Class: Enumerator::Lazy

Inherits:
Object show all
Defined in:
lib/core/facets/enumerator/lazy/squeeze.rb,
lib/core/facets/array/indexes.rb

Instance Method Summary collapse

Instance Method Details

#indexes(*args) ⇒ Object Also known as: index_all

Returns an enumerator of indexes of all object in receiver such that the object is == to obj.

If a block is given instead of an argument, returns the indexes of all objects for which the block returns true.

If neither a block nor argument is given, an Enumerator for all indexes is returned.

enum = (42 .. Float::INFINITY).lazy.indexes
#=> #<Enumerator::Lazy: ...>
enum.next #=> 0
enum.next #=> 1
enum.first(5)  #=> [0, 1, 2, 3, 4]

Author:

  • Tyler Rick



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# File 'lib/core/facets/array/indexes.rb', line 97

def indexes(*args)
  case args.length
  when 0
    if block_given?
      each_with_index.lazy.select {|el, i| yield(el)   }.map {|el, i| i }
    else
      each_with_index.lazy.                              map {|el, i| i }.to_enum
    end
  when 1
    other = args.first
    each_with_index.lazy.  select {|el, i| el == other }.map {|el, i| i }
  else
    raise ArgumentError, "wrong number of arguments (given #{args.length}, expected 0..1)"
  end
end

#squeeze(*limited_to) ⇒ Object

Enumerator::Lazy version of Enumerable#squeeze. Note: you must use Ruby 2.0+ or require ‘backports’. For now, you have to require ‘facets/enumerator/lazy/squeeze’ explicitly.

Examples

[1,2,2,3,3,2,1].lazy.squeeze.to_a #=> [1,2,3,2,1]
[1,2,2,3,3,2,1].lazy.squeeze(*[3]).to_a #=> [1,2,2,3,2,1]

Returns Enumerator::Lazy.

CREDIT: T. Yamada



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# File 'lib/core/facets/enumerator/lazy/squeeze.rb', line 18

def squeeze(*limited_to)
  first = true
  cur = nil
  self.class.new(self) do |y,v|
    if !limited_to.empty? && !limited_to.include?(v)
      y << v
    elsif first || cur != v
      y << v
      first = false
      cur = v
    end
  end
end