Last Update: 2021-12-10 10:40:35 -0800


ruby-cicphash is a library that adds the CICPHash class, which has the same interface as Hash, but is case insensitive and case preserving. Any value can be used as a key. However, you cannot have two keys in the same CICPHash that would be the same if when converted to strings would be equal or differing only in case.

For example, all of the following keys would be considered equalivalent: 'ab', 'Ab', 'AB', 'aB', :ab, :Ab, :AB, :aB

CICPHash uses a last match wins policy. If an key-value pair is added to a CICPHash and a case insensitive variant of the key is already in the hash the instance of the key in the hash becomes the same the most recently added key (and the value is updated to reflect the new value).


require 'cicphash'
hash =
hash[:AB] = 1
hash['ab'] # => 1
hash['ab']  = 2
hash # => {"ab"=>2}


gem install cicphash

Source Code

Source code is available on GitHub at

Reporting Bugs

The bug tracker is located at




Jeremy Evans <>