CaseInsensitiveHash

case_insensitive_hash.rb

##
# This Hash subclass stores keys in a case-insensitive manner.
class CaseInsensitiveHash < Hash
  ##
  # @see Hash#[]
  def [](key)
    return super(key.downcase)
  end

  ##
  # @see Hash#[]=
  def []=(key, value)
    @key_labels ||= {}
    @key_labels[key.downcase] = key
    return super(key.downcase, value)
  end

  ##
  # @see Hash#store
  alias_method :store, :[]=

  ##
  # @see Hash#include?
  def include?(key)
    return super(key.downcase)
  end

  ##
  # Returns the labels for the keys, exactly as they were originally
  # entered.
  #
  # @return [Array] The key labels.
  def key_labels
    @key_labels ||= {}
    self.keys.map { |key| @key_labels[key] }
  end

  ##
  # Converts to a normal Hash object.  The key labels are used as the
  # Hash keys.
  #
  # @return [Hash] The converted Hash.
  def to_hash
    # Iterate over key labels, and look up the value, stuffing everything
    # into a new Hash as we go.
    self.key_labels.inject({}) do |accu, label|
      accu[label] = self[label]
      accu
    end
  end

  ##
  # @see Hash#to_s
  def to_s
    return self.to_hash.to_s
  end

  ##
  # @see Hash#inspect
  def inspect
    return self.to_hash.inspect
  end
end

irb

>> hash = CaseInsensitiveHash.new
=> {}
>> hash["ETag"] = "asdf"
=> "asdf"
>> hash["X-Originating-IP"] = "localhost"
=> "localhost"
>> hash["Content-MD5"] = "asdf"
=> "asdf"
>> hash
=> {"X-Originating-IP"=>"localhost", "ETag"=>"asdf", "Content-MD5"=>"asdf"}
>> hash.include?("ETag")
=> true
>> hash.include?("etag")
=> true