Module: KeyDial::Coercion::Structs

Included in:
Struct
Defined in:
lib/key_dial/coercion.rb

Defined Under Namespace

Modules: ClassMethods

Constant Summary collapse

EMPTY = 
Struct.new(:'0').new.freeze

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.create(from_obj, type_class = nil) ⇒ Object

Struct creation function not really meant to be used directly. Prefer Struct.from(obj).

Parameters:

  • from_obj —

    Keys/values from this object will be used to fill out the new Struct.

  • type_class (defaults to: nil) —

    If a sub-class of Struct is provided, this sub-class will be instantiated



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# File 'lib/key_dial/coercion.rb', line 122

def self.create(from_obj, type_class = nil)
  if from_obj.is_a?(Hash) || from_obj.is_a?(Array) || from_obj.is_a?(Struct)
     return EMPTY.dup if from_obj.empty? && type_class == nil
    from = from_obj
  else
    from = [from_obj]
  end

  # Has a specific type of Struct been specified?

  if type_class.is_a?(Class) && type_class < Struct
    if from.is_a?(type_class)
      # Has an instantiation of that type of Struct been passed in? If so, just return it

      return from
    else
      values = []
      if from.is_a?(Array)
        # Get as many elements of array as this Struct can handle - discard the rest

        values = from.first(type_class.members.size)
      else 
        # Not an Array, so must be another Struct or Hash

        type_class.members.each { |key|
          if from.key?(key)
            # If the object has this expected key, use it

            values << from[key]
          else
            # Otherwise, fill this key with nil

            values << nil
            # Keys in the from object which don't match expected keys are discarded

          end
        }
      end
      # values now contains a value or nil for each of this class's expected keys

      return type_class.new(*values)
    end
  else
    # Anonymous Struct

    new_values = from.is_a?(Array) ? from : from.values
    # Iterate over the keys of the from object

    # (Array.keys is monkeypatched in)

    new_keys = from.keys.each_with_index.map { |k, i|
      if k.respond_to?(:to_sym) && k != ''
        k.to_sym
      elsif k.respond_to?(:to_s) && !k.nil?
        k.to_s.to_sym
      else
        # If we can't construct a valid Struct key for this key, we discard the corresponding value

        new_values.delete_at(i)
        nil
      end
    }.reject(&:nil?)
    if new_keys.size > 0
      # Create anonymous Struct with the specified keys and values

      return Struct.new(*new_keys).new(*new_values)
    else
      # Return the Empty Struct

      return EMPTY.dup
    end
  end

rescue
  return EMPTY.dup
end

.included(base) ⇒ Object 



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# File 'lib/key_dial/coercion.rb', line 95

def self.included(base)
    base.extend ClassMethods
end

Instance Method Details

#to_struct(type_class = nil) ⇒ Object

Convert a Struct to another Struct.

Parameters:

  • type_class (defaults to: nil) —

    If a sub-class of Struct is provided, the Struct will be converted to this sub-class



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# File 'lib/key_dial/coercion.rb', line 87

def to_struct(type_class = nil)
  if type_class.is_a?(Class) && type_class < Struct
    return Struct.from(self, type_class)
  else
    return self
  end
end