Class: Immutable::Splitter

Inherits:
Object
  • Object
show all
Defined in:
lib/immutable/list.rb

Overview

This class can divide a list up into 2 ‘List`s, one for the prefix of elements for which the block returns true, and another for all the elements after that. It guarantees that the block will only be called ONCE for each item

Defined Under Namespace

Classes: Left, Right

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(list, block) ⇒ Splitter

Returns a new instance of Splitter.



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# File 'lib/immutable/list.rb', line 1486

def initialize(list, block)
  @list, @block, @left, @right = list, block, [], EmptyList
end

Instance Attribute Details

#left ⇒ Object (readonly)

Returns the value of attribute left.



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# File 'lib/immutable/list.rb', line 1485

def left
  @left
end

#right ⇒ Object (readonly)

Returns the value of attribute right.



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# File 'lib/immutable/list.rb', line 1485

def right
  @right
end

Instance Method Details

#done? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/immutable/list.rb', line 1503

def done?
  @list.empty?
end

#next_item ⇒ Object 



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# File 'lib/immutable/list.rb', line 1490

def next_item
  unless @list.empty?
    item = @list.head
    if @block.call(item)
      @left << item
      @list = @list.tail
    else
      @right = @list
      @list  = EmptyList
    end
  end
end