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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
//
//===----------------------------------------------------------------------===//
#if !COLLECTIONS_SINGLE_MODULE
import InternalCollectionsUtilities
#endif
extension TreeSet {
/// Returns a new set with the elements that are common to both this set and
/// the provided other one.
///
/// var a: TreeSet = [1, 2, 3, 4]
/// let b: TreeSet = [0, 2, 4, 6]
/// let c = a.intersection(b)
/// // `c` is some permutation of `[2, 4]`
///
/// The result will only contain instances that were originally in `self`.
/// (This matters if equal members can be distinguished by comparing their
/// identities, or by some other means.)
///
/// - Parameter other: An arbitrary set of elements.
///
/// - Complexity: Expected complexity is O(`self.count`) in
/// the worst case, if `Element` properly implements hashing.
/// However, the implementation is careful to make the best use of
/// hash tree structure to minimize work when possible, e.g. by linking
/// parts of the input trees directly into the result.
@inlinable @inline(__always)
public func intersection(_ other: Self) -> Self {
_intersection(other._root)
}
/// Returns a new set with the elements that are common to both this set and
/// the provided keys view of a persistent dictionary.
///
/// var a: TreeSet = [1, 2, 3, 4]
/// let b: TreeDictionary = [0: "a", 2: "b", 4: "c", 6: "d"]
/// let c = a.intersection(b.keys)
/// // `c` is some permutation of `[2, 4]`
///
/// The result will only contain instances that were originally in `self`.
/// (This matters if equal members can be distinguished by comparing their
/// identities, or by some other means.)
///
/// - Parameter other: The keys view of a persistent dictionary.
///
/// - Complexity: Expected complexity is O(`self.count`) in
/// the worst case, if `Element` properly implements hashing.
/// However, the implementation is careful to make the best use of
/// hash tree structure to minimize work when possible, e.g. by linking
/// parts of the input trees directly into the result.
@inlinable @inline(__always)
public func intersection<Value>(
_ other: TreeDictionary<Element, Value>.Keys
) -> Self {
_intersection(other._base._root)
}
@inlinable
internal func _intersection<V>(_ other: _HashNode<Element, V>) -> Self {
guard let r = _root.intersection(.top, other) else { return self }
return Self(_new: r)
}
/// Returns a new set with the elements that are common to both this set and
/// the provided sequence.
///
/// var a: TreeSet = [1, 2, 3, 4]
/// let b = [0, 2, 4, 6]
/// let c = a.intersection(b)
/// // `c` is some permutation of `[2, 4]`
///
/// The result will only contain instances that were originally in `self`.
/// (This matters if equal members can be distinguished by comparing their
/// identities, or by some other means.)
///
/// - Parameter other: An arbitrary finite sequence of items,
/// possibly containing duplicate values.
@inlinable
public func intersection(
_ other: some Sequence<Element>
) -> Self {
if let other = _specialize(other, for: Self.self) {
return intersection(other)
}
guard let first = self.first else { return Self() }
if other._customContainsEquatableElement(first) != nil {
// Fast path: the sequence has fast containment checks.
return self.filter { other.contains($0) }
}
var result: _Node = ._emptyNode()
for item in other {
let hash = _Hash(item)
if let r = self._root.lookup(.top, item, hash) {
let itemInSelf = _UnsafeHandle.read(r.node) { $0[item: r.slot] }
_ = result.updateValue(.top, forKey: itemInSelf.key, hash) {
$0.initialize(to: itemInSelf)
}
}
}
return Self(_new: result)
}
}
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