BloomFilter minor fixes.

Author: trekhleb

src/data-structures/bloom-filter/BloomFilter.js

@@ -1,6 +1,6 @@
 exportdefaultclassBloomFilter{
 /**
- * @param{number} size
+ * @param{number} size - the size of the storage.
  */
 constructor(size=100){
 // Bloom filter size directly affects the likelihood of false positives.
@@ -15,7 +15,7 @@ export default class BloomFilter{
 insert(item){
 consthashValues=this.getHashValues(item);
 
-// Set each hashValue index to true
+// Set each hashValue index to true.
 hashValues.forEach(val=>this.storage.setValue(val));
 }
 
@@ -26,8 +26,8 @@ export default class BloomFilter{
 mayContain(item){
 consthashValues=this.getHashValues(item);
 
-for(leti=0;i<hashValues.length;i+=1){
-if(!this.storage.getValue(hashValues[i])){
+for(lethashIndex=0;hashIndex<hashValues.length;hashIndex+=1){
+if(!this.storage.getValue(hashValues[hashIndex])){
 // We know that the item was definitely not inserted.
 returnfalse;
 }
@@ -50,7 +50,7 @@ export default class BloomFilter{
 conststorage=[];
 
 // Initialize all indexes to false
-for(leti=0;i<size;i+=1){
+for(letstorageCellIndex=0;storageCellIndex<size;storageCellIndex+=1){
 storage.push(false);
 }
 
@@ -67,14 +67,14 @@ export default class BloomFilter{
 }
 
 /**
- * @param{string} str
+ * @param{string} item
  * @return{number}
  */
-hash1(str){
+hash1(item){
 lethash=0;
 
-for(leti=0;i<str.length;i+=1){
-constchar=str.charCodeAt(i);
+for(letcharIndex=0;charIndex<item.length;charIndex+=1){
+constchar=item.charCodeAt(charIndex);
 hash=(hash<<5)+hash+char;
 hash&=hash;// Convert to 32bit integer
 hash=Math.abs(hash);
@@ -84,44 +84,48 @@ export default class BloomFilter{
 }
 
 /**
- * @param{string} str
+ * @param{string} item
  * @return{number}
  */
-hash2(str){
+hash2(item){
 lethash=5381;
 
-for(leti=0;i<str.length;i+=1){
-constchar=str.charCodeAt(i);
+for(letcharIndex=0;charIndex<item.length;charIndex+=1){
+constchar=item.charCodeAt(charIndex);
 hash=(hash<<5)+hash+char;/* hash * 33 + c */
 }
 
-returnhash%this.size;
+returnMath.abs(hash%this.size);
 }
 
 /**
- * @param{string} str
+ * @param{string} item
  * @return{number}
  */
-hash3(str){
+hash3(item){
 lethash=0;
 
-for(leti=0;i<str.length;i+=1){
-constchar=str.charCodeAt(i);
+for(letcharIndex=0;charIndex<item.length;charIndex+=1){
+constchar=item.charCodeAt(charIndex);
 hash=(hash<<5)-hash;
 hash+=char;
 hash&=hash;// Convert to 32bit integer
 }
 
-returnhash%this.size;
+returnMath.abs(hash%this.size);
 }
 
 /**
- * Runs all 3 hash functions on the input and returns an array of results
+ * Runs all 3 hash functions on the input and returns an array of results.
  *
- * @param{string} str
+ * @param{string} item
  * @return{number[]}
  */
 getHashValues(item){
-return[this.hash1(item),Math.abs(this.hash2(item)),Math.abs(this.hash3(item))];
+return[
+this.hash1(item),
+this.hash2(item),
+this.hash3(item),
+];
 }
 }

src/data-structures/bloom-filter/__test__/BloomFilter.test.js

@@ -1,39 +1,62 @@
 importBloomFilterfrom'../BloomFilter';
 
-describe('Bloom Filter',()=>{
+describe('BloomFilter',()=>{
 letbloomFilter;
-constpeople=['Bruce Wayne','Clark Kent','Barry Allen'];
+constpeople=[
+'Bruce Wayne',
+'Clark Kent',
+'Barry Allen',
+];
 
 beforeEach(()=>{
 bloomFilter=newBloomFilter();
 });
 
-it('Should have methods named "insert" and "mayContain"',()=>{
+it('should have methods named "insert" and "mayContain"',()=>{
 expect(typeofbloomFilter.insert).toBe('function');
 expect(typeofbloomFilter.mayContain).toBe('function');
 });
 
-it('Should create a new filter store with the appropriate methods',()=>{
+it('should create a new filter store with the appropriate methods',()=>{
 conststore=bloomFilter.createStore(18);
 expect(typeofstore.getValue).toBe('function');
 expect(typeofstore.setValue).toBe('function');
 });
 
-it('Should hash deterministically with all 3 hash functions',()=>{
-conststr='abc';
-expect(bloomFilter.hash1(str)).toEqual(bloomFilter.hash1(str));
-expect(bloomFilter.hash2(str)).toEqual(bloomFilter.hash2(str));
-expect(bloomFilter.hash3(str)).toEqual(bloomFilter.hash3(str));
+it('should hash deterministically with all 3 hash functions',()=>{
+conststr1='apple';
+
+expect(bloomFilter.hash1(str1)).toEqual(bloomFilter.hash1(str1));
+expect(bloomFilter.hash2(str1)).toEqual(bloomFilter.hash2(str1));
+expect(bloomFilter.hash3(str1)).toEqual(bloomFilter.hash3(str1));
+
+expect(bloomFilter.hash1(str1)).toBe(14);
+expect(bloomFilter.hash2(str1)).toBe(43);
+expect(bloomFilter.hash3(str1)).toBe(10);
+
+conststr2='orange';
+
+expect(bloomFilter.hash1(str2)).toEqual(bloomFilter.hash1(str2));
+expect(bloomFilter.hash2(str2)).toEqual(bloomFilter.hash2(str2));
+expect(bloomFilter.hash3(str2)).toEqual(bloomFilter.hash3(str2));
+
+expect(bloomFilter.hash1(str2)).toBe(0);
+expect(bloomFilter.hash2(str2)).toBe(61);
+expect(bloomFilter.hash3(str2)).toBe(10);
 });
 
-it('Should create an array with 3 hash values',()=>{
-expect(bloomFilter.getHashValues('abc').length).toEqual(3);
+it('should create an array with 3 hash values',()=>{
+expect(bloomFilter.getHashValues('abc').length).toBe(3);
+expect(bloomFilter.getHashValues('abc')).toEqual([66,63,54]);
 });
 
-it('Should insert strings correctly and return true when checking for inserted values',()=>{
+it('should insert strings correctly and return true when checking for inserted values',()=>{
 people.forEach(person=>bloomFilter.insert(person));
-expect(bloomFilter.mayContain('Bruce Wayne')).toBe(true);
-expect(bloomFilter.mayContain('Clark Kent')).toBe(true);
-expect(bloomFilter.mayContain('Barry Allen')).toBe(true);
+
+expect(bloomFilter.mayContain('Bruce Wayne')).toBeTruthy();
+expect(bloomFilter.mayContain('Clark Kent')).toBeTruthy();
+expect(bloomFilter.mayContain('Barry Allen')).toBeTruthy();
+
+expect(bloomFilter.mayContain('Tony Stark')).toBeFalsy();
 });
 });