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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Collections open source project
//
// Copyright (c) 2022 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
extension _HashNode {
@inlinable
internal func symmetricDifference<Value2>(
_ level: _HashLevel,
_ other: _HashNode<Key, Value2>
) -> _HashNode<Key, Void>.Builder? {
guard self.count > 0 else {
return .init(level, other.mapValuesToVoid())
}
guard other.count > 0 else { return nil }
return _symmetricDifference(level, other)
}
@inlinable
internal func _symmetricDifference<Value2>(
_ level: _HashLevel,
_ other: _HashNode<Key, Value2>
) -> _HashNode<Key, Void>.Builder {
typealias VoidNode = _HashNode<Key, Void>
assert(self.count > 0 && other.count > 0)
if self.raw.storage === other.raw.storage {
return .empty(level)
}
if self.isCollisionNode || other.isCollisionNode {
return _symmetricDifference_slow(level, other)
}
return self.read { l in
other.read { r in
var result: VoidNode.Builder = .empty(level)
for (bucket, lslot) in l.itemMap {
let lp = l.itemPtr(at: lslot)
if r.itemMap.contains(bucket) {
let rslot = r.itemMap.slot(of: bucket)
let rp = r.itemPtr(at: rslot)
if lp.pointee.key != rp.pointee.key {
let h1 = _Hash(lp.pointee.key)
let h2 = _Hash(rp.pointee.key)
let child = VoidNode.build(
level: level.descend(),
item1: (lp.pointee.key, ()), h1,
item2: { $0.initialize(to: (rp.pointee.key, ())) }, h2)
result.addNewChildNode(level, child.top, at: bucket)
}
}
else if r.childMap.contains(bucket) {
let rslot = r.childMap.slot(of: bucket)
let rp = r.childPtr(at: rslot)
let h = _Hash(lp.pointee.key)
let child = rp.pointee
.removing(level.descend(), lp.pointee.key, h)?.replacement
if let child = child {
let child = child.mapValuesToVoid()
result.addNewChildBranch(level, child, at: bucket)
}
else {
var child2 = rp.pointee
.mapValuesToVoid(
copy: true, extraBytes: VoidNode.spaceForNewItem)
let r = child2.insert(level.descend(), (lp.pointee.key, ()), h)
assert(r.inserted)
result.addNewChildNode(level, child2, at: bucket)
}
}
else {
result.addNewItem(level, (lp.pointee.key, ()), at: bucket)
}
}
for (bucket, lslot) in l.childMap {
let lp = l.childPtr(at: lslot)
if r.itemMap.contains(bucket) {
let rslot = r.itemMap.slot(of: bucket)
let rp = r.itemPtr(at: rslot)
let h = _Hash(rp.pointee.key)
let child = lp.pointee
.mapValuesToVoid()
.removing(level.descend(), rp.pointee.key, h)?.replacement
if let child = child {
result.addNewChildBranch(level, child, at: bucket)
}
else {
var child2 = lp.pointee.mapValuesToVoid(
copy: true, extraBytes: VoidNode.spaceForNewItem)
let r2 = child2.insert(level.descend(), (rp.pointee.key, ()), h)
assert(r2.inserted)
result.addNewChildNode(level, child2, at: bucket)
}
}
else if r.childMap.contains(bucket) {
let rslot = r.childMap.slot(of: bucket)
let b = l[child: lslot]._symmetricDifference(
level.descend(), r[child: rslot])
result.addNewChildBranch(level, b, at: bucket)
}
else {
result.addNewChildNode(
level, lp.pointee.mapValuesToVoid(), at: bucket)
}
}
let seen = l.itemMap.union(l.childMap)
for (bucket, rslot) in r.itemMap {
guard !seen.contains(bucket) else { continue }
result.addNewItem(level, (r[item: rslot].key, ()), at: bucket)
}
for (bucket, rslot) in r.childMap {
guard !seen.contains(bucket) else { continue }
result.addNewChildNode(
level, r[child: rslot].mapValuesToVoid(), at: bucket)
}
return result
}
}
}
@inlinable @inline(never)
internal func _symmetricDifference_slow<Value2>(
_ level: _HashLevel,
_ other: _HashNode<Key, Value2>
) -> _HashNode<Key, Void>.Builder {
switch (self.isCollisionNode, other.isCollisionNode) {
case (true, true):
return self._symmetricDifference_slow_both(level, other)
case (true, false):
return self._symmetricDifference_slow_left(level, other)
case (false, _):
return other._symmetricDifference_slow_left(level, self)
}
}
@inlinable
internal func _symmetricDifference_slow_both<Value2>(
_ level: _HashLevel,
_ other: _HashNode<Key, Value2>
) -> _HashNode<Key, Void>.Builder {
typealias VoidNode = _HashNode<Key, Void>
return read { l in
other.read { r in
guard l.collisionHash == r.collisionHash else {
let node = VoidNode.build(
level: level,
child1: self.mapValuesToVoid(), l.collisionHash,
child2: other.mapValuesToVoid(), r.collisionHash)
return .node(level, node)
}
var result: VoidNode.Builder = .empty(level)
let ritems = r.reverseItems
for ls: _HashSlot in stride(from: .zero, to: l.itemsEndSlot, by: 1) {
let lp = l.itemPtr(at: ls)
let include = !ritems.contains(where: { $0.key == lp.pointee.key })
if include {
result.addNewCollision(level, (lp.pointee.key, ()), l.collisionHash)
}
}
// FIXME: Consider remembering slots of shared items in r by
// caching them in a bitset.
let litems = l.reverseItems
for rs: _HashSlot in stride(from: .zero, to: r.itemsEndSlot, by: 1) {
let rp = r.itemPtr(at: rs)
let include = !litems.contains(where: { $0.key == rp.pointee.key })
if include {
result.addNewCollision(level, (rp.pointee.key, ()), r.collisionHash)
}
}
return result
}
}
}
@inlinable
internal func _symmetricDifference_slow_left<Value2>(
_ level: _HashLevel,
_ other: _HashNode<Key, Value2>
) -> _HashNode<Key, Void>.Builder {
typealias VoidNode = _HashNode<Key, Void>
// `self` is a collision node on a compressed path. The other tree might
// have the same set of collisions, just expanded a bit deeper.
return read { l in
other.read { r in
assert(l.isCollisionNode && !r.isCollisionNode)
let bucket = l.collisionHash[level]
if r.itemMap.contains(bucket) {
let rslot = r.itemMap.slot(of: bucket)
let rp = r.itemPtr(at: rslot)
let rh = _Hash(rp.pointee.key)
guard rh == l.collisionHash else {
var copy = other.mapValuesToVoid(
copy: true, extraBytes: VoidNode.spaceForSpawningChild)
let item = copy.removeItem(at: bucket, rslot)
let child = VoidNode.build(
level: level.descend(),
item1: { $0.initialize(to: (item.key, ())) }, rh,
child2: self.mapValuesToVoid(), l.collisionHash)
copy.insertChild(child.top, bucket)
return .node(level, copy)
}
let litems = l.reverseItems
if let li = litems.firstIndex(where: { $0.key == rp.pointee.key }) {
if l.itemCount == 2 {
var node = other.mapValuesToVoid(copy: true)
node.replaceItem(
at: bucket, rslot,
with: (litems[1 &- li].key, ()))
return .node(level, node)
}
let lslot = _HashSlot(litems.count &- 1 &- li)
var child = self.mapValuesToVoid(copy: true)
_ = child.removeItem(at: .invalid, lslot)
if other.hasSingletonItem {
// Compression
return .collisionNode(level, child)
}
var node = other.mapValuesToVoid(
copy: true, extraBytes: VoidNode.spaceForSpawningChild)
_ = node.removeItem(at: bucket, rslot)
node.insertChild(child, bucket)
return .node(level, node)
}
if other.hasSingletonItem {
// Compression
var copy = self.mapValuesToVoid(
copy: true, extraBytes: VoidNode.spaceForNewItem)
_ = copy.ensureUniqueAndAppendCollision(
isUnique: true,
(r[item: .zero].key, ()))
return .collisionNode(level, copy)
}
var node = other.mapValuesToVoid(
copy: true, extraBytes: VoidNode.spaceForSpawningChild)
let item = node.removeItem(at: bucket, rslot)
var child = self.mapValuesToVoid(
copy: true, extraBytes: VoidNode.spaceForNewItem)
_ = child.ensureUniqueAndAppendCollision(
isUnique: true, (item.key, ()))
node.insertChild(child, bucket)
return .node(level, node)
}
if r.childMap.contains(bucket) {
let rslot = r.childMap.slot(of: bucket)
let rp = r.childPtr(at: rslot)
let child = rp.pointee._symmetricDifference(level.descend(), self)
return other
.mapValuesToVoid()
.replacingChild(level, at: bucket, rslot, with: child)
}
var node = other
.mapValuesToVoid(copy: true, extraBytes: VoidNode.spaceForNewChild)
node.insertChild(self.mapValuesToVoid(), bucket)
return .node(level, node)
}
}
}
}
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