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Fixed some missing points in linked list example #5

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Fixed some missing points in linked list example #5

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bb198fc
fix: fix the missing assignment of tail in copyNode(returningCopyOf:)
Apr 28, 2022
aed0196
fix: add the missing copyNodes(returningCopyOf:) in insert(_:, after:)
Apr 28, 2022
3191c09
fix: fix the wrong return value of copyNodes(returningCopyOf:) when …
Apr 28, 2022
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18 changes: 17 additions & 1 deletion 06-linked-list/projects/finished/LinkedList.playground/Contents.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -38,7 +38,7 @@ example(of: "inserting at a particular index") {
print("Before inserting: \(list)")
var middleNode = list.node(at: 1)!
for _ in 1...4 {
middleNode = list.insert(-1, after: middleNode)
middleNode = list.insert(-1, after: middleNode) ?? Node(value: 0)
}
print("After inserting: \(list)")
}
Expand Down Expand Up @@ -129,4 +129,20 @@ example(of: "linked list cow") {
list2.remove(after: node)
}
print("List2: \(list2)")

print("Append node on list2")
list2.append(4)
print("List2: \(list2)")

print("Insert node on list2")
if let node2 = list2.node(at: 0) {
list2.insert(5, after: node2)
}
print("List2: \(list2)")

print("Removing middle node on list2")
if let node3 = list2.node(at: 1) {
list2.remove(after: node3)
}
print("List2: \(list2)")
}
7 changes: 4 additions & 3 deletions 06-linked-list/projects/finished/LinkedList.playground/Sources/LinkedList.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,8 @@ public struct LinkedList<Value> {
}

@discardableResult
public mutating func insert(_ value: Value, after node: Node<Value>) -> Node<Value> {
copyNodes()
public mutating func insert(_ value: Value, after node: Node<Value>) -> Node<Value>? {
guard let node = copyNodes(returningCopyOf: node) else { return nil }
guard tail !== node else {
append(value)
return tail!
Expand Down Expand Up @@ -117,7 +117,7 @@ public struct LinkedList<Value> {

private mutating func copyNodes(returningCopyOf node: Node<Value>?) -> Node<Value>? {
guard !isKnownUniquelyReferenced(&head) else {
return nil
return node
}
guard var oldNode = head else {
return nil
Expand All @@ -135,6 +135,7 @@ public struct LinkedList<Value> {
newNode = newNode!.next
oldNode = nextOldNode
}
tail = newNode

return nodeCopy
}
Expand Down