Add a custom stringifier to linked lists (#5)

Kevin K. Lee · web-flow · commit 81754b71d9e1 · 2018-08-05T16:51:46.000-04:00
* Update singly linked list exercise to accept custom stringifier

* Update doubly linked list exercise to accept custom stringifier
diff --git a/skeletons/data-structures/doubly-linked-list/DoublyLinkedList.js b/skeletons/data-structures/doubly-linked-list/DoublyLinkedList.js
@@ -61,7 +61,7 @@ export default class DoublyLinkedList {
    * @param {function} [callback]
    * @return {string}
    */
-  toString() {
-    return this.toArray().map(node => node.toString()).toString();
+  toString(callback) {
+    return this.toArray().map(node => node.toString(callback)).toString();
   }
 }
diff --git a/skeletons/data-structures/doubly-linked-list/DoublyLinkedListNode.js b/skeletons/data-structures/doubly-linked-list/DoublyLinkedListNode.js
@@ -3,7 +3,7 @@ export default class DoublyLinkedListNode {
     this.value = value;
   }
 
-  toString() {
-    return this.value.toString();
+  toString(callback) {
+    return callback ? callback(this.value) : `${this.value}`;
   }
 }
diff --git a/skeletons/data-structures/doubly-linked-list/__test__/DoublyLinkedList.test.js b/skeletons/data-structures/doubly-linked-list/__test__/DoublyLinkedList.test.js
@@ -199,4 +199,25 @@ describe('DoublyLinkedList', () => {
     expect(linkedList.head).toBeNull();
     expect(linkedList.tail).toBeNull();
   });
+
+  it('should be possible to store objects in the list and to print them out', () => {
+    const linkedList = new DoublyLinkedList();
+
+    const nodeValue1 = {
+      value: 1,
+      key: 'key1',
+    };
+    const nodeValue2 = {
+      value: 2,
+      key: 'key2',
+    };
+
+    linkedList
+      .append(nodeValue1)
+      .prepend(nodeValue2);
+
+    const nodeStringifier = value => `${value.key}:${value.value}`;
+
+    expect(linkedList.toString(nodeStringifier)).toBe('key2:2,key1:1');
+  });
 });
diff --git a/skeletons/data-structures/doubly-linked-list/__test__/DoublyLinkedListNode.test.js b/skeletons/data-structures/doubly-linked-list/__test__/DoublyLinkedListNode.test.js
@@ -47,4 +47,16 @@ describe('DoublyLinkedListNode', () => {
     node.value = 'string value';
     expect(node.toString()).toBe('string value');
   });
+
+  it('should convert node to string with custom stringifier', () => {
+    const nodeValue = {
+      value: 1,
+      key: 'test'
+    };
+
+    const node = new DoublyLinkedListNode(nodeValue);
+    const toStringCallback = value => `value: ${value.value}, key: ${value.key}`;
+
+    expect(node.toString(toStringCallback)).toBe('value: 1, key: test');
+  });
 });
diff --git a/skeletons/data-structures/linked-list/LinkedList.js b/skeletons/data-structures/linked-list/LinkedList.js
@@ -66,7 +66,7 @@ export default class LinkedList {
    * @param {function} [callback]
    * @return {string}
    */
-  toString() {
-    return this.toArray().map(node => node.toString()).toString();
+  toString(callback) {
+    return this.toArray().map(node => node.toString(callback)).toString();
   }
 }
diff --git a/skeletons/data-structures/linked-list/LinkedListNode.js b/skeletons/data-structures/linked-list/LinkedListNode.js
@@ -3,7 +3,7 @@ export default class LinkedListNode {
     this.value = value;
   }
 
-  toString() {
-    return this.value.toString();
+  toString(callback) {
+    return callback ? callback(this.value) : `${this.value}`;
   }
 }
diff --git a/skeletons/data-structures/linked-list/__test__/LinkedListNode.test.js b/skeletons/data-structures/linked-list/__test__/LinkedListNode.test.js
@@ -38,4 +38,16 @@ describe('LinkedListNode', () => {
     node.value = 'string value';
     expect(node.toString()).toBe('string value');
   });
+
+  it('should convert node to string with custom stringifier', () => {
+    const nodeValue = {
+      value: 1,
+      key: 'test'
+    };
+
+    const node = new LinkedListNode(nodeValue);
+    const toStringCallback = value => `value: ${value.value}, key: ${value.key}`;
+
+    expect(node.toString(toStringCallback)).toBe('value: 1, key: test');
+  });
 });
diff --git a/solutions/data-structures/doubly-linked-list/DoublyLinkedList.js b/solutions/data-structures/doubly-linked-list/DoublyLinkedList.js
@@ -161,7 +161,7 @@ export default class DoublyLinkedList {
    * @param {function} [callback]
    * @return {string}
    */
-  toString() {
-    return this.toArray().map(node => node.toString()).toString();
+  toString(callback) {
+    return this.toArray().map(node => node.toString(callback)).toString();
   }
 }
diff --git a/solutions/data-structures/doubly-linked-list/DoublyLinkedListNode.js b/solutions/data-structures/doubly-linked-list/DoublyLinkedListNode.js
@@ -5,7 +5,7 @@ export default class DoublyLinkedListNode {
     this.previous = previous;
   }
 
-  toString() {
-    return this.value.toString();
+  toString(callback) {
+    return callback ? callback(this.value) : `${this.value}`;
   }
 }
diff --git a/solutions/data-structures/doubly-linked-list/__test__/DoublyLinkedList.test.js b/solutions/data-structures/doubly-linked-list/__test__/DoublyLinkedList.test.js
@@ -199,4 +199,25 @@ describe('DoublyLinkedList', () => {
     expect(linkedList.head).toBeNull();
     expect(linkedList.tail).toBeNull();
   });
+
+  it('should be possible to store objects in the list and to print them out', () => {
+    const linkedList = new DoublyLinkedList();
+
+    const nodeValue1 = {
+      value: 1,
+      key: 'key1',
+    };
+    const nodeValue2 = {
+      value: 2,
+      key: 'key2',
+    };
+
+    linkedList
+      .append(nodeValue1)
+      .prepend(nodeValue2);
+
+    const nodeStringifier = value => `${value.key}:${value.value}`;
+
+    expect(linkedList.toString(nodeStringifier)).toBe('key2:2,key1:1');
+  });
 });
diff --git a/solutions/data-structures/doubly-linked-list/__test__/DoublyLinkedListNode.test.js b/solutions/data-structures/doubly-linked-list/__test__/DoublyLinkedListNode.test.js
@@ -47,4 +47,16 @@ describe('DoublyLinkedListNode', () => {
     node.value = 'string value';
     expect(node.toString()).toBe('string value');
   });
+
+  it('should convert node to string with custom stringifier', () => {
+    const nodeValue = {
+      value: 1,
+      key: 'test'
+    };
+
+    const node = new DoublyLinkedListNode(nodeValue);
+    const toStringCallback = value => `value: ${value.value}, key: ${value.key}`;
+
+    expect(node.toString(toStringCallback)).toBe('value: 1, key: test');
+  });
 });
diff --git a/solutions/data-structures/linked-list/LinkedList.js b/solutions/data-structures/linked-list/LinkedList.js
@@ -198,7 +198,7 @@ export default class LinkedList {
    * @param {function} [callback]
    * @return {string}
    */
-  toString() {
-    return this.toArray().map(node => node.toString()).toString();
+  toString(callback) {
+    return this.toArray().map(node => node.toString(callback)).toString();
   }
 }
diff --git a/solutions/data-structures/linked-list/LinkedListNode.js b/solutions/data-structures/linked-list/LinkedListNode.js
@@ -1,9 +1,10 @@
 export default class LinkedListNode {
   constructor(value, next = null) {
     this.value = value;
+    this.next = next;
   }
 
-  toString() {
-    return this.value.toString();
+  toString(callback) {
+    return callback ? callback(this.value) : `${this.value}`;
   }
 }
diff --git a/solutions/data-structures/linked-list/__test__/LinkedListNode.test.js b/solutions/data-structures/linked-list/__test__/LinkedListNode.test.js
@@ -38,4 +38,16 @@ describe('LinkedListNode', () => {
     node.value = 'string value';
     expect(node.toString()).toBe('string value');
   });
+
+  it('should convert node to string with custom stringifier', () => {
+    const nodeValue = {
+      value: 1,
+      key: 'test'
+    };
+
+    const node = new LinkedListNode(nodeValue);
+    const toStringCallback = value => `value: ${value.value}, key: ${value.key}`;
+
+    expect(node.toString(toStringCallback)).toBe('value: 1, key: test');
+  });
 });
diff --git a/src/data-structures/doubly-linked-list/DoublyLinkedList.js b/src/data-structures/doubly-linked-list/DoublyLinkedList.js
@@ -61,7 +61,7 @@ export default class DoublyLinkedList {
    * @param {function} [callback]
    * @return {string}
    */
-  toString() {
-    return this.toArray().map(node => node.toString()).toString();
+  toString(callback) {
+    return this.toArray().map(node => node.toString(callback)).toString();
   }
 }
diff --git a/src/data-structures/doubly-linked-list/DoublyLinkedListNode.js b/src/data-structures/doubly-linked-list/DoublyLinkedListNode.js
@@ -3,7 +3,7 @@ export default class DoublyLinkedListNode {
     this.value = value;
   }
 
-  toString() {
-    return this.value.toString();
+  toString(callback) {
+    return callback ? callback(this.value) : `${this.value}`;
   }
 }
diff --git a/src/data-structures/doubly-linked-list/__test__/DoublyLinkedList.test.js b/src/data-structures/doubly-linked-list/__test__/DoublyLinkedList.test.js
@@ -199,4 +199,25 @@ describe('DoublyLinkedList', () => {
     expect(linkedList.head).toBeNull();
     expect(linkedList.tail).toBeNull();
   });
+
+  it('should be possible to store objects in the list and to print them out', () => {
+    const linkedList = new DoublyLinkedList();
+
+    const nodeValue1 = {
+      value: 1,
+      key: 'key1',
+    };
+    const nodeValue2 = {
+      value: 2,
+      key: 'key2',
+    };
+
+    linkedList
+      .append(nodeValue1)
+      .prepend(nodeValue2);
+
+    const nodeStringifier = value => `${value.key}:${value.value}`;
+
+    expect(linkedList.toString(nodeStringifier)).toBe('key2:2,key1:1');
+  });
 });
diff --git a/src/data-structures/doubly-linked-list/__test__/DoublyLinkedListNode.test.js b/src/data-structures/doubly-linked-list/__test__/DoublyLinkedListNode.test.js
@@ -47,4 +47,16 @@ describe('DoublyLinkedListNode', () => {
     node.value = 'string value';
     expect(node.toString()).toBe('string value');
   });
+
+  it('should convert node to string with custom stringifier', () => {
+    const nodeValue = {
+      value: 1,
+      key: 'test'
+    };
+
+    const node = new DoublyLinkedListNode(nodeValue);
+    const toStringCallback = value => `value: ${value.value}, key: ${value.key}`;
+
+    expect(node.toString(toStringCallback)).toBe('value: 1, key: test');
+  });
 });
diff --git a/src/data-structures/linked-list/LinkedList.js b/src/data-structures/linked-list/LinkedList.js
@@ -66,7 +66,7 @@ export default class LinkedList {
    * @param {function} [callback]
    * @return {string}
    */
-  toString() {
-    return this.toArray().map(node => node.toString()).toString();
+  toString(callback) {
+    return this.toArray().map(node => node.toString(callback)).toString();
   }
 }
diff --git a/src/data-structures/linked-list/LinkedListNode.js b/src/data-structures/linked-list/LinkedListNode.js
@@ -4,7 +4,7 @@ export default class LinkedListNode {
     this.next = next;
   }
 
-  toString() {
-    return this.value.toString();
+  toString(callback) {
+    return callback ? callback(this.value) : `${this.value}`;
   }
 }
diff --git a/src/data-structures/linked-list/__test__/LinkedListNode.test.js b/src/data-structures/linked-list/__test__/LinkedListNode.test.js
@@ -38,4 +38,16 @@ describe('LinkedListNode', () => {
     node.value = 'string value';
     expect(node.toString()).toBe('string value');
   });
+
+  it('should convert node to string with custom stringifier', () => {
+    const nodeValue = {
+      value: 1,
+      key: 'test'
+    };
+
+    const node = new LinkedListNode(nodeValue);
+    const toStringCallback = value => `value: ${value.value}, key: ${value.key}`;
+
+    expect(node.toString(toStringCallback)).toBe('value: 1, key: test');
+  });
 });

Original file line number	Diff line number	Diff line change
`@@ -61,7 +61,7 @@ export default class DoublyLinkedList {`
`61`	`61`	`* @param {function} [callback]`
`62`	`62`	`* @return {string}`
`63`	`63`	`*/`
`64`		`- toString() {`
`65`		`- return this.toArray().map(node => node.toString()).toString();`
	`64`	`+ toString(callback) {`
	`65`	`+ return this.toArray().map(node => node.toString(callback)).toString();`
`66`	`66`	`}`
`67`	`67`	`}`
Original file line number	Diff line number	Diff line change
`@@ -3,7 +3,7 @@ export default class DoublyLinkedListNode {`
`3`	`3`	`this.value = value;`
`4`	`4`	`}`
`5`	`5`
`6`		`- toString() {`
`7`		`- return this.value.toString();`
	`6`	`+ toString(callback) {`
	`7`	+ return callback ? callback(this.value) : `${this.value}`;
`8`	`8`	`}`
`9`	`9`	`}`
Original file line number	Diff line number	Diff line change
`@@ -66,7 +66,7 @@ export default class LinkedList {`
`66`	`66`	`* @param {function} [callback]`
`67`	`67`	`* @return {string}`
`68`	`68`	`*/`
`69`		`- toString() {`
`70`		`- return this.toArray().map(node => node.toString()).toString();`
	`69`	`+ toString(callback) {`
	`70`	`+ return this.toArray().map(node => node.toString(callback)).toString();`
`71`	`71`	`}`
`72`	`72`	`}`
Original file line number	Diff line number	Diff line change
`@@ -3,7 +3,7 @@ export default class LinkedListNode {`
`3`	`3`	`this.value = value;`
`4`	`4`	`}`
`5`	`5`
`6`		`- toString() {`
`7`		`- return this.value.toString();`
	`6`	`+ toString(callback) {`
	`7`	+ return callback ? callback(this.value) : `${this.value}`;
`8`	`8`	`}`
`9`	`9`	`}`
Original file line number	Diff line number	Diff line change
`@@ -161,7 +161,7 @@ export default class DoublyLinkedList {`
`161`	`161`	`* @param {function} [callback]`
`162`	`162`	`* @return {string}`
`163`	`163`	`*/`
`164`		`- toString() {`
`165`		`- return this.toArray().map(node => node.toString()).toString();`
	`164`	`+ toString(callback) {`
	`165`	`+ return this.toArray().map(node => node.toString(callback)).toString();`
`166`	`166`	`}`
`167`	`167`	`}`
Original file line number	Diff line number	Diff line change
`@@ -5,7 +5,7 @@ export default class DoublyLinkedListNode {`
`5`	`5`	`this.previous = previous;`
`6`	`6`	`}`
`7`	`7`
`8`		`- toString() {`
`9`		`- return this.value.toString();`
	`8`	`+ toString(callback) {`
	`9`	+ return callback ? callback(this.value) : `${this.value}`;
`10`	`10`	`}`
`11`	`11`	`}`
Original file line number	Diff line number	Diff line change
`@@ -198,7 +198,7 @@ export default class LinkedList {`
`198`	`198`	`* @param {function} [callback]`
`199`	`199`	`* @return {string}`
`200`	`200`	`*/`
`201`		`- toString() {`
`202`		`- return this.toArray().map(node => node.toString()).toString();`
	`201`	`+ toString(callback) {`
	`202`	`+ return this.toArray().map(node => node.toString(callback)).toString();`
`203`	`203`	`}`
`204`	`204`	`}`
Original file line number	Diff line number	Diff line change
`@@ -1,9 +1,10 @@`
`1`	`1`	`export default class LinkedListNode {`
`2`	`2`	`constructor(value, next = null) {`
`3`	`3`	`this.value = value;`
	`4`	`+ this.next = next;`
`4`	`5`	`}`
`5`	`6`
`6`		`- toString() {`
`7`		`- return this.value.toString();`
	`7`	`+ toString(callback) {`
	`8`	+ return callback ? callback(this.value) : `${this.value}`;
`8`	`9`	`}`
`9`	`10`	`}`
Original file line number	Diff line number	Diff line change
`@@ -4,7 +4,7 @@ export default class LinkedListNode {`
`4`	`4`	`this.next = next;`
`5`	`5`	`}`
`6`	`6`
`7`		`- toString() {`
`8`		`- return this.value.toString();`
	`7`	`+ toString(callback) {`
	`8`	+ return callback ? callback(this.value) : `${this.value}`;
`9`	`9`	`}`
`10`	`10`	`}`