Class: Enumerator::Lazy

Inherits:
Enumerator show all
Defined in:
lib/lazy_enumerator.rb,
lib/lazy_enumerator/version.rb

Constant Summary collapse

VERSION = 
"2.0.0"

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Lazy

Returns a new instance of Lazy.



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# File 'lib/lazy_enumerator.rb', line 5

def initialize(*)
  _block_error(:new) unless block_given?
  super
end

Instance Method Details

#collect ⇒ Object Also known as: map 



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# File 'lib/lazy_enumerator.rb', line 10

def collect()
  _block_error(:collect) unless block_given?
  Lazy.new do |output|
    each do |element|
      output.yield yield(element)
    end
  end
end

#cycle(n = nil, &block) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 20

def cycle(n = nil, &block)
  if block
    if n
      n.times do
        each {|*elt| block.call(*elt)}
      end
    else
      loop do
        each {|*elt| block.call(*elt)}
      end
    end
    nil
  else
    if n
      Lazy.new do |output|
        n.times do
          each do |elt|
            output.yield elt
          end
        end
      end
    else
      Lazy.new do |output|
        loop do
          each do |elt|
            output.yield elt
          end
        end
      end
    end
  end
end

#drop(n) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 53

def drop(n)
  Lazy.new do |output|
    each_with_index do |element, index|
      next if index < n
      output.yield(element)
    end
  end
end

#drop_while(&block) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 62

def drop_while(&block)
  _block_error(:collect) unless block
  Lazy.new do |output|
    each do |element|
      output.yield(element) unless yield(element)..true
    end
  end
end

#flat_map(&block) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 73

def flat_map(&block)
  _block_error(:collect) unless block
  Lazy.new do |output|
    each do |element|
      result = yield element
      if result.is_a? Array
        ary = result
      elsif result.respond_to?(:force) && result.respond_to?(:each)
        lazy = result
      else
        ary = result.to_ary if result.respond_to?(:to_ary)
      end


      if ary
        # if it's an array or coerced to an array, iterate directly
        i, max = 0, ary.size
        while i < max
          output.yield ary.at(i)
          i+=1
        end
      elsif lazy
        # if it's lazy, each over it
        lazy.each {|value| output.yield value}
      else
        # otherwise just yield it
        output.yield(result)
      end
    end
  end
end

#grep(pattern, &block) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 105

def grep(pattern, &block)
  if block_given?
    Lazy.new do |output|
      each do |element|
        output.yield(yield element) if pattern === element
      end
    end
  else
    Lazy.new do |output|
      each do |element|
        output.yield(element) if pattern === element
      end
    end
  end
end

#lazy ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 120

def lazy
  self
end

#reject(&block) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 124

def reject(&block)
  _block_error(:collect) unless block
  Lazy.new do |output|
    each do |element|
      output.yield(element) unless yield(element)
    end
  end
end

#select(&block) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 133

def select(&block)
  _block_error(:collect) unless block
  Lazy.new do |output|
    each do |element|
      output.yield(element) if yield(element)
    end
  end
end

#slice_before(pattern) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 142

def slice_before(pattern)
  Lazy.new do |output|
    slice = []
    catch(output) do
      each do |element|
        if pattern === element
          slice << element
        else
          throw output
        end
      end
    end
    output.yield slice
  end
end

#take(n) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 158

def take(n)
  Lazy.new do |output|
    if n > 0
      catch(output) do
        each_with_index do |element, index|
          output.yield(element)
          # break failed to work for some reason
          throw output if index + 1 == n
        end
      end
    end
  end
end

#take_while(&block) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 183

def take_while(&block)
  _block_error(:collect) unless block
  Lazy.new do |output|
    catch(output) do
      each do |element|
        # break failed to work for some reason
        throw output unless yield(element)
        output.yield(element)
      end
    end
  end
end

#to_enum(name = nil, *args) ⇒ Object Also known as: enum_for 



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# File 'lib/lazy_enumerator.rb', line 172

def to_enum(name = nil, *args)
  if name
    Lazy.new do |yielder|
      send(name, *args) {|element| yielder.yield(element)}
    end
  else
    self
  end
end

#zip(*enumerables, &block) ⇒ Object 



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# File 'lib/lazy_enumerator.rb', line 196

def zip(*enumerables, &block)
  if block
    return super
  end
  
  all_arrays = true
  enumerators = enumerables.map do |enumerable|
    if enumerable.kind_of? Array
      next enumerable
    elsif enumerable.respond_to?(:to_ary)
      enumerator = enumerable.to_ary
      
      next enumerator unless enumerator.nil?
    end
    
    all_arrays = false
    next enumerable if enumerable.respond_to?(:each)
    
    raise TypeError, "wront argument type #{enumerable.class.name} (must respond to :each)"
  end
  
  if all_arrays
    Lazy.new do |output|
      each_with_index do |element, index|
        ary = [element]
        enumerators.each {|array| ary << array[index] if index < array.size}
        output.yield ary
      end
    end
  else
    Lazy.new do |output|
      enumerators = enumerators.map(&:to_enum)
      each do |element|
        ary = [element]
        enumerators.each {|enumerator| ary << (enumerator.next rescue nil)}
        output.yield ary
      end
    end
  end
end