Class: Shamu::Services::LazyTransform

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/shamu/services/lazy_transform.rb

Overview

Lazily transform one enumerable to another with shortcuts for common collection methods such as first, count, etc.

Instance Method Summary collapse

Constructor Details

#initialize(source) {|object| ... } ⇒ LazyTransform

Returns a new instance of LazyTransform.

Yields:

  • (object)

Yield Parameters:

  • objects (Array<Object>) —

    the original values.

Yield Returns:

  • the transformed values.



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# File 'lib/shamu/services/lazy_transform.rb', line 13

def initialize( source, &transformer )
  @transformer = transformer
  @source      = source
end

Instance Method Details

#count(*args) ⇒ Integer Also known as: size, length 



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# File 'lib/shamu/services/lazy_transform.rb', line 30

def count( *args )
  if args.any? || block_given?
    super
  else
    source.count
  end
end

#drop(n) ⇒ LazyTransform 



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# File 'lib/shamu/services/lazy_transform.rb', line 75

def drop( n )
  if transformed?
    super
  else
    self.class.new( source.drop( n ), &transformer )
  end
end

#each {|object| ... } ⇒ self

Yields each transformed value from the original source to the block.

Yields:

  • (object)

Yield Parameters:

  • object (Object) 


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# File 'lib/shamu/services/lazy_transform.rb', line 23

def each( &block )
  transformed.each( &block )
  self
end

#empty? ⇒ Boolean 



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# File 'lib/shamu/services/lazy_transform.rb', line 57

def empty?
  source.empty?
end

#first(n) ⇒ Object #first ⇒ Object

Get the first transformed value without transforming the entire list.



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# File 'lib/shamu/services/lazy_transform.rb', line 44

def first( *args )
  if args.any?
    super
  else
    return @first if defined? @first
    @first = begin
      value = source.first
      raise_if_not_transformed( transformer.call( [ value ] ) ).first unless value.nil?
    end
  end
end

#take(n) ⇒ LazyTransform 



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# File 'lib/shamu/services/lazy_transform.rb', line 64

def take( n )
  if transformed?
    super
  else
    self.class.new( source.take( n ), &transformer )
  end
end