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Commit 353b2ae

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Add unit tests for singly and doubly linked list. fix bug with pop where new tail node was not being assigned the proper node as its next prop
1 parent bde2d44 commit 353b2ae

13 files changed

+4981
-42
lines changed

‎dist/datastructures/DoublyLinkedList.js

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -16,7 +16,7 @@ class DoublyLinkedList extends SinglyLinkedList_1.default {
1616
this.pop = () => {
1717
// returns deleted item, O(1) time, unlike SinglyLinkedList's O(n) pop
1818
if (!this.tail)
19-
returnnull;
19+
return;
2020
const oldTail = this.tail;
2121
if (oldTail.prev) {
2222
this.tail = oldTail.prev;
Lines changed: 88 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,88 @@
1+
"use strict";
2+
var __importDefault = (this && this.__importDefault) || function (mod) {
3+
return (mod && mod.__esModule) ? mod : { "default": mod };
4+
};
5+
Object.defineProperty(exports, "__esModule", { value: true });
6+
const DoublyLinkedList_1 = __importDefault(require("./DoublyLinkedList"));
7+
const SinglyLinkedList_test_1 = require("./SinglyLinkedList.test");
8+
function testTraversalDLL(list) {
9+
// backwards traversal
10+
if (!list.tail)
11+
return true; // empty list
12+
let node = list.tail;
13+
let countedLength = 1;
14+
while (node) {
15+
// console.log(node.data)
16+
if (node.prev) {
17+
node = node.prev;
18+
countedLength++;
19+
}
20+
else
21+
break;
22+
}
23+
return (node === list.head && countedLength === list.length);
24+
}
25+
exports.testTraversalDLL = testTraversalDLL;
26+
test('popping from an empty list returns void', () => {
27+
const list = new DoublyLinkedList_1.default();
28+
expect(list.pop()).toBeUndefined();
29+
});
30+
test('shifting from an empty list returns void', () => {
31+
const list = new DoublyLinkedList_1.default();
32+
expect(list.shift()).toBeUndefined();
33+
});
34+
test('pushed node to empty list, node -> new head & tail', () => {
35+
const list = new DoublyLinkedList_1.default();
36+
list.push('value');
37+
expect(list.head.data === 'value' && list.tail.data === 'value').toBe(true);
38+
});
39+
test('unshifting node to empty list, node -> new head & tail', () => {
40+
const list = new DoublyLinkedList_1.default();
41+
list.unshift('value');
42+
expect(list.head.data === 'value' && list.tail.data === 'value').toBe(true);
43+
});
44+
test('insert as 0, or without index, on empty list, node -> new head & tail', () => {
45+
const list = new DoublyLinkedList_1.default();
46+
list.insert('value', 0);
47+
expect(list.head.data === 'value' && list.tail.data === 'value').toBe(true);
48+
});
49+
test('Able to insert in the middle of the list and maintain traversal', () => {
50+
const list = new DoublyLinkedList_1.default();
51+
list.push('Van Gogh');
52+
list.unshift('Matisse');
53+
list.push('Gauguin');
54+
list.unshift('Picasso');
55+
list.insert('Toulouse-Lautrec', 1);
56+
expect(SinglyLinkedList_test_1.testTraverseSLL(list)).toBe(true);
57+
expect(testTraversalDLL(list)).toBe(true);
58+
});
59+
test(`Able to traverse a list mutated by pushes, pops, shifts, unshifts, inserts, and removals all the way from head to tail`, () => {
60+
const list = new DoublyLinkedList_1.default();
61+
for (let i = 1; i < 100; i++) {
62+
if (list.length > 1 && list.head.next === null) {
63+
console.log('caught length inconsistency at: ', i);
64+
console.log(list.log());
65+
throw new Error;
66+
}
67+
if (i % 2 === 0) {
68+
list.push(`push: ${i}`);
69+
}
70+
if (i % 3 === 0) {
71+
list.unshift(`unshift: ${i}`);
72+
}
73+
if (i % 5 === 0) {
74+
list.pop();
75+
}
76+
if (i % 7 === 0) {
77+
list.shift();
78+
}
79+
if (i % 9 === 0) {
80+
list.insert(`insert: ${i}`, Math.floor(Math.random() * list.length));
81+
}
82+
if (i % 11 === 0) {
83+
list.removeIndex(Math.floor(Math.random() * list.length));
84+
}
85+
}
86+
expect(SinglyLinkedList_test_1.testTraverseSLL(list)).toBe(true);
87+
expect(testTraversalDLL(list)).toBe(true);
88+
});

‎dist/datastructures/SinglyLinkedList.js

Lines changed: 57 additions & 17 deletions
Original file line numberDiff line numberDiff line change
@@ -4,8 +4,10 @@ var __importDefault = (this && this.__importDefault) || function (mod) {
44
};
55
Object.defineProperty(exports, "__esModule", { value: true });
66
const Node_1 = __importDefault(require("./Node"));
7+
const IndexError_1 = __importDefault(require("../utils/IndexError"));
78
class SinglyLinkedList {
89
constructor() {
10+
// TODO: use constructor to initiate a filled linked list like you can do with sets?
911
this._length = 0;
1012
this.head = null;
1113
this.tail = null;
@@ -14,7 +16,7 @@ class SinglyLinkedList {
1416
// ? maybe make length a public getter with a private setter so that it's readonly outside
1517
// ? the class, but modifiable inside by the other methods?
1618
// when implemented, tsc error: Getter and setter accessors do not agree in visibility.ts(2379)
17-
// typescript doesn't support this,
19+
// typescript doesn't support this,
1820
// see https://github.com/microsoft/TypeScript/issues/2845
1921
// design meeting notes: https://github.com/microsoft/TypeScript/issues/6735
2022
// instead, i'm using a slightly uglier work around where there is no setter,
@@ -42,42 +44,48 @@ class SinglyLinkedList {
4244
// O(n) time since we have to iterate over the whole list to find the new tail,
4345
// and make the new tail's next point to null.
4446
if (!this.head)
45-
returnnull;
46-
const node = this.head;
47+
return;
48+
let node = this.head;
4749
if (!node.next) {
4850
this.head = null;
4951
this.tail = null;
5052
this._length--;
5153
return node;
5254
}
5355
else {
54-
let childNode = node.next;
55-
while (childNode.next !== null) {
56+
console.assert(this.length > 1);
57+
let targetNode = node.next;
58+
while (targetNode.next !== null) {
5659
// list traversal
57-
childNode = childNode.next;
60+
node = targetNode;
61+
targetNode = targetNode.next;
5862
}
5963
node.next = null;
6064
this.tail = node;
6165
this._length--;
62-
return childNode;
66+
return targetNode;
6367
}
6468
}
6569
unshift(value) {
6670
// add node as first of list
6771
// O(1)
6872
const node = new Node_1.default(value);
69-
if (!this.length)
73+
if (!this.head) {
74+
this.head = node;
7075
this.tail = node;
71-
node.next = this.head;
72-
this.head = node;
76+
}
77+
else {
78+
node.next = this.head;
79+
this.head = node;
80+
}
7381
this._length++;
7482
return this.head;
7583
}
7684
shift() {
7785
// remove first node from list
7886
// O(1)
7987
if (!this.head)
80-
returnnull;
88+
return;
8189
const newHead = this.head.next;
8290
const oldHead = this.head;
8391
oldHead.next = null;
@@ -88,8 +96,8 @@ class SinglyLinkedList {
8896
return oldHead;
8997
}
9098
get(index) {
91-
if (!this.head || (index > this.length -1|| index < 0))
92-
returnnull;
99+
if (!this.head || (index > this.length || index < 0))
100+
thrownewIndexError_1.default;
93101
let counter = 0;
94102
let node = this.head;
95103
while (counter < index) {
@@ -108,8 +116,10 @@ class SinglyLinkedList {
108116
return selectedNode;
109117
}
110118
insert(value, index, options = { prevEnabled: false }) {
111-
if (index > this.length - 1 || index < 0)
112-
return null; // TODO: throw indexError ? user tried to insert at out of range index.
119+
if (!index)
120+
return this.push(value);
121+
if (index > this.length || index < 0)
122+
throw new IndexError_1.default;
113123
if (index === 0)
114124
return this.unshift(value);
115125
if (index === this.length)
@@ -129,8 +139,8 @@ class SinglyLinkedList {
129139
return newNode;
130140
}
131141
removeIndex(index, options = { prevEnabled: false }) {
132-
if (index > this.length -1|| index < 0)
133-
returnnull;
142+
if (index > this.length || index < 0)
143+
thrownewIndexError_1.default;
134144
if (index === 0)
135145
return this.shift();
136146
if (index === this.length - 1)
@@ -148,5 +158,35 @@ class SinglyLinkedList {
148158
this._length--;
149159
return targetNode;
150160
}
161+
log(beginning = 0, end = this.length - 1) {
162+
if ((beginning > this.length - 1 || beginning < 0)
163+
|| (end > this.length - 1 || end < 0))
164+
throw new IndexError_1.default;
165+
let node = this.get(beginning);
166+
let count = beginning;
167+
while (node) {
168+
console.log(`node ${count}`, node);
169+
if (node.next) {
170+
node = node.next;
171+
count++;
172+
}
173+
else
174+
return;
175+
}
176+
}
177+
toString(beginning = 0, end = this.length - 1) {
178+
if ((beginning > this.length - 1 || beginning < 0)
179+
|| (end > this.length - 1 || end < 0))
180+
throw new IndexError_1.default;
181+
let node = this.get(beginning);
182+
while (node) {
183+
console.log(node.data);
184+
if (node.next) {
185+
node = node.next;
186+
}
187+
else
188+
return;
189+
}
190+
}
151191
}
152192
exports.default = SinglyLinkedList;
Lines changed: 84 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,84 @@
1+
"use strict";
2+
var __importDefault = (this && this.__importDefault) || function (mod) {
3+
return (mod && mod.__esModule) ? mod : { "default": mod };
4+
};
5+
Object.defineProperty(exports, "__esModule", { value: true });
6+
const SinglyLinkedList_1 = __importDefault(require("./SinglyLinkedList"));
7+
function testTraverseSLL(list) {
8+
if (!list.head)
9+
return true; // empty list
10+
let node = list.head;
11+
let countedLength = 1;
12+
while (node) {
13+
// console.log(node.data)
14+
if (node.next) {
15+
node = node.next;
16+
countedLength++;
17+
}
18+
else
19+
break;
20+
}
21+
return (node === list.tail && countedLength === list.length);
22+
}
23+
exports.testTraverseSLL = testTraverseSLL;
24+
test('popping from an empty list returns void', () => {
25+
const list = new SinglyLinkedList_1.default();
26+
expect(list.pop()).toBeUndefined();
27+
});
28+
test('shifting from an empty list returns void', () => {
29+
const list = new SinglyLinkedList_1.default();
30+
expect(list.shift()).toBeUndefined();
31+
});
32+
test('pushed node to empty list, node -> new head & tail', () => {
33+
const list = new SinglyLinkedList_1.default();
34+
list.push('value');
35+
expect(list.head.data === 'value' && list.tail.data === 'value').toBe(true);
36+
});
37+
test('unshifting node to empty list, node -> new head & tail', () => {
38+
const list = new SinglyLinkedList_1.default();
39+
list.unshift('value');
40+
expect(list.head.data === 'value' && list.tail.data === 'value').toBe(true);
41+
});
42+
test('insert as 0, or without index, on empty list, node -> new head & tail', () => {
43+
const list = new SinglyLinkedList_1.default();
44+
list.insert('value', 0);
45+
expect(list.head.data === 'value' && list.tail.data === 'value').toBe(true);
46+
});
47+
test('Able to insert in the middle of the list and maintain traversal', () => {
48+
const list = new SinglyLinkedList_1.default();
49+
list.push('Van Gogh');
50+
list.unshift('Matisse');
51+
list.push('Gauguin');
52+
list.unshift('Picasso');
53+
list.insert('Toulouse-Lautrec', 1);
54+
expect(testTraverseSLL(list)).toBe(true);
55+
});
56+
test(`Able to traverse a list mutated by pushes, pops, shifts, unshifts, inserts, and removals all the way from head to tail`, () => {
57+
const list = new SinglyLinkedList_1.default();
58+
for (let i = 1; i < 100; i++) {
59+
if (list.length > 1 && list.head.next === null) {
60+
console.log('caught length inconsistency at: ', i);
61+
console.log(list.log());
62+
throw new Error;
63+
}
64+
if (i % 2 === 0) {
65+
list.push(`push: ${i}`);
66+
}
67+
if (i % 3 === 0) {
68+
list.unshift(`unshift: ${i}`);
69+
}
70+
if (i % 5 === 0) {
71+
list.pop();
72+
}
73+
if (i % 7 === 0) {
74+
list.shift();
75+
}
76+
if (i % 9 === 0) {
77+
list.insert(`insert: ${i}`, Math.floor(Math.random() * list.length));
78+
}
79+
if (i % 11 === 0) {
80+
list.removeIndex(Math.floor(Math.random() * list.length));
81+
}
82+
}
83+
expect(testTraverseSLL(list)).toBe(true);
84+
});

‎dist/utils/IndexError.js

Lines changed: 5 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,5 @@
1+
"use strict";
2+
Object.defineProperty(exports, "__esModule", { value: true });
3+
class IndexError extends Error {
4+
}
5+
exports.default = IndexError;

‎jest.config.js

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,3 @@
1+
module.exports = {
2+
rootDir: './dist',
3+
};

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