From 55b722595252e492e86e7bf3fd1223d8c62fb01d Mon Sep 17 00:00:00 2001
From: Hannes Kuchelmeister <hannes@kuchelmeister.org>
Date: Thu, 31 Dec 2020 15:33:21 +0100
Subject: [PATCH] implement lazy list

---
 Assignment_2/LazyList.cpp | 91 +++++++++++++++++++++++++++++++++++++++
 Assignment_2/Node.cpp     |  2 +
 2 files changed, 93 insertions(+)
 create mode 100644 Assignment_2/LazyList.cpp

diff --git a/Assignment_2/LazyList.cpp b/Assignment_2/LazyList.cpp
new file mode 100644
index 0000000..32dc305
--- /dev/null
+++ b/Assignment_2/LazyList.cpp
@@ -0,0 +1,91 @@
+#include <bits/stdc++.h>
+
+#include"Node.cpp"
+
+class LazySet {
+    protected:
+        Node* first;
+        std::tuple<Node*, Node*> locate(int element);
+    
+    public:
+        LazySet();
+        bool add(int element);
+        bool rmv(int element);
+        bool ctn(int element);
+};
+
+LazySet::LazySet(){
+    first = Node::Dummy(); // dummy node;
+    Node* last = Node::Dummy();
+    first->next = last;
+}
+
+bool LazySet::add(int element) {
+    auto tuple = locate(element);
+    Node* p = std::get<0>(tuple);
+    Node* c = std::get<1>(tuple);
+
+    if (c->is_equal(element)) {
+        p->unlock();
+        c->unlock();
+        return false;
+    } else  {
+        Node* n = new Node(element);
+        p->next = n;
+
+        p->unlock();
+        c->unlock();
+        return true;
+    }
+}
+bool LazySet::rmv(int element) {
+    auto tuple = locate(element);
+    Node* p = std::get<0>(tuple);
+    Node* c = std::get<1>(tuple);
+
+    if (c->is_equal(element)) {
+        c->deleted = true;
+        p->next = c->next;
+
+        p->unlock();
+        c->unlock();
+        return true;
+    } else  {
+        p->unlock();
+        c->unlock();
+        return false;
+    }
+}
+bool LazySet::ctn(int element) {
+    Node* c = first;
+    while (c->is_smaller_than(element)) {
+        c = c->next;
+    }
+    if (!c->is_equal(element) || c->deleted) {
+        return false;
+    } else {
+        return true;
+    }
+}
+
+
+std::tuple<Node*, Node*> LazySet::locate(int element) {
+    Node* p = first;
+    Node* c = p->next;
+
+    while (c->is_smaller_than(element)) {
+        p = c;
+        c = c->next;
+    }
+    p->lock();
+    c->lock();
+    if (!p->deleted && !c->deleted && p->next == c) {
+        p->unlock();
+        c->unlock();
+        return {p, c};
+    }
+    
+    p->unlock();
+    c->unlock();
+    return {Node::Dummy(), Node::Dummy()};
+}
\ No newline at end of file
diff --git a/Assignment_2/Node.cpp b/Assignment_2/Node.cpp
index 75f33b4..c2b110e 100644
--- a/Assignment_2/Node.cpp
+++ b/Assignment_2/Node.cpp
@@ -8,6 +8,7 @@ class Node {
 
     public:
         Node* next;
+        bool deleted;
 
         Node(int element);
         static Node* Dummy();
@@ -24,6 +25,7 @@ class Node {
 Node::Node(int element){
     data = element;
     is_dummy = false;
+    deleted = false;
 }
 
 Node* Node::Dummy(){