Commit 6a1186c

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add basic hash function which takes only strings

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Lines changed: 13 additions & 0 deletions

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	`1`	`+"use strict";`
	`2`	`+Object.defineProperty(exports, "__esModule", { value: true });`
	`3`	`+class HashTable {`
	`4`	`+ constructor() {`
	`5`	`+ this.hash = (value, max) => {`
	`6`	`+ // naive hash fn for illustrative purposes`
	`7`	`+ if (max <= 0)`
	`8`	`+ throw TypeError('Max hash value must be a positive integer');`
	`9`	`+ return value.split('').reduce((a, b) => a * b.charCodeAt(0), 1) % max;`
	`10`	`+ };`
	`11`	`+ }`
	`12`	`+}`
	`13`	`+exports.default = HashTable;`

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	`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 HashTable_1 = __importDefault(require("./HashTable"));`
	`7`	`+let HT = new HashTable_1.default();`
	`8`	`+beforeEach(() => HT = new HashTable_1.default());`
	`9`	`+describe('basic hash table', () => {`
	`10`	`+ test('hash fn exists', () => {`
	`11`	`+ expect(typeof HT.hash).toBe('function');`
	`12`	`+ });`
	`13`	`+ test('hash fn takes string and returns number between 0 and specified max', () => {`
	`14`	`+ const max = 50;`
	`15`	`+ expect(HT.hash('test', max)).toBeLessThan(50);`
	`16`	`+ });`
	`17`	`+ test('hash fn throws error if max argument is <= 0', () => {`
	`18`	`+ let max = 0;`
	`19`	`+ try {`
	`20`	`+ HT.hash('test', max);`
	`21`	`+ }`
	`22`	`+ catch (e) {`
	`23`	`+ expect(e.message).toBe("Max hash value must be a positive integer");`
	`24`	`+ }`
	`25`	`+ max = -1;`
	`26`	`+ try {`
	`27`	`+ HT.hash('test', max);`
	`28`	`+ }`
	`29`	`+ catch (e) {`
	`30`	`+ expect(e.message).toBe("Max hash value must be a positive integer");`
	`31`	`+ }`
	`32`	`+ });`
	`33`	`+});`

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	`1`	`+import HashTable from './HashTable';`
	`2`	`+`
	`3`	`+let HT = new HashTable<string>();`
	`4`	`+beforeEach(() => HT = new HashTable<string>());`
	`5`	`+`
	`6`	`+describe('basic hash table', () => {`
	`7`	`+ test('hash fn exists', () => {`
	`8`	`+ expect(typeof HT.hash).toBe('function');`
	`9`	`+ });`
	`10`	`+ test('hash fn takes string and returns number between 0 and specified max', () => {`
	`11`	`+ const max = 50;`
	`12`	`+ expect(HT.hash('test', max)).toBeLessThan(50);`
	`13`	`+ });`
	`14`	`+ test('hash fn throws error if max argument is <= 0', () => {`
	`15`	`+ let max = 0;`
	`16`	`+ try {`
	`17`	`+ HT.hash('test', max);`
	`18`	`+ } catch (e) {`
	`19`	`+ expect(e.message).toBe("Max hash value must be a positive integer");`
	`20`	`+ }`
	`21`	`+ max = -1;`
	`22`	`+ try {`
	`23`	`+ HT.hash('test', max);`
	`24`	`+ } catch (e) {`
	`25`	`+ expect(e.message).toBe("Max hash value must be a positive integer");`
	`26`	`+ }`
	`27`	`+ });`
	`28`	`+})`

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	`1`	`+class HashTable<T> {`
	`2`	`+ constructor() {`
	`3`	`+`
	`4`	`+ }`
	`5`	`+ hash = (value: string, max: number): number => {`
	`6`	`+ // naive hash fn for illustrative purposes`
	`7`	`+ if (max <= 0) throw TypeError('Max hash value must be a positive integer');`
	`8`	`+ return value.split('').reduce((a, b) => a * b.charCodeAt(0), 1) % max;`
	`9`	`+ }`
	`10`	`+}`
	`11`	`+`
	`12`	`+export default HashTable;`

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