Module: Hm::Dig

Defined in:
lib/hm/dig.rb

Constant Summary collapse

DIGGABLE_CLASSES =

TODO: Struct/OpenStruct are also diggable in Ruby core, can be added for future implementation

[Hash, Array].freeze
NotFound = 
Object.new.freeze

Class Method Summary collapse

Class Method Details

.dig(what, key, *keys) ⇒ Object 



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# File 'lib/hm/dig.rb', line 8

def self.dig(what, key, *keys)
  # We want to return special value when key is not present, because
  # 1. "at some point in path, we have a value, and this value is `nil`", and
  # 2. "at some point in path, we don't have a value (key is absent)"
  # ...should be different in Algo.visit
  return NotFound unless key?(what, key)

  return what.dig(key, *keys) if what.respond_to?(:dig)

  ensure_diggable?(what) or fail TypeError, "#{value.class} is not diggable"
  value = what[key]
  keys.empty? ? value : dig(value, *keys)
end

.diggable?(what) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hm/dig.rb', line 31

def self.diggable?(what)
  DIGGABLE_CLASSES.include?(what.class)
end

.key?(what, key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hm/dig.rb', line 22

def self.key?(what, key)
  case what
  when Array
    (0...what.size).cover?(key)
  when Hash
    what.key?(key)
  end
end