A Swift Stack class

A Swift Stack class implemented by an internal Swift single linked list class

Stack.playground/Contents.swift

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+//import Cocoa
+
+var str = "Hello, playground"
+
+typealias CStackInt = CStack<Int>
+
+let testStack : CStackInt = CStackInt()
+
+testStack.Push(value: 1)
+testStack.Push(value: 2)
+testStack.Push(value: 3)
+testStack.Push(value: 4)
+testStack.Push(value: 5)
+testStack.Push(value: 6)
+testStack.Push(value: 7)
+testStack.Push(value: 8)
+
+while testStack.Empty() == false {
+    let v = testStack.Peek()
+    print(v ?? "v is nil")
+    let v2 = testStack.Pop()
+    print(v2 ?? "v2 is nil")
+
+}
+

Stack.playground/Sources/CSingleLList.swift

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+//
+//  CSingleLList.swift
+//  LinkList
+//
+//  Created by Zhaohui Xing on 10/26/18.
+//  Copyright © 2018 Zhaohui Xing. All rights reserved.
+//
+import Foundation
+
+//class base sll as reference type
+public class CSingleLinkedList<T : Equatable> { //Equatable for ! operator in line#60
+    var m_Head: CSingleLinkedListNode<T>?
+    var m_Tail: CSingleLinkedListNode<T>?
+
+    init() {
+    }
+
+    public init(head: CSingleLinkedListNode<T>) {
+        self.m_Head = head
+        self.m_Tail = self.m_Head?.tail
+    }
+}
+
+extension CSingleLinkedList {
+    public var head : CSingleLinkedListNode<T>? {
+        get {
+            return m_Head
+        }
+        set (newNode) {
+            m_Head = newNode;
+            m_Tail = newNode?.tail
+        }
+    }
+}
+
+extension CSingleLinkedList {
+    public var tail : CSingleLinkedListNode<T>? {
+        return m_Tail
+    }
+}
+
+extension CSingleLinkedList {
+    public var count : Int {
+        var nCount : Int = 0
+        var cur : CSingleLinkedListNode<T>? = m_Head
+
+        while cur != nil {
+            cur = cur?.next
+            nCount += 1
+        }
+
+        return nCount
+    }
+}
+
+extension CSingleLinkedList {
+    public subscript (value : T) -> CSingleLinkedListNode<T>? {
+        var cur : CSingleLinkedListNode<T>? = m_Head
+
+        while cur != nil && cur!.data != value {
+            cur = cur?.next
+        }
+
+        return cur
+    }
+}
+
+extension CSingleLinkedList {
+    public func reverse() {
+        let prev : CSingleLinkedListNode<T>? = CSingleLinkedListNode<T>(); //This avoid the tail node is nil and while loop cannot go through all nodes
+        prev?.next = m_Head   //prev.next as temperory head shifting cursor
+        let cur : CSingleLinkedListNode<T>? = m_Head //Using cur.next as moving cursor, Note: this approach the orginal head's next is altered after the loop
+
+        while cur?.next != nil {
+            let temp: CSingleLinkedListNode<T>? = cur?.next
+            cur?.next = temp?.next;
+            temp?.next = prev?.next
+            prev?.next = temp
+        }
+        m_Head = prev?.next
+    }
+}
+
+extension CSingleLinkedList {
+    public func reverse2() {
+        let prev : CSingleLinkedListNode<T>? = CSingleLinkedListNode<T>(); //This avoid the tail node is nil and while loop cannot go through all nodes
+        prev?.next = m_Head   //prev.next as temperory head shifting cursor
+        var cur : CSingleLinkedListNode<T>? = m_Head?.next //Using cur as moving cursor
+
+        while cur != nil {
+            let temp: CSingleLinkedListNode<T>? = cur
+            cur = temp?.next;
+            temp?.next = prev?.next
+            prev?.next = temp
+        }
+        m_Head?.next = nil;  //This one need this call, since using cur as moving cursor and orginal head.next is not altered
+        m_Head = prev?.next
+    }
+}
+
+extension CSingleLinkedList {
+    public func iscycled()->(retFlag : Bool, cycleNode:CSingleLinkedListNode<T>?, tailNode:CSingleLinkedListNode<T>?) {
+        var bRet : (retFlag : Bool, cycleNode:CSingleLinkedListNode<T>?, tailNode:CSingleLinkedListNode<T>?) = (false, nil, nil)
+
+        if m_Head != nil {
+            bRet = m_Head!.iscycled()
+        }
+
+        return bRet
+    }
+}
+
+extension CSingleLinkedList {
+    public func AddHead(head: CSingleLinkedListNode<T>) {
+        head.next = m_Head;
+        m_Head = head;
+    }
+}
+
+extension CSingleLinkedList {
+    public func RemoveHead() {
+        m_Head = m_Head?.next;
+    }
+}
+
+extension CSingleLinkedList {
+    public func reverseBetween(start startIndex: Int, end endIndex: Int) {
+        if endIndex <= startIndex {
+            return
+        }
+
+        var cur : CSingleLinkedListNode<T>? = m_Head
+
+        //tempPrev is the start node to swap sequence.
+        var tempPrev : CSingleLinkedListNode<T>? //"?" allowing following calling "tempPrev = nil", otherwise compiling error for it
+        tempPrev = nil
+
+        let steps : Int = (0 < startIndex) ? startIndex-1 : 0
+        for _ in 0...steps {
+            if cur != nil {
+                tempPrev = cur
+                cur = cur?.next;
+            }
+        }
+        if cur == nil {
+            return
+        }
+
+        var tempHead: CSingleLinkedListNode<T>? = cur;
+
+
+        for _ in startIndex...(endIndex-1) {
+            if cur?.next != nil {
+                let temp: CSingleLinkedListNode<T>? = cur?.next
+                cur?.next = temp?.next;
+                temp?.next = tempHead
+                tempHead = temp
+            }
+        }
+
+        if tempPrev != nil {
+           tempPrev?.next = tempHead
+        }
+        else {
+            m_Head = tempHead
+        }
+
+    }
+}
+

Stack.playground/Sources/CStack.swift

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+//
+//  CStack.swift
+//  A stack class implemented by single linkedin list class CSingleList
+//
+//  Created by Zhaohui Xing on 01/02/19.
+//  Copyright © 2019 Zhaohui Xing. All rights reserved.
+//
+import Foundation
+
+public class CStack<T : Equatable> {
+    let m_Container: CSingleLinkedList<T>
+
+    //Make default initializer public to be accessible
+    public init() {
+        m_Container = CSingleLinkedList()
+    }
+}
+
+extension CStack {
+    public func Push(value: T) {
+        let newHead : CSingleLinkedListNode<T> = CSingleLinkedListNode<T>(data:value)
+        m_Container.AddHead(head: newHead)
+    }
+}
+
+extension CStack {
+    public func Pop()->T? {
+        var tempValue : T? //"?" allowing following calling "tempValue = nil", otherwise compiling error for it
+        tempValue = nil
+
+        if m_Container.head != nil {
+            tempValue = m_Container.head?.data
+            m_Container.RemoveHead()
+        }
+
+        return tempValue
+    }
+}
+
+extension CStack {
+    public func Peek()->T? {
+        var tempValue : T? //"?" allowing following calling "tempValue = nil", otherwise compiling error for it
+        tempValue = nil
+
+        if m_Container.head != nil {
+            tempValue = m_Container.head?.data
+        }
+
+        return tempValue
+    }
+}
+
+extension CStack {
+    public func Empty()->Bool {
+        var ret : Bool = true
+
+        if m_Container.head != nil {
+            ret = false
+        }
+        return ret
+    }
+}

Stack.playground/Sources/SingleLLNode.swift

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+//
+//  SingleLList.swift
+//  LinkList
+//
+//  Created by Zhaohui Xing on 10/26/18.
+//  Copyright © 2018 Zhaohui Xing. All rights reserved.
+//
+import Foundation
+
+public class CSingleLinkedListNode<T> {
+    var m_Data: T?
+    var m_Next: CSingleLinkedListNode<T>?
+    var m_Hashvalue : Int64 //The hash value for hash table
+    init() {
+        let m : Int64 = Int64(INT_MAX)
+        let v1 : Int64 = Int64.random(in: 0 ..< m)
+        let v2 : Int64 = Int64.random(in: 0 ..< m)
+
+        m_Hashvalue = v1 ^ v2
+    }
+
+    public init(data: T) {
+        let m : Int64 = Int64(INT_MAX)
+        let v1 : Int64 = Int64.random(in: 0 ..< m)
+        let v2 : Int64 = Int64.random(in: 0 ..< m)
+        m_Hashvalue = v1 ^ v2
+
+        self.m_Data = data
+    }
+
+    public func clone()-> CSingleLinkedListNode<T> {
+        let cloneNode : CSingleLinkedListNode<T> = CSingleLinkedListNode<T>(data: self.data!) //reference type "cloneNode", avoid "mutated warning for var"
+        //cloneNode.next = ((m_Next!) ?? m_Next?.clone() , nil)
+        /*guard let cloneNode.next = self.m_Next?.clone() else
+        {
+            print("Catched the source next nil")
+            cloneNode.next = nil
+        }*/
+        if m_Next != nil
+        {
+            cloneNode.next = self.m_Next!.clone()
+        }
+        return cloneNode
+    }
+}
+
+extension CSingleLinkedListNode {
+    public var data : T? {
+        return m_Data
+    }
+}
+
+extension CSingleLinkedListNode {
+    public var next : CSingleLinkedListNode<T>? {
+        set (newNode) {
+            m_Next = newNode
+        }
+        get {
+            return m_Next
+        }
+    }
+}
+
+extension CSingleLinkedListNode {
+    public var tail : CSingleLinkedListNode<T>? {
+        let ret = iscycled()
+        if ret.retFlag {
+            return ret.tailNode
+        }
+        else {
+            if m_Next != nil {
+                if m_Next?.tail != nil {
+                    return m_Next?.tail
+                }
+                else {
+                    return m_Next
+                }
+            }
+            else {
+                return self;
+            }
+        }
+    }
+}
+
+extension CSingleLinkedListNode { //: Hashable {
+    public var hashValue: Int64 {
+        return m_Hashvalue
+    }
+}
+
+
+extension CSingleLinkedListNode {
+    public func iscycled()->(retFlag : Bool, cycleNode:CSingleLinkedListNode?, tailNode:CSingleLinkedListNode?) {
+        var bRet : Bool = false
+        var cycleNode:CSingleLinkedListNode?
+        var tailNode:CSingleLinkedListNode?
+
+        var hashLut = [Int64: CSingleLinkedListNode]() //hash table by Dictionary
+        var cur : CSingleLinkedListNode<T>? = self;
+
+        cycleNode = nil
+        tailNode = nil
+
+        while cur != nil {
+            if cur!.next != nil && hashLut[cur!.next!.hashValue] != nil {
+                cycleNode = cur!.next!
+                tailNode = cur!
+                bRet = true
+                break
+            }
+            hashLut[cur!.hashValue] = cur
+            cur = cur!.next
+        }
+
+    return (bRet, cycleNode, tailNode);
+    }
+}
+
+

Stack.playground/contents.xcplayground

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+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='macos' executeOnSourceChanges='false'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>