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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
// FIXME: These are non-standard extensions generalizing ==.
extension TreeSet {
/// Returns a Boolean value indicating whether persistent sets are equal. Two
/// persistent sets are considered equal if they contain the same elements,
/// but not necessarily in the same order.
///
/// - Parameter other: Another set.
///
/// - Returns: `true` if the set is equal to `other`; otherwise, `false`.
///
/// - Complexity: Generally O(`count`), as long as`Element` properly
/// implements hashing. That said, the implementation is careful to take
/// every available shortcut to reduce complexity, e.g. by skipping
/// comparing elements in shared subtrees.
@inlinable
public func isEqualSet(to other: Self) -> Bool {
_root.isEqualSet(to: other._root, by: { _, _ in true })
}
/// Returns a Boolean value indicating whether a persistent set compares equal
/// to the given keys view of a persistent dictionary. The two input
/// collections are considered equal if they contain the same elements,
/// but not necessarily in the same order.
///
/// - Parameter other: The keys view of a persistent dictionary.
///
/// - Returns: `true` if the set contains exactly the same members as `other`;
/// otherwise, `false`.
///
/// - Complexity: Generally O(`count`), as long as`Element` properly
/// implements hashing. That said, the implementation is careful to take
/// every available shortcut to reduce complexity, e.g. by skipping
/// comparing elements in shared subtrees.
@inlinable
public func isEqualSet<Value>(
to other: TreeDictionary<Element, Value>.Keys
) -> Bool {
_root.isEqualSet(to: other._base._root, by: { _, _ in true })
}
/// Returns a Boolean value indicating whether this persistent set contains
/// the same elements as the given `other` sequence, but not necessarily
/// in the same order.
///
/// Duplicate items in `other` do not prevent it from comparing equal to
/// `self`.
///
/// let this: TreeSet = [0, 1, 5, 6]
/// let that = [5, 5, 0, 1, 1, 6, 5, 0, 1, 6, 6, 5]
///
/// this.isEqualSet(to: that) // true
///
/// - Parameter other: The keys view of a persistent dictionary.
///
/// - Returns: `true` if the set contains exactly the same members as `other`;
/// otherwise, `false`. This function does not consider the order of
/// elements and it ignores duplicate items in `other`.
///
/// - Complexity: Generally O(*n*), where *n* is the number of items in
/// `other`, as long as`Element` properly implements hashing.
/// That said, the implementation is careful to take
/// every available shortcut to reduce complexity, e.g. by skipping
/// comparing elements in shared subtrees.
@inlinable
public func isEqualSet(to other: some Sequence<Element>) -> Bool {
if let other = _specialize(other, for: Self.self) {
return isEqualSet(to: other)
}
if self.isEmpty {
return other.allSatisfy { _ in false }
}
if other is _UniqueCollection {
// We don't need to create a temporary set.
guard other.underestimatedCount <= self.count else { return false }
var seen = 0
for item in other {
guard self.contains(item) else { return false }
seen &+= 1
}
precondition(
seen <= self.count,
// Otherwise other.underestimatedCount != other.count
"Invalid Collection '\(type(of: other))' (bad underestimatedCount)")
return seen == self.count
}
// FIXME: Would making this a BitSet of seen positions be better?
var seen: _Node? = ._emptyNode()
var it = other.makeIterator()
while let item = it.next() {
let hash = _Hash(item)
guard self._root.containsKey(.top, item, hash) else { return false }
_ = seen!.insert(.top, (item, ()), hash) // Ignore dupes
if seen!.count == self.count {
// We've seen them all. Stop further accounting.
seen = nil
break
}
}
guard seen == nil else { return false }
while let item = it.next() {
guard self.contains(item) else { return false }
}
return true
}
}
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