-
Notifications
You must be signed in to change notification settings - Fork 107
/
LinkedList.sol
210 lines (192 loc) · 4.89 KB
/
LinkedList.sol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
pragma solidity ^0.6.0;
/**
* @title LinkedList
* @dev Data structure
* @author Alberto Cuesta Cañada
*/
contract LinkedList {
event ObjectCreated(uint256 id, address data);
event ObjectsLinked(uint256 prev, uint256 next);
event ObjectRemoved(uint256 id);
event NewHead(uint256 id);
struct Object{
uint256 id;
uint256 next;
address data;
}
uint256 public head;
uint256 public idCounter;
mapping (uint256 => Object) public objects;
/**
* @dev Creates an empty list.
*/
constructor() public {
head = 0;
idCounter = 1;
}
/**
* @dev Retrieves the Object denoted by `_id`.
*/
function get(uint256 _id)
public
virtual
view
returns (uint256, uint256, address)
{
Object memory object = objects[_id];
return (object.id, object.next, object.data);
}
/**
* @dev Given an Object, denoted by `_id`, returns the id of the Object that points to it, or 0 if `_id` refers to the Head.
*/
function findPrevId(uint256 _id)
public
virtual
view
returns (uint256)
{
if (_id == head) return 0;
Object memory prevObject = objects[head];
while (prevObject.next != _id) {
prevObject = objects[prevObject.next];
}
return prevObject.id;
}
/**
* @dev Returns the id for the Tail.
*/
function findTailId()
public
virtual
view
returns (uint256)
{
Object memory oldTailObject = objects[head];
while (oldTailObject.next != 0) {
oldTailObject = objects[oldTailObject.next];
}
return oldTailObject.id;
}
/**
* @dev Return the id of the first Object matching `_data` in the data field.
*/
function findIdForData(address _data)
public
virtual
view
returns (uint256)
{
Object memory object = objects[head];
while (object.data != _data) {
object = objects[object.next];
}
return object.id;
}
/**
* @dev Insert a new Object as the new Head with `_data` in the data field.
*/
function addHead(address _data)
public
virtual
{
uint256 objectId = _createObject(_data);
_link(objectId, head);
_setHead(objectId);
}
/**
* @dev Insert a new Object as the new Tail with `_data` in the data field.
*/
function addTail(address _data)
public
virtual
{
if (head == 0) {
addHead(_data);
}
else {
uint256 oldTailId = findTailId();
uint256 newTailId = _createObject(_data);
_link(oldTailId, newTailId);
}
}
/**
* @dev Remove the Object denoted by `_id` from the List.
*/
function remove(uint256 _id)
public
virtual
{
Object memory removeObject = objects[_id];
if (head == _id) {
_setHead(removeObject.next);
}
else {
uint256 prevObjectId = findPrevId(_id);
_link(prevObjectId, removeObject.next);
}
delete objects[removeObject.id];
emit ObjectRemoved(_id);
}
/**
* @dev Insert a new Object after the Object denoted by `_id` with `_data` in the data field.
*/
function insertAfter(uint256 _prevId, address _data)
public
virtual
{
Object memory prevObject = objects[_prevId];
uint256 newObjectId = _createObject(_data);
_link(newObjectId, prevObject.next);
_link(prevObject.id, newObjectId);
}
/**
* @dev Insert a new Object before the Object denoted by `_id` with `_data` in the data field.
*/
function insertBefore(uint256 _nextId, address _data)
public
virtual
{
if (_nextId == head) {
addHead(_data);
}
else {
uint256 prevId = findPrevId(_nextId);
insertAfter(prevId, _data);
}
}
/**
* @dev Internal function to update the Head pointer.
*/
function _setHead(uint256 _id)
internal
{
head = _id;
emit NewHead(_id);
}
/**
* @dev Internal function to create an unlinked Object.
*/
function _createObject(address _data)
internal
returns (uint256)
{
uint256 newId = idCounter;
idCounter += 1;
Object memory object = Object(newId, 0, _data);
objects[object.id] = object;
emit ObjectCreated(
object.id,
object.data
);
return object.id;
}
/**
* @dev Internal function to link an Object to another.
*/
function _link(uint256 _prevId, uint256 _nextId)
internal
{
objects[_prevId].next = _nextId;
emit ObjectsLinked(_prevId, _nextId);
}
}