class Rack::Headers

# File lib/rack/headers.rb, line 7
def self.[](*items)
  if items.length % 2 != 0
    if items.length == 1 && items.first.is_a?(Hash)
      new.merge!(items.first)
    else
      raise ArgumentError, "odd number of arguments for Rack::Headers"
    end
  else
    hash = new
    loop do
      break if items.length == 0
      key = items.shift
      value = items.shift
      hash[key] = value
    end
    hash
  end
end

# File lib/rack/headers.rb, line 26
def [](key)
  super(downcase_key(key))
end

# File lib/rack/headers.rb, line 30
def []=(key, value)
  super(key.downcase.freeze, value)
end

# File lib/rack/headers.rb, line 35
def assoc(key)
  super(downcase_key(key))
end

# File lib/rack/headers.rb, line 39
def compare_by_identity
  raise TypeError, "Rack::Headers cannot compare by identity, use regular Hash"
end

# File lib/rack/headers.rb, line 43
def delete(key)
  super(downcase_key(key))
end

# File lib/rack/headers.rb, line 47
def dig(key, *a)
  super(downcase_key(key), *a)
end

# File lib/rack/headers.rb, line 143
def except(*a)
  super(*a.map!{|key| downcase_key(key)})
end

# File lib/rack/headers.rb, line 51
def fetch(key, *default, &block)
  key = downcase_key(key)
  super
end

# File lib/rack/headers.rb, line 56
def fetch_values(*a)
  super(*a.map!{|key| downcase_key(key)})
end

# File lib/rack/headers.rb, line 60
def has_key?(key)
  super(downcase_key(key))
end

# File lib/rack/headers.rb, line 67
def invert
  hash = self.class.new
  each{|key, value| hash[value] = key}
  hash
end

# File lib/rack/headers.rb, line 73
def merge(hash, &block)
  dup.merge!(hash, &block)
end

# File lib/rack/headers.rb, line 77
def reject(&block)
  hash = dup
  hash.reject!(&block)
  hash
end

# File lib/rack/headers.rb, line 83
def replace(hash)
  clear
  update(hash)
end

# File lib/rack/headers.rb, line 88
def select(&block)
  hash = dup
  hash.select!(&block)
  hash
end

# File lib/rack/headers.rb, line 121
def slice(*a)
  h = self.class.new
  a.each{|k| h[k] = self[k] if has_key?(k)}
  h
end

# File lib/rack/headers.rb, line 94
def to_proc
  lambda{|x| self[x]}
end

# File lib/rack/headers.rb, line 127
def transform_keys(&block)
  dup.transform_keys!(&block)
end

# File lib/rack/headers.rb, line 131
def transform_keys!
  hash = self.class.new
  each do |k, v|
    hash[yield k] = v
  end
  replace(hash)
end

# File lib/rack/headers.rb, line 98
def transform_values(&block)
  dup.transform_values!(&block)
end

# File lib/rack/headers.rb, line 102
def update(hash, &block)
  hash.each do |key, value|
    self[key] = if block_given? && include?(key)
      block.call(key, self[key], value)
    else
      value
    end
  end
  self
end

# File lib/rack/headers.rb, line 114
def values_at(*keys)
  keys.map{|key| self[key]}
end