Libraries.Containers.HashTable

The HashTable class is a data structure that stores and allows access to items through the use of a key. In the hash table keys and values are paired. Some basic examples and explanations of Lists can be found below.

Example Code

use Libraries.Containers.HashTable
class Main
   action Main
      //make the hash table
      HashTable<text, integer> phoneBook
      //add a value(2626984) with a key(Jane)
      phoneBook:Add("Jane", 2626984)
      //get it back
      integer value = phoneBook:GetValue("Jane")
   end
end

This action adds an item to the hash table, given the key-value pair. The implementation of this action is identical to that of Set.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)

This action compares two object hash codes and returns an integer. The result is larger if this hash code is larger than the object passed as a parameter, smaller, or equal. In this case, -1 means smaller, 0 means equal, and 1 means larger. This action was changed in Quorum 7 to return an integer, instead of a CompareResult object, because the previous implementation was causing efficiency issues.

Example Code

Object o
        Object t
        integer result = o:Compare(t) //1 (larger), 0 (equal), or -1 (smaller)

This action removes a key-value pair given a key. As the HashTable class requires unique values, this action really only removes the one value

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        boolean removed = phoneBook:RemoveAllKeys("Jane")

This action gets an array that contains all the keys in the hash table. This method requires iterating over all elements in the array, and as such, should be used sparing.

Example Code

use Libraries.Containers.HashTable
        use Libraries.Containers.Iterator

        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        Array<text> keysIterator = phoneBook:GetKeyArray()

This action gets an array that contains all the values in the hash table. This method requires iterating over all elements in the array, and as such, should be used sparingly.

Example Code

use Libraries.Containers.HashTable
        use Libraries.Containers.Iterator

        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        Array<text> keysIterator = phoneBook:GetKeyArray()

This action empties or clears out the hash table.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        phoneBook:Empty()

This action determines if two objects are equal based on their hash code values.

Example Code

use Libraries.Language.Object
        use Libraries.Language.Types.Text
        Object o
        Text t
        boolean result = o:Equals(t)

This action gets the hash code for an object.

Example Code

Object o
        integer hash = o:GetHashCode()

This action gets the key that matches the value. Warning: this method is inefficient, you should access items in a hash table through their keys.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        text key = phoneBook:GetKey(2626984)

This action gets an iterator that iterates over all the keys in the hash table.

Example Code

use Libraries.Containers.HashTable
        use Libraries.Containers.Iterator

        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        Iterator<text> keysIterator = phoneBook:GetKeyIterator()

This action gets the number of items in the hash table.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        integer size = phoneBook:GetSize()

This action gets a value with a given key.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        integer value = phoneBook:GetValue("Jane")

This action gets an iterator that iterates over all the values in the hash table.

Example Code

use Libraries.Containers.HashTable
        use Libraries.Containers.Iterator

        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        Iterator<integer> keysIterator = phoneBook:GetValueIterator()

This action determines if the hash table contains a certain key.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        phoneBook:HasKey("Jane")

This action determines if the hash table contains a certain value.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        phoneBook:HasValue(2626984)

This action determines if a hash table is empty.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        boolean empty = phoneBook:IsEmpty()

This action removes a key-value pair given a key. As the HashTable class requires unique values, this action really only removes the one value

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        boolean removed = phoneBook:RemoveAllKeys("Jane")

This action removes all instances of a key-value pair given a key. As the HashTable class requires all values are unique, this only removes at most one value.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        boolean removed = phoneBook:RemoveAllValues(2626984)

This action removes a key-value pair given a key.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        integer value = phoneBook:RemoveKey("Jane")

This action removes a key-value pair given a value.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)
        text key = phoneBook:RemoveValue(2626984)

This action adds an item to the hash table, given the key-value pair. It functions identically to the add action and exists only as a convenience action, given that there are also actions named with the prefix Get.

Example Code

use Libraries.Containers.HashTable
        HashTable<text, integer> phoneBook
        phoneBook:Add("Jane", 2626984)

This action sets the size of the hash table. If this table already has entries, it forces it to resize, manually rehashing all objects. For this reason, we recommend selecting a size before adding items to the table.

Example Code

use Libraries.Containers.HashTable
        use Libraries.Containers.Iterator

        HashTable<text, integer> phoneBook
        phoneBook:SetSize(20)
        phoneBook:Add("Jane", 2626984)
        Array<text> keysIterator = phoneBook:GetKeyArray()