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require 'set'
module ActiveSupport #:nodoc:
module CoreExtensions #:nodoc:
module Hash #:nodoc:
# Slice a hash to include only the given keys. This is useful for
# limiting an options hash to valid keys before passing to a method:
#
# def search(criteria = {})
# assert_valid_keys(:mass, :velocity, :time)
# end
#
# search(options.slice(:mass, :velocity, :time))
module Slice
# Returns a new hash with only the given keys.
def slice(*keys)
allowed = Set.new(respond_to?(:convert_key) ? keys.map { |key| convert_key(key) } : keys)
hash = self.class.new
allowed.each { |k| hash[k] = self[k] if has_key?(k) }
hash
end
# Replaces the hash with only the given keys.
def slice!(*keys)
replace(slice(*keys))
end
end
end
end
end