Skip to content
This repository
Fetching contributors…

Octocat-spinner-32-eaf2f5

Cannot retrieve contributors at this time

file 242 lines (202 sloc) 4.961 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241
#!/usr/bin/env ruby
#--
# $Idaemons: /home/cvs/rb/generator.rb,v 1.8 2001/10/03 08:54:32 knu Exp $
# $RoughId: generator.rb,v 1.10 2003/10/14 19:36:58 knu Exp $
# $Id: generator.rb 15954 2008-04-10 10:52:50Z knu $
#++
#
# = generator.rb: convert an internal iterator to an external one
#
# Copyright (c) 2001,2003 Akinori MUSHA <knu@iDaemons.org>
#
# All rights reserved. You can redistribute and/or modify it under
# the same terms as Ruby.
#
# == Overview
#
# This library provides the Generator class, which converts an
# internal iterator (i.e. an Enumerable object) to an external
# iterator. In that form, you can roll many iterators independently.
#
# The SyncEnumerator class, which is implemented using Generator,
# makes it easy to roll many Enumerable objects synchronously.
#
# See the respective classes for examples of usage.


#
# Generator converts an internal iterator (i.e. an Enumerable object)
# to an external iterator.
#
# Note that it is not very fast since it is implemented using
# continuations, which are currently slow.
#
# == Example
#
# require 'generator'
#
# # Generator from an Enumerable object
# g = Generator.new(['A', 'B', 'C', 'Z'])
#
# while g.next?
# puts g.next
# end
#
# # Generator from a block
# g = Generator.new { |g|
# for i in 'A'..'C'
# g.yield i
# end
#
# g.yield 'Z'
# }
#
# # The same result as above
# while g.next?
# puts g.next
# end
#
class Generator
  include Enumerable

  # Creates a new generator either from an Enumerable object or from a
  # block.
  #
  # In the former, block is ignored even if given.
  #
  # In the latter, the given block is called with the generator
  # itself, and expected to call the +yield+ method for each element.
  def initialize(enum=nil, &block)
    if enum
      @block = proc do |g|
        enum.each { |x| g.yield x }
      end
    else
      @block = block
    end

    @index = 0
    @queue = []

    @done = false

    @fiber = Rubinius::Fiber.new do
      @block.call(self)
      @done = true
      @fiber = nil
    end

    self
  end

  # Yields an element to the generator.
  def yield(value)
    # Running inside @fiber
    @queue << value
    Rubinius::Fiber.yield

    self
  end

  # Returns true if the generator has reached the end.
  def end?
    return true if @done
    return false unless @queue.empty?

    # Turn the loop over and see if we hit the end
    @fiber.resume

    return @done
  end

  # Returns true if the generator has not reached the end yet.
  def next?
    !end?
  end

  # Returns the current index (position) counting from zero.
  def index
    @index
  end

  # Returns the current index (position) counting from zero.
  def pos
    @index
  end

  # Returns the element at the current position and moves forward.
  def next
    raise EOFError, "end of iteration hit" if end?

    @fiber.resume if @queue.empty?

    # We've driven the fiber ahead and least once now, so we should
    # have values if there are values to be had

    unless @queue.empty?
      @index += 1
      return @queue.shift
    end

    raise EOFError, "end of iteration hit"
  end

  # Returns the element at the current position.
  def current
    if @queue.empty?
      raise EOFError, "no more elements available"
    end

    @queue.first
  end

  # Rewinds the generator.
  def rewind
    initialize(nil, &@block) if @index.nonzero?

    self
  end

  # Rewinds the generator and enumerates the elements.
  def each
    rewind

    until end?
      yield self.next
    end

    self
  end
end

#
# SyncEnumerator creates an Enumerable object from multiple Enumerable
# objects and enumerates them synchronously.
#
# == Example
#
# require 'generator'
#
# s = SyncEnumerator.new([1,2,3], ['a', 'b', 'c'])
#
# # Yields [1, 'a'], [2, 'b'], and [3,'c']
# s.each { |row| puts row.join(', ') }
#
class SyncEnumerator
  include Enumerable

  # Creates a new SyncEnumerator which enumerates rows of given
  # Enumerable objects.
  def initialize(*enums)
    @gens = enums.map { |e| Generator.new(e) }
  end

  # Returns the number of enumerated Enumerable objects, i.e. the size
  # of each row.
  def size
    @gens.size
  end

  # Returns the number of enumerated Enumerable objects, i.e. the size
  # of each row.
  def length
    @gens.length
  end

  # Returns true if the given nth Enumerable object has reached the
  # end. If no argument is given, returns true if any of the
  # Enumerable objects has reached the end.
  def end?(i = nil)
    if i.nil?
      @gens.detect { |g| g.end? } ? true : false
    else
      @gens[i].end?
    end
  end

  # Enumerates rows of the Enumerable objects.
  def each
    @gens.each { |g| g.rewind }

    while true
      count = 0

      ret = @gens.map { |g|
        if g.end?
          count += 1
          nil
        else
          g.next
        end
      }

      break if count == @gens.size

      yield ret
    end

    self
  end
end

Something went wrong with that request. Please try again.