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Commit 6974354

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Merge pull request #56 from nuintun/patch-1
feat(hashmap): Better hash function using TextEncoder Improves hash function using TextEncoder instead of codePointAt Closes #55
2 parents 142c301 + c253938 commit 6974354

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‎src/data-structures/maps/hash-maps/hash-map.js

Lines changed: 10 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,9 @@
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const LinkedList = require('../../linked-lists/linked-list');
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const { nextPrime } = require('./primes');
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// Text encoding
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const encoding = new TextEncoder();
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/**
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* The map holds key-value pairs.
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* Any value (both objects and primitive values) may be used as either a key or a value.
@@ -50,12 +53,16 @@ class HashMap {
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* @return {integer} bucket index
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*/
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hashFunction(key) {
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const str = String(key);
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const bytes = encoding.encode(key);
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const { length } = bytes;
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let hash = 2166136261; // FNV_offset_basis (32 bit)
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for (let i = 0; i < str.length; i += 1) {
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hash ^= str.codePointAt(i); // XOR
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for (let i = 0; i < length; ) {
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hash ^= bytes[i++]; // XOR
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hash *= 16777619; // 32 bit FNV_prime
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}
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return (hash >>> 0) % this.buckets.length;
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}
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// end::hashFunction[]

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