ken-ux / hashmap

Implementation of hash map data structure.

hashmap

This is an implementation of a HashMap. The constructor for the HashMap class takes in an integer to specify the number of buckets in its array. The HashMap class contains the following methods:

• hash(value): Takes a value and produces a hash code with it.
• set(key, value): Adds a new key-value pair to the HashMap. If a key already exists, then the old value is overwritten.
• get(key): Returns the value that is assigned to this key in the HashMap. If key is not found, returns null.
• has(key): Returns true or false based on whether or not the key is in the HashMap.
• remove(key): Removes the given key from the HashMap. If it does not exist or does not match the bucket it's led to, throws an error.
• length(): Returns the number of stored keys in the HashMap.
• clear(): Removes all entries in the HashMap.
• keys(): Returns an array containing all the keys inside the HashMap.
• values(): Returns an array containing all the values.
• entries(): Returns an array that contains each key-value pair. Example: [[firstKey, firstValue], [secondKey, secondValue]]

The following utility method assists any main methods that iterate over the HashMap:

• indexError(index): Throws an error when a given index is outside the bounds of the size range for HashMap's buckets array. This emulates errors thrown in other programming languages where arrays cannot be dynamically sized.

Lessons Learned

• Using hash functions to sort key-value pairs into buckets.
• As a second layer of security, confirming that a given key matches the key in a bucket it has been hashed to.