based operations and structural mutation
* helpers shared by the sorted map and set node implementations.
* @typeparam E - the stored entry type
* @typeparam TS - the concrete non‑empty node type
*/
export class SortedNonEmptyBase extends NonEmptyBase {
get mutateEntries() {
return this.entries;
}
}
/**
* Removes and returns the minimum entry from the given leaf node while
* returning the updated leaf.
* @param source - the leaf node to operate on
*/
export function leafDeleteMin(source) {
return [source.entries[0], source.copy(Arr.tail(source.entries))];
}
/**
* Removes and returns the maximum entry from the given leaf node while
* returning the updated leaf.
* @param source - the leaf node to operate on
*/
export function leafDeleteMax(source) {
return [Arr.last(source.entries), source.copy(Arr.init(source.entries))];
}
/**
* Splits the given leaf node into two nodes and returns the promoted
* separator entry together with the newly created right node.<br/>
* <br/>
* The split position can be customised through the optional `index`.
* @param source - the leaf node to split
* @param index - (optional) the split index, defaults to the middle entry
*/
export function leafMutateSplitRight(source, index = source.entries.length >>> 1) {
const rightEntries = source.mutateEntries.splice(index);
const rightNode = source.copy(rightEntries);
const upEntry = rightEntries.shift();
return [upEntry, rightNode];
}
/**
* Moves the given `toLeft` entry from `source` to the left sibling and
* returns the separator entry that should be stored in the parent node.
* @param source - the leaf that donates an entry to the left sibling
* @param left - the left sibling leaf to receive the entry
* @param toLeft - the entry that must end up in the left sibling
*/
export function leafMutateGiveToLeft(source, left, toLeft) {
const toUp = source.mutateEntries.shift();
const newLeft = left.copy(Arr.append(left.entries, toLeft));
return [toUp, newLeft];
}
/**
* Moves the given `toRight` entry from `source` to the right sibling and
* returns the separator entry that should be stored in the parent node.
* @param source - the leaf that donates an entry to the right sibling
* @param right - the right sibling leaf to receive the entry
* @param toRight - the entry that must end up in the right sibling
*/
export function leafMutateGiveToRight(source, right, toRight) {
const toUp = source.mutateEntries.pop();
const newRight = right.copy(Arr.prepend(right.entries, toRight));
return [toUp, newRight];
}
/**
* Pulls an entry from the left sibling into `source` and returns the
* separator entry that should be stored in the parent node.
* @param source - the leaf receiving an entry
* @param left - the left sibling leaf to donate an entry
* @param toMe - the entry that must end up in `source`
*/
export function leafMutateGetFromLeft(source, left, toMe) {
const toUp = Arr.last(left.entries);
const newLeft = left.copy(Arr.init(left.entries));
source.mutateEntries.unshift(toMe);
return [toUp, newLeft];
}
/**
* Pulls an entry from the right sibling into `source` and returns the
* separator entry that should be stored in the parent node.
* @param source - the leaf receiving an entry
* @param right - the right sibling leaf to donate an entry
* @param toMe - the entry that must end up in `source`
*/
export function leafMutateGetFromRight(source, right, toMe) {
const toUp = right.entries[0];
const newRight = right.copy(Arr.tail(right.entries));
source.mutateEntries.push(toMe);
return [toUp, newRight];
}
/**
* Joins the given left sibling leaf and `source` into a single leaf by
* inserting the given separator `entry` between them.
* @param source - the right leaf that will absorb the left sibling
* @param left - the left sibling leaf to merge
* @param entry - the separator entry from the parent
*/
export function leafMutateJoinLeft(source, left, entry) {
source.mutateEntries.unshift(entry);
source.entries = left.entries.concat(source.entries);
}
/**
* Joins the given right sibling leaf and `source` into a single leaf by
* inserting the given separator `entry` between them.
* @param source - the left leaf that will absorb the right sibling
* @param right - the right sibling leaf to merge
* @param entry - the separator entry from the parent
*/
export function leafMutateJoinRight(source, right, entry) {
source.mutateEntries.push(entry);
source.entries = source.entries.concat(right.entries);
}
/**
* Removes and returns the minimum entry from the left‑most child of the
* given inner node and returns the updated node.
* @param source - the inner node to operate on
*/
export function innerDeleteMin(source) {
const [min, newFirst] = source.children[0].deleteMin();
const newSelf = source.normalizeIncreaseChild(0, newFirst, source.size - 1);
return [min, newSelf];
}
/**
* Removes and returns the maximum entry from the right‑most child of the
* given inner node and returns the updated node.
* @param source - the inner node to operate on
*/
export function innerDeleteMax(source) {
const lastChildIndex = source.children.length - 1;
const [max, newLast] = source.children[lastChildIndex].deleteMax();
const newSelf = source.normalizeIncreaseChild(lastChildIndex, newLast, source.size - 1);
return [max, newSelf];
}
/**
* Splits the given inner node into two nodes and returns the promoted
* separator entry together with the new right node.<br/>
* <br/>
* The split position can be customised through the optional `index`.
* @param source - the inner node to split
* @param index - (optional) the split index, defaults to the middle entry
*/
export function innerMutateSplitRight(source, index = source.entries.length >>> 1) {
const size = source.size;
const rightEntries = source.mutateEntries.splice(index - 1);
const rightChildren = source.mutateChildren.splice(index);
source.size = source.children.reduce((r, c) => r + c.size, source.entries.length);
const rightSize = size - source.size - 1;
const upEntry = rightEntries.shift();
const rightNode = source.copy(rightEntries, rightChildren, rightSize);
return [upEntry, rightNode];
}
/**
* Moves the given `toLeft` entry and its child from `source` to the left
* sibling and returns the separator entry that should be stored in the
* parent node.
* @param source - the inner node donating an entry to the left sibling
* @param left - the left sibling node to receive the entry and child
* @param toLeft - the entry that must end up in the left sibling
*/
export function innerMutateGiveToLeft(source, left, toLeft) {
const toUp = source.mutateEntries.shift();
const toLeftChild = source.mutateChildren.shift();
source.size -= toLeftChild.size + 1;
const newLeft = left.copy(Arr.append(left.entries, toLeft), Arr.append(left.children, toLeftChild), left.size + toLeftChild.size + 1);
return [toUp, newLeft];
}
/**
* Moves the given `toRight` entry and its child from `source` to the right
* sibling and returns the separator entry that should be stored in the
* parent node.
* @param source - the inner node donating an entry to the right sibling
* @param right - the right sibling node to receive the entry and child
* @param toRight - the entry that must end up in the right sibling
*/
export function innerMutateGiveToRight(source, right, toRight) {
const toUp = source.mutateEntries.pop();
const toRightChild = source.mutateChildren.pop();
source.size -= toRightChild.size + 1;
const newRight = right.copy(Arr.prepend(right.entries, toRight), Arr.prepend(right.children, toRightChild), right.size + toRightChild.size + 1);
return [toUp, newRight];
}
/**
* Pulls an entry and child from the left sibling into `source` and returns
* the separator entry that should be stored in the parent node.
* @param source - the inner node receiving the entry and child
* @param left - the left sibling node to donate the entry and child
* @param toMe - the entry that must end up in `source`
*/
export function innerMutateGetFromLeft(source, left, toMe) {
const toUp = Arr.last(left.entries);
const toMeChild = Arr.last(left.children);
const leftShrink = toMeChild.size + 1;
const newLeft = left.copy(Arr.init(left.entries), Arr.init(left.children), left.size - leftShrink);
source.mutateEntries.unshift(toMe);
source.mutateChildren.unshift(toMeChild);
source.size += leftShrink;
return [toUp, newLeft];
}
/**
* Pulls an entry and child from the right sibling into `source` and returns
* the separator entry that should be stored in the parent node.
* @param source - the inner node receiving the entry and child
* @param right - the right sibling node to donate the entry and child
* @param toMe - the entry that must end up in `source`
*/
export function innerMutateGetFromRight(source, right, toMe) {
const toUp = right.entries[0];
const toMeChild = right.children[0];
const rightShrink = toMeChild.size + 1;
const newLeft = right.copy(Arr.tail(right.entries), Arr.tail(right.children), right.size - rightShrink);
source.mutateEntries.push(toMe);
source.mutateChildren.push(toMeChild);
source.size += rightShrink;
return [toUp, newLeft];
}
/**
* Joins the given left sibling inner node and `source` into a single node by
* inserting the given separator `entry` between them.
* @param source - the right inner node that will absorb the left sibling
* @param left - the left sibling node to merge
* @param entry - the separator entry from the parent
*/
export function innerMutateJoinLeft(source, left, entry) {
source.mutateEntries.unshift(entry);
source.entries = left.entries.concat(source.entries);
source.children = left.children.concat(source.children);
source.size += left.size + 1;
}
/**
* Joins the given right sibling inner node and `source` into a single node by
* inserting the given separator `entry` between them.
* @param source - the left inner node that will absorb the right sibling
* @param right - the right sibling node to merge
* @param entry - the separator entry from the parent
*/
export function innerMutateJoinRight(source, right, entry) {
source.mutateEntries.push(entry);
source.entries = source.entries.concat(right.entries);
source.children = source.children.concat(right.children);
source.size += right.size + 1;
}
/**
* Normalises the given child after it has decreased in size so that it
* satisfies the minimum entry constraint of the B‑tree.<br/>
* <br/>
* Depending on the neighbouring children this may rotate entries between
* nodes or perform a split.
* @param source - the inner node that contains the child
* @param childIndex - the index of the child within `source`
* @param newChild - the updated child node
* @param newSize - the new total size for `source`
*/
export function innerNormalizeDownsizeChild(source, childIndex, newChild, newSize) {
// try to shift
const leftChild = source.children[childIndex - 1];
const rightChild = source.children[childIndex + 1];
if ((undefined === leftChild ||
leftChild.entries.length >= source.context.maxEntries) &&
(undefined === rightChild ||
rightChild.entries.length >= source.context.maxEntries)) {
// cannot shift
const [upEntry, rightChild] = newChild.mutateSplitRight();
const newEntries = Arr.insert(source.entries, childIndex, upEntry);
const newChildren = Arr.splice(source.children, childIndex, 1, newChild, rightChild);
return source.copy(newEntries, newChildren, newSize);
}
if (undefined !== leftChild &&
(undefined === rightChild ||
rightChild.entries.length >= leftChild.entries.length)) {
// shiftleft
const [newSep, newLeft] = newChild.mutateGiveToLeft(leftChild, source.entries[childIndex - 1]);
const newEntries = Arr.update(source.entries, childIndex - 1, newSep);
const newChildren = Arr.splice(source.children, childIndex - 1, 2, newLeft, newChild);
return source.copy(newEntries, newChildren, newSize);
}
// shiftright
const [newSep, newRight] = newChild.mutateGiveToRight(rightChild, source.entries[childIndex]);
const newEntries = Arr.update(source.entries, childIndex, newSep);
const newChildren = Arr.splice(source.children, childIndex, 2, newChild, newRight);
return source.copy(newEntries, newChildren, newSize);
}
/**
* Normalises the given child after it has increased in size so that it
* satisfies the maximum entry constraint of the B‑tree.<br/>
* <br/>
* Depending on the neighbouring children this may rotate entries between
* nodes or merge nodes together.
* @param source - the inner node that contains the child
* @param childIndex - the index of the child within `source`
* @param newChild - the updated child node
* @param newSize - the new total size for `source`
*/
export function innerNormalizeIncreaseChild(source, childIndex, newChild, newSize) {
if (newChild.entries.length >= source.context.minEntries) {
const newChildren = Arr.update(source.children, childIndex, newChild);
return source.copy(undefined, newChildren, newSize);
}
// try to shift
const leftChild = source.children[childIndex - 1];
const rightChild = source.children[childIndex + 1];
if ((undefined === leftChild ||
leftChild.entries.length <= source.context.minEntries) &&
(undefined === rightChild ||
rightChild.entries.length <= source.context.minEntries)) {
// cannot shift
if (undefined !== leftChild) {
newChild.mutateJoinLeft(leftChild, source.entries[childIndex - 1]);
const newEntries = Arr.splice(source.entries, childIndex - 1, 1);
const newChildren = Arr.splice(source.children, childIndex - 1, 2, newChild);
return source.copy(newEntries, newChildren, newSize);
}
newChild.mutateJoinRight(rightChild, source.entries[childIndex]);
const newEntries = Arr.splice(source.entries, childIndex, 1);
const newChildren = Arr.splice(source.children, childIndex, 2, newChild);
return source.copy(newEntries, newChildren, newSize);
}
if (undefined !== leftChild &&
(undefined === rightChild ||
rightChild.entries.length <= leftChild.entries.length)) {
// get from left
const [newSep, newLeft] = newChild.mutateGetFromLeft(leftChild, source.entries[childIndex - 1]);
const newEntries = Arr.update(source.entries, childIndex - 1, newSep);
const newChildren = Arr.splice(source.children, childIndex - 1, 2, newLeft, newChild);
return source.copy(newEntries, newChildren, newSize);
}
// get from right
const [newSep, newRight] = newChild.mutateGetFromRight(rightChild, source.entries[childIndex]);
const newEntries = Arr.update(source.entries, childIndex, newSep);
const newChildren = Arr.splice(source.children, childIndex, 2, newChild, newRight);
return source.copy(newEntries, newChildren, newSize);
}
/**
* Returns the index of the element in the sources element array, or a tuple with the child index and the index within the child
* @param source the collection to operate on
* @param index the index to find
*/
export function innerGetSubIndex(source, index) {
let elemIndex = -1;
let i = index;
while (true) {
if (elemIndex >= 0) {
if (i === 0)
return elemIndex;
i--;
}
else {
const childIndex = SortedIndex.next(elemIndex);
const child = source.children[childIndex];
if (i < child.size)
return [childIndex, i];
i -= child.size;
}
elemIndex = SortedIndex.next(elemIndex);
}
}
/**
* Returns the entry at the given `index` from the B‑tree represented by the
* given inner node, or the provided fallback value if the index is out of
* bounds.<br/>
* <br/>
* Negative indices are interpreted from the end of the collection.
* @param source - the inner node to read from
* @param index - the (possibly negative) index to look up
* @param otherwise - (default: undefined) fallback value when out of bounds
*/
export function innerGetAtIndex(source, index, otherwise) {
if (index >= source.size || -index > source.size)
return OptLazy(otherwise);
if (index < 0)
return innerGetAtIndex(source, source.size + index, otherwise);
const subIndex = innerGetSubIndex(source, index);
if (Array.isArray(subIndex))
return source.children[subIndex[0]].getAtIndex(subIndex[1], otherwise);
return source.entries[subIndex];
}
/**
* Returns a new inner node containing only the first `amount` of entries
* and children of the given `source` node.<br/>
* <br/>
* The amount must be between `1` and `source.size - 1`.
* @param source - the inner node to operate on
* @param amount - the amount of entries to keep
*/
export function innerTakeInternal(source, amount) {
if (amount <= 0 || amount >= source.size)
RimbuError.throwInvalidStateError();
const indexResult = innerGetSubIndex(source, amount - 1);
if (Array.isArray(indexResult)) {
const [childIndex, inChildIndex] = indexResult;
const untilChild = childIndex;
const entries = source.entries.slice(0, untilChild);
const children = source.children.slice(0, untilChild);
const takeAmount = inChildIndex + 1;
const lastChild = source.children[childIndex].takeInternal(takeAmount);
children.push(lastChild);
let result = source.context.inner(entries, children, amount);
if (childIndex === 0)
return result;
while (Arr.last(result.children).entries.length < source.context.minEntries) {
result = result.normalizeIncreaseChild(result.entries.length, Arr.last(result.children), amount);
}
return result;
}
const elemIndex = indexResult;
const entries = source.entries.slice(0, elemIndex);
const children = source.children.slice(0, elemIndex + 1);
return source.context
.inner(entries, children, amount - 1)
.addInternal(source.entries[elemIndex]);
}
/**
* Returns a new inner node containing all entries and children of the given
* `source` node except for the first `amount` entries.<br/>
* <br/>
* The amount must be between `1` and `source.size - 1`.
* @param source - the inner node to operate on
* @param amount - the amount of entries to drop
*/
export function innerDropInternal(source, amount) {
if (amount <= 0 || amount >= source.size)
RimbuError.throwInvalidStateError();
const newSize = source.size - amount;
const indexResult = innerGetSubIndex(source, amount);
if (Array.isArray(indexResult)) {
const [childIndex, inChildIndex] = indexResult;
const fromChild = childIndex;
const entries = source.entries.slice(fromChild);
const children = source.children.slice(fromChild + 1);
const dropAmount = inChildIndex;
const firstChild = source.children[childIndex].dropInternal(dropAmount);
children.unshift(firstChild);
let result = source.context.inner(entries, children, newSize);
if (childIndex === source.entries.length)
return result;
while (result.children[0].entries.length < source.context.minEntries) {
result = result.normalizeIncreaseChild(0, result.children[0], newSize);
}
return result;
}
const elemIndex = indexResult;
const entries = source.entries.slice(elemIndex + 1);
const children = source.children.slice(elemIndex + 1);
return source.context
.inner(entries, children, newSize - 1)
.addInternal(source.entries[elemIndex]);
}
/**
* Returns a `Stream` of entries of the given inner node limited to the
* provided index `range`.<br/>
* <br/>
* When `reversed` is true, the stream iterates the selected range in
* reverse order.
* @param source - the inner node to stream from
* @param range - the index range to include
* @param reversed - (default: false) when true reverses the stream order
*/
export function innerStreamSliceIndex(source, range, reversed = false) {
const result = IndexRange.getIndicesFor(range, source.size);
if (result === 'all')
return source.stream({ reversed });
if (result === 'empty')
return Stream.empty();
const [startIndex, endIndex] = result;
const startSubIndex = innerGetSubIndex(source, startIndex);
const endSubIndex = innerGetSubIndex(source, endIndex);
let startElemIndex = 0;
let inStartElemIndex = 0;
if (Array.isArray(startSubIndex)) {
startElemIndex = SortedIndex.prev(startSubIndex[0]);
inStartElemIndex = startSubIndex[1];
}
else {
startElemIndex = startSubIndex;
}
let endElemIndex = 0;
let inEndElemIndex = 0;
if (Array.isArray(endSubIndex)) {
endElemIndex = SortedIndex.prev(endSubIndex[0]);
inEndElemIndex = endSubIndex[1];
}
else {
endElemIndex = endSubIndex;
}
if (startElemIndex === endElemIndex) {
if (startElemIndex >= 0)
return Stream.of(source.entries[startElemIndex]);
return source.children[SortedIndex.next(startElemIndex)].streamSliceIndex({
start: inStartElemIndex,
end: inEndElemIndex,
}, { reversed });
}
const indices = reversed
? Stream.unfold(endElemIndex, (i, _, stop) => SortedIndex.compare(i, startElemIndex) <= 0 ? stop : SortedIndex.prev(i))
: Stream.unfold(startElemIndex, (i, _, stop) => SortedIndex.compare(i, endElemIndex) >= 0 ? stop : SortedIndex.next(i));
return indices.flatMap((index) => {
if (index >= 0)
return Stream.of(source.entries[index]);
const childIndex = SortedIndex.next(index);
const child = source.children[childIndex];
if (index === startElemIndex) {
return child.streamSliceIndex({ start: inStartElemIndex }, { reversed });
}
if (index === endElemIndex) {
return child.streamSliceIndex({ end: inEndElemIndex }, { reversed });
}
return child.stream({ reversed });
});
}
/**
* Abstract base class for mutable sorted builders used by the sorted map
* and set implementations.<br/>
* <br/>
* It encapsulates the shared tree‑based logic for computing `min`, `max`,
* index‑based access and traversal while allowing concrete builders to plug
* in their own entry and child representations.
* @typeparam E - the entry type stored in the builder
*/
export class SortedBuilder {
constructor() {
this._lock = 0;
}
/**
* Throws an error when the builder is mutated while it is being iterated,
* for example from within {@link SortedBuilder.forEach}.
*/
checkLock() {
if (this._lock)
RimbuError.throwModifiedBuilderWhileLoopingOverItError();
}
get entries() {
this.prepareMutate();
return this._entries;
}
set entries(value) {
this.prepareMutate();
this.source = undefined;
this._entries = value;
}
get hasChildren() {
return undefined !== this._children && this._children.length > 0;
}
get isEmpty() {
return this.size === 0;
}
/**
* Returns the minimum entry of the builder, or the given fallback value
* if the builder is empty.
* @param otherwise - (default: undefined) fallback value when empty
*/
min(otherwise) {
if (undefined !== this.source)
return this.source.min(otherwise);
if (this.size === 0)
return OptLazy(otherwise);
if (this.hasChildren)
return this.children[0].min(otherwise);
return this.entries[0];
}
/**
* Returns the maximum entry of the builder, or the given fallback value
* if the builder is empty.
* @param otherwise - (default: undefined) fallback value when empty
*/
max(otherwise) {
if (undefined !== this.source)
return this.source.max(otherwise);
if (this.size === 0)
return OptLazy(otherwise);
if (this.hasChildren)
return Arr.last(this.children).max(otherwise);
else
return Arr.last(this.entries);
}
/**
* Returns the entry at the given `index`, or the provided fallback value
* when the index is out of bounds.<br/>
* <br/>
* Negative indices are interpreted from the end of the builder.
* @param index - the (possibly negative) index to look up
* @param otherwise - (default: undefined) fallback value when out of bounds
*/
getAtIndex(index, otherwise) {
if (undefined !== this.source) {
return this.source.getAtIndex(index, otherwise);
}
if (index >= this.size || -index > this.size) {
return OptLazy(otherwise);
}
if (index < 0) {
return this.getAtIndex(this.size + index, otherwise);
}
if (!this.hasChildren)
return this.entries[index];
let elemIndex = -1;
let i = index;
while (true) {
if (elemIndex >= 0) {
if (i === 0)
return this.entries[elemIndex];
i--;
}
else {
const childIndex = SortedIndex.next(elemIndex);
const child = this.children[childIndex];
if (i < child.size)
return child.getAtIndex(i, otherwise);
i -= child.size;
}
elemIndex = SortedIndex.next(elemIndex);
}
}
/**
* Calls the given function `f` for every entry in the builder in key
* sort‑order, passing in the entry, its zero‑based index and a `halt`
* function that can be used to stop iteration early.
* @param f - the callback function to invoke for each entry
* @param options - (optional) traversal options including a custom state
*/
forEach(f, options = {}) {
const { state = TraverseState() } = options;
if (state.halted || this.isEmpty)
return;
this._lock++;
if (undefined !== this.source) {
this.source.forEach(f, { state });
}
else {
if (!this.hasChildren) {
Arr.forEach(this.entries, f, state);
}
else {
let i = -1;
const entryLength = this.entries.length;
const { halt } = state;
while (!state.halted && i < entryLength) {
if (i >= 0)
f(this.entries[i], state.nextIndex(), halt);
else {
const childIndex = SortedIndex.next(i);
this.children[childIndex].forEach(f, { state });
}
i = SortedIndex.next(i);
}
}
}
this._lock--;
}
/**
* Restores the builder invariants after mutations by splitting the root
* node when it grows beyond the configured maximum block size.
*/
normalize() {
if (this.entries.length === 0) {
if (!this.hasChildren)
return;
const firstChild = this.children[0];
this.entries = firstChild.entries;
this.children = firstChild.children;
this.size = firstChild.size;
return;
}
if (this.entries.length <= this.context.maxEntries)
return;
const index = this.entries.length >>> 1;
const leftEntries = this.entries;
const rightEntries = leftEntries.splice(index);
const upEntry = rightEntries.shift();
if (!this.hasChildren) {
const leftNode = this.createNew(undefined, leftEntries, undefined, leftEntries.length);
const rightNode = this.createNew(undefined, rightEntries, undefined, rightEntries.length);
this.entries = [upEntry];
this.children = [leftNode, rightNode];
}
else {
const leftChildren = this.children;
const rightChildren = leftChildren.splice(index + 1);
const leftSize = leftChildren.reduce((r, c) => r + c.size, leftEntries.length);
const rightSize = this.size - leftSize - 1;
const leftNode = this.createNew(undefined, leftEntries, leftChildren, leftSize);
const rightNode = this.createNew(undefined, rightEntries, rightChildren, rightSize);
this.entries = [upEntry];
this.children = [leftNode, rightNode];
}
}
// check whether child at given `childIndex` has gotten too small
// get from neighbouring children if it is too small so child increases
normalizeChildIncrease(childIndex) {
const child = this.children[childIndex];
if (child.entries.length >= this.context.minEntries)
return;
const leftChild = this.children[childIndex - 1];
const rightChild = this.children[childIndex + 1];
if ((undefined === leftChild ||
leftChild.entries.length <= this.context.minEntries) &&
(undefined === rightChild ||
rightChild.entries.length <= this.context.minEntries)) {
// cannot shift
if (undefined !== leftChild) {
// join left
leftChild.source = undefined;
const [down] = this.entries.splice(childIndex - 1, 1);
leftChild.entries.push(down);
leftChild.entries = leftChild.entries.concat(child.entries);
leftChild.size += child.size + 1;
if (leftChild.hasChildren) {
leftChild.children = leftChild.children.concat(child.children);
}
this.children.splice(childIndex, 1);
return;
}
// join right
rightChild.source = undefined;
child.source = undefined;
const [down] = this.entries.splice(childIndex, 1);
rightChild.entries.unshift(down);
rightChild.entries = child.entries.concat(rightChild.entries);
rightChild.size += child.size + 1;
if (rightChild.hasChildren) {
rightChild.children = child.children.concat(rightChild.children);
}
this.children.splice(childIndex, 1);
return;
}
if (undefined !== leftChild &&
(undefined === rightChild ||
rightChild.entries.length < leftChild.entries.length)) {
// get from left
child.source = undefined;
leftChild.source = undefined;
child.entries.unshift(this.entries[childIndex - 1]);
child.size++;
this.entries[childIndex - 1] = leftChild.entries.pop();
leftChild.size--;
if (leftChild.hasChildren) {
const shiftChild = leftChild.children.pop();
child.children.unshift(shiftChild);
leftChild.size -= shiftChild.size;
child.size += shiftChild.size;
}
return;
}
// get from right
child.source = undefined;
rightChild.source = undefined;
child.entries.push(this.entries[childIndex]);
child.size++;
this.entries[childIndex] = rightChild.entries.shift();
rightChild.size--;
if (rightChild.hasChildren) {
const shiftChild = rightChild.children.shift();
child.children.push(shiftChild);
rightChild.size -= shiftChild.size;
child.size += shiftChild.size;
}
}
// check whether child at given `childIndex` has gotten too large
// shift to neighbouring children if it is too large so child decreases
normalizeChildDecrease(childIndex) {
const child = this.children[childIndex];
if (child.entries.length <= this.context.maxEntries)
return;
const leftChild = this.children[childIndex - 1];
const rightChild = this.children[childIndex + 1];
if ((undefined === leftChild ||
leftChild.entries.length >= this.context.maxEntries) &&
(undefined === rightChild ||
rightChild.entries.length >= this.context.maxEntries)) {
// need to split child
child.source = undefined;
const index = (child.entries.length >>> 1) + 1;
const preSize = child.size;
const rightEntries = child.entries.splice(index);
const upEntry = child.entries.pop();
let rightChildren = undefined;
if (child.hasChildren) {
rightChildren = child.children.splice(index);
child.size = child.children.reduce((r, c) => r + c.size, child.entries.length);
}
else {
child.size = child.entries.length;
}
const rightSize = preSize - child.size - 1;
const rightNode = this.createNew(undefined, rightEntries, rightChildren, rightSize);
this.entries.splice(childIndex, 0, upEntry);
this.children.splice(childIndex + 1, 0, rightNode);
return;
}
if (undefined !== leftChild &&
(undefined === rightChild ||
rightChild.entries.length >= leftChild.entries.length)) {
// shiftleft
leftChild.source = undefined;
child.source = undefined;
leftChild.entries.push(this.entries[childIndex - 1]);
leftChild.size++;
this.entries[childIndex - 1] = child.entries.shift();
child.size--;
if (child.hasChildren) {
const shiftChild = child.children.shift();
leftChild.children.push(shiftChild);
leftChild.size += shiftChild.size;
child.size -= shiftChild.size;
}
return;
}
rightChild.source = undefined;
child.source = undefined;
rightChild.entries.unshift(this.entries[childIndex]);
rightChild.size++;
this.entries[childIndex] = child.entries.pop();
child.size--;
if (child.hasChildren) {
const shiftChild = child.children.pop();
rightChild.children.unshift(shiftChild);
rightChild.size += shiftChild.size;
child.size -= shiftChild.size;
}
}
/**
* Removes and returns the minimum entry from the builder while keeping
* the internal B‑tree structure valid.
*/
deleteMin() {
this.size--;
if (!this.hasChildren)
return this.entries.shift();
const result = this.children[0].deleteMin();
this.normalizeChildIncrease(0);
return result;
}
/**
* Removes and returns the maximum entry from the builder while keeping
* the internal B‑tree structure valid.
*/
deleteMax() {
this.size--;
if (!this.hasChildren)
return this.entries.pop();
const lastChildIndex = this.children.length - 1;
const result = this.children[lastChildIndex].deleteMax();
this.normalizeChildIncrease(lastChildIndex);
return result;
}
}
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