Casidoo-179

HashMap.js

// Our HashMap can have up to 5077 entries
const MAX_INDEX = 5077;

// helpers
let isMultipleOf = k => n => n%k === 0
let isMultipleOfFour = isMultipleOf(4);

// hash function for strings using 4 char word folding
let hash = s => {
  let total = 0;
  let charMultiplier = 1;
  for (let i=0; i<s.length; i++) {
    total += s.charCodeAt(i) * charMultiplier;
    charMultiplier = isMultipleOfFour(i+1) ? charMultiplier = 1 : charMultiplier * 256;
  }
  return total % MAX_INDEX;
}

// Our HashMap class, lacks error handling.
class HashMap {
  constructor() {
    this.hashMap = [];
  }
  
  get(k) {
    return (this.hashMap[hash(k)] ?? [])[1]
  } 
  put(k,v) {
    this.hashMap[hash(k)] = [k,v]
  }
  remove(k) {
    this.hashMap[hash(k)] = undefined
  }
  print() {
    let output = "\n{\n"
    this.hashMap.forEach(([k, v] = []) => output += `  ${k}: ${v},\n`)
    output += "}\n"
    console.log(output)
  }
}

let m = new HashMap();

let add = (x,y) => x+y

m.put("alice", "Some value for alice")
m.put("add", add)
m.put("myHashMap", new HashMap)
m.get("add")
m.get("myHashMap").put("bob", "Bob's Burgers")
m.put("bobby", m.get("myHashMap").get("bob"))
m.print()

/* OUTPUT:
"
{
  myHashMap: [object Object],
  alice: Some value for alice,
  bobby: Bob's Burgers,
  add: (x, y) => x + y,
}
"
/*