Module: Rekey

Defined in:
lib/rekey.rb

Constant Summary collapse

VERSION = 
'2.0.1'

Class Method Summary collapse

Class Method Details

.rekey(enumerable, key_handle = nil, value_handle = nil, &block) ⇒ Object 



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# File 'lib/rekey.rb', line 9

def rekey(enumerable, key_handle = nil, value_handle = nil, &block)
  # validate input
  validate_input key_handle, value_handle, &block

  key_fn = if enumerable.respond_to?(:keys)
    proc {|k, v| k}
  else
    proc {|v| nil}
  end

  value_fn = if enumerable.respond_to?(:values)
    proc {|k, v| v}
  else
    proc {|v| v}
  end

  res = get_return_type enumerable, key_handle, value_handle, &block

  # rekey input
  enumerable.each do |*args|
    key = key_fn.call *args
    value = value_fn.call *args
    new_key = key
    new_value = value

    if block
      if block.arity <= 0
        # function pointer, eg. &:to_i
        new_key = block.call value
      elsif block.arity == 1
        # standard block
        new_key = block.call value
      else
        # block that wants both key and value
        data = block.call key, value
        if data.is_a? Array
          new_key, new_value = data
        else
          # only returned a new key value
          new_key = data
        end
      end
    else
      new_key = PluckIt.pluck value, key_handle if key_handle
      new_value = PluckIt.pluck value, value_handle if value_handle
    end

    # collect results

    unless res
      # determine return type based on the first
      # computed key value
      res = new_key ? {} : []
    end

    if res.is_a? Array
      unless new_key.nil?
        # safeguard against stupidity
        raise ArgumentError.new(
          "not expecting a key value, got: #{new_key}"
        )
      end

      res.push new_value
    else
      res[new_key] = new_value
    end
  end

  res
end